Farnell PDF Keyboard, Mouse and Cable Bundles for the Raspberry Pi - Farnell Element 14

Keyboard, Mouse and Cable Bundles for the Raspberry Pi - Farnell Element 14 - Revenir à l'accueil

 

 

Branding Farnell element14 (France)

 

Farnell Element 14 :

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Everything You Need To Know About Arduino

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Tutorial 01 for Arduino: Getting Acquainted with Arduino

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The Cube® 3D Printer

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What's easier- DIY Dentistry or our new our website features?

 

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Ben Heck's Getting Started with the BeagleBone Black Trailer

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Ben Heck's Home-Brew Solder Reflow Oven 2.0 Trailer

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Get Started with Pi Episode 3 - Online with Raspberry Pi

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Discover Simulink Promo -- Exclusive element14 Webinar

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Ben Heck's TV Proximity Sensor Trailer

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Ben Heck's PlayStation 4 Teardown Trailer

See the trailer for the next exciting episode of The Ben Heck show. Check back on Friday to be among the first to see the exclusive full show on element…

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Get Started with Pi Episode 4 - Your First Raspberry Pi Project

Connect your Raspberry Pi to a breadboard, download some code and create a push-button audio play project.

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Ben Heck Anti-Pickpocket Wallet Trailer

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Molex Earphones - The 14 Holiday Products of Newark element14 Promotion

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Tripp Lite Surge Protector - The 14 Holiday Products of Newark element14 Promotion

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Microchip ChipKIT Pi - The 14 Holiday Products of Newark element14 Promotion

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Beagle Bone Black - The 14 Holiday Products of Newark element14 Promotion

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3M E26, LED Lamps - The 14 Holiday Products of Newark element14 Promotion

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3M Colored Duct Tape - The 14 Holiday Products of Newark element14 Promotion

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Tenma Soldering Station - The 14 Holiday Products of Newark element14 Promotion

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Duratool Screwdriver Kit - The 14 Holiday Products of Newark element14 Promotion

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Cubify 3D Cube - The 14 Holiday Products of Newark element14 Promotion

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Bud Boardganizer - The 14 Holiday Products of Newark element14 Promotion

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Raspberry Pi Starter Kit - The 14 Holiday Products of Newark element14 Promotion

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Fluke 323 True-rms Clamp Meter - The 14 Holiday Products of Newark element14 Promotion

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Dymo RHINO 6000 Label Printer - The 14 Holiday Products of Newark element14 Promotion

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3M LED Advanced Lights A-19 - The 14 Holiday Products of Newark element14 Promotion

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Innovative LPS Resistor Features Very High Power Dissipation

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Charge Injection Evaluation Board for DG508B Multiplexer Demo

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Ben Heck The Great Glue Gun Trailer Part 2

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Introducing element14 TV

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Ben Heck Time to Meet Your Maker Trailer

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Détecteur de composants

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Recherche intégrée

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Ben Builds an Accessibility Guitar Trailer Part 1

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Ben Builds an Accessibility Guitar - Part 2 Trailer

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PiFace Control and Display Introduction

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Flashmob Farnell

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Express Yourself in 3D with Cube 3D Printers from Newark element14

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Farnell YouTube Channel Move

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Farnell: Design with the best

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French Farnell Quest

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Altera - 3 Ways to Quickly Adapt to Changing Ethernet Protocols

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Cy-Net3 Network Module

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MC AT - Professional and Precision Series Thin Film Chip Resistors

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Solderless LED Connector

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PSA-T Series Spectrum Analyser: PSA1301T/ PSA2701T

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3-axis Universal Motion Controller For Stepper Motor Drivers: TMC429

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Voltage Level Translation

Puce électronique / Microchip :

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Microchip - 8-bit Wireless Development Kit

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Microchip - Introduction to mTouch Capacitive Touch Sensing Part 2 of 3

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Microchip - Introduction to mTouch Capacitive Touch Sensing Part 3 of 3

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Microchip - Introduction to mTouch Capacitive Touch Sensing Part 1 of 3

Sans fil - Wireless :

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Microchip - 8-bit Wireless Development Kit

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Wireless Power Solutions - Wurth Electronics, Texas Instruments, CadSoft and element14

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Analog Devices - Remote Water Quality Monitoring via a Low Power, Wireless Network

Texas instrument :

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Texas Instruments - Automotive LED Headlights

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Texas Instruments - Digital Power Solutions

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Texas Instruments - Industrial Sensor Solutions

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Texas Instruments - Wireless Pen Input Demo (Mobile World Congress)

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Texas Instruments - Industrial Automation System Components

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Texas Instruments - TMS320C66x - Industry's first 10-GHz fixed/floating point DSP

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Texas Instruments - TMS320C66x KeyStone Multicore Architecture

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Texas Instruments - Industrial Interfaces

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Texas Instruments - Concerto™ MCUs - Connectivity without compromise

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Texas Instruments - Stellaris Robot Chronos

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Texas Instruments - DRV8412-C2-KIT, Brushed DC and Stepper Motor Control Kit

Ordinateurs :

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Ask Ben Heck - Connect Raspberry Pi to Car Computer

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Ben's Portable Raspberry Pi Computer Trailer

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Ben's Raspberry Pi Portable Computer Trailer 2

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Ben Heck's Pocket Computer Trailer

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Ask Ben Heck - Atari Computer

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Ask Ben Heck - Using Computer Monitors for External Displays

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Raspberry Pi Partnership with BBC Computer Literacy Project - Answers from co-founder Eben Upton

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Installing RaspBMC on your Raspberry Pi with the Farnell element14 Accessory kit

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Raspberry Pi Served - Joey Hudy

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Happy Birthday Raspberry Pi

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Raspberry Pi board B product overview

Logiciels :

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Ask Ben Heck - Best Opensource or Free CAD Software

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Tektronix FPGAView™ software makes debugging of FPGAs faster than ever!

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Ask Ben Heck - Best Open-Source Schematic Capture and PCB Layout Software

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Introduction to Cadsoft EAGLE PCB Design Software in Chinese

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Altera - Developing Software for Embedded Systems on FPGAs

Tutoriels :

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Ben Heck The Great Glue Gun Trailer Part 1

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the knode tutorial - element14

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Ben's Autodesk 123D Tutorial Trailer

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Ben's CadSoft EAGLE Tutorial Trailer

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Ben Heck's Soldering Tutorial Trailer

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Ben Heck's AVR Dev Board tutorial

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Ben Heck's Pinball Tutorial Trailer

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Ben Heck's Interface Tutorial Trailer

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First Stage with Python and PiFace Digital

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Cypress - Getting Started with PSoC® 3 - Part 2

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Energy Harvesting Challenge

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New Features of CadSoft EAGLE v6

Autres documentations :

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Keyboard, Mouse and Cable Bundles for the Raspberry Pi Kit Contents: HDMI Bundle DVI Bundle RPI-CABLE+ACC/HDMI RPI-CABLE+ACC/DVI Mini QWERTY Keyboard Optical USB Mouse 3.5mm Stereo Jack Plug Cable – 2m Stereo Phono (RCA) to 3.5mm Stereo Jack Plug Cable – 1.8m Cat5e Patch Cable, RJ45 Plug to RJ45 Plug – 3m High Speed HDMI Cable – 2m HDMI to DVI Cable – 2m LM3S6952 Microcontroller DATA SHEET DS-LM3S6952-1972 Copyright © 2007 Luminary Micro, Inc. PRELIMINARY Legal Disclaimers and Trademark Information INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH LUMINARY MICRO PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN LUMINARY MICRO'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, LUMINARY MICRO ASSUMES NO LIABILITY WHATSOEVER, AND LUMINARY MICRO DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF LUMINARY MICRO'S PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LUMINARY MICRO'S PRODUCTS ARE NOT INTENDED FOR USE IN MEDICAL, LIFE SAVING, OR LIFE-SUSTAINING APPLICATIONS. Luminary Micro may make changes to specifications and product descriptions at any time, without notice. Contact your local Luminary Micro sales office or your distributor to obtain the latest specifications before placing your product order. Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Luminary Micro reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them. Copyright © 2007 Luminary Micro, Inc. All rights reserved. Stellaris, Luminary Micro, and the Luminary Micro logo are registered trademarks of Luminary Micro, Inc. or its subsidiaries in the United States and other countries. ARM and Thumb are registered trademarks and Cortex is a trademark of ARM Limited. Other names and brands may be claimed as the property of others. Luminary Micro, Inc. 108 Wild Basin, Suite 350 Austin, TX 78746 Main: +1-512-279-8800 Fax: +1-512-279-8879 http://www.luminarymicro.com 2 November 30, 2007 Preliminary Table of Contents About This Document .................................................................................................................... 20 Audience .............................................................................................................................................. 20 About This Manual ................................................................................................................................ 20 Related Documents ............................................................................................................................... 20 Documentation Conventions .................................................................................................................. 20 1 Architectural Overview ...................................................................................................... 22 1.1 Product Features ...................................................................................................................... 22 1.2 Target Applications .................................................................................................................... 28 1.3 High-Level Block Diagram ......................................................................................................... 29 1.4 Functional Overview .................................................................................................................. 29 1.4.1 ARM Cortex™-M3 ..................................................................................................................... 30 1.4.2 Motor Control Peripherals .......................................................................................................... 30 1.4.3 Analog Peripherals .................................................................................................................... 31 1.4.4 Serial Communications Peripherals ............................................................................................ 32 1.4.5 System Peripherals ................................................................................................................... 33 1.4.6 Memory Peripherals .................................................................................................................. 34 1.4.7 Additional Features ................................................................................................................... 35 1.4.8 Hardware Details ...................................................................................................................... 35 2 ARM Cortex-M3 Processor Core ...................................................................................... 37 2.1 Block Diagram .......................................................................................................................... 38 2.2 Functional Description ............................................................................................................... 38 2.2.1 Serial Wire and JTAG Debug ..................................................................................................... 38 2.2.2 Embedded Trace Macrocell (ETM) ............................................................................................. 39 2.2.3 Trace Port Interface Unit (TPIU) ................................................................................................. 39 2.2.4 ROM Table ............................................................................................................................... 39 2.2.5 Memory Protection Unit (MPU) ................................................................................................... 39 2.2.6 Nested Vectored Interrupt Controller (NVIC) ................................................................................ 39 3 Memory Map ....................................................................................................................... 43 4 Interrupts ............................................................................................................................ 45 5 JTAG Interface .................................................................................................................... 48 5.1 Block Diagram .......................................................................................................................... 49 5.2 Functional Description ............................................................................................................... 49 5.2.1 JTAG Interface Pins .................................................................................................................. 50 5.2.2 JTAG TAP Controller ................................................................................................................. 51 5.2.3 Shift Registers .......................................................................................................................... 52 5.2.4 Operational Considerations ........................................................................................................ 52 5.3 Initialization and Configuration ................................................................................................... 55 5.4 Register Descriptions ................................................................................................................ 55 5.4.1 Instruction Register (IR) ............................................................................................................. 55 5.4.2 Data Registers .......................................................................................................................... 57 6 System Control ................................................................................................................... 59 6.1 Functional Description ............................................................................................................... 59 6.1.1 Device Identification .................................................................................................................. 59 6.1.2 Reset Control ............................................................................................................................ 59 November 30, 2007 3 Preliminary LM3S6952 Microcontroller 6.1.3 Power Control ........................................................................................................................... 62 6.1.4 Clock Control ............................................................................................................................ 62 6.1.5 System Control ......................................................................................................................... 64 6.2 Initialization and Configuration ................................................................................................... 65 6.3 Register Map ............................................................................................................................ 65 6.4 Register Descriptions ................................................................................................................ 66 7 Hibernation Module .......................................................................................................... 120 7.1 Block Diagram ........................................................................................................................ 121 7.2 Functional Description ............................................................................................................. 121 7.2.1 Register Access Timing ........................................................................................................... 121 7.2.2 Clock Source .......................................................................................................................... 122 7.2.3 Battery Management ............................................................................................................... 122 7.2.4 Real-Time Clock ...................................................................................................................... 122 7.2.5 Non-Volatile Memory ............................................................................................................... 123 7.2.6 Power Control ......................................................................................................................... 123 7.2.7 Interrupts and Status ............................................................................................................... 123 7.3 Initialization and Configuration ................................................................................................. 124 7.3.1 Initialization ............................................................................................................................. 124 7.3.2 RTC Match Functionality (No Hibernation) ................................................................................ 124 7.3.3 RTC Match/Wake-Up from Hibernation ..................................................................................... 124 7.3.4 External Wake-Up from Hibernation .......................................................................................... 125 7.3.5 RTC/External Wake-Up from Hibernation .................................................................................. 125 7.4 Register Map .......................................................................................................................... 125 7.5 Register Descriptions .............................................................................................................. 126 8 Internal Memory ............................................................................................................... 139 8.1 Block Diagram ........................................................................................................................ 139 8.2 Functional Description ............................................................................................................. 139 8.2.1 SRAM Memory ........................................................................................................................ 139 8.2.2 Flash Memory ......................................................................................................................... 140 8.3 Flash Memory Initialization and Configuration ........................................................................... 141 8.3.1 Flash Programming ................................................................................................................. 141 8.3.2 Nonvolatile Register Programming ........................................................................................... 142 8.4 Register Map .......................................................................................................................... 142 8.5 Flash Register Descriptions (Flash Control Offset) ..................................................................... 143 8.6 Flash Register Descriptions (System Control Offset) .................................................................. 150 9 General-Purpose Input/Outputs (GPIOs) ....................................................................... 163 9.1 Functional Description ............................................................................................................. 163 9.1.1 Data Control ........................................................................................................................... 164 9.1.2 Interrupt Control ...................................................................................................................... 165 9.1.3 Mode Control .......................................................................................................................... 166 9.1.4 Commit Control ....................................................................................................................... 166 9.1.5 Pad Control ............................................................................................................................. 166 9.1.6 Identification ........................................................................................................................... 166 9.2 Initialization and Configuration ................................................................................................. 166 9.3 Register Map .......................................................................................................................... 168 9.4 Register Descriptions .............................................................................................................. 169 4 November 30, 2007 Preliminary Table of Contents 10 General-Purpose Timers ................................................................................................. 204 10.1 Block Diagram ........................................................................................................................ 204 10.2 Functional Description ............................................................................................................. 205 10.2.1 GPTM Reset Conditions .......................................................................................................... 205 10.2.2 32-Bit Timer Operating Modes .................................................................................................. 206 10.2.3 16-Bit Timer Operating Modes .................................................................................................. 207 10.3 Initialization and Configuration ................................................................................................. 211 10.3.1 32-Bit One-Shot/Periodic Timer Mode ....................................................................................... 211 10.3.2 32-Bit Real-Time Clock (RTC) Mode ......................................................................................... 212 10.3.3 16-Bit One-Shot/Periodic Timer Mode ....................................................................................... 212 10.3.4 16-Bit Input Edge Count Mode ................................................................................................. 213 10.3.5 16-Bit Input Edge Timing Mode ................................................................................................ 213 10.3.6 16-Bit PWM Mode ................................................................................................................... 214 10.4 Register Map .......................................................................................................................... 214 10.5 Register Descriptions .............................................................................................................. 215 11 Watchdog Timer ............................................................................................................... 240 11.1 Block Diagram ........................................................................................................................ 240 11.2 Functional Description ............................................................................................................. 240 11.3 Initialization and Configuration ................................................................................................. 241 11.4 Register Map .......................................................................................................................... 241 11.5 Register Descriptions .............................................................................................................. 242 12 Analog-to-Digital Converter (ADC) ................................................................................. 263 12.1 Block Diagram ........................................................................................................................ 264 12.2 Functional Description ............................................................................................................. 264 12.2.1 Sample Sequencers ................................................................................................................ 264 12.2.2 Module Control ........................................................................................................................ 265 12.2.3 Hardware Sample Averaging Circuit ......................................................................................... 266 12.2.4 Analog-to-Digital Converter ...................................................................................................... 266 12.2.5 Test Modes ............................................................................................................................. 266 12.2.6 Internal Temperature Sensor .................................................................................................... 266 12.3 Initialization and Configuration ................................................................................................. 267 12.3.1 Module Initialization ................................................................................................................. 267 12.3.2 Sample Sequencer Configuration ............................................................................................. 267 12.4 Register Map .......................................................................................................................... 268 12.5 Register Descriptions .............................................................................................................. 269 13 Universal Asynchronous Receivers/Transmitters (UARTs) ......................................... 296 13.1 Block Diagram ........................................................................................................................ 297 13.2 Functional Description ............................................................................................................. 297 13.2.1 Transmit/Receive Logic ........................................................................................................... 297 13.2.2 Baud-Rate Generation ............................................................................................................. 298 13.2.3 Data Transmission .................................................................................................................. 299 13.2.4 Serial IR (SIR) ......................................................................................................................... 299 13.2.5 FIFO Operation ....................................................................................................................... 300 13.2.6 Interrupts ................................................................................................................................ 300 13.2.7 Loopback Operation ................................................................................................................ 301 13.2.8 IrDA SIR block ........................................................................................................................ 301 13.3 Initialization and Configuration ................................................................................................. 301 13.4 Register Map .......................................................................................................................... 302 November 30, 2007 5 Preliminary LM3S6952 Microcontroller 13.5 Register Descriptions .............................................................................................................. 303 14 Synchronous Serial Interface (SSI) ................................................................................ 337 14.1 Block Diagram ........................................................................................................................ 337 14.2 Functional Description ............................................................................................................. 337 14.2.1 Bit Rate Generation ................................................................................................................. 338 14.2.2 FIFO Operation ....................................................................................................................... 338 14.2.3 Interrupts ................................................................................................................................ 338 14.2.4 Frame Formats ....................................................................................................................... 339 14.3 Initialization and Configuration ................................................................................................. 346 14.4 Register Map .......................................................................................................................... 347 14.5 Register Descriptions .............................................................................................................. 348 15 Inter-Integrated Circuit (I2C) Interface ............................................................................ 374 15.1 Block Diagram ........................................................................................................................ 374 15.2 Functional Description ............................................................................................................. 374 15.2.1 I2C Bus Functional Overview .................................................................................................... 375 15.2.2 Available Speed Modes ........................................................................................................... 377 15.2.3 Interrupts ................................................................................................................................ 378 15.2.4 Loopback Operation ................................................................................................................ 378 15.2.5 Command Sequence Flow Charts ............................................................................................ 379 15.3 Initialization and Configuration ................................................................................................. 385 15.4 I2C Register Map ..................................................................................................................... 386 15.5 Register Descriptions (I2C Master) ........................................................................................... 387 15.6 Register Descriptions (I2C Slave) ............................................................................................. 400 16 Ethernet Controller .......................................................................................................... 409 16.1 Block Diagram ........................................................................................................................ 410 16.2 Functional Description ............................................................................................................. 410 16.2.1 Internal MII Operation .............................................................................................................. 410 16.2.2 PHY Configuration/Operation ................................................................................................... 411 16.2.3 MAC Configuration/Operation .................................................................................................. 412 16.2.4 Interrupts ................................................................................................................................ 414 16.3 Initialization and Configuration ................................................................................................. 415 16.4 Ethernet Register Map ............................................................................................................. 415 16.5 Ethernet MAC Register Descriptions ......................................................................................... 417 16.6 MII Management Register Descriptions ..................................................................................... 434 17 Analog Comparators ....................................................................................................... 453 17.1 Block Diagram ........................................................................................................................ 454 17.2 Functional Description ............................................................................................................. 454 17.2.1 Internal Reference Programming .............................................................................................. 456 17.3 Initialization and Configuration ................................................................................................. 457 17.4 Register Map .......................................................................................................................... 457 17.5 Register Descriptions .............................................................................................................. 458 18 Pulse Width Modulator (PWM) ........................................................................................ 466 18.1 Block Diagram ........................................................................................................................ 466 18.2 Functional Description ............................................................................................................. 466 18.2.1 PWM Timer ............................................................................................................................. 466 18.2.2 PWM Comparators .................................................................................................................. 467 18.2.3 PWM Signal Generator ............................................................................................................ 468 6 November 30, 2007 Preliminary Table of Contents 18.2.4 Dead-Band Generator ............................................................................................................. 469 18.2.5 Interrupt/ADC-Trigger Selector ................................................................................................. 469 18.2.6 Synchronization Methods ......................................................................................................... 469 18.2.7 Fault Conditions ...................................................................................................................... 470 18.2.8 Output Control Block ............................................................................................................... 470 18.3 Initialization and Configuration ................................................................................................. 470 18.4 Register Map .......................................................................................................................... 471 18.5 Register Descriptions .............................................................................................................. 472 19 Quadrature Encoder Interface (QEI) ............................................................................... 501 19.1 Block Diagram ........................................................................................................................ 501 19.2 Functional Description ............................................................................................................. 502 19.3 Initialization and Configuration ................................................................................................. 504 19.4 Register Map .......................................................................................................................... 504 19.5 Register Descriptions .............................................................................................................. 505 20 Pin Diagram ...................................................................................................................... 518 21 Signal Tables .................................................................................................................... 519 22 Operating Characteristics ............................................................................................... 533 23 Electrical Characteristics ................................................................................................ 534 23.1 DC Characteristics .................................................................................................................. 534 23.1.1 Maximum Ratings ................................................................................................................... 534 23.1.2 Recommended DC Operating Conditions .................................................................................. 534 23.1.3 On-Chip Low Drop-Out (LDO) Regulator Characteristics ............................................................ 535 23.1.4 Power Specifications ............................................................................................................... 535 23.1.5 Flash Memory Characteristics .................................................................................................. 537 23.2 AC Characteristics ................................................................................................................... 537 23.2.1 Load Conditions ...................................................................................................................... 537 23.2.2 Clocks .................................................................................................................................... 537 23.2.3 Analog-to-Digital Converter ...................................................................................................... 538 23.2.4 Analog Comparator ................................................................................................................. 539 23.2.5 I2C ......................................................................................................................................... 539 23.2.6 Ethernet Controller .................................................................................................................. 540 23.2.7 Hibernation Module ................................................................................................................. 543 23.2.8 Synchronous Serial Interface (SSI) ........................................................................................... 543 23.2.9 JTAG and Boundary Scan ........................................................................................................ 545 23.2.10 General-Purpose I/O ............................................................................................................... 546 23.2.11 Reset ..................................................................................................................................... 547 24 Package Information ........................................................................................................ 549 A Serial Flash Loader .......................................................................................................... 551 A.1 Serial Flash Loader ................................................................................................................. 551 A.2 Interfaces ............................................................................................................................... 551 A.2.1 UART ..................................................................................................................................... 551 A.2.2 SSI ......................................................................................................................................... 551 A.3 Packet Handling ...................................................................................................................... 552 A.3.1 Packet Format ........................................................................................................................ 552 A.3.2 Sending Packets ..................................................................................................................... 552 A.3.3 Receiving Packets ................................................................................................................... 552 November 30, 2007 7 Preliminary LM3S6952 Microcontroller A.4 Commands ............................................................................................................................. 553 A.4.1 COMMAND_PING (0X20) ........................................................................................................ 553 A.4.2 COMMAND_GET_STATUS (0x23) ........................................................................................... 553 A.4.3 COMMAND_DOWNLOAD (0x21) ............................................................................................. 553 A.4.4 COMMAND_SEND_DATA (0x24) ............................................................................................. 554 A.4.5 COMMAND_RUN (0x22) ......................................................................................................... 554 A.4.6 COMMAND_RESET (0x25) ..................................................................................................... 554 B Register Quick Reference ............................................................................................... 556 C Ordering and Contact Information ................................................................................. 575 C.1 Ordering Information ................................................................................................................ 575 C.2 Kits ......................................................................................................................................... 575 C.3 Company Information .............................................................................................................. 575 C.4 Support Information ................................................................................................................. 576 8 November 30, 2007 Preliminary Table of Contents List of Figures Figure 1-1. Stellaris® 6000 Series High-Level Block Diagram ............................................................... 29 Figure 2-1. CPU Block Diagram ......................................................................................................... 38 Figure 2-2. TPIU Block Diagram ........................................................................................................ 39 Figure 5-1. JTAG Module Block Diagram ............................................................................................ 49 Figure 5-2. Test Access Port State Machine ....................................................................................... 52 Figure 5-3. IDCODE Register Format ................................................................................................. 57 Figure 5-4. BYPASS Register Format ................................................................................................ 58 Figure 5-5. Boundary Scan Register Format ....................................................................................... 58 Figure 6-1. External Circuitry to Extend Reset .................................................................................... 60 Figure 7-1. Hibernation Module Block Diagram ................................................................................. 121 Figure 8-1. Flash Block Diagram ...................................................................................................... 139 Figure 9-1. GPIO Port Block Diagram ............................................................................................... 164 Figure 9-2. GPIODATA Write Example ............................................................................................. 165 Figure 9-3. GPIODATA Read Example ............................................................................................. 165 Figure 10-1. GPTM Module Block Diagram ........................................................................................ 205 Figure 10-2. 16-Bit Input Edge Count Mode Example .......................................................................... 209 Figure 10-3. 16-Bit Input Edge Time Mode Example ........................................................................... 210 Figure 10-4. 16-Bit PWM Mode Example ............................................................................................ 211 Figure 11-1. WDT Module Block Diagram .......................................................................................... 240 Figure 12-1. ADC Module Block Diagram ........................................................................................... 264 Figure 12-2. Internal Temperature Sensor Characteristic ..................................................................... 267 Figure 13-1. UART Module Block Diagram ......................................................................................... 297 Figure 13-2. UART Character Frame ................................................................................................. 298 Figure 13-3. IrDA Data Modulation ..................................................................................................... 300 Figure 14-1. SSI Module Block Diagram ............................................................................................. 337 Figure 14-2. TI Synchronous Serial Frame Format (Single Transfer) .................................................... 339 Figure 14-3. TI Synchronous Serial Frame Format (Continuous Transfer) ............................................ 340 Figure 14-4. Freescale SPI Format (Single Transfer) with SPO=0 and SPH=0 ...................................... 341 Figure 14-5. Freescale SPI Format (Continuous Transfer) with SPO=0 and SPH=0 .............................. 341 Figure 14-6. Freescale SPI Frame Format with SPO=0 and SPH=1 ..................................................... 342 Figure 14-7. Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0 ........................... 343 Figure 14-8. Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0 .................... 343 Figure 14-9. Freescale SPI Frame Format with SPO=1 and SPH=1 ..................................................... 344 Figure 14-10. MICROWIRE Frame Format (Single Frame) .................................................................... 345 Figure 14-11. MICROWIRE Frame Format (Continuous Transfer) ......................................................... 346 Figure 14-12. MICROWIRE Frame Format, SSIFss Input Setup and Hold Requirements ........................ 346 Figure 15-1. I2C Block Diagram ......................................................................................................... 374 Figure 15-2. I2C Bus Configuration .................................................................................................... 375 Figure 15-3. START and STOP Conditions ......................................................................................... 375 Figure 15-4. Complete Data Transfer with a 7-Bit Address ................................................................... 376 Figure 15-5. R/S Bit in First Byte ........................................................................................................ 376 Figure 15-6. Data Validity During Bit Transfer on the I2C Bus ............................................................... 376 Figure 15-7. Master Single SEND ...................................................................................................... 379 Figure 15-8. Master Single RECEIVE ................................................................................................. 380 Figure 15-9. Master Burst SEND ....................................................................................................... 381 November 30, 2007 9 Preliminary LM3S6952 Microcontroller Figure 15-10. Master Burst RECEIVE .................................................................................................. 382 Figure 15-11. Master Burst RECEIVE after Burst SEND ........................................................................ 383 Figure 15-12. Master Burst SEND after Burst RECEIVE ........................................................................ 384 Figure 15-13. Slave Command Sequence ............................................................................................ 385 Figure 16-1. Ethernet Controller Block Diagram .................................................................................. 410 Figure 16-2. Ethernet Controller ......................................................................................................... 410 Figure 16-3. Ethernet Frame ............................................................................................................. 412 Figure 17-1. Analog Comparator Module Block Diagram ..................................................................... 454 Figure 17-2. Structure of Comparator Unit .......................................................................................... 455 Figure 17-3. Comparator Internal Reference Structure ........................................................................ 456 Figure 18-1. PWM Module Block Diagram .......................................................................................... 466 Figure 18-2. PWM Count-Down Mode ................................................................................................ 467 Figure 18-3. PWM Count-Up/Down Mode .......................................................................................... 468 Figure 18-4. PWM Generation Example In Count-Up/Down Mode ....................................................... 468 Figure 18-5. PWM Dead-Band Generator ........................................................................................... 469 Figure 19-1. QEI Block Diagram ........................................................................................................ 501 Figure 19-2. Quadrature Encoder and Velocity Predivider Operation .................................................... 503 Figure 20-1. Pin Connection Diagram ................................................................................................ 518 Figure 23-1. Load Conditions ............................................................................................................ 537 Figure 23-2. I2C Timing ..................................................................................................................... 540 Figure 23-3. External XTLP Oscillator Characteristics ......................................................................... 542 Figure 23-4. Hibernation Module Timing ............................................................................................. 543 Figure 23-5. SSI Timing for TI Frame Format (FRF=01), Single Transfer Timing Measurement .............. 544 Figure 23-6. SSI Timing for MICROWIRE Frame Format (FRF=10), Single Transfer ............................. 544 Figure 23-7. SSI Timing for SPI Frame Format (FRF=00), with SPH=1 ................................................. 545 Figure 23-8. JTAG Test Clock Input Timing ......................................................................................... 546 Figure 23-9. JTAG Test Access Port (TAP) Timing .............................................................................. 546 Figure 23-10. JTAG TRST Timing ........................................................................................................ 546 Figure 23-11. External Reset Timing (RST) .......................................................................................... 547 Figure 23-12. Power-On Reset Timing ................................................................................................. 548 Figure 23-13. Brown-Out Reset Timing ................................................................................................ 548 Figure 23-14. Software Reset Timing ................................................................................................... 548 Figure 23-15. Watchdog Reset Timing ................................................................................................. 548 Figure 24-1. 100-Pin LQFP Package .................................................................................................. 549 10 November 30, 2007 Preliminary Table of Contents List of Tables Table 1. Documentation Conventions ............................................................................................ 20 Table 3-1. Memory Map ................................................................................................................... 43 Table 4-1. Exception Types .............................................................................................................. 45 Table 4-2. Interrupts ........................................................................................................................ 46 Table 5-1. JTAG Port Pins Reset State ............................................................................................. 50 Table 5-2. JTAG Instruction Register Commands ............................................................................... 55 Table 6-1. System Control Register Map ........................................................................................... 65 Table 7-1. Hibernation Module Register Map ................................................................................... 125 Table 8-1. Flash Protection Policy Combinations ............................................................................. 141 Table 8-2. Flash Resident Registers ............................................................................................... 142 Table 8-3. Flash Register Map ........................................................................................................ 142 Table 9-1. GPIO Pad Configuration Examples ................................................................................. 167 Table 9-2. GPIO Interrupt Configuration Example ............................................................................ 167 Table 9-3. GPIO Register Map ....................................................................................................... 168 Table 10-1. Available CCP Pins ........................................................................................................ 205 Table 10-2. 16-Bit Timer With Prescaler Configurations ..................................................................... 208 Table 10-3. Timers Register Map ...................................................................................................... 214 Table 11-1. Watchdog Timer Register Map ........................................................................................ 241 Table 12-1. Samples and FIFO Depth of Sequencers ........................................................................ 264 Table 12-2. ADC Register Map ......................................................................................................... 268 Table 13-1. UART Register Map ....................................................................................................... 302 Table 14-1. SSI Register Map .......................................................................................................... 347 Table 15-1. Examples of I2C Master Timer Period versus Speed Mode ............................................... 377 Table 15-2. Inter-Integrated Circuit (I2C) Interface Register Map ......................................................... 386 Table 15-3. Write Field Decoding for I2CMCS[3:0] Field (Sheet 1 of 3) ................................................ 391 Table 16-1. TX & RX FIFO Organization ........................................................................................... 413 Table 16-2. Ethernet Register Map ................................................................................................... 416 Table 17-1. Comparator 0 Operating Modes ..................................................................................... 455 Table 17-2. Comparator 1 Operating Modes ..................................................................................... 455 Table 17-3. Comparator 2 Operating Modes ...................................................................................... 456 Table 17-4. Internal Reference Voltage and ACREFCTL Field Values ................................................. 456 Table 17-5. Analog Comparators Register Map ................................................................................. 458 Table 18-1. PWM Register Map ........................................................................................................ 471 Table 19-1. QEI Register Map .......................................................................................................... 504 Table 21-1. Signals by Pin Number ................................................................................................... 519 Table 21-2. Signals by Signal Name ................................................................................................. 523 Table 21-3. Signals by Function, Except for GPIO ............................................................................. 527 Table 21-4. GPIO Pins and Alternate Functions ................................................................................. 531 Table 22-1. Temperature Characteristics ........................................................................................... 533 Table 22-2. Thermal Characteristics ................................................................................................. 533 Table 23-1. Maximum Ratings .......................................................................................................... 534 Table 23-2. Recommended DC Operating Conditions ........................................................................ 534 Table 23-3. LDO Regulator Characteristics ....................................................................................... 535 Table 23-4. Detailed Power Specifications ........................................................................................ 536 Table 23-5. Flash Memory Characteristics ........................................................................................ 537 Table 23-6. Phase Locked Loop (PLL) Characteristics ....................................................................... 537 November 30, 2007 11 Preliminary LM3S6952 Microcontroller Table 23-7. Clock Characteristics ..................................................................................................... 537 Table 23-8. Crystal Characteristics ................................................................................................... 538 Table 23-9. ADC Characteristics ....................................................................................................... 538 Table 23-10. Analog Comparator Characteristics ................................................................................. 539 Table 23-11. Analog Comparator Voltage Reference Characteristics .................................................... 539 Table 23-12. I2C Characteristics ......................................................................................................... 539 Table 23-13. 100BASE-TX Transmitter Characteristics ........................................................................ 540 Table 23-14. 100BASE-TX Transmitter Characteristics (informative) ..................................................... 540 Table 23-15. 100BASE-TX Receiver Characteristics ............................................................................ 540 Table 23-16. 10BASE-T Transmitter Characteristics ............................................................................ 540 Table 23-17. 10BASE-T Transmitter Characteristics (informative) ......................................................... 541 Table 23-18. 10BASE-T Receiver Characteristics ................................................................................ 541 Table 23-19. Isolation Transformers ................................................................................................... 541 Table 23-20. Ethernet Reference Crystal ............................................................................................ 542 Table 23-21. External XTLP Oscillator Characteristics ......................................................................... 542 Table 23-22. Hibernation Module Characteristics ................................................................................. 543 Table 23-23. SSI Characteristics ........................................................................................................ 543 Table 23-24. JTAG Characteristics ..................................................................................................... 545 Table 23-25. GPIO Characteristics ..................................................................................................... 547 Table 23-26. Reset Characteristics ..................................................................................................... 547 Table C-1. Part Ordering Information ............................................................................................... 575 12 November 30, 2007 Preliminary Table of Contents List of Registers System Control .............................................................................................................................. 59 Register 1: Device Identification 0 (DID0), offset 0x000 ....................................................................... 67 Register 2: Brown-Out Reset Control (PBORCTL), offset 0x030 .......................................................... 69 Register 3: LDO Power Control (LDOPCTL), offset 0x034 ................................................................... 70 Register 4: Raw Interrupt Status (RIS), offset 0x050 ........................................................................... 71 Register 5: Interrupt Mask Control (IMC), offset 0x054 ........................................................................ 72 Register 6: Masked Interrupt Status and Clear (MISC), offset 0x058 .................................................... 73 Register 7: Reset Cause (RESC), offset 0x05C .................................................................................. 74 Register 8: Run-Mode Clock Configuration (RCC), offset 0x060 .......................................................... 75 Register 9: XTAL to PLL Translation (PLLCFG), offset 0x064 .............................................................. 79 Register 10: Run-Mode Clock Configuration 2 (RCC2), offset 0x070 ...................................................... 80 Register 11: Deep Sleep Clock Configuration (DSLPCLKCFG), offset 0x144 .......................................... 82 Register 12: Device Identification 1 (DID1), offset 0x004 ....................................................................... 83 Register 13: Device Capabilities 0 (DC0), offset 0x008 ......................................................................... 85 Register 14: Device Capabilities 1 (DC1), offset 0x010 ......................................................................... 86 Register 15: Device Capabilities 2 (DC2), offset 0x014 ......................................................................... 88 Register 16: Device Capabilities 3 (DC3), offset 0x018 ......................................................................... 90 Register 17: Device Capabilities 4 (DC4), offset 0x01C ......................................................................... 92 Register 18: Run Mode Clock Gating Control Register 0 (RCGC0), offset 0x100 .................................... 94 Register 19: Sleep Mode Clock Gating Control Register 0 (SCGC0), offset 0x110 .................................. 96 Register 20: Deep Sleep Mode Clock Gating Control Register 0 (DCGC0), offset 0x120 ......................... 98 Register 21: Run Mode Clock Gating Control Register 1 (RCGC1), offset 0x104 ................................... 100 Register 22: Sleep Mode Clock Gating Control Register 1 (SCGC1), offset 0x114 ................................. 103 Register 23: Deep Sleep Mode Clock Gating Control Register 1 (DCGC1), offset 0x124 ....................... 106 Register 24: Run Mode Clock Gating Control Register 2 (RCGC2), offset 0x108 ................................... 109 Register 25: Sleep Mode Clock Gating Control Register 2 (SCGC2), offset 0x118 ................................. 111 Register 26: Deep Sleep Mode Clock Gating Control Register 2 (DCGC2), offset 0x128 ....................... 113 Register 27: Software Reset Control 0 (SRCR0), offset 0x040 ............................................................. 115 Register 28: Software Reset Control 1 (SRCR1), offset 0x044 ............................................................. 116 Register 29: Software Reset Control 2 (SRCR2), offset 0x048 ............................................................. 118 Hibernation Module ..................................................................................................................... 120 Register 1: Hibernation RTC Counter (HIBRTCC), offset 0x000 ......................................................... 127 Register 2: Hibernation RTC Match 0 (HIBRTCM0), offset 0x004 ....................................................... 128 Register 3: Hibernation RTC Match 1 (HIBRTCM1), offset 0x008 ....................................................... 129 Register 4: Hibernation RTC Load (HIBRTCLD), offset 0x00C ........................................................... 130 Register 5: Hibernation Control (HIBCTL), offset 0x010 ..................................................................... 131 Register 6: Hibernation Interrupt Mask (HIBIM), offset 0x014 ............................................................. 133 Register 7: Hibernation Raw Interrupt Status (HIBRIS), offset 0x018 .................................................. 134 Register 8: Hibernation Masked Interrupt Status (HIBMIS), offset 0x01C ............................................ 135 Register 9: Hibernation Interrupt Clear (HIBIC), offset 0x020 ............................................................. 136 Register 10: Hibernation RTC Trim (HIBRTCT), offset 0x024 ............................................................... 137 Register 11: Hibernation Data (HIBDATA), offset 0x030-0x12C ............................................................ 138 Internal Memory ........................................................................................................................... 139 Register 1: Flash Memory Address (FMA), offset 0x000 .................................................................... 144 Register 2: Flash Memory Data (FMD), offset 0x004 ......................................................................... 145 November 30, 2007 13 Preliminary LM3S6952 Microcontroller Register 3: Flash Memory Control (FMC), offset 0x008 ..................................................................... 146 Register 4: Flash Controller Raw Interrupt Status (FCRIS), offset 0x00C ............................................ 148 Register 5: Flash Controller Interrupt Mask (FCIM), offset 0x010 ........................................................ 149 Register 6: Flash Controller Masked Interrupt Status and Clear (FCMISC), offset 0x014 ..................... 150 Register 7: USec Reload (USECRL), offset 0x140 ............................................................................ 151 Register 8: Flash Memory Protection Read Enable 0 (FMPRE0), offset 0x130 and 0x200 ................... 152 Register 9: Flash Memory Protection Program Enable 0 (FMPPE0), offset 0x134 and 0x400 ............... 153 Register 10: User Debug (USER_DBG), offset 0x1D0 ......................................................................... 154 Register 11: User Register 0 (USER_REG0), offset 0x1E0 .................................................................. 155 Register 12: User Register 1 (USER_REG1), offset 0x1E4 .................................................................. 156 Register 13: Flash Memory Protection Read Enable 1 (FMPRE1), offset 0x204 .................................... 157 Register 14: Flash Memory Protection Read Enable 2 (FMPRE2), offset 0x208 .................................... 158 Register 15: Flash Memory Protection Read Enable 3 (FMPRE3), offset 0x20C ................................... 159 Register 16: Flash Memory Protection Program Enable 1 (FMPPE1), offset 0x404 ............................... 160 Register 17: Flash Memory Protection Program Enable 2 (FMPPE2), offset 0x408 ............................... 161 Register 18: Flash Memory Protection Program Enable 3 (FMPPE3), offset 0x40C ............................... 162 General-Purpose Input/Outputs (GPIOs) ................................................................................... 163 Register 1: GPIO Data (GPIODATA), offset 0x000 ............................................................................ 170 Register 2: GPIO Direction (GPIODIR), offset 0x400 ......................................................................... 171 Register 3: GPIO Interrupt Sense (GPIOIS), offset 0x404 .................................................................. 172 Register 4: GPIO Interrupt Both Edges (GPIOIBE), offset 0x408 ........................................................ 173 Register 5: GPIO Interrupt Event (GPIOIEV), offset 0x40C ................................................................ 174 Register 6: GPIO Interrupt Mask (GPIOIM), offset 0x410 ................................................................... 175 Register 7: GPIO Raw Interrupt Status (GPIORIS), offset 0x414 ........................................................ 176 Register 8: GPIO Masked Interrupt Status (GPIOMIS), offset 0x418 ................................................... 177 Register 9: GPIO Interrupt Clear (GPIOICR), offset 0x41C ................................................................ 178 Register 10: GPIO Alternate Function Select (GPIOAFSEL), offset 0x420 ............................................ 179 Register 11: GPIO 2-mA Drive Select (GPIODR2R), offset 0x500 ........................................................ 181 Register 12: GPIO 4-mA Drive Select (GPIODR4R), offset 0x504 ........................................................ 182 Register 13: GPIO 8-mA Drive Select (GPIODR8R), offset 0x508 ........................................................ 183 Register 14: GPIO Open Drain Select (GPIOODR), offset 0x50C ......................................................... 184 Register 15: GPIO Pull-Up Select (GPIOPUR), offset 0x510 ................................................................ 185 Register 16: GPIO Pull-Down Select (GPIOPDR), offset 0x514 ........................................................... 186 Register 17: GPIO Slew Rate Control Select (GPIOSLR), offset 0x518 ................................................ 187 Register 18: GPIO Digital Enable (GPIODEN), offset 0x51C ................................................................ 188 Register 19: GPIO Lock (GPIOLOCK), offset 0x520 ............................................................................ 189 Register 20: GPIO Commit (GPIOCR), offset 0x524 ............................................................................ 190 Register 21: GPIO Peripheral Identification 4 (GPIOPeriphID4), offset 0xFD0 ....................................... 192 Register 22: GPIO Peripheral Identification 5 (GPIOPeriphID5), offset 0xFD4 ....................................... 193 Register 23: GPIO Peripheral Identification 6 (GPIOPeriphID6), offset 0xFD8 ....................................... 194 Register 24: GPIO Peripheral Identification 7 (GPIOPeriphID7), offset 0xFDC ...................................... 195 Register 25: GPIO Peripheral Identification 0 (GPIOPeriphID0), offset 0xFE0 ....................................... 196 Register 26: GPIO Peripheral Identification 1 (GPIOPeriphID1), offset 0xFE4 ....................................... 197 Register 27: GPIO Peripheral Identification 2 (GPIOPeriphID2), offset 0xFE8 ....................................... 198 Register 28: GPIO Peripheral Identification 3 (GPIOPeriphID3), offset 0xFEC ...................................... 199 Register 29: GPIO PrimeCell Identification 0 (GPIOPCellID0), offset 0xFF0 .......................................... 200 Register 30: GPIO PrimeCell Identification 1 (GPIOPCellID1), offset 0xFF4 .......................................... 201 Register 31: GPIO PrimeCell Identification 2 (GPIOPCellID2), offset 0xFF8 .......................................... 202 14 November 30, 2007 Preliminary Table of Contents Register 32: GPIO PrimeCell Identification 3 (GPIOPCellID3), offset 0xFFC ......................................... 203 General-Purpose Timers ............................................................................................................. 204 Register 1: GPTM Configuration (GPTMCFG), offset 0x000 .............................................................. 216 Register 2: GPTM TimerA Mode (GPTMTAMR), offset 0x004 ............................................................ 217 Register 3: GPTM TimerB Mode (GPTMTBMR), offset 0x008 ............................................................ 219 Register 4: GPTM Control (GPTMCTL), offset 0x00C ........................................................................ 221 Register 5: GPTM Interrupt Mask (GPTMIMR), offset 0x018 .............................................................. 224 Register 6: GPTM Raw Interrupt Status (GPTMRIS), offset 0x01C ..................................................... 226 Register 7: GPTM Masked Interrupt Status (GPTMMIS), offset 0x020 ................................................ 227 Register 8: GPTM Interrupt Clear (GPTMICR), offset 0x024 .............................................................. 228 Register 9: GPTM TimerA Interval Load (GPTMTAILR), offset 0x028 ................................................. 230 Register 10: GPTM TimerB Interval Load (GPTMTBILR), offset 0x02C ................................................ 231 Register 11: GPTM TimerA Match (GPTMTAMATCHR), offset 0x030 ................................................... 232 Register 12: GPTM TimerB Match (GPTMTBMATCHR), offset 0x034 .................................................. 233 Register 13: GPTM TimerA Prescale (GPTMTAPR), offset 0x038 ........................................................ 234 Register 14: GPTM TimerB Prescale (GPTMTBPR), offset 0x03C ....................................................... 235 Register 15: GPTM TimerA Prescale Match (GPTMTAPMR), offset 0x040 ........................................... 236 Register 16: GPTM TimerB Prescale Match (GPTMTBPMR), offset 0x044 ........................................... 237 Register 17: GPTM TimerA (GPTMTAR), offset 0x048 ........................................................................ 238 Register 18: GPTM TimerB (GPTMTBR), offset 0x04C ....................................................................... 239 Watchdog Timer ........................................................................................................................... 240 Register 1: Watchdog Load (WDTLOAD), offset 0x000 ...................................................................... 243 Register 2: Watchdog Value (WDTVALUE), offset 0x004 ................................................................... 244 Register 3: Watchdog Control (WDTCTL), offset 0x008 ..................................................................... 245 Register 4: Watchdog Interrupt Clear (WDTICR), offset 0x00C .......................................................... 246 Register 5: Watchdog Raw Interrupt Status (WDTRIS), offset 0x010 .................................................. 247 Register 6: Watchdog Masked Interrupt Status (WDTMIS), offset 0x014 ............................................. 248 Register 7: Watchdog Test (WDTTEST), offset 0x418 ....................................................................... 249 Register 8: Watchdog Lock (WDTLOCK), offset 0xC00 ..................................................................... 250 Register 9: Watchdog Peripheral Identification 4 (WDTPeriphID4), offset 0xFD0 ................................. 251 Register 10: Watchdog Peripheral Identification 5 (WDTPeriphID5), offset 0xFD4 ................................. 252 Register 11: Watchdog Peripheral Identification 6 (WDTPeriphID6), offset 0xFD8 ................................. 253 Register 12: Watchdog Peripheral Identification 7 (WDTPeriphID7), offset 0xFDC ................................ 254 Register 13: Watchdog Peripheral Identification 0 (WDTPeriphID0), offset 0xFE0 ................................. 255 Register 14: Watchdog Peripheral Identification 1 (WDTPeriphID1), offset 0xFE4 ................................. 256 Register 15: Watchdog Peripheral Identification 2 (WDTPeriphID2), offset 0xFE8 ................................. 257 Register 16: Watchdog Peripheral Identification 3 (WDTPeriphID3), offset 0xFEC ................................. 258 Register 17: Watchdog PrimeCell Identification 0 (WDTPCellID0), offset 0xFF0 .................................... 259 Register 18: Watchdog PrimeCell Identification 1 (WDTPCellID1), offset 0xFF4 .................................... 260 Register 19: Watchdog PrimeCell Identification 2 (WDTPCellID2), offset 0xFF8 .................................... 261 Register 20: Watchdog PrimeCell Identification 3 (WDTPCellID3 ), offset 0xFFC .................................. 262 Analog-to-Digital Converter (ADC) ............................................................................................. 263 Register 1: ADC Active Sample Sequencer (ADCACTSS), offset 0x000 ............................................. 270 Register 2: ADC Raw Interrupt Status (ADCRIS), offset 0x004 ........................................................... 271 Register 3: ADC Interrupt Mask (ADCIM), offset 0x008 ..................................................................... 272 Register 4: ADC Interrupt Status and Clear (ADCISC), offset 0x00C .................................................. 273 Register 5: ADC Overflow Status (ADCOSTAT), offset 0x010 ............................................................ 274 Register 6: ADC Event Multiplexer Select (ADCEMUX), offset 0x014 ................................................. 275 November 30, 2007 15 Preliminary LM3S6952 Microcontroller Register 7: ADC Underflow Status (ADCUSTAT), offset 0x018 ........................................................... 278 Register 8: ADC Sample Sequencer Priority (ADCSSPRI), offset 0x020 ............................................. 279 Register 9: ADC Processor Sample Sequence Initiate (ADCPSSI), offset 0x028 ................................. 280 Register 10: ADC Sample Averaging Control (ADCSAC), offset 0x030 ................................................. 281 Register 11: ADC Sample Sequence Input Multiplexer Select 0 (ADCSSMUX0), offset 0x040 ............... 282 Register 12: ADC Sample Sequence Control 0 (ADCSSCTL0), offset 0x044 ........................................ 284 Register 13: ADC Sample Sequence Result FIFO 0 (ADCSSFIFO0), offset 0x048 ................................ 287 Register 14: ADC Sample Sequence Result FIFO 1 (ADCSSFIFO1), offset 0x068 ................................ 287 Register 15: ADC Sample Sequence Result FIFO 2 (ADCSSFIFO2), offset 0x088 ................................ 287 Register 16: ADC Sample Sequence Result FIFO 3 (ADCSSFIFO3), offset 0x0A8 ............................... 287 Register 17: ADC Sample Sequence FIFO 0 Status (ADCSSFSTAT0), offset 0x04C ............................. 288 Register 18: ADC Sample Sequence FIFO 1 Status (ADCSSFSTAT1), offset 0x06C ............................. 288 Register 19: ADC Sample Sequence FIFO 2 Status (ADCSSFSTAT2), offset 0x08C ............................ 288 Register 20: ADC Sample Sequence FIFO 3 Status (ADCSSFSTAT3), offset 0x0AC ............................ 288 Register 21: ADC Sample Sequence Input Multiplexer Select 1 (ADCSSMUX1), offset 0x060 ............... 289 Register 22: ADC Sample Sequence Input Multiplexer Select 2 (ADCSSMUX2), offset 0x080 ............... 289 Register 23: ADC Sample Sequence Control 1 (ADCSSCTL1), offset 0x064 ........................................ 290 Register 24: ADC Sample Sequence Control 2 (ADCSSCTL2), offset 0x084 ........................................ 290 Register 25: ADC Sample Sequence Input Multiplexer Select 3 (ADCSSMUX3), offset 0x0A0 ............... 292 Register 26: ADC Sample Sequence Control 3 (ADCSSCTL3), offset 0x0A4 ........................................ 293 Register 27: ADC Test Mode Loopback (ADCTMLB), offset 0x100 ....................................................... 294 Universal Asynchronous Receivers/Transmitters (UARTs) ..................................................... 296 Register 1: UART Data (UARTDR), offset 0x000 ............................................................................... 304 Register 2: UART Receive Status/Error Clear (UARTRSR/UARTECR), offset 0x004 ........................... 306 Register 3: UART Flag (UARTFR), offset 0x018 ................................................................................ 308 Register 4: UART IrDA Low-Power Register (UARTILPR), offset 0x020 ............................................. 310 Register 5: UART Integer Baud-Rate Divisor (UARTIBRD), offset 0x024 ............................................ 311 Register 6: UART Fractional Baud-Rate Divisor (UARTFBRD), offset 0x028 ....................................... 312 Register 7: UART Line Control (UARTLCRH), offset 0x02C ............................................................... 313 Register 8: UART Control (UARTCTL), offset 0x030 ......................................................................... 315 Register 9: UART Interrupt FIFO Level Select (UARTIFLS), offset 0x034 ........................................... 317 Register 10: UART Interrupt Mask (UARTIM), offset 0x038 ................................................................. 319 Register 11: UART Raw Interrupt Status (UARTRIS), offset 0x03C ...................................................... 321 Register 12: UART Masked Interrupt Status (UARTMIS), offset 0x040 ................................................. 322 Register 13: UART Interrupt Clear (UARTICR), offset 0x044 ............................................................... 323 Register 14: UART Peripheral Identification 4 (UARTPeriphID4), offset 0xFD0 ..................................... 325 Register 15: UART Peripheral Identification 5 (UARTPeriphID5), offset 0xFD4 ..................................... 326 Register 16: UART Peripheral Identification 6 (UARTPeriphID6), offset 0xFD8 ..................................... 327 Register 17: UART Peripheral Identification 7 (UARTPeriphID7), offset 0xFDC ..................................... 328 Register 18: UART Peripheral Identification 0 (UARTPeriphID0), offset 0xFE0 ...................................... 329 Register 19: UART Peripheral Identification 1 (UARTPeriphID1), offset 0xFE4 ...................................... 330 Register 20: UART Peripheral Identification 2 (UARTPeriphID2), offset 0xFE8 ...................................... 331 Register 21: UART Peripheral Identification 3 (UARTPeriphID3), offset 0xFEC ..................................... 332 Register 22: UART PrimeCell Identification 0 (UARTPCellID0), offset 0xFF0 ........................................ 333 Register 23: UART PrimeCell Identification 1 (UARTPCellID1), offset 0xFF4 ........................................ 334 Register 24: UART PrimeCell Identification 2 (UARTPCellID2), offset 0xFF8 ........................................ 335 Register 25: UART PrimeCell Identification 3 (UARTPCellID3), offset 0xFFC ........................................ 336 16 November 30, 2007 Preliminary Table of Contents Synchronous Serial Interface (SSI) ............................................................................................ 337 Register 1: SSI Control 0 (SSICR0), offset 0x000 .............................................................................. 349 Register 2: SSI Control 1 (SSICR1), offset 0x004 .............................................................................. 351 Register 3: SSI Data (SSIDR), offset 0x008 ...................................................................................... 353 Register 4: SSI Status (SSISR), offset 0x00C ................................................................................... 354 Register 5: SSI Clock Prescale (SSICPSR), offset 0x010 .................................................................. 356 Register 6: SSI Interrupt Mask (SSIIM), offset 0x014 ......................................................................... 357 Register 7: SSI Raw Interrupt Status (SSIRIS), offset 0x018 .............................................................. 359 Register 8: SSI Masked Interrupt Status (SSIMIS), offset 0x01C ........................................................ 360 Register 9: SSI Interrupt Clear (SSIICR), offset 0x020 ....................................................................... 361 Register 10: SSI Peripheral Identification 4 (SSIPeriphID4), offset 0xFD0 ............................................. 362 Register 11: SSI Peripheral Identification 5 (SSIPeriphID5), offset 0xFD4 ............................................. 363 Register 12: SSI Peripheral Identification 6 (SSIPeriphID6), offset 0xFD8 ............................................. 364 Register 13: SSI Peripheral Identification 7 (SSIPeriphID7), offset 0xFDC ............................................ 365 Register 14: SSI Peripheral Identification 0 (SSIPeriphID0), offset 0xFE0 ............................................. 366 Register 15: SSI Peripheral Identification 1 (SSIPeriphID1), offset 0xFE4 ............................................. 367 Register 16: SSI Peripheral Identification 2 (SSIPeriphID2), offset 0xFE8 ............................................. 368 Register 17: SSI Peripheral Identification 3 (SSIPeriphID3), offset 0xFEC ............................................ 369 Register 18: SSI PrimeCell Identification 0 (SSIPCellID0), offset 0xFF0 ............................................... 370 Register 19: SSI PrimeCell Identification 1 (SSIPCellID1), offset 0xFF4 ............................................... 371 Register 20: SSI PrimeCell Identification 2 (SSIPCellID2), offset 0xFF8 ............................................... 372 Register 21: SSI PrimeCell Identification 3 (SSIPCellID3), offset 0xFFC ............................................... 373 Inter-Integrated Circuit (I2C) Interface ........................................................................................ 374 Register 1: I2C Master Slave Address (I2CMSA), offset 0x000 ........................................................... 388 Register 2: I2C Master Control/Status (I2CMCS), offset 0x004 ........................................................... 389 Register 3: I2C Master Data (I2CMDR), offset 0x008 ......................................................................... 393 Register 4: I2C Master Timer Period (I2CMTPR), offset 0x00C ........................................................... 394 Register 5: I2C Master Interrupt Mask (I2CMIMR), offset 0x010 ......................................................... 395 Register 6: I2C Master Raw Interrupt Status (I2CMRIS), offset 0x014 ................................................. 396 Register 7: I2C Master Masked Interrupt Status (I2CMMIS), offset 0x018 ........................................... 397 Register 8: I2C Master Interrupt Clear (I2CMICR), offset 0x01C ......................................................... 398 Register 9: I2C Master Configuration (I2CMCR), offset 0x020 ............................................................ 399 Register 10: I2C Slave Own Address (I2CSOAR), offset 0x000 ............................................................ 401 Register 11: I2C Slave Control/Status (I2CSCSR), offset 0x004 ........................................................... 402 Register 12: I2C Slave Data (I2CSDR), offset 0x008 ........................................................................... 404 Register 13: I2C Slave Interrupt Mask (I2CSIMR), offset 0x00C ........................................................... 405 Register 14: I2C Slave Raw Interrupt Status (I2CSRIS), offset 0x010 ................................................... 406 Register 15: I2C Slave Masked Interrupt Status (I2CSMIS), offset 0x014 .............................................. 407 Register 16: I2C Slave Interrupt Clear (I2CSICR), offset 0x018 ............................................................ 408 Ethernet Controller ...................................................................................................................... 409 Register 1: Ethernet MAC Raw Interrupt Status (MACRIS), offset 0x000 ............................................ 418 Register 2: Ethernet MAC Interrupt Acknowledge (MACIACK), offset 0x000 ....................................... 420 Register 3: Ethernet MAC Interrupt Mask (MACIM), offset 0x004 ....................................................... 421 Register 4: Ethernet MAC Receive Control (MACRCTL), offset 0x008 ................................................ 422 Register 5: Ethernet MAC Transmit Control (MACTCTL), offset 0x00C ............................................... 423 Register 6: Ethernet MAC Data (MACDATA), offset 0x010 ................................................................. 424 Register 7: Ethernet MAC Individual Address 0 (MACIA0), offset 0x014 ............................................. 426 November 30, 2007 17 Preliminary LM3S6952 Microcontroller Register 8: Ethernet MAC Individual Address 1 (MACIA1), offset 0x018 ............................................. 427 Register 9: Ethernet MAC Threshold (MACTHR), offset 0x01C .......................................................... 428 Register 10: Ethernet MAC Management Control (MACMCTL), offset 0x020 ........................................ 429 Register 11: Ethernet MAC Management Divider (MACMDV), offset 0x024 .......................................... 430 Register 12: Ethernet MAC Management Transmit Data (MACMTXD), offset 0x02C ............................. 431 Register 13: Ethernet MAC Management Receive Data (MACMRXD), offset 0x030 .............................. 432 Register 14: Ethernet MAC Number of Packets (MACNP), offset 0x034 ............................................... 433 Register 15: Ethernet MAC Transmission Request (MACTR), offset 0x038 ........................................... 434 Register 16: Ethernet PHY Management Register 0 – Control (MR0), address 0x00 ............................. 435 Register 17: Ethernet PHY Management Register 1 – Status (MR1), address 0x01 .............................. 437 Register 18: Ethernet PHY Management Register 2 – PHY Identifier 1 (MR2), address 0x02 ................. 439 Register 19: Ethernet PHY Management Register 3 – PHY Identifier 2 (MR3), address 0x03 ................. 440 Register 20: Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4), address 0x04 ............................................................................................................................. 441 Register 21: Ethernet PHY Management Register 5 – Auto-Negotiation Link Partner Base Page Ability (MR5), address 0x05 ..................................................................................................... 443 Register 22: Ethernet PHY Management Register 6 – Auto-Negotiation Expansion (MR6), address 0x06 ............................................................................................................................. 444 Register 23: Ethernet PHY Management Register 16 – Vendor-Specific (MR16), address 0x10 ............. 445 Register 24: Ethernet PHY Management Register 17 – Interrupt Control/Status (MR17), address 0x11 .............................................................................................................................. 447 Register 25: Ethernet PHY Management Register 18 – Diagnostic (MR18), address 0x12 ..................... 449 Register 26: Ethernet PHY Management Register 19 – Transceiver Control (MR19), address 0x13 ....... 450 Register 27: Ethernet PHY Management Register 23 – LED Configuration (MR23), address 0x17 ......... 451 Register 28: Ethernet PHY Management Register 24 –MDI/MDIX Control (MR24), address 0x18 .......... 452 Analog Comparators ................................................................................................................... 453 Register 1: Analog Comparator Masked Interrupt Status (ACMIS), offset 0x00 .................................... 459 Register 2: Analog Comparator Raw Interrupt Status (ACRIS), offset 0x04 ......................................... 460 Register 3: Analog Comparator Interrupt Enable (ACINTEN), offset 0x08 ........................................... 461 Register 4: Analog Comparator Reference Voltage Control (ACREFCTL), offset 0x10 ......................... 462 Register 5: Analog Comparator Status 0 (ACSTAT0), offset 0x20 ....................................................... 463 Register 6: Analog Comparator Status 1 (ACSTAT1), offset 0x40 ....................................................... 463 Register 7: Analog Comparator Status 2 (ACSTAT2), offset 0x60 ....................................................... 463 Register 8: Analog Comparator Control 0 (ACCTL0), offset 0x24 ....................................................... 464 Register 9: Analog Comparator Control 1 (ACCTL1), offset 0x44 ....................................................... 464 Register 10: Analog Comparator Control 2 (ACCTL2), offset 0x64 ...................................................... 464 Pulse Width Modulator (PWM) .................................................................................................... 466 Register 1: PWM Master Control (PWMCTL), offset 0x000 ................................................................ 473 Register 2: PWM Time Base Sync (PWMSYNC), offset 0x004 ........................................................... 474 Register 3: PWM Output Enable (PWMENABLE), offset 0x008 .......................................................... 475 Register 4: PWM Output Inversion (PWMINVERT), offset 0x00C ....................................................... 476 Register 5: PWM Output Fault (PWMFAULT), offset 0x010 ................................................................ 477 Register 6: PWM Interrupt Enable (PWMINTEN), offset 0x014 ........................................................... 478 Register 7: PWM Raw Interrupt Status (PWMRIS), offset 0x018 ........................................................ 479 Register 8: PWM Interrupt Status and Clear (PWMISC), offset 0x01C ................................................ 480 Register 9: PWM Status (PWMSTATUS), offset 0x020 ...................................................................... 481 Register 10: PWM0 Control (PWM0CTL), offset 0x040 ....................................................................... 482 Register 11: PWM1 Control (PWM1CTL), offset 0x080 ....................................................................... 482 18 November 30, 2007 Preliminary Table of Contents Register 12: PWM0 Interrupt and Trigger Enable (PWM0INTEN), offset 0x044 .................................... 484 Register 13: PWM1 Interrupt and Trigger Enable (PWM1INTEN), offset 0x084 .................................... 484 Register 14: PWM0 Raw Interrupt Status (PWM0RIS), offset 0x048 .................................................... 486 Register 15: PWM1 Raw Interrupt Status (PWM1RIS), offset 0x088 .................................................... 486 Register 16: PWM0 Interrupt Status and Clear (PWM0ISC), offset 0x04C ........................................... 487 Register 17: PWM1 Interrupt Status and Clear (PWM1ISC), offset 0x08C ........................................... 487 Register 18: PWM0 Load (PWM0LOAD), offset 0x050 ....................................................................... 488 Register 19: PWM1 Load (PWM1LOAD), offset 0x090 ....................................................................... 488 Register 20: PWM0 Counter (PWM0COUNT), offset 0x054 ................................................................ 489 Register 21: PWM1 Counter (PWM1COUNT), offset 0x094 ................................................................ 489 Register 22: PWM0 Compare A (PWM0CMPA), offset 0x058 ............................................................. 490 Register 23: PWM1 Compare A (PWM1CMPA), offset 0x098 ............................................................. 490 Register 24: PWM0 Compare B (PWM0CMPB), offset 0x05C ............................................................. 491 Register 25: PWM1 Compare B (PWM1CMPB), offset 0x09C ............................................................. 491 Register 26: PWM0 Generator A Control (PWM0GENA), offset 0x060 ................................................ 492 Register 27: PWM1 Generator A Control (PWM1GENA), offset 0x0A0 ................................................ 492 Register 28: PWM0 Generator B Control (PWM0GENB), offset 0x064 ................................................ 495 Register 29: PWM1 Generator B Control (PWM1GENB), offset 0x0A4 ................................................ 495 Register 30: PWM0 Dead-Band Control (PWM0DBCTL), offset 0x068 ................................................ 498 Register 31: PWM1 Dead-Band Control (PWM1DBCTL), offset 0x0A8 ................................................. 498 Register 32: PWM0 Dead-Band Rising-Edge Delay (PWM0DBRISE), offset 0x06C ............................. 499 Register 33: PWM1 Dead-Band Rising-Edge Delay (PWM1DBRISE), offset 0x0AC ............................. 499 Register 34: PWM0 Dead-Band Falling-Edge-Delay (PWM0DBFALL), offset 0x070 ............................. 500 Register 35: PWM1 Dead-Band Falling-Edge-Delay (PWM1DBFALL), offset 0x0B0 ............................. 500 Quadrature Encoder Interface (QEI) .......................................................................................... 501 Register 1: QEI Control (QEICTL), offset 0x000 ................................................................................ 506 Register 2: QEI Status (QEISTAT), offset 0x004 ................................................................................ 508 Register 3: QEI Position (QEIPOS), offset 0x008 .............................................................................. 509 Register 4: QEI Maximum Position (QEIMAXPOS), offset 0x00C ....................................................... 510 Register 5: QEI Timer Load (QEILOAD), offset 0x010 ....................................................................... 511 Register 6: QEI Timer (QEITIME), offset 0x014 ................................................................................. 512 Register 7: QEI Velocity Counter (QEICOUNT), offset 0x018 ............................................................. 513 Register 8: QEI Velocity (QEISPEED), offset 0x01C .......................................................................... 514 Register 9: QEI Interrupt Enable (QEIINTEN), offset 0x020 ............................................................... 515 Register 10: QEI Raw Interrupt Status (QEIRIS), offset 0x024 ............................................................. 516 Register 11: QEI Interrupt Status and Clear (QEIISC), offset 0x028 ..................................................... 517 November 30, 2007 19 Preliminary LM3S6952 Microcontroller About This Document This data sheet provides reference information for the LM3S6952 microcontroller, describing the functional blocks of the system-on-chip (SoC) device designed around the ARM® Cortex™-M3 core. Audience This manual is intended for system software developers, hardware designers, and application developers. About This Manual This document is organized into sections that correspond to each major feature. Related Documents The following documents are referenced by the data sheet, and available on the documentation CD or from the Luminary Micro web site at www.luminarymicro.com: ■ ARM® Cortex™-M3 Technical Reference Manual ■ ARM® CoreSight Technical Reference Manual ■ ARM® v7-M Architecture Application Level Reference Manual The following related documents are also referenced: ■ IEEE Standard 1149.1-Test Access Port and Boundary-Scan Architecture This documentation list was current as of publication date. Please check the Luminary Micro web site for additional documentation, including application notes and white papers. Documentation Conventions This document uses the conventions shown in Table 1 on page 20. Table 1. Documentation Conventions Notation Meaning General Register Notation APB registers are indicated in uppercase bold. For example, PBORCTL is the Power-On and Brown-Out Reset Control register. If a register name contains a lowercase n, it represents more than one register. For example, SRCRn represents any (or all) of the three Software Reset Control registers: SRCR0, SRCR1 , and SRCR2. REGISTER bit A single bit in a register. bit field Two or more consecutive and related bits. A hexadecimal increment to a register's address, relative to that module's base address as specified in “Memory Map” on page 43. offset 0xnnn Registers are numbered consecutively throughout the document to aid in referencing them. The register number has no meaning to software. Register N 20 November 30, 2007 Preliminary About This Document Notation Meaning Register bits marked reserved are reserved for future use. In most cases, reserved bits are set to 0; however, user software should not rely on the value of a reserved bit. To provide software compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. reserved The range of register bits inclusive from xx to yy. For example, 31:15 means bits 15 through 31 in that register. yy:xx This value in the register bit diagram indicates whether software running on the controller can change the value of the bit field. Register Bit/Field Types RC Software can read this field. The bit or field is cleared by hardware after reading the bit/field. RO Software can read this field. Always write the chip reset value. R/W Software can read or write this field. Software can read or write this field. A write of a 0 to a W1C bit does not affect the bit value in the register. A write of a 1 clears the value of the bit in the register; the remaining bits remain unchanged. This register type is primarily used for clearing interrupt status bits where the read operation provides the interrupt status and the write of the read value clears only the interrupts being reported at the time the register was read. R/W1C Software can write this field. A write of a 0 to a W1C bit does not affect the bit value in the register. A write of a 1 clears the value of the bit in the register; the remaining bits remain unchanged. A read of the register returns no meaningful data. This register is typically used to clear the corresponding bit in an interrupt register. W1C WO Only a write by software is valid; a read of the register returns no meaningful data. Register Bit/Field This value in the register bit diagram shows the bit/field value after any reset, unless noted. Reset Value 0 Bit cleared to 0 on chip reset. 1 Bit set to 1 on chip reset. - Nondeterministic. Pin/Signal Notation [ ] Pin alternate function; a pin defaults to the signal without the brackets. pin Refers to the physical connection on the package. signal Refers to the electrical signal encoding of a pin. Change the value of the signal from the logically False state to the logically True state. For active High signals, the asserted signal value is 1 (High); for active Low signals, the asserted signal value is 0 (Low). The active polarity (High or Low) is defined by the signal name (see SIGNAL and SIGNAL below). assert a signal deassert a signal Change the value of the signal from the logically True state to the logically False state. Signal names are in uppercase and in the Courier font. An overbar on a signal name indicates that it is active Low. To assert SIGNAL is to drive it Low; to deassert SIGNAL is to drive it High. SIGNAL Signal names are in uppercase and in the Courier font. An active High signal has no overbar. To assert SIGNAL is to drive it High; to deassert SIGNAL is to drive it Low. SIGNAL Numbers An uppercase X indicates any of several values is allowed, where X can be any legal pattern. For example, a binary value of 0X00 can be either 0100 or 0000, a hex value of 0xX is 0x0 or 0x1, and so on. X Hexadecimal numbers have a prefix of 0x. For example, 0x00FF is the hexadecimal number FF. All other numbers within register tables are assumed to be binary. Within conceptual information, binary numbers are indicated with a b suffix, for example, 1011b, and decimal numbers are written without a prefix or suffix. 0x November 30, 2007 21 Preliminary LM3S6952 Microcontroller 1 Architectural Overview The Luminary Micro Stellaris® family of microcontrollers—the first ARM® Cortex™-M3 based controllers—brings high-performance 32-bit computing to cost-sensitive embedded microcontroller applications. These pioneering parts deliver customers 32-bit performance at a cost equivalent to legacy 8- and 16-bit devices, all in a package with a small footprint. The Stellaris® family offers efficient performance and extensive integration, favorably positioning the device into cost-conscious applications requiring significant control-processing and connectivity capabilities. The Stellaris® LM3S1000 series extends the Stellaris® family with larger on-chip memories, enhanced power management, and expanded I/O and control capabilities. The Stellaris® LM3S2000 series, designed for Controller Area Network (CAN) applications, extends the Stellaris family with Bosch CAN networking technology, the golden standard in short-haul industrial networks. The Stellaris® LM3S2000 series also marks the first integration of CAN capabilities with the revolutionary Cortex-M3 core. The Stellaris® LM3S6000 series combines both a 10/100 Ethernet Media Access Control (MAC) and Physical (PHY) layer, marking the first time that integrated connectivity is available with an ARM Cortex-M3 MCU and the only integrated 10/100 Ethernet MAC and PHY available in an ARM architecture MCU. The Stellaris® LM3S8000 series combines Bosch Controller Area Network technology with both a 10/100 Ethernet Media Access Control (MAC) and Physical (PHY) layer. The LM3S6952 microcontroller is targeted for industrial applications, including remote monitoring, electronic point-of-sale machines, test and measurement equipment, network appliances and switches, factory automation, HVAC and building control, gaming equipment, motion control, medical instrumentation, and fire and security. For applications requiring extreme conservation of power, the LM3S6952 microcontroller features a Battery-backed Hibernation module to efficiently power down the LM3S6952 to a low-power state during extended periods of inactivity. With a power-up/power-down sequencer, a continuous time counter (RTC), a pair of match registers, an APB interface to the system bus, and dedicated non-volatile memory, the Hibernation module positions the LM3S6952 microcontroller perfectly for battery applications. In addition, the LM3S6952 microcontroller offers the advantages of ARM's widely available development tools, System-on-Chip (SoC) infrastructure IP applications, and a large user community. Additionally, the microcontroller uses ARM's Thumb®-compatible Thumb-2 instruction set to reduce memory requirements and, thereby, cost. Finally, the LM3S6952 microcontroller is code-compatible to all members of the extensive Stellaris® family; providing flexibility to fit our customers' precise needs. Luminary Micro offers a complete solution to get to market quickly, with evaluation and development boards, white papers and application notes, an easy-to-use peripheral driver library, and a strong support, sales, and distributor network. 1.1 Product Features The LM3S6952 microcontroller includes the following product features: ■ 32-Bit RISC Performance – 32-bit ARM® Cortex™-M3 v7M architecture optimized for small-footprint embedded applications 22 November 30, 2007 Preliminary Architectural Overview – System timer (SysTick), providing a simple, 24-bit clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism – Thumb®-compatible Thumb-2-only instruction set processor core for high code density – 50-MHz operation – Hardware-division and single-cycle-multiplication – Integrated Nested Vectored Interrupt Controller (NVIC) providing deterministic interrupt handling – 34 interrupts with eight priority levels – Memory protection unit (MPU), providing a privileged mode for protected operating system functionality – Unaligned data access, enabling data to be efficiently packed into memory – Atomic bit manipulation (bit-banding), delivering maximum memory utilization and streamlined peripheral control ■ Internal Memory – 256 KB single-cycle flash • User-managed flash block protection on a 2-KB block basis • User-managed flash data programming • User-defined and managed flash-protection block – 64 KB single-cycle SRAM ■ General-Purpose Timers – Three General-Purpose Timer Modules (GPTM), each of which provides two 16-bit timers. Each GPTM can be configured to operate independently: • As a single 32-bit timer • As one 32-bit Real-Time Clock (RTC) to event capture • For Pulse Width Modulation (PWM) • To trigger analog-to-digital conversions – 32-bit Timer modes • Programmable one-shot timer • Programmable periodic timer • Real-Time Clock when using an external 32.768-KHz clock as the input November 30, 2007 23 Preliminary LM3S6952 Microcontroller • User-enabled stalling in periodic and one-shot mode when the controller asserts the CPU Halt flag during debug • ADC event trigger – 16-bit Timer modes • General-purpose timer function with an 8-bit prescaler • Programmable one-shot timer • Programmable periodic timer • User-enabled stalling when the controller asserts CPU Halt flag during debug • ADC event trigger – 16-bit Input Capture modes • Input edge count capture • Input edge time capture – 16-bit PWM mode • Simple PWM mode with software-programmable output inversion of the PWM signal ■ ARM FiRM-compliant Watchdog Timer – 32-bit down counter with a programmable load register – Separate watchdog clock with an enable – Programmable interrupt generation logic with interrupt masking – Lock register protection from runaway software – Reset generation logic with an enable/disable – User-enabled stalling when the controller asserts the CPU Halt flag during debug ■ 10/100 Ethernet Controller – Conforms to the IEEE 802.3-2002 Specification – Full- and half-duplex for both 100 Mbps and 10 Mbps operation – Integrated 10/100 Mbps Transceiver (PHY) – Automatic MDI/MDI-X cross-over correction – Programmable MAC address – Power-saving and power-down modes ■ Synchronous Serial Interface (SSI) 24 November 30, 2007 Preliminary Architectural Overview – Master or slave operation – Programmable clock bit rate and prescale – Separate transmit and receive FIFOs, 16 bits wide, 8 locations deep – Programmable interface operation for Freescale SPI, MICROWIRE, or Texas Instruments synchronous serial interfaces – Programmable data frame size from 4 to 16 bits – Internal loopback test mode for diagnostic/debug testing ■ UART – Three fully programmable 16C550-type UARTs with IrDA support – Separate 16x8 transmit (TX) and 16x12 receive (RX) FIFOs to reduce CPU interrupt service loading – Programmable baud-rate generator with fractional divider – Programmable FIFO length, including 1-byte deep operation providing conventional double-buffered interface – FIFO trigger levels of 1/8, 1/4, 1/2, 3/4, and 7/8 – Standard asynchronous communication bits for start, stop, and parity – False-start-bit detection – Line-break generation and detection ■ ADC – Single- and differential-input configurations – Three 10-bit channels (inputs) when used as single-ended inputs – Sample rate of 500 thousand samples/second – Flexible, configurable analog-to-digital conversion – Four programmable sample conversion sequences from one to eight entries long, with corresponding conversion result FIFOs – Each sequence triggered by software or internal event (timers, analog comparators, PWM or GPIO) – On-chip temperature sensor ■ Analog Comparators – Three independent integrated analog comparators November 30, 2007 25 Preliminary LM3S6952 Microcontroller – Configurable for output to: drive an output pin, generate an interrupt, or initiate an ADC sample sequence – Compare external pin input to external pin input or to internal programmable voltage reference ■ I2C – Master and slave receive and transmit operation with transmission speed up to 100 Kbps in Standard mode and 400 Kbps in Fast mode – Interrupt generation – Master with arbitration and clock synchronization, multimaster support, and 7-bit addressing mode ■ PWM – Two PWM generator blocks, each with one 16-bit counter, two comparators, a PWM generator, and a dead-band generator – One 16-bit counter • Runs in Down or Up/Down mode • Output frequency controlled by a 16-bit load value • Load value updates can be synchronized • Produces output signals at zero and load value – Two PWM comparators • Comparator value updates can be synchronized • Produces output signals on match – PWM generator • Output PWM signal is constructed based on actions taken as a result of the counter and PWM comparator output signals • Produces two independent PWM signals – Dead-band generator • Produces two PWM signals with programmable dead-band delays suitable for driving a half-H bridge • Can be bypassed, leaving input PWM signals unmodified – Flexible output control block with PWM output enable of each PWM signal • PWM output enable of each PWM signal • Optional output inversion of each PWM signal (polarity control) 26 November 30, 2007 Preliminary Architectural Overview • Optional fault handling for each PWM signal • Synchronization of timers in the PWM generator blocks • Synchronization of timer/comparator updates across the PWM generator blocks • Interrupt status summary of the PWM generator blocks – Can initiate an ADC sample sequence ■ QEI – Hardware position integrator tracks the encoder position – Velocity capture using built-in timer – Interrupt generation on index pulse, velocity-timer expiration, direction change, and quadrature error detection ■ GPIOs – 6-43 GPIOs, depending on configuration – 5-V-tolerant input/outputs – Programmable interrupt generation as either edge-triggered or level-sensitive – Bit masking in both read and write operations through address lines – Can initiate an ADC sample sequence – Programmable control for GPIO pad configuration: • Weak pull-up or pull-down resistors • 2-mA, 4-mA, and 8-mA pad drive • Slew rate control for the 8-mA drive • Open drain enables • Digital input enables ■ Power – On-chip Low Drop-Out (LDO) voltage regulator, with programmable output user-adjustable from 2.25 V to 2.75 V – Hibernation module handles the power-up/down 3.3 V sequencing and control for the core digital logic and analog circuits – Low-power options on controller: Sleep and Deep-sleep modes – Low-power options for peripherals: software controls shutdown of individual peripherals – User-enabled LDO unregulated voltage detection and automatic reset November 30, 2007 27 Preliminary LM3S6952 Microcontroller – 3.3-V supply brown-out detection and reporting via interrupt or reset ■ Flexible Reset Sources – Power-on reset (POR) – Reset pin assertion – Brown-out (BOR) detector alerts to system power drops – Software reset – Watchdog timer reset – Internal low drop-out (LDO) regulator output goes unregulated ■ Additional Features – Six reset sources – Programmable clock source control – Clock gating to individual peripherals for power savings – IEEE 1149.1-1990 compliant Test Access Port (TAP) controller – Debug access via JTAG and Serial Wire interfaces – Full JTAG boundary scan ■ Industrial-range 100-pin RoHS-compliant LQFP package 1.2 Target Applications ■ Remote monitoring ■ Electronic point-of-sale (POS) machines ■ Test and measurement equipment ■ Network appliances and switches ■ Factory automation ■ HVAC and building control ■ Gaming equipment ■ Motion control ■ Medical instrumentation ■ Fire and security ■ Power and energy ■ Transportation 28 November 30, 2007 Preliminary Architectural Overview 1.3 High-Level Block Diagram Figure 1-1 on page 29 represents the full set of features in the Stellaris® 6000 series of devices; not all features may be available on the LM3S6952 microcontroller. Figure 1-1. Stellaris® 6000 Series High-Level Block Diagram 1.4 Functional Overview The following sections provide an overview of the features of the LM3S6952 microcontroller. The page number in parenthesis indicates where that feature is discussed in detail. Ordering and support information can be found in “Ordering and Contact Information” on page 575. November 30, 2007 29 Preliminary LM3S6952 Microcontroller 1.4.1 ARM Cortex™-M3 1.4.1.1 Processor Core (see page 37) All members of the Stellaris® product family, including the LM3S6952 microcontroller, are designed around an ARM Cortex™-M3 processor core. The ARM Cortex-M3 processor provides the core for a high-performance, low-cost platform that meets the needs of minimal memory implementation, reduced pin count, and low-power consumption, while delivering outstanding computational performance and exceptional system response to interrupts. “ARM Cortex-M3 Processor Core” on page 37 provides an overview of the ARM core; the core is detailed in the ARM® Cortex™-M3 Technical Reference Manual. 1.4.1.2 System Timer (SysTick) Cortex-M3 includes an integrated system timer, SysTick. SysTick provides a simple, 24-bit clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism. The counter can be used in several different ways, for example: ■ An RTOS tick timer which fires at a programmable rate (for example, 100 Hz) and invokes a SysTick routine. ■ A high-speed alarm timer using the system clock. ■ A variable rate alarm or signal timer—the duration is range-dependent on the reference clock used and the dynamic range of the counter. ■ A simple counter. Software can use this to measure time to completion and time used. ■ An internal clock source control based on missing/meeting durations. The COUNTFLAG bit-field in the control and status register can be used to determine if an action completed within a set duration, as part of a dynamic clock management control loop. 1.4.1.3 Nested Vectored Interrupt Controller (NVIC) The LM3S6952 controller includes the ARM Nested Vectored Interrupt Controller (NVIC) on the ARM Cortex-M3 core. The NVIC and Cortex-M3 prioritize and handle all exceptions. All exceptions are handled in Handler Mode. The processor state is automatically stored to the stack on an exception, and automatically restored from the stack at the end of the Interrupt Service Routine (ISR). The vector is fetched in parallel to the state saving, which enables efficient interrupt entry. The processor supports tail-chaining, which enables back-to-back interrupts to be performed without the overhead of state saving and restoration. Software can set eight priority levels on 7 exceptions (system handlers) and 34 interrupts. “Interrupts” on page 45 provides an overview of the NVIC controller and the interrupt map. Exceptions and interrupts are detailed in the ARM® Cortex™-M3 Technical Reference Manual. 1.4.2 Motor Control Peripherals To enhance motor control, the LM3S6952 controller features Pulse Width Modulation (PWM) outputs and the Quadrature Encoder Interface (QEI). 1.4.2.1 PWM Pulse width modulation (PWM) is a powerful technique for digitally encoding analog signal levels. High-resolution counters are used to generate a square wave, and the duty cycle of the square 30 November 30, 2007 Preliminary Architectural Overview wave is modulated to encode an analog signal. Typical applications include switching power supplies and motor control. On the LM3S6952, PWM motion control functionality can be achieved through: ■ Dedicated, flexible motion control hardware using the PWM pins ■ The motion control features of the general-purpose timers using the CCP pins PWM Pins (see page 466) The LM3S6952 PWM module consists of two PWM generator blocks and a control block. Each PWM generator block contains one timer (16-bit down or up/down counter), two comparators, a PWM signal generator, a dead-band generator, and an interrupt/ADC-trigger selector. The control block determines the polarity of the PWM signals, and which signals are passed through to the pins. Each PWM generator block produces two PWM signals that can either be independent signals or a single pair of complementary signals with dead-band delays inserted. The output of the PWM generation blocks are managed by the output control block before being passed to the device pins. CCP Pins (see page 210) The General-Purpose Timer Module's CCP (Capture Compare PWM) pins are software programmable to support a simple PWM mode with a software-programmable output inversion of the PWM signal. 1.4.2.2 QEI (see page 501) A quadrature encoder, also known as a 2-channel incremental encoder, converts linear displacement into a pulse signal. By monitoring both the number of pulses and the relative phase of the two signals, you can track the position, direction of rotation, and speed. In addition, a third channel, or index signal, can be used to reset the position counter. The Stellaris quadrature encoder with index (QEI) module interprets the code produced by a quadrature encoder wheel to integrate position over time and determine direction of rotation. In addition, it can capture a running estimate of the velocity of the encoder wheel. 1.4.3 Analog Peripherals To handle analog signals, the LM3S6952 microcontroller offers an Analog-to-Digital Converter (ADC). For support of analog signals, the LM3S6952 microcontroller offers three analog comparators. 1.4.3.1 ADC (see page 263) An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a discrete digital number. The LM3S6952 ADC module features 10-bit conversion resolution and supports three input channels, plus an internal temperature sensor. Four buffered sample sequences allow rapid sampling of up to eight analog input sources without controller intervention. Each sample sequence provides flexible programming with fully configurable input source, trigger events, interrupt generation, and sequence priority. 1.4.3.2 Analog Comparators (see page 453) An analog comparator is a peripheral that compares two analog voltages, and provides a logical output that signals the comparison result. November 30, 2007 31 Preliminary LM3S6952 Microcontroller The LM3S6952 microcontroller provides three independent integrated analog comparators that can be configured to drive an output or generate an interrupt or ADC event. A comparator can compare a test voltage against any one of these voltages: ■ An individual external reference voltage ■ A shared single external reference voltage ■ A shared internal reference voltage The comparator can provide its output to a device pin, acting as a replacement for an analog comparator on the board, or it can be used to signal the application via interrupts or triggers to the ADC to cause it to start capturing a sample sequence. The interrupt generation and ADC triggering logic is separate. This means, for example, that an interrupt can be generated on a rising edge and the ADC triggered on a falling edge. 1.4.4 Serial Communications Peripherals The LM3S6952 controller supports both asynchronous and synchronous serial communications with: ■ Three fully programmable 16C550-type UARTs ■ One SSI module ■ One I2C module ■ Ethernet controller 1.4.4.1 UART (see page 296) A Universal Asynchronous Receiver/Transmitter (UART) is an integrated circuit used for RS-232C serial communications, containing a transmitter (parallel-to-serial converter) and a receiver (serial-to-parallel converter), each clocked separately. The LM3S6952 controller includes three fully programmable 16C550-type UARTs that support data transfer speeds up to 460.8 Kbps. (Although similar in functionality to a 16C550 UART, it is not register-compatible.) In addition, each UART is capable of supporting IrDA. Separate 16x8 transmit (TX) and 16x12 receive (RX) FIFOs reduce CPU interrupt service loading. The UART can generate individually masked interrupts from the RX, TX, modem status, and error conditions. The module provides a single combined interrupt when any of the interrupts are asserted and are unmasked. 1.4.4.2 SSI (see page 337) Synchronous Serial Interface (SSI) is a four-wire bi-directional communications interface. The LM3S6952 controller includes one SSI module that provides the functionality for synchronous serial communications with peripheral devices, and can be configured to use the Freescale SPI, MICROWIRE, or TI synchronous serial interface frame formats. The size of the data frame is also configurable, and can be set between 4 and 16 bits, inclusive. The SSI module performs serial-to-parallel conversion on data received from a peripheral device, and parallel-to-serial conversion on data transmitted to a peripheral device. The TX and RX paths are buffered with internal FIFOs, allowing up to eight 16-bit values to be stored independently. 32 November 30, 2007 Preliminary Architectural Overview The SSI module can be configured as either a master or slave device. As a slave device, the SSI module can also be configured to disable its output, which allows a master device to be coupled with multiple slave devices. The SSI module also includes a programmable bit rate clock divider and prescaler to generate the output serial clock derived from the SSI module's input clock. Bit rates are generated based on the input clock and the maximum bit rate is determined by the connected peripheral. 1.4.4.3 I2C (see page 374) The Inter-Integrated Circuit (I2C) bus provides bi-directional data transfer through a two-wire design (a serial data line SDA and a serial clock line SCL). The I2C bus interfaces to external I2C devices such as serial memory (RAMs and ROMs), networking devices, LCDs, tone generators, and so on. The I2C bus may also be used for system testing and diagnostic purposes in product development and manufacture. The LM3S6952 controller includes one I2C module that provides the ability to communicate to other IC devices over an I2C bus. The I2C bus supports devices that can both transmit and receive (write and read) data. Devices on the I2C bus can be designated as either a master or a slave. The I2C module supports both sending and receiving data as either a master or a slave, and also supports the simultaneous operation as both a master and a slave. The four I2C modes are: Master Transmit, Master Receive, Slave Transmit, and Slave Receive. A Stellaris® I2C module can operate at two speeds: Standard (100 Kbps) and Fast (400 Kbps). Both the I2C master and slave can generate interrupts. The I2C master generates interrupts when a transmit or receive operation completes (or aborts due to an error). The I2C slave generates interrupts when data has been sent or requested by a master. 1.4.4.4 Ethernet Controller (see page 409) Ethernet is a frame-based computer networking technology for local area networks (LANs). Ethernet has been standardized as IEEE 802.3. It defines a number of wiring and signaling standards for the physical layer, two means of network access at the Media Access Control (MAC)/Data Link Layer, and a common addressing format. The Stellaris® Ethernet Controller consists of a fully integrated media access controller (MAC) and network physical (PHY) interface device. The Ethernet Controller conforms to IEEE 802.3 specifications and fully supports 10BASE-T and 100BASE-TX standards. In addition, the Ethernet Controller supports automatic MDI/MDI-X cross-over correction. 1.4.5 System Peripherals 1.4.5.1 Programmable GPIOs (see page 163) General-purpose input/output (GPIO) pins offer flexibility for a variety of connections. The Stellaris® GPIO module is composed of seven physical GPIO blocks, each corresponding to an individual GPIO port. The GPIO module is FiRM-compliant (compliant to the ARM Foundation IP for Real-Time Microcontrollers specification) and supports 6-43 programmable input/output pins. The number of GPIOs available depends on the peripherals being used (see “Signal Tables” on page 519 for the signals available to each GPIO pin). November 30, 2007 33 Preliminary LM3S6952 Microcontroller The GPIO module features programmable interrupt generation as either edge-triggered or level-sensitive on all pins, programmable control for GPIO pad configuration, and bit masking in both read and write operations through address lines. 1.4.5.2 Three Programmable Timers (see page 204) Programmable timers can be used to count or time external events that drive the Timer input pins. The Stellaris® General-Purpose Timer Module (GPTM) contains three GPTM blocks. Each GPTM block provides two 16-bit timers/counters that can be configured to operate independently as timers or event counters, or configured to operate as one 32-bit timer or one 32-bit Real-Time Clock (RTC). Timers can also be used to trigger analog-to-digital (ADC) conversions. When configured in 32-bit mode, a timer can run as a Real-Time Clock (RTC), one-shot timer or periodic timer. When in 16-bit mode, a timer can run as a one-shot timer or periodic timer, and can extend its precision by using an 8-bit prescaler. A 16-bit timer can also be configured for event capture or Pulse Width Modulation (PWM) generation. 1.4.5.3 Watchdog Timer (see page 240) A watchdog timer can generate nonmaskable interrupts (NMIs) or a reset when a time-out value is reached. The watchdog timer is used to regain control when a system has failed due to a software error or to the failure of an external device to respond in the expected way. The Stellaris® Watchdog Timer module consists of a 32-bit down counter, a programmable load register, interrupt generation logic, and a locking register. The Watchdog Timer can be configured to generate an interrupt to the controller on its first time-out, and to generate a reset signal on its second time-out. Once the Watchdog Timer has been configured, the lock register can be written to prevent the timer configuration from being inadvertently altered. 1.4.6 Memory Peripherals The LM3S6952 controller offers both single-cycle SRAM and single-cycle Flash memory. 1.4.6.1 SRAM (see page 139) The LM3S6952 static random access memory (SRAM) controller supports 64 KB SRAM. The internal SRAM of the Stellaris® devices is located at offset 0x0000.0000 of the device memory map. To reduce the number of time-consuming read-modify-write (RMW) operations, ARM has introduced bit-banding technology in the new Cortex-M3 processor. With a bit-band-enabled processor, certain regions in the memory map (SRAM and peripheral space) can use address aliases to access individual bits in a single, atomic operation. 1.4.6.2 Flash (see page 140) The LM3S6952 Flash controller supports 256 KB of flash memory. The flash is organized as a set of 1-KB blocks that can be individually erased. Erasing a block causes the entire contents of the block to be reset to all 1s. These blocks are paired into a set of 2-KB blocks that can be individually protected. The blocks can be marked as read-only or execute-only, providing different levels of code protection. Read-only blocks cannot be erased or programmed, protecting the contents of those blocks from being modified. Execute-only blocks cannot be erased or programmed, and can only be read by the controller instruction fetch mechanism, protecting the contents of those blocks from being read by either the controller or by a debugger. 34 November 30, 2007 Preliminary Architectural Overview 1.4.7 Additional Features 1.4.7.1 Memory Map (see page 43) A memory map lists the location of instructions and data in memory. The memory map for the LM3S6952 controller can be found in “Memory Map” on page 43. Register addresses are given as a hexadecimal increment, relative to the module's base address as shown in the memory map. The ARM® Cortex™-M3 Technical Reference Manual provides further information on the memory map. 1.4.7.2 JTAG TAP Controller (see page 48) The Joint Test Action Group (JTAG) port provides a standardized serial interface for controlling the Test Access Port (TAP) and associated test logic. The TAP, JTAG instruction register, and JTAG data registers can be used to test the interconnects of assembled printed circuit boards, obtain manufacturing information on the components, and observe and/or control the inputs and outputs of the controller during normal operation. The JTAG port provides a high degree of testability and chip-level access at a low cost. The JTAG port is comprised of the standard five pins: TRST, TCK, TMS, TDI, and TDO. Data is transmitted serially into the controller on TDI and out of the controller on TDO. The interpretation of this data is dependent on the current state of the TAP controller. For detailed information on the operation of the JTAG port and TAP controller, please refer to the IEEE Standard 1149.1-Test Access Port and Boundary-Scan Architecture. The Luminary Micro JTAG controller works with the ARM JTAG controller built into the Cortex-M3 core. This is implemented by multiplexing the TDO outputs from both JTAG controllers. ARM JTAG instructions select the ARM TDO output while Luminary Micro JTAG instructions select the Luminary Micro TDO outputs. The multiplexer is controlled by the Luminary Micro JTAG controller, which has comprehensive programming for the ARM, Luminary Micro, and unimplemented JTAG instructions. 1.4.7.3 System Control and Clocks (see page 59) System control determines the overall operation of the device. It provides information about the device, controls the clocking of the device and individual peripherals, and handles reset detection and reporting. 1.4.7.4 Hibernation Module (see page 120) The Hibernation module provides logic to switch power off to the main processor and peripherals, and to wake on external or time-based events. The Hibernation module includes power-sequencing logic, a real-time clock with a pair of match registers, low-battery detection circuitry, and interrupt signalling to the processor. It also includes 64 32-bit words of non-volatile memory that can be used for saving state during hibernation. 1.4.8 Hardware Details Details on the pins and package can be found in the following sections: ■ “Pin Diagram” on page 518 ■ “Signal Tables” on page 519 ■ “Operating Characteristics” on page 533 ■ “Electrical Characteristics” on page 534 November 30, 2007 35 Preliminary LM3S6952 Microcontroller ■ “Package Information” on page 549 36 November 30, 2007 Preliminary Architectural Overview 2 ARM Cortex-M3 Processor Core The ARM Cortex-M3 processor provides the core for a high-performance, low-cost platform that meets the needs of minimal memory implementation, reduced pin count, and low power consumption, while delivering outstanding computational performance and exceptional system response to interrupts. Features include: ■ Compact core. ■ Thumb-2 instruction set, delivering the high-performance expected of an ARM core in the memory size usually associated with 8- and 16-bit devices; typically in the range of a few kilobytes of memory for microcontroller class applications. ■ Rapid application execution through Harvard architecture characterized by separate buses for instruction and data. ■ Exceptional interrupt handling, by implementing the register manipulations required for handling an interrupt in hardware. ■ Memory protection unit (MPU) to provide a privileged mode of operation for complex applications. ■ Migration from the ARM7™ processor family for better performance and power efficiency. ■ Full-featured debug solution with a: – Serial Wire JTAG Debug Port (SWJ-DP) – Flash Patch and Breakpoint (FPB) unit for implementing breakpoints – Data Watchpoint and Trigger (DWT) unit for implementing watchpoints, trigger resources, and system profiling – Instrumentation Trace Macrocell (ITM) for support of printf style debugging – Trace Port Interface Unit (TPIU) for bridging to a Trace Port Analyzer The Stellaris® family of microcontrollers builds on this core to bring high-performance 32-bit computing to cost-sensitive embedded microcontroller applications, such as factory automation and control, industrial control power devices, building and home automation, and stepper motors. For more information on the ARM Cortex-M3 processor core, see the ARM® Cortex™-M3 Technical Reference Manual. For information on SWJ-DP, see the ARM® CoreSight Technical Reference Manual. November 30, 2007 37 Preliminary LM3S6952 Microcontroller 2.1 Block Diagram Figure 2-1. CPU Block Diagram Private Peripheral Bus (internal) Data Watchpoint and Trace Interrupts Debug Sleep Instrumentation Trace Macrocell Trace Port Interface Unit CM3 Core Instructions Data Flash Patch and Breakpoint Memory Protection Unit Adv. High- Perf. Bus Access Port Nested Vectored Interrupt Controller Serial Wire JTAG Debug Port Bus Matrix Adv. Peripheral Bus I-code bus D-code bus System bus ROM Table Private Peripheral Bus (external) Serial Wire Output Trace Port (SWO) ARM Cortex-M3 2.2 Functional Description Important: The ARM® Cortex™-M3 Technical Reference Manual describes all the features of an ARM Cortex-M3 in detail. However, these features differ based on the implementation. This section describes the Stellaris® implementation. Luminary Micro has implemented the ARM Cortex-M3 core as shown in Figure 2-1 on page 38. As noted in the ARM® Cortex™-M3 Technical Reference Manual, several Cortex-M3 components are flexible in their implementation: SW/JTAG-DP, ETM, TPIU, the ROM table, the MPU, and the Nested Vectored Interrupt Controller (NVIC). Each of these is addressed in the sections that follow. 2.2.1 Serial Wire and JTAG Debug Luminary Micro has replaced the ARM SW-DP and JTAG-DP with the ARM CoreSight™-compliant Serial Wire JTAG Debug Port (SWJ-DP) interface. This means Chapter 12, “Debug Port,” of the ARM® Cortex™-M3 Technical Reference Manual does not apply to Stellaris® devices. The SWJ-DP interface combines the SWD and JTAG debug ports into one module. See the CoreSight™ Design Kit Technical Reference Manual for details on SWJ-DP. 38 November 30, 2007 Preliminary ARM Cortex-M3 Processor Core 2.2.2 Embedded Trace Macrocell (ETM) ETM was not implemented in the Stellaris® devices. This means Chapters 15 and 16 of the ARM® Cortex™-M3 Technical Reference Manual can be ignored. 2.2.3 Trace Port Interface Unit (TPIU) The TPIU acts as a bridge between the Cortex-M3 trace data from the ITM, and an off-chip Trace Port Analyzer. The Stellaris® devices have implemented TPIU as shown in Figure 2-2 on page 39. This is similar to the non-ETM version described in the ARM® Cortex™-M3 Technical Reference Manual, however, SWJ-DP only provides SWV output for the TPIU. Figure 2-2. TPIU Block Diagram ATB Interface Asynchronous FIFO APB Interface Trace Out (serializer) Debug ATB Slave Port APB Slave Port Serial Wire Trace Port (SWO) 2.2.4 ROM Table The default ROM table was implemented as described in the ARM® Cortex™-M3 Technical Reference Manual. 2.2.5 Memory Protection Unit (MPU) The Memory Protection Unit (MPU) is included on the LM3S6952 controller and supports the standard ARMv7 Protected Memory System Architecture (PMSA) model. The MPU provides full support for protection regions, overlapping protection regions, access permissions, and exporting memory attributes to the system. 2.2.6 Nested Vectored Interrupt Controller (NVIC) The Nested Vectored Interrupt Controller (NVIC): ■ Facilitates low-latency exception and interrupt handling ■ Controls power management ■ Implements system control registers November 30, 2007 39 Preliminary LM3S6952 Microcontroller The NVIC supports up to 240 dynamically reprioritizable interrupts each with up to 256 levels of priority. The NVIC and the processor core interface are closely coupled, which enables low latency interrupt processing and efficient processing of late arriving interrupts. The NVIC maintains knowledge of the stacked (nested) interrupts to enable tail-chaining of interrupts. You can only fully access the NVIC from privileged mode, but you can pend interrupts in user-mode if you enable the Configuration Control Register (see the ARM® Cortex™-M3 Technical Reference Manual). Any other user-mode access causes a bus fault. All NVIC registers are accessible using byte, halfword, and word unless otherwise stated. All NVIC registers and system debug registers are little endian regardless of the endianness state of the processor. 2.2.6.1 Interrupts The ARM® Cortex™-M3 Technical Reference Manual describes the maximum number of interrupts and interrupt priorities. The LM3S6952 microcontroller supports 34 interrupts with eight priority levels. 2.2.6.2 System Timer (SysTick) Cortex-M3 includes an integrated system timer, SysTick. SysTick provides a simple, 24-bit clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism. The counter can be used in several different ways, for example: ■ An RTOS tick timer which fires at a programmable rate (for example, 100 Hz) and invokes a SysTick routine. ■ A high-speed alarm timer using the system clock. ■ A variable rate alarm or signal timer—the duration is range-dependent on the reference clock used and the dynamic range of the counter. ■ A simple counter. Software can use this to measure time to completion and time used. ■ An internal clock source control based on missing/meeting durations. The COUNTFLAG bit-field in the control and status register can be used to determine if an action completed within a set duration, as part of a dynamic clock management control loop. Functional Description The timer consists of three registers: ■ A control and status counter to configure its clock, enable the counter, enable the SysTick interrupt, and determine counter status. ■ The reload value for the counter, used to provide the counter's wrap value. ■ The current value of the counter. A fourth register, the SysTick Calibration Value Register, is not implemented in the Stellaris® devices. When enabled, the timer counts down from the reload value to zero, reloads (wraps) to the value in the SysTick Reload Value register on the next clock edge, then decrements on subsequent clocks. Writing a value of zero to the Reload Value register disables the counter on the next wrap. When the counter reaches zero, the COUNTFLAG status bit is set. The COUNTFLAG bit clears on reads. 40 November 30, 2007 Preliminary ARM Cortex-M3 Processor Core Writing to the Current Value register clears the register and the COUNTFLAG status bit. The write does not trigger the SysTick exception logic. On a read, the current value is the value of the register at the time the register is accessed. If the core is in debug state (halted), the counter will not decrement. The timer is clocked with respect to a reference clock. The reference clock can be the core clock or an external clock source. SysTick Control and Status Register Use the SysTick Control and Status Register to enable the SysTick features. The reset is 0x0000.0000. Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:17 reserved RO 0 Returns 1 if timer counted to 0 since last time this was read. Clears on read by application. If read by the debugger using the DAP, this bit is cleared on read-only if the MasterType bit in the AHB-AP Control Register is set to 0. Otherwise, the COUNTFLAG bit is not changed by the debugger read. 16 COUNTFLAG R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:3 reserved RO 0 0 = external reference clock. (Not implemented for Stellaris microcontrollers.) 1 = core clock. If no reference clock is provided, it is held at 1 and so gives the same time as the core clock. The core clock must be at least 2.5 times faster than the reference clock. If it is not, the count values are unpredictable. 2 CLKSOURCE R/W 0 1 = counting down to 0 pends the SysTick handler. 0 = counting down to 0 does not pend the SysTick handler. Software can use the COUNTFLAG to determine if ever counted to 0. 1 TICKINT R/W 0 1 = counter operates in a multi-shot way. That is, counter loads with the Reload value and then begins counting down. On reaching 0, it sets the COUNTFLAG to 1 and optionally pends the SysTick handler, based on TICKINT. It then loads the Reload value again, and begins counting. 0 = counter disabled. 0 ENABLE R/W 0 SysTick Reload Value Register Use the SysTick Reload Value Register to specify the start value to load into the current value register when the counter reaches 0. It can be any value between 1 and 0x00FF.FFFF. A start value of 0 is possible, but has no effect because the SysTick interrupt and COUNTFLAG are activated when counting from 1 to 0. Therefore, as a multi-shot timer, repeated over and over, it fires every N+1 clock pulse, where N is any value from 1 to 0x00FF.FFFF. So, if the tick interrupt is required every 100 clock pulses, 99 must be written into the RELOAD. If a new value is written on each tick interrupt, so treated as single shot, then the actual count down must be written. For example, if a tick is next required after 400 clock pulses, 400 must be written into the RELOAD. Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:24 reserved RO 0 November 30, 2007 41 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description 23:0 RELOAD W1C - Value to load into the SysTick Current Value Register when the counter reaches 0. SysTick Current Value Register Use the SysTick Current Value Register to find the current value in the register. Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:24 reserved RO 0 Current value at the time the register is accessed. No read-modify-write protection is provided, so change with care. This register is write-clear. Writing to it with any value clears the register to 0. Clearing this register also clears the COUNTFLAG bit of the SysTick Control and Status Register. 23:0 CURRENT W1C - SysTick Calibration Value Register The SysTick Calibration Value register is not implemented. 42 November 30, 2007 Preliminary ARM Cortex-M3 Processor Core 3 Memory Map The memory map for the LM3S6952 controller is provided in Table 3-1 on page 43. In this manual, register addresses are given as a hexadecimal increment, relative to the module’s base address as shown in the memory map. See also Chapter 4, “Memory Map” in the ARM® Cortex™-M3 Technical Reference Manual. Important: In Table 3-1 on page 43, addresses not listed are reserved. Table 3-1. Memory Mapa For details on registers, see page ... Start End Description Memory 0x0000.0000 0x0003.FFFF On-chip flash b 143 0x2000.0000 0x2000.FFFF Bit-banded on-chip SRAMc 143 0x2010.0000 0x21FF.FFFF Reserved non-bit-banded SRAM space - 0x2200.0000 0x23FF.FFFF Bit-band alias of 0x2000.0000 through 0x200F.FFFF 139 0x2400.0000 0x3FFF.FFFF Reserved non-bit-banded SRAM space - FiRM Peripherals 0x4000.0000 0x4000.0FFF Watchdog timer 242 0x4000.4000 0x4000.4FFF GPIO Port A 169 0x4000.5000 0x4000.5FFF GPIO Port B 169 0x4000.6000 0x4000.6FFF GPIO Port C 169 0x4000.7000 0x4000.7FFF GPIO Port D 169 0x4000.8000 0x4000.8FFF SSI0 348 0x4000.C000 0x4000.CFFF UART0 303 0x4000.D000 0x4000.DFFF UART1 303 0x4000.E000 0x4000.EFFF UART2 303 Peripherals 0x4002.0000 0x4002.07FF I2C Master 0 387 0x4002.0800 0x4002.0FFF I2C Slave 0 400 0x4002.4000 0x4002.4FFF GPIO Port E 169 0x4002.5000 0x4002.5FFF GPIO Port F 169 0x4002.6000 0x4002.6FFF GPIO Port G 169 0x4002.8000 0x4002.8FFF PWM 472 0x4002.C000 0x4002.CFFF QEI0 505 0x4003.0000 0x4003.0FFF Timer0 215 0x4003.1000 0x4003.1FFF Timer1 215 0x4003.2000 0x4003.2FFF Timer2 215 0x4003.8000 0x4003.8FFF ADC 269 0x4003.C000 0x4003.CFFF Analog Comparators 453 0x4004.8000 0x4004.8FFF Ethernet Controller 417 0x400F.C000 0x400F.CFFF Hibernation Module 126 November 30, 2007 43 Preliminary LM3S6952 Microcontroller For details on registers, see page ... Start End Description 0x400F.D000 0x400F.DFFF Flash control 143 0x400F.E000 0x400F.EFFF System control 66 0x4200.0000 0x43FF.FFFF Bit-banded alias of 0x4000.0000 through 0x400F.FFFF - Private Peripheral Bus ARM® Cortex™-M3 Technical Reference Manual 0xE000.0000 0xE000.0FFF Instrumentation Trace Macrocell (ITM) 0xE000.1000 0xE000.1FFF Data Watchpoint and Trace (DWT) 0xE000.2000 0xE000.2FFF Flash Patch and Breakpoint (FPB) 0xE000.3000 0xE000.DFFF Reserved 0xE000.E000 0xE000.EFFF Nested Vectored Interrupt Controller (NVIC) 0xE000.F000 0xE003.FFFF Reserved 0xE004.0000 0xE004.0FFF Trace Port Interface Unit (TPIU) 0xE004.1000 0xE004.1FFF Reserved - 0xE004.2000 0xE00F.FFFF Reserved - 0xE010.0000 0xFFFF.FFFF Reserved for vendor peripherals - a. All reserved space returns a bus fault when read or written. b. The unavailable flash will bus fault throughout this range. c. The unavailable SRAM will bus fault throughout this range. 44 November 30, 2007 Preliminary Memory Map 4 Interrupts The ARM Cortex-M3 processor and the Nested Vectored Interrupt Controller (NVIC) prioritize and handle all exceptions. All exceptions are handled in Handler Mode. The processor state is automatically stored to the stack on an exception, and automatically restored from the stack at the end of the Interrupt Service Routine (ISR). The vector is fetched in parallel to the state saving, which enables efficient interrupt entry. The processor supports tail-chaining, which enables back-to-back interrupts to be performed without the overhead of state saving and restoration. Table 4-1 on page 45 lists all the exceptions. Software can set eight priority levels on seven of these exceptions (system handlers) as well as on 34 interrupts (listed in Table 4-2 on page 46). Priorities on the system handlers are set with the NVIC System Handler Priority registers. Interrupts are enabled through the NVIC Interrupt Set Enable register and prioritized with the NVIC Interrupt Priority registers. You can also group priorities by splitting priority levels into pre-emption priorities and subpriorities. All the interrupt registers are described in Chapter 8, “Nested Vectored Interrupt Controller” in the ARM® Cortex™-M3 Technical Reference Manual. Internally, the highest user-settable priority (0) is treated as fourth priority, after a Reset, NMI, and a Hard Fault. Note that 0 is the default priority for all the settable priorities. If you assign the same priority level to two or more interrupts, their hardware priority (the lower the position number) determines the order in which the processor activates them. For example, if both GPIO Port A and GPIO Port B are priority level 1, then GPIO Port A has higher priority. See Chapter 5, “Exceptions” and Chapter 8, “Nested Vectored Interrupt Controller” in the ARM® Cortex™-M3 Technical Reference Manual for more information on exceptions and interrupts. Note: In Table 4-2 on page 46 interrupts not listed are reserved. Table 4-1. Exception Types Exception Type Position Prioritya Description - 0 - Stack top is loaded from first entry of vector table on reset. Invoked on power up and warm reset. On first instruction, drops to lowest priority (and then is called the base level of activation). This is asynchronous. Reset 1 -3 (highest) Cannot be stopped or preempted by any exception but reset. This is asynchronous. An NMI is only producible by software, using the NVIC Interrupt Control State register. Non-Maskable 2 -2 Interrupt (NMI) All classes of Fault, when the fault cannot activate due to priority or the configurable fault handler has been disabled. This is synchronous. Hard Fault 3 -1 MPU mismatch, including access violation and no match. This is synchronous. The priority of this exception can be changed. Memory Management 4 settable Pre-fetch fault, memory access fault, and other address/memory related faults. This is synchronous when precise and asynchronous when imprecise. You can enable or disable this fault. Bus Fault 5 settable Usage fault, such as undefined instruction executed or illegal state transition attempt. This is synchronous. Usage Fault 6 settable - 7-10 - Reserved. SVCall 11 settable System service call with SVC instruction. This is synchronous. November 30, 2007 45 Preliminary LM3S6952 Microcontroller Exception Type Position Prioritya Description Debug monitor (when not halting). This is synchronous, but only active when enabled. It does not activate if lower priority than the current activation. Debug Monitor 12 settable - 13 - Reserved. Pendable request for system service. This is asynchronous and only pended by software. PendSV 14 settable SysTick 15 settable System tick timer has fired. This is asynchronous. Asserted from outside the ARM Cortex-M3 core and fed through the NVIC (prioritized). These are all asynchronous. Table 4-2 on page 46 lists the interrupts on the LM3S6952 controller. 16 and settable above Interrupts a. 0 is the default priority for all the settable priorities. Table 4-2. Interrupts Interrupt (Bit in Interrupt Registers) Description 0 GPIO Port A 1 GPIO Port B 2 GPIO Port C 3 GPIO Port D 4 GPIO Port E 5 UART0 6 UART1 7 SSI0 8 I2C0 9 PWM Fault 10 PWM Generator 0 11 PWM Generator 1 13 QEI0 14 ADC Sequence 0 15 ADC Sequence 1 16 ADC Sequence 2 17 ADC Sequence 3 18 Watchdog timer 19 Timer0 A 20 Timer0 B 21 Timer1 A 22 Timer1 B 23 Timer2 A 24 Timer2 B 25 Analog Comparator 0 26 Analog Comparator 1 27 Analog Comparator 2 28 System Control 29 Flash Control 30 GPIO Port F 46 November 30, 2007 Preliminary Interrupts Interrupt (Bit in Interrupt Registers) Description 31 GPIO Port G 33 UART2 42 Ethernet Controller 43 Hibernation Module November 30, 2007 47 Preliminary LM3S6952 Microcontroller 5 JTAG Interface The Joint Test Action Group (JTAG) port is an IEEE standard that defines a Test Access Port and Boundary Scan Architecture for digital integrated circuits and provides a standardized serial interface for controlling the associated test logic. The TAP, Instruction Register (IR), and Data Registers (DR) can be used to test the interconnections of assembled printed circuit boards and obtain manufacturing information on the components. The JTAG Port also provides a means of accessing and controlling design-for-test features such as I/O pin observation and control, scan testing, and debugging. The JTAG port is comprised of the standard five pins: TRST, TCK, TMS, TDI, and TDO. Data is transmitted serially into the controller on TDI and out of the controller on TDO. The interpretation of this data is dependent on the current state of the TAP controller. For detailed information on the operation of the JTAG port and TAP controller, please refer to the IEEE Standard 1149.1-Test Access Port and Boundary-Scan Architecture. The Luminary Micro JTAG controller works with the ARM JTAG controller built into the Cortex-M3 core. This is implemented by multiplexing the TDO outputs from both JTAG controllers. ARM JTAG instructions select the ARM TDO output while Luminary Micro JTAG instructions select the Luminary Micro TDO outputs. The multiplexer is controlled by the Luminary Micro JTAG controller, which has comprehensive programming for the ARM, Luminary Micro, and unimplemented JTAG instructions. The JTAG module has the following features: ■ IEEE 1149.1-1990 compatible Test Access Port (TAP) controller ■ Four-bit Instruction Register (IR) chain for storing JTAG instructions ■ IEEE standard instructions: – BYPASS instruction – IDCODE instruction – SAMPLE/PRELOAD instruction – EXTEST instruction – INTEST instruction ■ ARM additional instructions: – APACC instruction – DPACC instruction – ABORT instruction ■ Integrated ARM Serial Wire Debug (SWD) See the ARM® Cortex™-M3 Technical Reference Manual for more information on the ARM JTAG controller. 48 November 30, 2007 Preliminary JTAG Interface 5.1 Block Diagram Figure 5-1. JTAG Module Block Diagram Instruction Register (IR) TAP Controller BYPASS Data Register Boundary Scan Data Register IDCODE Data Register ABORT Data Register DPACC Data Register APACC Data Register TRST TCK TMS TDI TDO Cortex-M3 Debug Port 5.2 Functional Description A high-level conceptual drawing of the JTAG module is shown in Figure 5-1 on page 49. The JTAG module is composed of the Test Access Port (TAP) controller and serial shift chains with parallel update registers. The TAP controller is a simple state machine controlled by the TRST, TCK and TMS inputs. The current state of the TAP controller depends on the current value of TRST and the sequence of values captured on TMS at the rising edge of TCK. The TAP controller determines when the serial shift chains capture new data, shift data from TDI towards TDO, and update the parallel load registers. The current state of the TAP controller also determines whether the Instruction Register (IR) chain or one of the Data Register (DR) chains is being accessed. The serial shift chains with parallel load registers are comprised of a single Instruction Register (IR) chain and multiple Data Register (DR) chains. The current instruction loaded in the parallel load register determines which DR chain is captured, shifted, or updated during the sequencing of the TAP controller. Some instructions, like EXTEST and INTEST, operate on data currently in a DR chain and do not capture, shift, or update any of the chains. Instructions that are not implemented decode to the BYPASS instruction to ensure that the serial path between TDI and TDO is always connected (see Table 5-2 on page 55 for a list of implemented instructions). See “JTAG and Boundary Scan” on page 545 for JTAG timing diagrams. November 30, 2007 49 Preliminary LM3S6952 Microcontroller 5.2.1 JTAG Interface Pins The JTAG interface consists of five standard pins: TRST, TCK, TMS, TDI, and TDO. These pins and their associated reset state are given in Table 5-1 on page 50. Detailed information on each pin follows. Table 5-1. JTAG Port Pins Reset State Pin Name Data Direction Internal Pull-Up Internal Pull-Down Drive Strength Drive Value TRST Input Enabled Disabled N/A N/A TCK Input Enabled Disabled N/A N/A TMS Input Enabled Disabled N/A N/A TDI Input Enabled Disabled N/A N/A TDO Output Enabled Disabled 2-mA driver High-Z 5.2.1.1 Test Reset Input (TRST) The TRST pin is an asynchronous active Low input signal for initializing and resetting the JTAG TAP controller and associated JTAG circuitry. When TRST is asserted, the TAP controller resets to the Test-Logic-Reset state and remains there while TRST is asserted. When the TAP controller enters the Test-Logic-Reset state, the JTAG Instruction Register (IR) resets to the default instruction, IDCODE. By default, the internal pull-up resistor on the TRST pin is enabled after reset. Changes to the pull-up resistor settings on GPIO Port B should ensure that the internal pull-up resistor remains enabled on PB7/TRST; otherwise JTAG communication could be lost. 5.2.1.2 Test Clock Input (TCK) The TCK pin is the clock for the JTAG module. This clock is provided so the test logic can operate independently of any other system clocks. In addition, it ensures that multiple JTAG TAP controllers that are daisy-chained together can synchronously communicate serial test data between components. During normal operation, TCK is driven by a free-running clock with a nominal 50% duty cycle. When necessary, TCK can be stopped at 0 or 1 for extended periods of time. While TCK is stopped at 0 or 1, the state of the TAP controller does not change and data in the JTAG Instruction and Data Registers is not lost. By default, the internal pull-up resistor on the TCK pin is enabled after reset. This assures that no clocking occurs if the pin is not driven from an external source. The internal pull-up and pull-down resistors can be turned off to save internal power as long as the TCK pin is constantly being driven by an external source. 5.2.1.3 Test Mode Select (TMS) The TMS pin selects the next state of the JTAG TAP controller. TMS is sampled on the rising edge of TCK. Depending on the current TAP state and the sampled value of TMS, the next state is entered. Because the TMS pin is sampled on the rising edge of TCK, the IEEE Standard 1149.1 expects the value on TMS to change on the falling edge of TCK. Holding TMS high for five consecutive TCK cycles drives the TAP controller state machine to the Test-Logic-Reset state. When the TAP controller enters the Test-Logic-Reset state, the JTAG Instruction Register (IR) resets to the default instruction, IDCODE. Therefore, this sequence can be used as a reset mechanism, similar to asserting TRST. The JTAG Test Access Port state machine can be seen in its entirety in Figure 5-2 on page 52. 50 November 30, 2007 Preliminary JTAG Interface By default, the internal pull-up resistor on the TMS pin is enabled after reset. Changes to the pull-up resistor settings on GPIO Port C should ensure that the internal pull-up resistor remains enabled on PC1/TMS; otherwise JTAG communication could be lost. 5.2.1.4 Test Data Input (TDI) The TDI pin provides a stream of serial information to the IR chain and the DR chains. TDI is sampled on the rising edge of TCK and, depending on the current TAP state and the current instruction, presents this data to the proper shift register chain. Because the TDI pin is sampled on the rising edge of TCK, the IEEE Standard 1149.1 expects the value on TDI to change on the falling edge of TCK. By default, the internal pull-up resistor on the TDI pin is enabled after reset. Changes to the pull-up resistor settings on GPIO Port C should ensure that the internal pull-up resistor remains enabled on PC2/TDI; otherwise JTAG communication could be lost. 5.2.1.5 Test Data Output (TDO) The TDO pin provides an output stream of serial information from the IR chain or the DR chains. The value of TDO depends on the current TAP state, the current instruction, and the data in the chain being accessed. In order to save power when the JTAG port is not being used, the TDO pin is placed in an inactive drive state when not actively shifting out data. Because TDO can be connected to the TDI of another controller in a daisy-chain configuration, the IEEE Standard 1149.1 expects the value on TDO to change on the falling edge of TCK. By default, the internal pull-up resistor on the TDO pin is enabled after reset. This assures that the pin remains at a constant logic level when the JTAG port is not being used. The internal pull-up and pull-down resistors can be turned off to save internal power if a High-Z output value is acceptable during certain TAP controller states. 5.2.2 JTAG TAP Controller The JTAG TAP controller state machine is shown in Figure 5-2 on page 52. The TAP controller state machine is reset to the Test-Logic-Reset state on the assertion of a Power-On-Reset (POR) or the assertion of TRST. Asserting the correct sequence on the TMS pin allows the JTAG module to shift in new instructions, shift in data, or idle during extended testing sequences. For detailed information on the function of the TAP controller and the operations that occur in each state, please refer to IEEE Standard 1149.1. November 30, 2007 51 Preliminary LM3S6952 Microcontroller Figure 5-2. Test Access Port State Machine Test Logic Reset Run Test Idle Select DR Scan Select IR Scan Capture DR Capture IR Shift DR Shift IR Exit 1 DR Exit 1 IR Exit 2 DR Exit 2 IR Pause DR Pause IR Update DR Update IR 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5.2.3 Shift Registers The Shift Registers consist of a serial shift register chain and a parallel load register. The serial shift register chain samples specific information during the TAP controller’s CAPTURE states and allows this information to be shifted out of TDO during the TAP controller’s SHIFT states. While the sampled data is being shifted out of the chain on TDO, new data is being shifted into the serial shift register on TDI. This new data is stored in the parallel load register during the TAP controller’s UPDATE states. Each of the shift registers is discussed in detail in “Register Descriptions” on page 55. 5.2.4 Operational Considerations There are certain operational considerations when using the JTAG module. Because the JTAG pins can be programmed to be GPIOs, board configuration and reset conditions on these pins must be considered. In addition, because the JTAG module has integrated ARM Serial Wire Debug, the method for switching between these two operational modes is described below. 52 November 30, 2007 Preliminary JTAG Interface 5.2.4.1 GPIO Functionality When the controller is reset with either a POR or RST, the JTAG/SWD port pins default to their JTAG/SWD configurations. The default configuration includes enabling digital functionality (setting GPIODEN to 1), enabling the pull-up resistors (setting GPIOPUR to 1), and enabling the alternate hardware function (setting GPIOAFSEL to 1) for the PB7 and PC[3:0] JTAG/SWD pins. It is possible for software to configure these pins as GPIOs after reset by writing 0s to PB7 and PC[3:0] in the GPIOAFSEL register. If the user does not require the JTAG/SWD port for debugging or board-level testing, this provides five more GPIOs for use in the design. Caution – If the JTAG pins are used as GPIOs in a design, PB7 and PC2 cannot have external pull-down resistors connected to both of them at the same time. If both pins are pulled Low during reset, the controller has unpredictable behavior. If this happens, remove one or both of the pull-down resistors, and apply RST or power-cycle the part. In addition, it is possible to create a software sequence that prevents the debugger from connecting to the Stellaris® microcontroller. If the program code loaded into flash immediately changes the JTAG pins to their GPIO functionality, the debugger may not have enough time to connect and halt the controller before the JTAG pin functionality switches. This may lock the debugger out of the part. This can be avoided with a software routine that restores JTAG functionality based on an external or software trigger. The commit control registers provide a layer of protection against accidental programming of critical hardware peripherals. Writes to protected bits of the GPIO Alternate Function Select (GPIOAFSEL) register (see page 179) are not committed to storage unless the GPIO Lock (GPIOLOCK) register (see page 189) has been unlocked and the appropriate bits of the GPIO Commit (GPIOCR) register (see page 190) have been set to 1. Recovering a "Locked" Device If software configures any of the JTAG/SWD pins as GPIO and loses the ability to communicate with the debugger, there is a debug sequence that can be used to recover the device. Performing a total of ten JTAG-to-SWD and SWD-to-JTAG switch sequences while holding the device in reset mass erases the flash memory. The sequence to recover the device is: 1. Assert and hold the RST signal. 2. Perform the JTAG-to-SWD switch sequence. 3. Perform the SWD-to-JTAG switch sequence. 4. Perform the JTAG-to-SWD switch sequence. 5. Perform the SWD-to-JTAG switch sequence. 6. Perform the JTAG-to-SWD switch sequence. 7. Perform the SWD-to-JTAG switch sequence. 8. Perform the JTAG-to-SWD switch sequence. 9. Perform the SWD-to-JTAG switch sequence. 10. Perform the JTAG-to-SWD switch sequence. 11. Perform the SWD-to-JTAG switch sequence. November 30, 2007 53 Preliminary LM3S6952 Microcontroller 12. Release the RST signal. The JTAG-to-SWD and SWD-to-JTAG switch sequences are described in “ARM Serial Wire Debug (SWD)” on page 54. When performing switch sequences for the purpose of recovering the debug capabilities of the device, only steps 1 and 2 of the switch sequence need to be performed. 5.2.4.2 ARM Serial Wire Debug (SWD) In order to seamlessly integrate the ARM Serial Wire Debug (SWD) functionality, a serial-wire debugger must be able to connect to the Cortex-M3 core without having to perform, or have any knowledge of, JTAG cycles. This is accomplished with a SWD preamble that is issued before the SWD session begins. The preamble used to enable the SWD interface of the SWJ-DP module starts with the TAP controller in the Test-Logic-Reset state. From here, the preamble sequences the TAP controller through the following states: Run Test Idle, Select DR, Select IR, Test Logic Reset, Test Logic Reset, Run Test Idle, Run Test Idle, Select DR, Select IR, Test Logic Reset, Test Logic Reset, Run Test Idle, Run Test Idle, Select DR, Select IR, and Test Logic Reset states. Stepping through this sequences of the TAP state machine enables the SWD interface and disables the JTAG interface. For more information on this operation and the SWD interface, see the ARM® Cortex™-M3 Technical Reference Manual and the ARM® CoreSight Technical Reference Manual. Because this sequence is a valid series of JTAG operations that could be issued, the ARM JTAG TAP controller is not fully compliant to the IEEE Standard 1149.1. This is the only instance where the ARM JTAG TAP controller does not meet full compliance with the specification. Due to the low probability of this sequence occurring during normal operation of the TAP controller, it should not affect normal performance of the JTAG interface. JTAG-to-SWD Switching To switch the operating mode of the Debug Access Port (DAP) from JTAG to SWD mode, the external debug hardware must send a switch sequence to the device. The 16-bit switch sequence for switching to SWD mode is defined as b1110011110011110, transmitted LSB first. This can also be represented as 16'hE79E when transmitted LSB first. The complete switch sequence should consist of the following transactions on the TCK/SWCLK and TMS/SWDIO signals: 1. Send at least 50 TCK/SWCLK cycles with TMS/SWDIO set to 1. This ensures that both JTAG and SWD are in their reset/idle states. 2. Send the 16-bit JTAG-to-SWD switch sequence, 16'hE79E. 3. Send at least 50 TCK/SWCLK cycles with TMS/SWDIO set to 1. This ensures that if SWJ-DP was already in SWD mode, before sending the switch sequence, the SWD goes into the line reset state. SWD-to-JTAG Switching To switch the operating mode of the Debug Access Port (DAP) from SWD to JTAG mode, the external debug hardware must send a switch sequence to the device. The 16-bit switch sequence for switching to JTAG mode is defined as b1110011110011110, transmitted LSB first. This can also be represented as 16'hE73C when transmitted LSB first. The complete switch sequence should consist of the following transactions on the TCK/SWCLK and TMS/SWDIO signals: 1. Send at least 50 TCK/SWCLK cycles with TMS/SWDIO set to 1. This ensures that both JTAG and SWD are in their reset/idle states. 54 November 30, 2007 Preliminary JTAG Interface 2. Send the 16-bit SWD-to-JTAG switch sequence, 16'hE73C. 3. Send at least 5 TCK/SWCLK cycles with TMS/SWDIO set to 1. This ensures that if SWJ-DP was already in JTAG mode, before sending the switch sequence, the JTAG goes into the Test Logic Reset state. 5.3 Initialization and Configuration After a Power-On-Reset or an external reset (RST), the JTAG pins are automatically configured for JTAG communication. No user-defined initialization or configuration is needed. However, if the user application changes these pins to their GPIO function, they must be configured back to their JTAG functionality before JTAG communication can be restored. This is done by enabling the five JTAG pins (PB7 and PC[3:0]) for their alternate function using the GPIOAFSEL register. 5.4 Register Descriptions There are no APB-accessible registers in the JTAG TAP Controller or Shift Register chains. The registers within the JTAG controller are all accessed serially through the TAP Controller. The registers can be broken down into two main categories: Instruction Registers and Data Registers. 5.4.1 Instruction Register (IR) The JTAG TAP Instruction Register (IR) is a four-bit serial scan chain with a parallel load register connected between the JTAG TDI and TDO pins. When the TAP Controller is placed in the correct states, bits can be shifted into the Instruction Register. Once these bits have been shifted into the chain and updated, they are interpreted as the current instruction. The decode of the Instruction Register bits is shown in Table 5-2 on page 55. A detailed explanation of each instruction, along with its associated Data Register, follows. Table 5-2. JTAG Instruction Register Commands IR[3:0] Instruction Description Drives the values preloaded into the Boundary Scan Chain by the SAMPLE/PRELOAD instruction onto the pads. 0000 EXTEST Drives the values preloaded into the Boundary Scan Chain by the SAMPLE/PRELOAD instruction into the controller. 0001 INTEST Captures the current I/O values and shifts the sampled values out of the Boundary Scan Chain while new preload data is shifted in. 0010 SAMPLE / PRELOAD 1000 ABORT Shifts data into the ARM Debug Port Abort Register. 1010 DPACC Shifts data into and out of the ARM DP Access Register. 1011 APACC Shifts data into and out of the ARM AC Access Register. Loads manufacturing information defined by the IEEE Standard 1149.1 into the IDCODE chain and shifts it out. 1110 IDCODE 1111 BYPASS Connects TDI to TDO through a single Shift Register chain. All Others Reserved Defaults to the BYPASS instruction to ensure that TDI is always connected to TDO. 5.4.1.1 EXTEST Instruction The EXTEST instruction does not have an associated Data Register chain. The EXTEST instruction uses the data that has been preloaded into the Boundary Scan Data Register using the SAMPLE/PRELOAD instruction. When the EXTEST instruction is present in the Instruction Register, the preloaded data in the Boundary Scan Data Register associated with the outputs and output enables are used to drive the GPIO pads rather than the signals coming from the core. This allows November 30, 2007 55 Preliminary LM3S6952 Microcontroller tests to be developed that drive known values out of the controller, which can be used to verify connectivity. 5.4.1.2 INTEST Instruction The INTEST instruction does not have an associated Data Register chain. The INTEST instruction uses the data that has been preloaded into the Boundary Scan Data Register using the SAMPLE/PRELOAD instruction. When the INTEST instruction is present in the Instruction Register, the preloaded data in the Boundary Scan Data Register associated with the inputs are used to drive the signals going into the core rather than the signals coming from the GPIO pads. This allows tests to be developed that drive known values into the controller, which can be used for testing. It is important to note that although the RST input pin is on the Boundary Scan Data Register chain, it is only observable. 5.4.1.3 SAMPLE/PRELOAD Instruction The SAMPLE/PRELOAD instruction connects the Boundary Scan Data Register chain between TDI and TDO. This instruction samples the current state of the pad pins for observation and preloads new test data. Each GPIO pad has an associated input, output, and output enable signal. When the TAP controller enters the Capture DR state during this instruction, the input, output, and output-enable signals to each of the GPIO pads are captured. These samples are serially shifted out of TDO while the TAP controller is in the Shift DR state and can be used for observation or comparison in various tests. While these samples of the inputs, outputs, and output enables are being shifted out of the Boundary Scan Data Register, new data is being shifted into the Boundary Scan Data Register from TDI. Once the new data has been shifted into the Boundary Scan Data Register, the data is saved in the parallel load registers when the TAP controller enters the Update DR state. This update of the parallel load register preloads data into the Boundary Scan Data Register that is associated with each input, output, and output enable. This preloaded data can be used with the EXTEST and INTEST instructions to drive data into or out of the controller. Please see “Boundary Scan Data Register” on page 58 for more information. 5.4.1.4 ABORT Instruction The ABORT instruction connects the associated ABORT Data Register chain between TDI and TDO. This instruction provides read and write access to the ABORT Register of the ARM Debug Access Port (DAP). Shifting the proper data into this Data Register clears various error bits or initiates a DAP abort of a previous request. Please see the “ABORT Data Register” on page 58 for more information. 5.4.1.5 DPACC Instruction The DPACC instruction connects the associated DPACC Data Register chain between TDI and TDO. This instruction provides read and write access to the DPACC Register of the ARM Debug Access Port (DAP). Shifting the proper data into this register and reading the data output from this register allows read and write access to the ARM debug and status registers. Please see “DPACC Data Register” on page 58 for more information. 5.4.1.6 APACC Instruction The APACC instruction connects the associated APACC Data Register chain between TDI and TDO. This instruction provides read and write access to the APACC Register of the ARM Debug Access Port (DAP). Shifting the proper data into this register and reading the data output from this register allows read and write access to internal components and buses through the Debug Port. Please see “APACC Data Register” on page 58 for more information. 56 November 30, 2007 Preliminary JTAG Interface 5.4.1.7 IDCODE Instruction The IDCODE instruction connects the associated IDCODE Data Register chain between TDI and TDO. This instruction provides information on the manufacturer, part number, and version of the ARM core. This information can be used by testing equipment and debuggers to automatically configure their input and output data streams. IDCODE is the default instruction that is loaded into the JTAG Instruction Register when a power-on-reset (POR) is asserted, TRST is asserted, or the Test-Logic-Reset state is entered. Please see “IDCODE Data Register” on page 57 for more information. 5.4.1.8 BYPASS Instruction The BYPASS instruction connects the associated BYPASS Data Register chain between TDI and TDO. This instruction is used to create a minimum length serial path between the TDI and TDO ports. The BYPASS Data Register is a single-bit shift register. This instruction improves test efficiency by allowing components that are not needed for a specific test to be bypassed in the JTAG scan chain by loading them with the BYPASS instruction. Please see “BYPASS Data Register” on page 57 for more information. 5.4.2 Data Registers The JTAG module contains six Data Registers. These include: IDCODE, BYPASS, Boundary Scan, APACC, DPACC, and ABORT serial Data Register chains. Each of these Data Registers is discussed in the following sections. 5.4.2.1 IDCODE Data Register The format for the 32-bit IDCODE Data Register defined by the IEEE Standard 1149.1 is shown in Figure 5-3 on page 57. The standard requires that every JTAG-compliant device implement either the IDCODE instruction or the BYPASS instruction as the default instruction. The LSB of the IDCODE Data Register is defined to be a 1 to distinguish it from the BYPASS instruction, which has an LSB of 0. This allows auto configuration test tools to determine which instruction is the default instruction. The major uses of the JTAG port are for manufacturer testing of component assembly, and program development and debug. To facilitate the use of auto-configuration debug tools, the IDCODE instruction outputs a value of 0x3BA00477. This value indicates an ARM Cortex-M3, Version 1 processor. This allows the debuggers to automatically configure themselves to work correctly with the Cortex-M3 during debug. Figure 5-3. IDCODE Register Format 5.4.2.2 BYPASS Data Register The format for the 1-bit BYPASS Data Register defined by the IEEE Standard 1149.1 is shown in Figure 5-4 on page 58. The standard requires that every JTAG-compliant device implement either the BYPASS instruction or the IDCODE instruction as the default instruction. The LSB of the BYPASS Data Register is defined to be a 0 to distinguish it from the IDCODE instruction, which has an LSB of 1. This allows auto configuration test tools to determine which instruction is the default instruction. November 30, 2007 57 Preliminary LM3S6952 Microcontroller Figure 5-4. BYPASS Register Format 5.4.2.3 Boundary Scan Data Register The format of the Boundary Scan Data Register is shown in Figure 5-5 on page 58. Each GPIO pin, in a counter-clockwise direction from the JTAG port pins, is included in the Boundary Scan Data Register. Each GPIO pin has three associated digital signals that are included in the chain. These signals are input, output, and output enable, and are arranged in that order as can be seen in the figure. In addition to the GPIO pins, the controller reset pin, RST, is included in the chain. Because the reset pin is always an input, only the input signal is included in the Data Register chain. When the Boundary Scan Data Register is accessed with the SAMPLE/PRELOAD instruction, the input, output, and output enable from each digital pad are sampled and then shifted out of the chain to be verified. The sampling of these values occurs on the rising edge of TCK in the Capture DR state of the TAP controller. While the sampled data is being shifted out of the Boundary Scan chain in the Shift DR state of the TAP controller, new data can be preloaded into the chain for use with the EXTEST and INTEST instructions. These instructions either force data out of the controller, with the EXTEST instruction, or into the controller, with the INTEST instruction. Figure 5-5. Boundary Scan Register Format O TDO TDI O IN E UT O O IN U E T O O IN E UT O O IN U E T I N ... ... GPIO PB6 GPIO m RST GPIO m+1 GPIO n For detailed information on the order of the input, output, and output enable bits for each of the GPIO ports, please refer to the Stellaris® Family Boundary Scan Description Language (BSDL) files, downloadable from www.luminarymicro.com. 5.4.2.4 APACC Data Register The format for the 35-bit APACC Data Register defined by ARM is described in the ARM® Cortex™-M3 Technical Reference Manual. 5.4.2.5 DPACC Data Register The format for the 35-bit DPACC Data Register defined by ARM is described in the ARM® Cortex™-M3 Technical Reference Manual. 5.4.2.6 ABORT Data Register The format for the 35-bit ABORT Data Register defined by ARM is described in the ARM® Cortex™-M3 Technical Reference Manual. 58 November 30, 2007 Preliminary JTAG Interface 6 System Control System control determines the overall operation of the device. It provides information about the device, controls the clocking to the core and individual peripherals, and handles reset detection and reporting. 6.1 Functional Description The System Control module provides the following capabilities: ■ Device identification, see “Device Identification” on page 59 ■ Local control, such as reset (see “Reset Control” on page 59), power (see “Power Control” on page 62) and clock control (see “Clock Control” on page 62) ■ System control (Run, Sleep, and Deep-Sleep modes), see “System Control” on page 64 6.1.1 Device Identification Seven read-only registers provide software with information on the microcontroller, such as version, part number, SRAM size, flash size, and other features. See the DID0, DID1, and DC0-DC4 registers. 6.1.2 Reset Control This section discusses aspects of hardware functions during reset as well as system software requirements following the reset sequence. 6.1.2.1 CMOD0 and CMOD1 Test-Mode Control Pins Two pins, CMOD0 and CMOD1, are defined for use by Luminary Micro for testing the devices during manufacture. They have no end-user function and should not be used. The CMOD pins should be connected to ground. 6.1.2.2 Reset Sources The controller has five sources of reset: 1. External reset input pin (RST) assertion, see “RST Pin Assertion” on page 59. 2. Power-on reset (POR), see “Power-On Reset (POR)” on page 60. 3. Internal brown-out (BOR) detector, see “Brown-Out Reset (BOR)” on page 60. 4. Software-initiated reset (with the software reset registers), see “Software Reset” on page 61. 5. A watchdog timer reset condition violation, see “Watchdog Timer Reset” on page 61. After a reset, the Reset Cause (RESC) register is set with the reset cause. The bits in this register are sticky and maintain their state across multiple reset sequences, except when an internal POR is the cause, and then all the other bits in the RESC register are cleared except for the POR indicator. 6.1.2.3 RST Pin Assertion The external reset pin (RST) resets the controller. This resets the core and all the peripherals except the JTAG TAP controller (see “JTAG Interface” on page 48). The external reset sequence is as follows: November 30, 2007 59 Preliminary LM3S6952 Microcontroller 1. The external reset pin (RST) is asserted and then de-asserted. 2. The internal reset is released and the core loads from memory the initial stack pointer, the initial program counter, the first instruction designated by the program counter, and begins execution. A few clocks cycles from RST de-assertion to the start of the reset sequence is necessary for synchronization. The external reset timing is shown in Figure 23-11 on page 547. 6.1.2.4 Power-On Reset (POR) The Power-On Reset (POR) circuit monitors the power supply voltage (VDD). The POR circuit generates a reset signal to the internal logic when the power supply ramp reaches a threshold value (VTH). If the application only uses the POR circuit, the RST input needs to be connected to the power supply (VDD) through a pull-up resistor (1K to 10K Ω). The device must be operating within the specified operating parameters at the point when the on-chip power-on reset pulse is complete. The 3.3-V power supply to the device must reach 3.0 V within 10 msec of it crossing 2.0 V to guarantee proper operation. For applications that require the use of an external reset to hold the device in reset longer than the internal POR, the RST input may be used with the circuit as shown in Figure 6-1 on page 60. Figure 6-1. External Circuitry to Extend Reset R1 C1 R2 RST Stellaris D1 The R1 and C1 components define the power-on delay. The R2 resistor mitigates any leakage from the RST input. The diode (D1) discharges C1 rapidly when the power supply is turned off. The Power-On Reset sequence is as follows: 1. The controller waits for the later of external reset (RST) or internal POR to go inactive. 2. The internal reset is released and the core loads from memory the initial stack pointer, the initial program counter, the first instruction designated by the program counter, and begins execution. The internal POR is only active on the initial power-up of the controller. The Power-On Reset timing is shown in Figure 23-12 on page 548. Note: The power-on reset also resets the JTAG controller. An external reset does not. 6.1.2.5 Brown-Out Reset (BOR) A drop in the input voltage resulting in the assertion of the internal brown-out detector can be used to reset the controller. This is initially disabled and may be enabled by software. The system provides a brown-out detection circuit that triggers if the power supply (VDD) drops below a brown-out threshold voltage (VBTH). If a brown-out condition is detected, the system may generate a controller interrupt or a system reset. 60 November 30, 2007 Preliminary System Control Brown-out resets are controlled with the Power-On and Brown-Out Reset Control (PBORCTL) register. The BORIOR bit in the PBORCTL register must be set for a brown-out condition to trigger a reset. The brown-out reset is equivelent to an assertion of the external RST input and the reset is held active until the proper VDD level is restored. The RESC register can be examined in the reset interrupt handler to determine if a Brown-Out condition was the cause of the reset, thus allowing software to determine what actions are required to recover. The internal Brown-Out Reset timing is shown in Figure 23-13 on page 548. 6.1.2.6 Software Reset Software can reset a specific peripheral or generate a reset to the entire system . Peripherals can be individually reset by software via three registers that control reset signals to each peripheral (see the SRCRn registers). If the bit position corresponding to a peripheral is set and subsequently cleared, the peripheral is reset. The encoding of the reset registers is consistent with the encoding of the clock gating control for peripherals and on-chip functions (see “System Control” on page 64). Note that all reset signals for all clocks of the specified unit are asserted as a result of a software-initiated reset. The entire system can be reset by software by setting the SYSRESETREQ bit in the Cortex-M3 Application Interrupt and Reset Control register resets the entire system including the core. The software-initiated system reset sequence is as follows: 1. A software system reset is initiated by writing the SYSRESETREQ bit in the ARM Cortex-M3 Application Interrupt and Reset Control register. 2. An internal reset is asserted. 3. The internal reset is deasserted and the controller loads from memory the initial stack pointer, the initial program counter, and the first instruction designated by the program counter, and then begins execution. The software-initiated system reset timing is shown in Figure 23-14 on page 548. 6.1.2.7 Watchdog Timer Reset The watchdog timer module's function is to prevent system hangs. The watchdog timer can be configured to generate an interrupt to the controller on its first time-out, and to generate a reset signal on its second time-out. After the first time-out event, the 32-bit counter is reloaded with the value of the Watchdog Timer Load (WDTLOAD) register, and the timer resumes counting down from that value. If the timer counts down to its zero state again before the first time-out interrupt is cleared, and the reset signal has been enabled, the watchdog timer asserts its reset signal to the system. The watchdog timer reset sequence is as follows: 1. The watchdog timer times out for the second time without being serviced. 2. An internal reset is asserted. 3. The internal reset is released and the controller loads from memory the initial stack pointer, the initial program counter, the first instruction designated by the program counter, and begins execution. November 30, 2007 61 Preliminary LM3S6952 Microcontroller The watchdog reset timing is shown in Figure 23-15 on page 548. 6.1.3 Power Control The Stellaris® microcontroller provides an integrated LDO regulator that may be used to provide power to the majority of the controller's internal logic. The LDO regulator provides software a mechanism to adjust the regulated value, in small increments (VSTEP), over the range of 2.25 V to 2.75 V (inclusive)—or 2.5 V ± 10%. The adjustment is made by changing the value of the VADJ field in the LDO Power Control (LDOPCTL) register. Note: The use of the LDO is optional. The internal logic may be supplied by the on-chip LDO or by an external regulator. If the LDO is used, the LDO output pin is connected to the VDD25 pins on the printed circuit board. The LDO requires decoupling capacitors on the printed circuit board. If an external regulator is used, it is strongly recommended that the external regulator supply the controller only and not be shared with other devices on the printed circuit board. 6.1.4 Clock Control System control determines the control of clocks in this part. 6.1.4.1 Fundamental Clock Sources There are four clock sources for use in the device: ■ Internal Oscillator (IOSC): The internal oscillator is an on-chip clock source. It does not require the use of any external components. The frequency of the internal oscillator is 12 MHz ± 30%. Applications that do not depend on accurate clock sources may use this clock source to reduce system cost. The internal oscillator is the clock source the device uses during and following POR. If the main oscillator is required, software must enable the main oscillator following reset and allow the main oscillator to stabilize before changing the clock reference. ■ Main Oscillator: The main oscillator provides a frequency-accurate clock source by one of two means: an external single-ended clock source is connected to the OSC0 input pin, or an external crystal is connected across the OSC0 input and OSC1 output pins. The crystal value allowed depends on whether the main oscillator is used as the clock reference source to the PLL. If so, the crystal must be one of the supported frequencies between 3.579545 MHz through 8.192 MHz (inclusive). If the PLL is not being used, the crystal may be any one of the supported frequencies between 1 MHz and 8.192 MHz. The single-ended clock source range is from DC through the specified speed of the device. The supported crystals are listed in the XTAL bit in the RCC register (see page 75). ■ Internal 30-kHz Oscillator: The internal 30-kHz oscillator is similar to the internal oscillator, except that it provides an operational frequency of 30 kHz ± 30%. It is intended for use during Deep-Sleep power-saving modes. This power-savings mode benefits from reduced internal switching and also allows the main oscillator to be powered down. ■ External Real-Time Oscillator: The external real-time oscillator provides a low-frequency, accurate clock reference. It is intended to provide the system with a real-time clock source. The real-time oscillator is part of the Hibernation Module (“Hibernation Module” on page 120) and may also provide an accurate source of Deep-Sleep or Hibernate mode power savings. The internal system clock (sysclk), is derived from any of the four sources plus two others: the output of the internal PLL, and the internal oscillator divided by four (3 MHz ± 30%). The frequency of the PLL clock reference must be in the range of 3.579545 MHz to 8.192 MHz (inclusive). 62 November 30, 2007 Preliminary System Control The Run-Mode Clock Configuration (RCC) and Run-Mode Clock Configuration 2 (RCC2) registers provide control for the system clock. The RCC2 register is provided to extend fields that offer additional encodings over the RCC register. When used, the RCC2 register field values are used by the logic over the corresponding field in the RCC register. In particular, RCC2 provides for a larger assortment of clock configuration options. 6.1.4.2 Crystal Configuration for the Main Oscillator (MOSC) The main oscillator supports the use of a select number of crystals. If the main oscillator is used by the PLL as a reference clock, the supported range of crystals is 3.579545 to 8.192 MHz, otherwise, the range of supported crystals is 1 to 8.192 MHz. The XTAL bit in the RCC register (see page 75) describes the available crystal choices and default programming values. Software configures the RCC register XTAL field with the crystal number. If the PLL is used in the design, the XTAL field value is internally translated to the PLL settings. 6.1.4.3 PLL Frequency Configuration The PLL is disabled by default during power-on reset and is enabled later by software if required. Software configures the PLL input reference clock source, specifies the output divisor to set the system clock frequency, and enables the PLL to drive the output. If the main oscillator provides the clock reference to the PLL, the translation provided by hardware and used to program the PLL is available for software in the XTAL to PLL Translation (PLLCFG) register (see page 79). The internal translation provides a translation within ± 1% of the targeted PLL VCO frequency. The Crystal Value field (XTAL) on page 75 describes the available crystal choices and default programming of the PLLCFG register. The crystal number is written into the XTAL field of the Run-Mode Clock Configuration (RCC) register. Any time the XTAL field changes, the new settings are translated and the internal PLL settings are updated. 6.1.4.4 PLL Modes The PLL has two modes of operation: Normal and Power-Down ■ Normal: The PLL multiplies the input clock reference and drives the output. ■ Power-Down: Most of the PLL internal circuitry is disabled and the PLL does not drive the output. The modes are programmed using the RCC/RCC2 register fields (see page 75 and page 80). 6.1.4.5 PLL Operation If the PLL configuration is changed, the PLL output frequency is unstable until it reconverges (relocks) to the new setting. The time between the configuration change and relock is TREADY (see Table 23-6 on page 537). During this time, the PLL is not usable as a clock reference. The PLL is changed by one of the following: ■ Change to the XTAL value in the RCC register—writes of the same value do not cause a relock. ■ Change in the PLL from Power-Down to Normal mode. A counter is defined to measure the TREADY requirement. The counter is clocked by the main oscillator. The range of the main oscillator has been taken into account and the down counter is set November 30, 2007 63 Preliminary LM3S6952 Microcontroller to 0x1200 (that is, ~600 μs at an 8.192 MHz external oscillator clock). . Hardware is provided to keep the PLL from being used as a system clock until the TREADY condition is met after one of the two changes above. It is the user's responsibility to have a stable clock source (like the main oscillator) before the RCC/RCC2 register is switched to use the PLL. 6.1.5 System Control For power-savings purposes, the RCGCn , SCGCn , and DCGCn registers control the clock gating logic for each peripheral or block in the system while the controller is in Run, Sleep, and Deep-Sleep mode, respectively. In Run mode, the processor executes code. In Sleep mode, the clock frequency of the active peripherals is unchanged, but the processor is not clocked and therefore no longer executes code. In Deep-Sleep mode, the clock frequency of the active peripherals may change (depending on the Run mode clock configuration) in addition to the processor clock being stopped. An interrupt returns the device to Run mode from one of the sleep modes; the sleep modes are entered on request from the code. Each mode is described in more detail below. There are four levels of operation for the device defined as: ■ Run Mode. Run mode provides normal operation of the processor and all of the peripherals that are currently enabled by the RCGCn registers. The system clock can be any of the available clock sources including the PLL. ■ Sleep Mode. Sleep mode is entered by the Cortex-M3 core executing a WFI (Wait for Interrupt) instruction. Any properly configured interrupt event in the system will bring the processor back into Run mode. See the system control NVIC section of the ARM® Cortex™-M3 Technical Reference Manual for more details. In Sleep mode, the Cortex-M3 processor core and the memory subsystem are not clocked. Peripherals are clocked that are enabled in the SCGCn register when auto-clock gating is enabled (see the RCC register) or the RCGCn register when the auto-clock gating is disabled. The system clock has the same source and frequency as that during Run mode. ■ Deep-Sleep Mode. Deep-Sleep mode is entered by first writing the Deep Sleep Enable bit in the ARM Cortex-M3 NVIC system control register and then executing a WFI instruction. Any properly configured interrupt event in the system will bring the processor back into Run mode. See the system control NVIC section of the ARM® Cortex™-M3 Technical Reference Manual for more details. The Cortex-M3 processor core and the memory subsystem are not clocked. Peripherals are clocked that are enabled in the DCGCn register when auto-clock gating is enabled (see the RCC register) or the RCGCn register when auto-clock gating is disabled. The system clock source is the main oscillator by default or the internal oscillator specified in the DSLPCLKCFG register if one is enabled. When the DSLPCLKCFG register is used, the internal oscillator is powered up, if necessary, and the main oscillator is powered down. If the PLL is running at the time of the WFI instruction, hardware will power the PLL down and override the SYSDIV field of the active RCC/RCC2 register to be /16 or /64, respectively. When the Deep-Sleep exit event occurs, hardware brings the system clock back to the source and frequency it had at the onset of Deep-Sleep mode before enabling the clocks that had been stopped during the Deep-Sleep duration. ■ Hibernate Mode. In this mode, the power supplies are turned off to the main part of the device and only the Hibernation module's circuitry is active. An external wake event or RTC event is required to bring the device back to Run mode. The Cortex-M3 processor and peripherals outside 64 November 30, 2007 Preliminary System Control of the Hibernation module see a normal "power on" sequence and the processor starts running code. It can determine that it has been restarted from Hibernate mode by inspecting the Hibernation module registers. 6.2 Initialization and Configuration The PLL is configured using direct register writes to the RCC/RCC2 register. If the RCC2 register is being used, the USERCC2 bit must be set and the appropriate RCC2 bit/field is used. The steps required to successfully change the PLL-based system clock are: 1. Bypass the PLL and system clock divider by setting the BYPASS bit and clearing the USESYS bit in the RCC register. This configures the system to run off a “raw” clock source (using the main oscillator or internal oscillator) and allows for the new PLL configuration to be validated before switching the system clock to the PLL. 2. Select the crystal value (XTAL) and oscillator source (OSCSRC), and clear the PWRDN bit in RCC/RCC2. Setting the XTAL field automatically pulls valid PLL configuration data for the appropriate crystal, and clearing the PWRDN bit powers and enables the PLL and its output. 3. Select the desired system divider (SYSDIV) in RCC/RCC2 and set the USESYS bit in RCC. The SYSDIV field determines the system frequency for the microcontroller. 4. Wait for the PLL to lock by polling the PLLLRIS bit in the Raw Interrupt Status (RIS) register. 5. Enable use of the PLL by clearing the BYPASS bit in RCC/RCC2. 6.3 Register Map Table 6-1 on page 65 lists the System Control registers, grouped by function. The offset listed is a hexadecimal increment to the register’s address, relative to the System Control base address of 0x400F.E000. Note: Spaces in the System Control register space that are not used are reserved for future or internal use by Luminary Micro, Inc. Software should not modify any reserved memory address. Table 6-1. System Control Register Map See Offset Name Type Reset Description page 0x000 DID0 RO - Device Identification 0 67 0x004 DID1 RO - Device Identification 1 83 0x008 DC0 RO 0x00FF.007F Device Capabilities 0 85 0x010 DC1 RO 0x0011.32FF Device Capabilities 1 86 0x014 DC2 RO 0x0707.1117 Device Capabilities 2 88 0x018 DC3 RO 0x0F07.BFCF Device Capabilities 3 90 0x01C DC4 RO 0x5000.007F Device Capabilities 4 92 0x030 PBORCTL R/W 0x0000.7FFD Brown-Out Reset Control 69 0x034 LDOPCTL R/W 0x0000.0000 LDO Power Control 70 November 30, 2007 65 Preliminary LM3S6952 Microcontroller See Offset Name Type Reset Description page 0x040 SRCR0 R/W 0x00000000 Software Reset Control 0 115 0x044 SRCR1 R/W 0x00000000 Software Reset Control 1 116 0x048 SRCR2 R/W 0x00000000 Software Reset Control 2 118 0x050 RIS RO 0x0000.0000 Raw Interrupt Status 71 0x054 IMC R/W 0x0000.0000 Interrupt Mask Control 72 0x058 MISC R/W1C 0x0000.0000 Masked Interrupt Status and Clear 73 0x05C RESC R/W - Reset Cause 74 0x060 RCC R/W 0x07AE.3AD1 Run-Mode Clock Configuration 75 0x064 PLLCFG RO - XTAL to PLL Translation 79 0x070 RCC2 R/W 0x0780.2800 Run-Mode Clock Configuration 2 80 0x100 RCGC0 R/W 0x00000040 Run Mode Clock Gating Control Register 0 94 0x104 RCGC1 R/W 0x00000000 Run Mode Clock Gating Control Register 1 100 0x108 RCGC2 R/W 0x00000000 Run Mode Clock Gating Control Register 2 109 0x110 SCGC0 R/W 0x00000040 Sleep Mode Clock Gating Control Register 0 96 0x114 SCGC1 R/W 0x00000000 Sleep Mode Clock Gating Control Register 1 103 0x118 SCGC2 R/W 0x00000000 Sleep Mode Clock Gating Control Register 2 111 0x120 DCGC0 R/W 0x00000040 Deep Sleep Mode Clock Gating Control Register 0 98 0x124 DCGC1 R/W 0x00000000 Deep Sleep Mode Clock Gating Control Register 1 106 0x128 DCGC2 R/W 0x00000000 Deep Sleep Mode Clock Gating Control Register 2 113 0x144 DSLPCLKCFG R/W 0x0780.0000 Deep Sleep Clock Configuration 82 6.4 Register Descriptions All addresses given are relative to the System Control base address of 0x400F.E000. 66 November 30, 2007 Preliminary System Control Register 1: Device Identification 0 (DID0), offset 0x000 This register identifies the version of the device. Device Identification 0 (DID0) Base 0x400F.E000 Offset 0x000 Type RO, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved VER reserved CLASS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MAJOR MINOR Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset - - - - - - - - - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 DID0 Version This field defines the DID0 register format version. The version number is numeric. The value of the VER field is encoded as follows: Value Description First revision of the DID0 register format, for Stellaris® Fury-class devices . 0x1 30:28 VER RO 0x1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:24 reserved RO 0x0 Device Class The CLASS field value identifies the internal design from which all mask sets are generated for all devices in a particular product line. The CLASS field value is changed for new product lines, for changes in fab process (for example, a remap or shrink), or any case where the MAJOR or MINOR fields require differentiation from prior devices. The value of the CLASS field is encoded as follows (all other encodings are reserved): Value Description 0x0 Stellaris® Sandstorm-class devices. 0x1 Stellaris® Fury-class devices. 23:16 CLASS RO 0x1 November 30, 2007 67 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Major Revision This field specifies the major revision number of the device. The major revision reflects changes to base layers of the design. The major revision number is indicated in the part number as a letter (A for first revision, B for second, and so on). This field is encoded as follows: Value Description 0x0 Revision A (initial device) 0x1 Revision B (first base layer revision) 0x2 Revision C (second base layer revision) and so on. 15:8 MAJOR RO - Minor Revision This field specifies the minor revision number of the device. The minor revision reflects changes to the metal layers of the design. The MINOR field value is reset when the MAJOR field is changed. This field is numeric and is encoded as follows: Value Description 0x0 Initial device, or a major revision update. 0x1 First metal layer change. 0x2 Second metal layer change. and so on. 7:0 MINOR RO - 68 November 30, 2007 Preliminary System Control Register 2: Brown-Out Reset Control (PBORCTL), offset 0x030 This register is responsible for controlling reset conditions after initial power-on reset. Brown-Out Reset Control (PBORCTL) Base 0x400F.E000 Offset 0x030 Type R/W, reset 0x0000.7FFD 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved BORIOR reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x0 BOR Interrupt or Reset This bit controls how a BOR event is signaled to the controller. If set, a reset is signaled. Otherwise, an interrupt is signaled. 1 BORIOR R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 November 30, 2007 69 Preliminary LM3S6952 Microcontroller Register 3: LDO Power Control (LDOPCTL), offset 0x034 The VADJ field in this register adjusts the on-chip output voltage (VOUT). LDO Power Control (LDOPCTL) Base 0x400F.E000 Offset 0x034 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved VADJ Type RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0 LDO Output Voltage This field sets the on-chip output voltage. The programming values for the VADJ field are provided below. Value VOUT (V) 0x00 2.50 0x01 2.45 0x02 2.40 0x03 2.35 0x04 2.30 0x05 2.25 0x06-0x3F Reserved 0x1B 2.75 0x1C 2.70 0x1D 2.65 0x1E 2.60 0x1F 2.55 5:0 VADJ R/W 0x0 70 November 30, 2007 Preliminary System Control Register 4: Raw Interrupt Status (RIS), offset 0x050 Central location for system control raw interrupts. These are set and cleared by hardware. Raw Interrupt Status (RIS) Base 0x400F.E000 Offset 0x050 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PLLLRIS reserved BORRIS reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0 PLL Lock Raw Interrupt Status This bit is set when the PLL TREADY Timer asserts. 6 PLLLRIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:2 reserved RO 0 Brown-Out Reset Raw Interrupt Status This bit is the raw interrupt status for any brown-out conditions. If set, a brown-out condition is currently active. This is an unregistered signal from the brown-out detection circuit. An interrupt is reported if the BORIM bit in the IMC register is set and the BORIOR bit in the PBORCTL register is cleared. 1 BORRIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 November 30, 2007 71 Preliminary LM3S6952 Microcontroller Register 5: Interrupt Mask Control (IMC), offset 0x054 Central location for system control interrupt masks. Interrupt Mask Control (IMC) Base 0x400F.E000 Offset 0x054 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PLLLIM reserved BORIM reserved Type RO RO RO RO RO RO RO RO RO R/W RO RO RO RO R/W RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0 PLL Lock Interrupt Mask This bit specifies whether a current limit detection is promoted to a controller interrupt. If set, an interrupt is generated if PLLLRIS in RIS is set; otherwise, an interrupt is not generated. 6 PLLLIM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:2 reserved RO 0 Brown-Out Reset Interrupt Mask This bit specifies whether a brown-out condition is promoted to a controller interrupt. If set, an interrupt is generated if BORRIS is set; otherwise, an interrupt is not generated. 1 BORIM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 72 November 30, 2007 Preliminary System Control Register 6: Masked Interrupt Status and Clear (MISC), offset 0x058 Central location for system control result of RIS AND IMC to generate an interrupt to the controller. All of the bits are R/W1C and this action also clears the corresponding raw interrupt bit in the RIS register (see page 71). Masked Interrupt Status and Clear (MISC) Base 0x400F.E000 Offset 0x058 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PLLLMIS reserved BORMIS reserved Type RO RO RO RO RO RO RO RO RO R/W1C RO RO RO RO R/W1C RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0 PLL Lock Masked Interrupt Status This bit is set when the PLL TREADY timer asserts. The interrupt is cleared by writing a 1 to this bit. 6 PLLLMIS R/W1C 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:2 reserved RO 0 BOR Masked Interrupt Status The BORMIS is simply the BORRIS ANDed with the mask value, BORIM. 1 BORMIS R/W1C 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 November 30, 2007 73 Preliminary LM3S6952 Microcontroller Register 7: Reset Cause (RESC), offset 0x05C This register is set with the reset cause after reset. The bits in this register are sticky and maintain their state across multiple reset sequences, except when an external reset is the cause, and then all the other bits in the RESC register are cleared. Reset Cause (RESC) Base 0x400F.E000 Offset 0x05C Type R/W, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved LDO SW WDT BOR POR EXT Type RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0 LDO Reset When set, indicates the LDO circuit has lost regulation and has generated a reset event. 5 LDO R/W - Software Reset When set, indicates a software reset is the cause of the reset event. 4 SW R/W - Watchdog Timer Reset When set, indicates a watchdog reset is the cause of the reset event. 3 WDT R/W - Brown-Out Reset When set, indicates a brown-out reset is the cause of the reset event. 2 BOR R/W - Power-On Reset When set, indicates a power-on reset is the cause of the reset event. 1 POR R/W - External Reset When set, indicates an external reset (RST assertion) is the cause of the reset event. 0 EXT R/W - 74 November 30, 2007 Preliminary System Control Register 8: Run-Mode Clock Configuration (RCC), offset 0x060 This register is defined to provide source control and frequency speed. Run-Mode Clock Configuration (RCC) Base 0x400F.E000 Offset 0x060 Type R/W, reset 0x07AE.3AD1 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved ACG SYSDIV USESYSDIV reserved USEPWMDIV PWMDIV reserved Type RO RO RO RO R/W R/W R/W R/W R/W R/W RO R/W R/W R/W R/W RO Reset 0 0 0 0 0 1 1 1 1 0 0 0 1 1 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PWRDN reserved BYPASS reserved XTAL OSCSRC reserved IOSCDIS MOSCDIS Type RO RO R/W RO R/W RO R/W R/W R/W R/W R/W R/W RO RO R/W R/W Reset 0 0 1 1 1 0 1 0 1 1 0 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:28 reserved RO 0x0 Auto Clock Gating This bit specifies whether the system uses the Sleep-Mode Clock Gating Control (SCGCn) registers and Deep-Sleep-Mode Clock Gating Control (DCGCn) registers if the controller enters a Sleep or Deep-Sleep mode (respectively). If set, the SCGCn or DCGCn registers are used to control the clocks distributed to the peripherals when the controller is in a sleep mode. Otherwise, the Run-Mode Clock Gating Control (RCGCn) registers are used when the controller enters a sleep mode. The RCGCn registers are always used to control the clocks in Run mode. This allows peripherals to consume less power when the controller is in a sleep mode and the peripheral is unused. 27 ACG R/W 0 November 30, 2007 75 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description System Clock Divisor Specifies which divisor is used to generate the system clock from the PLL output. The PLL VCO frequency is 400 MHz. Value Divisor (BYPASS=1) Frequency (BYPASS=0) 0x0 reserved reserved 0x1 /2 reserved 0x2 /3 reserved 0x3 /4 50 MHz 0x4 /5 40 MHz 0x5 /6 33.33 MHz 0x6 /7 28.57 MHz 0x7 /8 25 MHz 0x8 /9 22.22 MHz 0x9 /10 20 MHz 0xA /11 18.18 MHz 0xB /12 16.67 MHz 0xC /13 15.38 MHz 0xD /14 14.29 MHz 0xE /15 13.33 MHz 0xF /16 12.5 MHz (default) When reading the Run-Mode Clock Configuration (RCC) register (see page 75), the SYSDIV value is MINSYSDIV if a lower divider was requested and the PLL is being used. This lower value is allowed to divide a non-PLL source. 26:23 SYSDIV R/W 0xF Enable System Clock Divider Use the system clock divider as the source for the system clock. The system clock divider is forced to be used when the PLL is selected as the source. 22 USESYSDIV R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 21 reserved RO 0 Enable PWM Clock Divisor Use the PWM clock divider as the source for the PWM clock. 20 USEPWMDIV R/W 0 76 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description PWM Unit Clock Divisor This field specifies the binary divisor used to predivide the system clock down for use as the timing reference for the PWM module. This clock is only power 2 divide and rising edge is synchronous without phase shift from the system clock. Value Divisor 0x0 /2 0x1 /4 0x2 /8 0x3 /16 0x4 /32 0x5 /64 0x6 /64 0x7 /64 (default) 19:17 PWMDIV R/W 0x7 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 16:14 reserved RO 0 PLL Power Down This bit connects to the PLL PWRDN input. The reset value of 1 powers down the PLL. 13 PWRDN R/W 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 12 reserved RO 1 PLL Bypass Chooses whether the system clock is derived from the PLL output or the OSC source. If set, the clock that drives the system is the OSC source. Otherwise, the clock that drives the system is the PLL output clock divided by the system divider. Note: The ADC must be clocked from the PLL or directly from a 14-MHz to 18-MHz clock source to operate properly. While the ADC works in a 14-18 MHz range, to maintain a 1 M sample/second rate, the ADC must be provided a 16-MHz clock source. 11 BYPASS R/W 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 10 reserved RO 0 November 30, 2007 77 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Crystal Value This field specifies the crystal value attached to the main oscillator. The encoding for this field is provided below. Crystal Frequency (MHz) Using the PLL Crystal Frequency (MHz) Not Using the PLL Value 0x0 1.000 reserved 0x1 1.8432 reserved 0x2 2.000 reserved 0x3 2.4576 reserved 0x4 3.579545 MHz 0x5 3.6864 MHz 0x6 4 MHz 0x7 4.096 MHz 0x8 4.9152 MHz 0x9 5 MHz 0xA 5.12 MHz 0xB 6 MHz (reset value) 0xC 6.144 MHz 0xD 7.3728 MHz 0xE 8 MHz 0xF 8.192 MHz 9:6 XTAL R/W 0xB Oscillator Source Picks among the four input sources for the OSC. The values are: Value Input Source 0x0 Main oscillator (default) 0x1 Internal oscillator (default) 0x2 Internal oscillator / 4 (this is necessary if used as input to PLL) 0x3 reserved 5:4 OSCSRC R/W 0x1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:2 reserved RO 0x0 Internal Oscillator Disable 0: Internal oscillator (IOSC) is enabled. 1: Internal oscillator is disabled. 1 IOSCDIS R/W 0 Main Oscillator Disable 0: Main oscillator is enabled. 1: Main oscillator is disabled (default). 0 MOSCDIS R/W 1 78 November 30, 2007 Preliminary System Control Register 9: XTAL to PLL Translation (PLLCFG), offset 0x064 This register provides a means of translating external crystal frequencies into the appropriate PLL settings. This register is initialized during the reset sequence and updated anytime that the XTAL field changes in the Run-Mode Clock Configuration (RCC) register (see page 75). The PLL frequency is calculated using the PLLCFG field values, as follows: PLLFreq = OSCFreq * F / (R + 1) XTAL to PLL Translation (PLLCFG) Base 0x400F.E000 Offset 0x064 Type RO, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved F R Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 - - - - - - - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:14 reserved RO 0x0 PLL F Value This field specifies the value supplied to the PLL’s F input. 13:5 F RO - PLL R Value This field specifies the value supplied to the PLL’s R input. 4:0 R RO - November 30, 2007 79 Preliminary LM3S6952 Microcontroller Register 10: Run-Mode Clock Configuration 2 (RCC2), offset 0x070 This register overrides the RCC equivalent register fields when the USERCC2 bit is set. This allows RCC2 to be used to extend the capabilities, while also providing a means to be backward-compatible to previous parts. The fields within the RCC2 register occupy the same bit positions as they do within the RCC register as LSB-justified. The SYSDIV2 field is wider so that additional larger divisors are possible. This allows a lower system clock frequency for improved Deep Sleep power consumption. Run-Mode Clock Configuration 2 (RCC2) Base 0x400F.E000 Offset 0x070 Type R/W, reset 0x0780.2800 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 USERCC2 reserved SYSDIV2 reserved Type R/W RO RO R/W R/W R/W R/W R/W R/W RO RO RO RO RO RO RO Reset 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PWRDN2 reserved BYPASS2 reserved OSCSRC2 reserved Type RO RO R/W RO R/W RO RO RO RO R/W R/W R/W RO RO RO RO Reset 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Use RCC2 When set, overrides the RCC register fields. 31 USERCC2 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 30:29 reserved RO 0x0 System Clock Divisor Specifies which divisor is used to generate the system clock from the PLL output. The PLL VCO frequency is 400 MHz. This field is wider than the RCC register SYSDIV field in order to provide additional divisor values. This permits the system clock to be run at much lower frequencies during Deep Sleep mode. For example, where the RCC register SYSDIV encoding of 1111 provides /16, the RCC2 register SYSDIV2 encoding of 111111 provides /64. 28:23 SYSDIV2 R/W 0x0F Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 22:14 reserved RO 0x0 Power-Down PLL When set, powers down the PLL. 13 PWRDN2 R/W 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 12 reserved RO 0 Bypass PLL When set, bypasses the PLL for the clock source. 11 BYPASS2 R/W 1 80 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 10:7 reserved RO 0x0 System Clock Source Value Description 0x0 Main oscillator (MOSC) 0x1 Internal oscillator (IOSC) 0x2 Internal oscillator / 4 0x3 30 kHz internal oscillator 0x7 32 kHz external oscillator 6:4 OSCSRC2 R/W 0x0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0 November 30, 2007 81 Preliminary LM3S6952 Microcontroller Register 11: Deep Sleep Clock Configuration (DSLPCLKCFG), offset 0x144 This register provides configuration information for the hardware control of Deep Sleep Mode. Deep Sleep Clock Configuration (DSLPCLKCFG) Base 0x400F.E000 Offset 0x144 Type R/W, reset 0x0780.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved DSDIVORIDE reserved Type RO RO RO R/W R/W R/W R/W R/W R/W RO RO RO RO RO RO RO Reset 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DSOSCSRC reserved Type RO RO RO RO RO RO RO RO RO R/W R/W R/W RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:29 reserved RO 0x0 Divider Field Override 6-bit system divider field to override when Deep-Sleep occurs with PLL running. 28:23 DSDIVORIDE R/W 0x0F Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 22:7 reserved RO 0x0 Clock Source When set, forces IOSC to be clock source during Deep Sleep mode. Value Name Description 0x0 NOORIDE No override to the oscillator clock source is done 0x1 IOSC Use internal 12 MHz oscillator as source 0x3 30kHz Use 30 kHz internal oscillator 0x7 32kHz Use 32 kHz external oscillator 6:4 DSOSCSRC R/W 0x0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0x0 82 November 30, 2007 Preliminary System Control Register 12: Device Identification 1 (DID1), offset 0x004 This register identifies the device family, part number, temperature range, pin count, and package type. Device Identification 1 (DID1) Base 0x400F.E000 Offset 0x004 Type RO, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 VER FAM PARTNO Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 1 0 0 0 0 0 1 1 1 1 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PINCOUNT reserved TEMP PKG ROHS QUAL Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 1 0 0 0 0 0 0 0 0 1 0 1 1 - - Bit/Field Name Type Reset Description DID1 Version This field defines the DID1 register format version. The version number is numeric. The value of the VER field is encoded as follows (all other encodings are reserved): Value Description First revision of the DID1 register format, indicating a Stellaris Fury-class device. 0x1 31:28 VER RO 0x1 Family This field provides the family identification of the device within the Luminary Micro product portfolio. The value is encoded as follows (all other encodings are reserved): Value Description Stellaris family of microcontollers, that is, all devices with external part numbers starting with LM3S. 0x0 27:24 FAM RO 0x0 Part Number This field provides the part number of the device within the family. The value is encoded as follows (all other encodings are reserved): Value Description 0x78 LM3S6952 23:16 PARTNO RO 0x78 Package Pin Count This field specifies the number of pins on the device package. The value is encoded as follows (all other encodings are reserved): Value Description 0x2 100-pin package 15:13 PINCOUNT RO 0x2 November 30, 2007 83 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 12:8 reserved RO 0 Temperature Range This field specifies the temperature rating of the device. The value is encoded as follows (all other encodings are reserved): Value Description 0x1 Industrial temperature range (-40°C to 85°C) 7:5 TEMP RO 0x1 Package Type This field specifies the package type. The value is encoded as follows (all other encodings are reserved): Value Description 0x1 LQFP package 4:3 PKG RO 0x1 RoHS-Compliance This bit specifies whether the device is RoHS-compliant. A 1 indicates the part is RoHS-compliant. 2 ROHS RO 1 Qualification Status This field specifies the qualification status of the device. The value is encoded as follows (all other encodings are reserved): Value Description 0x0 Engineering Sample (unqualified) 0x1 Pilot Production (unqualified) 0x2 Fully Qualified 1:0 QUAL RO - 84 November 30, 2007 Preliminary System Control Register 13: Device Capabilities 0 (DC0), offset 0x008 This register is predefined by the part and can be used to verify features. Device Capabilities 0 (DC0) Base 0x400F.E000 Offset 0x008 Type RO, reset 0x00FF.007F 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 SRAMSZ Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 FLASHSZ Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description SRAM Size Indicates the size of the on-chip SRAM memory. Value Description 0x00FF 64 KB of SRAM 31:16 SRAMSZ RO 0x00FF Flash Size Indicates the size of the on-chip flash memory. Value Description 0x007F 256 KB of Flash 15:0 FLASHSZ RO 0x007F November 30, 2007 85 Preliminary LM3S6952 Microcontroller Register 14: Device Capabilities 1 (DC1), offset 0x010 This register provides a list of features available in the system. The Stellaris family uses this register format to indicate the availability of the following family features in the specific device: CANs, PWM, ADC, Watchdog timer, Hibernation module, and debug capabilities. This register also indicates the maximum clock frequency and maximum ADC sample rate. The format of this register is consistent with the RCGC0, SCGC0, and DCGC0 clock control registers and the SRCR0 software reset control register. Device Capabilities 1 (DC1) Base 0x400F.E000 Offset 0x010 Type RO, reset 0x0011.32FF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved PWM reserved ADC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MINSYSDIV MAXADCSPD MPU HIB TEMPSNS PLL WDT SWO SWD JTAG Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 1 1 0 0 1 0 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:21 reserved RO 0 PWM Module Present When set, indicates that the PWM module is present. 20 PWM RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:17 reserved RO 0 ADC Module Present When set, indicates that the ADC module is present. 16 ADC RO 1 System Clock Divider Minimum 4-bit divider value for system clock. The reset value is hardware-dependent. See the RCC register for how to change the system clock divisor using the SYSDIV bit. Value Description 0x3 Specifies a 50-MHz CPU clock with a PLL divider of 4. 15:12 MINSYSDIV RO 0x3 Max ADC Speed Indicates the maximum rate at which the ADC samples data. Value Description 0x2 500K samples/second 11:8 MAXADCSPD RO 0x2 86 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description MPU Present When set, indicates that the Cortex-M3 Memory Protection Unit (MPU) module is present. See the ARM Cortex-M3 Technical Reference Manual for details on the MPU. 7 MPU RO 1 Hibernation Module Present When set, indicates that the Hibernation module is present. 6 HIB RO 1 Temp Sensor Present When set, indicates that the on-chip temperature sensor is present. 5 TEMPSNS RO 1 PLL Present When set, indicates that the on-chip Phase Locked Loop (PLL) is present. 4 PLL RO 1 Watchdog Timer Present When set, indicates that a watchdog timer is present. 3 WDT RO 1 SWO Trace Port Present When set, indicates that the Serial Wire Output (SWO) trace port is present. 2 SWO RO 1 SWD Present When set, indicates that the Serial Wire Debugger (SWD) is present. 1 SWD RO 1 JTAG Present When set, indicates that the JTAG debugger interface is present. 0 JTAG RO 1 November 30, 2007 87 Preliminary LM3S6952 Microcontroller Register 15: Device Capabilities 2 (DC2), offset 0x014 This register provides a list of features available in the system. The Stellaris family uses this register format to indicate the availability of the following family features in the specific device: Analog Comparators, General-Purpose Timers, I2Cs, QEIs, SSIs, and UARTs. The format of this register is consistent with the RCGC1, SCGC1, and DCGC1 clock control registers and the SRCR1 software reset control register. Device Capabilities 2 (DC2) Base 0x400F.E000 Offset 0x014 Type RO, reset 0x0707.1117 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved COMP2 COMP1 COMP0 reserved TIMER2 TIMER1 TIMER0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved I2C0 reserved QEI0 reserved SSI0 reserved UART2 UART1 UART0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 1 0 0 0 1 0 0 0 1 0 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:27 reserved RO 0 Analog Comparator 2 Present When set, indicates that analog comparator 2 is present. 26 COMP2 RO 1 Analog Comparator 1 Present When set, indicates that analog comparator 1 is present. 25 COMP1 RO 1 Analog Comparator 0 Present When set, indicates that analog comparator 0 is present. 24 COMP0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 Timer 2 Present When set, indicates that General-Purpose Timer module 2 is present. 18 TIMER2 RO 1 Timer 1 Present When set, indicates that General-Purpose Timer module 1 is present. 17 TIMER1 RO 1 Timer 0 Present When set, indicates that General-Purpose Timer module 0 is present. 16 TIMER0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 I2C Module 0 Present When set, indicates that I2C module 0 is present. 12 I2C0 RO 1 88 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0 QEI0 Present When set, indicates that QEI module 0 is present. 8 QEI0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:5 reserved RO 0 SSI0 Present When set, indicates that SSI module 0 is present. 4 SSI0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0 UART2 Present When set, indicates that UART module 2 is present. 2 UART2 RO 1 UART1 Present When set, indicates that UART module 1 is present. 1 UART1 RO 1 UART0 Present When set, indicates that UART module 0 is present. 0 UART0 RO 1 November 30, 2007 89 Preliminary LM3S6952 Microcontroller Register 16: Device Capabilities 3 (DC3), offset 0x018 This register provides a list of features available in the system. The Stellaris family uses this register format to indicate the availability of the following family features in the specific device: Analog Comparator I/Os, CCP I/Os, ADC I/Os, and PWM I/Os. Device Capabilities 3 (DC3) Base 0x400F.E000 Offset 0x018 Type RO, reset 0x0F07.BFCF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved CCP3 CCP2 CCP1 CCP0 reserved ADC2 ADC1 ADC0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PWMFAULT reserved C2PLUS C2MINUS C1O C1PLUS C1MINUS C0O C0PLUS C0MINUS reserved PWM3 PWM2 PWM1 PWM0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 1 0 1 1 1 1 1 1 1 1 0 0 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:28 reserved RO 0 CCP3 Pin Present When set, indicates that Capture/Compare/PWM pin 3 is present. 27 CCP3 RO 1 CCP2 Pin Present When set, indicates that Capture/Compare/PWM pin 2 is present. 26 CCP2 RO 1 CCP1 Pin Present When set, indicates that Capture/Compare/PWM pin 1 is present. 25 CCP1 RO 1 CCP0 Pin Present When set, indicates that Capture/Compare/PWM pin 0 is present. 24 CCP0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 ADC2 Pin Present When set, indicates that ADC pin 2 is present. 18 ADC2 RO 1 ADC1 Pin Present When set, indicates that ADC pin 1 is present. 17 ADC1 RO 1 ADC0 Pin Present When set, indicates that ADC pin 0 is present. 16 ADC0 RO 1 PWM Fault Pin Present When set, indicates that the PWM Fault pin is present. 15 PWMFAULT RO 1 90 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 14 reserved RO 0 C2+ Pin Present When set, indicates that the analog comparator 2 (+) input pin is present. 13 C2PLUS RO 1 C2- Pin Present When set, indicates that the analog comparator 2 (-) input pin is present. 12 C2MINUS RO 1 C1o Pin Present When set, indicates that the analog comparator 1 output pin is present. 11 C1O RO 1 C1+ Pin Present When set, indicates that the analog comparator 1 (+) input pin is present. 10 C1PLUS RO 1 C1- Pin Present When set, indicates that the analog comparator 1 (-) input pin is present. 9 C1MINUS RO 1 C0o Pin Present When set, indicates that the analog comparator 0 output pin is present. 8 C0O RO 1 C0+ Pin Present When set, indicates that the analog comparator 0 (+) input pin is present. 7 C0PLUS RO 1 C0- Pin Present When set, indicates that the analog comparator 0 (-) input pin is present. 6 C0MINUS RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:4 reserved RO 0 PWM3 Pin Present When set, indicates that the PWM pin 3 is present. 3 PWM3 RO 1 PWM2 Pin Present When set, indicates that the PWM pin 2 is present. 2 PWM2 RO 1 PWM1 Pin Present When set, indicates that the PWM pin 1 is present. 1 PWM1 RO 1 PWM0 Pin Present When set, indicates that the PWM pin 0 is present. 0 PWM0 RO 1 November 30, 2007 91 Preliminary LM3S6952 Microcontroller Register 17: Device Capabilities 4 (DC4), offset 0x01C This register provides a list of features available in the system. The Stellaris family uses this register format to indicate the availability of the following family features in the specific device: Ethernet MAC and PHY, GPIOs, and CCP I/Os. The format of this register is consistent with the RCGC2, SCGC2, and DCGC2 clock control registers and the SRCR2 software reset control register. Device Capabilities 4 (DC4) Base 0x400F.E000 Offset 0x01C Type RO, reset 0x5000.007F 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved EPHY0 reserved EMAC0 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPIOG GPIOF GPIOE GPIOD GPIOC GPIOB GPIOA Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 Ethernet PHY0 Present When set, indicates that Ethernet PHY module 0 is present. 30 EPHY0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 29 reserved RO 0 Ethernet MAC0 Present When set, indicates that Ethernet MAC module 0 is present. 28 EMAC0 RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:7 reserved RO 0 GPIO Port G Present When set, indicates that GPIO Port G is present. 6 GPIOG RO 1 GPIO Port F Present When set, indicates that GPIO Port F is present. 5 GPIOF RO 1 GPIO Port E Present When set, indicates that GPIO Port E is present. 4 GPIOE RO 1 GPIO Port D Present When set, indicates that GPIO Port D is present. 3 GPIOD RO 1 GPIO Port C Present When set, indicates that GPIO Port C is present. 2 GPIOC RO 1 92 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description GPIO Port B Present When set, indicates that GPIO Port B is present. 1 GPIOB RO 1 GPIO Port A Present When set, indicates that GPIO Port A is present. 0 GPIOA RO 1 November 30, 2007 93 Preliminary LM3S6952 Microcontroller Register 18: Run Mode Clock Gating Control Register 0 (RCGC0), offset 0x100 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Run Mode Clock Gating Control Register 0 (RCGC0) Base 0x400F.E000 Offset 0x100 Type R/W, reset 0x00000040 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved PWM reserved ADC Type RO RO RO RO RO RO RO RO RO RO RO R/W RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MAXADCSPD reserved HIB reserved WDT reserved Type RO RO RO RO R/W R/W R/W R/W RO R/W RO RO R/W RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:21 reserved RO 0 PWM Clock Gating Control This bit controls the clock gating for the PWM module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 20 PWM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:17 reserved RO 0 ADC0 Clock Gating Control This bit controls the clock gating for SAR ADC module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 16 ADC R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:12 reserved RO 0 94 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description ADC Sample Speed This field sets the rate at which the ADC samples data. You cannot set the rate higher than the maximum rate. You can set the sample rate by setting the MAXADCSPD bit as follows: Value Description 0x2 500K samples/second 0x1 250K samples/second 0x0 125K samples/second 11:8 MAXADCSPD R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7 reserved RO 0 HIB Clock Gating Control This bit controls the clock gating for the Hibernation module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. 6 HIB R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:4 reserved RO 0 WDT Clock Gating Control This bit controls the clock gating for the WDT module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 3 WDT R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2:0 reserved RO 0 November 30, 2007 95 Preliminary LM3S6952 Microcontroller Register 19: Sleep Mode Clock Gating Control Register 0 (SCGC0), offset 0x110 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Sleep Mode Clock Gating Control Register 0 (SCGC0) Base 0x400F.E000 Offset 0x110 Type R/W, reset 0x00000040 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved PWM reserved ADC Type RO RO RO RO RO RO RO RO RO RO RO R/W RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MAXADCSPD reserved HIB reserved WDT reserved Type RO RO RO RO R/W R/W R/W R/W RO R/W RO RO R/W RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:21 reserved RO 0 PWM Clock Gating Control This bit controls the clock gating for the PWM module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 20 PWM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:17 reserved RO 0 ADC0 Clock Gating Control This bit controls the clock gating for SAR ADC module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 16 ADC R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:12 reserved RO 0 96 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description ADC Sample Speed This field sets the rate at which the ADC samples data. You cannot set the rate higher than the maximum rate. You can set the sample rate by setting the MAXADCSPD bit as follows: Value Description 0x2 500K samples/second 0x1 250K samples/second 0x0 125K samples/second 11:8 MAXADCSPD R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7 reserved RO 0 HIB Clock Gating Control This bit controls the clock gating for the Hibernation module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. 6 HIB R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:4 reserved RO 0 WDT Clock Gating Control This bit controls the clock gating for the WDT module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 3 WDT R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2:0 reserved RO 0 November 30, 2007 97 Preliminary LM3S6952 Microcontroller Register 20: Deep Sleep Mode Clock Gating Control Register 0 (DCGC0), offset 0x120 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Deep Sleep Mode Clock Gating Control Register 0 (DCGC0) Base 0x400F.E000 Offset 0x120 Type R/W, reset 0x00000040 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved PWM reserved ADC Type RO RO RO RO RO RO RO RO RO RO RO R/W RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MAXADCSPD reserved HIB reserved WDT reserved Type RO RO RO RO R/W R/W R/W R/W RO R/W RO RO R/W RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:21 reserved RO 0 PWM Clock Gating Control This bit controls the clock gating for the PWM module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 20 PWM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:17 reserved RO 0 ADC0 Clock Gating Control This bit controls the clock gating for SAR ADC module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 16 ADC R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:12 reserved RO 0 98 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description ADC Sample Speed This field sets the rate at which the ADC samples data. You cannot set the rate higher than the maximum rate. You can set the sample rate by setting the MAXADCSPD bit as follows: Value Description 0x2 500K samples/second 0x1 250K samples/second 0x0 125K samples/second 11:8 MAXADCSPD R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7 reserved RO 0 HIB Clock Gating Control This bit controls the clock gating for the Hibernation module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. 6 HIB R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:4 reserved RO 0 WDT Clock Gating Control This bit controls the clock gating for the WDT module. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, a read or write to the unit generates a bus fault. 3 WDT R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2:0 reserved RO 0 November 30, 2007 99 Preliminary LM3S6952 Microcontroller Register 21: Run Mode Clock Gating Control Register 1 (RCGC1), offset 0x104 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Run Mode Clock Gating Control Register 1 (RCGC1) Base 0x400F.E000 Offset 0x104 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved COMP2 COMP1 COMP0 reserved TIMER2 TIMER1 TIMER0 Type RO RO RO RO RO R/W R/W R/W RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved I2C0 reserved QEI0 reserved SSI0 reserved UART2 UART1 UART0 Type RO RO RO R/W RO RO RO R/W RO RO RO R/W RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:27 reserved RO 0 Analog Comparator 2 Clock Gating This bit controls the clock gating for analog comparator 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 26 COMP2 R/W 0 Analog Comparator 1 Clock Gating This bit controls the clock gating for analog comparator 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 25 COMP1 R/W 0 Analog Comparator 0 Clock Gating This bit controls the clock gating for analog comparator 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 24 COMP0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 100 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Timer 2 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 18 TIMER2 R/W 0 Timer 1 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 17 TIMER1 R/W 0 Timer 0 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 16 TIMER0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 I2C0 Clock Gating Control This bit controls the clock gating for I2C module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 12 I2C0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0 QEI0 Clock Gating Control This bit controls the clock gating for QEI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 8 QEI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:5 reserved RO 0 SSI0 Clock Gating Control This bit controls the clock gating for SSI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 SSI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0 UART2 Clock Gating Control This bit controls the clock gating for UART module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 UART2 R/W 0 November 30, 2007 101 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART1 Clock Gating Control This bit controls the clock gating for UART module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 UART1 R/W 0 UART0 Clock Gating Control This bit controls the clock gating for UART module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 UART0 R/W 0 102 November 30, 2007 Preliminary System Control Register 22: Sleep Mode Clock Gating Control Register 1 (SCGC1), offset 0x114 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Sleep Mode Clock Gating Control Register 1 (SCGC1) Base 0x400F.E000 Offset 0x114 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved COMP2 COMP1 COMP0 reserved TIMER2 TIMER1 TIMER0 Type RO RO RO RO RO R/W R/W R/W RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved I2C0 reserved QEI0 reserved SSI0 reserved UART2 UART1 UART0 Type RO RO RO R/W RO RO RO R/W RO RO RO R/W RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:27 reserved RO 0 Analog Comparator 2 Clock Gating This bit controls the clock gating for analog comparator 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 26 COMP2 R/W 0 Analog Comparator 1 Clock Gating This bit controls the clock gating for analog comparator 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 25 COMP1 R/W 0 Analog Comparator 0 Clock Gating This bit controls the clock gating for analog comparator 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 24 COMP0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 November 30, 2007 103 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Timer 2 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 18 TIMER2 R/W 0 Timer 1 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 17 TIMER1 R/W 0 Timer 0 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 16 TIMER0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 I2C0 Clock Gating Control This bit controls the clock gating for I2C module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 12 I2C0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0 QEI0 Clock Gating Control This bit controls the clock gating for QEI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 8 QEI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:5 reserved RO 0 SSI0 Clock Gating Control This bit controls the clock gating for SSI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 SSI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0 UART2 Clock Gating Control This bit controls the clock gating for UART module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 UART2 R/W 0 104 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description UART1 Clock Gating Control This bit controls the clock gating for UART module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 UART1 R/W 0 UART0 Clock Gating Control This bit controls the clock gating for UART module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 UART0 R/W 0 November 30, 2007 105 Preliminary LM3S6952 Microcontroller Register 23: Deep Sleep Mode Clock Gating Control Register 1 (DCGC1), offset 0x124 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Deep Sleep Mode Clock Gating Control Register 1 (DCGC1) Base 0x400F.E000 Offset 0x124 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved COMP2 COMP1 COMP0 reserved TIMER2 TIMER1 TIMER0 Type RO RO RO RO RO R/W R/W R/W RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved I2C0 reserved QEI0 reserved SSI0 reserved UART2 UART1 UART0 Type RO RO RO R/W RO RO RO R/W RO RO RO R/W RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:27 reserved RO 0 Analog Comparator 2 Clock Gating This bit controls the clock gating for analog comparator 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 26 COMP2 R/W 0 Analog Comparator 1 Clock Gating This bit controls the clock gating for analog comparator 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 25 COMP1 R/W 0 Analog Comparator 0 Clock Gating This bit controls the clock gating for analog comparator 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 24 COMP0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 106 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Timer 2 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 18 TIMER2 R/W 0 Timer 1 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 17 TIMER1 R/W 0 Timer 0 Clock Gating Control This bit controls the clock gating for General-Purpose Timer module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 16 TIMER0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 I2C0 Clock Gating Control This bit controls the clock gating for I2C module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 12 I2C0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0 QEI0 Clock Gating Control This bit controls the clock gating for QEI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 8 QEI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:5 reserved RO 0 SSI0 Clock Gating Control This bit controls the clock gating for SSI module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 SSI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0 UART2 Clock Gating Control This bit controls the clock gating for UART module 2. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 UART2 R/W 0 November 30, 2007 107 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART1 Clock Gating Control This bit controls the clock gating for UART module 1. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 UART1 R/W 0 UART0 Clock Gating Control This bit controls the clock gating for UART module 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 UART0 R/W 0 108 November 30, 2007 Preliminary System Control Register 24: Run Mode Clock Gating Control Register 2 (RCGC2), offset 0x108 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Run Mode Clock Gating Control Register 2 (RCGC2) Base 0x400F.E000 Offset 0x108 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved EPHY0 reserved EMAC0 reserved Type RO R/W RO R/W RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPIOG GPIOF GPIOE GPIOD GPIOC GPIOB GPIOA Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 PHY0 Clock Gating Control This bit controls the clock gating for Ethernet PHY unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 30 EPHY0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 29 reserved RO 0 MAC0 Clock Gating Control This bit controls the clock gating for Ethernet MAC unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 28 EMAC0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:7 reserved RO 0 Port G Clock Gating Control This bit controls the clock gating for Port G. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 6 GPIOG R/W 0 November 30, 2007 109 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Port F Clock Gating Control This bit controls the clock gating for Port F. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 5 GPIOF R/W 0 Port E Clock Gating Control This bit controls the clock gating for Port E. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 GPIOE R/W 0 Port D Clock Gating Control This bit controls the clock gating for Port D. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 3 GPIOD R/W 0 Port C Clock Gating Control This bit controls the clock gating for Port C. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 GPIOC R/W 0 Port B Clock Gating Control This bit controls the clock gating for Port B. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 GPIOB R/W 0 Port A Clock Gating Control This bit controls the clock gating for Port A. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 GPIOA R/W 0 110 November 30, 2007 Preliminary System Control Register 25: Sleep Mode Clock Gating Control Register 2 (SCGC2), offset 0x118 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Sleep Mode Clock Gating Control Register 2 (SCGC2) Base 0x400F.E000 Offset 0x118 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved EPHY0 reserved EMAC0 reserved Type RO R/W RO R/W RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPIOG GPIOF GPIOE GPIOD GPIOC GPIOB GPIOA Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 PHY0 Clock Gating Control This bit controls the clock gating for Ethernet PHY unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 30 EPHY0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 29 reserved RO 0 MAC0 Clock Gating Control This bit controls the clock gating for Ethernet MAC unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 28 EMAC0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:7 reserved RO 0 November 30, 2007 111 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Port G Clock Gating Control This bit controls the clock gating for Port G. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 6 GPIOG R/W 0 Port F Clock Gating Control This bit controls the clock gating for Port F. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 5 GPIOF R/W 0 Port E Clock Gating Control This bit controls the clock gating for Port E. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 GPIOE R/W 0 Port D Clock Gating Control This bit controls the clock gating for Port D. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 3 GPIOD R/W 0 Port C Clock Gating Control This bit controls the clock gating for Port C. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 GPIOC R/W 0 Port B Clock Gating Control This bit controls the clock gating for Port B. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 GPIOB R/W 0 Port A Clock Gating Control This bit controls the clock gating for Port A. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 GPIOA R/W 0 112 November 30, 2007 Preliminary System Control Register 26: Deep Sleep Mode Clock Gating Control Register 2 (DCGC2), offset 0x128 This register controls the clock gating logic. Each bit controls a clock enable for a given interface, function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault. The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are disabled. It is the responsibility of software to enable the ports necessary for the application. Note that these registers may contain more bits than there are interfaces, functions, or units to control. This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register specifies that the system uses sleep modes. Deep Sleep Mode Clock Gating Control Register 2 (DCGC2) Base 0x400F.E000 Offset 0x128 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved EPHY0 reserved EMAC0 reserved Type RO R/W RO R/W RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPIOG GPIOF GPIOE GPIOD GPIOC GPIOB GPIOA Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 PHY0 Clock Gating Control This bit controls the clock gating for Ethernet PHY unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 30 EPHY0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 29 reserved RO 0 MAC0 Clock Gating Control This bit controls the clock gating for Ethernet MAC unit 0. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 28 EMAC0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:7 reserved RO 0 November 30, 2007 113 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Port G Clock Gating Control This bit controls the clock gating for Port G. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 6 GPIOG R/W 0 Port F Clock Gating Control This bit controls the clock gating for Port F. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 5 GPIOF R/W 0 Port E Clock Gating Control This bit controls the clock gating for Port E. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 4 GPIOE R/W 0 Port D Clock Gating Control This bit controls the clock gating for Port D. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 3 GPIOD R/W 0 Port C Clock Gating Control This bit controls the clock gating for Port C. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 2 GPIOC R/W 0 Port B Clock Gating Control This bit controls the clock gating for Port B. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 1 GPIOB R/W 0 Port A Clock Gating Control This bit controls the clock gating for Port A. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and disabled. If the unit is unclocked, reads or writes to the unit will generate a bus fault. 0 GPIOA R/W 0 114 November 30, 2007 Preliminary System Control Register 27: Software Reset Control 0 (SRCR0), offset 0x040 Writes to this register are masked by the bits in the Device Capabilities 1 (DC1) register. Software Reset Control 0 (SRCR0) Base 0x400F.E000 Offset 0x040 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved PWM reserved ADC Type RO RO RO RO RO RO RO RO RO RO RO R/W RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved HIB reserved WDT reserved Type RO RO RO RO RO RO RO RO RO R/W RO RO R/W RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:21 reserved RO 0 PWM Reset Control Reset control for PWM module. 20 PWM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:17 reserved RO 0 ADC0 Reset Control Reset control for SAR ADC module 0. 16 ADC R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:7 reserved RO 0 HIB Reset Control Reset control for the Hibernation module. 6 HIB R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 5:4 reserved RO 0 WDT Reset Control Reset control for Watchdog unit. 3 WDT R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2:0 reserved RO 0 November 30, 2007 115 Preliminary LM3S6952 Microcontroller Register 28: Software Reset Control 1 (SRCR1), offset 0x044 Writes to this register are masked by the bits in the Device Capabilities 2 (DC2) register. Software Reset Control 1 (SRCR1) Base 0x400F.E000 Offset 0x044 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved COMP2 COMP1 COMP0 reserved TIMER2 TIMER1 TIMER0 Type RO RO RO RO RO R/W R/W R/W RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved I2C0 reserved QEI0 reserved SSI0 reserved UART2 UART1 UART0 Type RO RO RO R/W RO RO RO R/W RO RO RO R/W RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:27 reserved RO 0 Analog Comp 2 Reset Control Reset control for analog comparator 2. 26 COMP2 R/W 0 Analog Comp 1 Reset Control Reset control for analog comparator 1. 25 COMP1 R/W 0 Analog Comp 0 Reset Control Reset control for analog comparator 0. 24 COMP0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:19 reserved RO 0 Timer 2 Reset Control Reset control for General-Purpose Timer module 2. 18 TIMER2 R/W 0 Timer 1 Reset Control Reset control for General-Purpose Timer module 1. 17 TIMER1 R/W 0 Timer 0 Reset Control Reset control for General-Purpose Timer module 0. 16 TIMER0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 I2C0 Reset Control Reset control for I2C unit 0. 12 I2C0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0 116 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description QEI0 Reset Control Reset control for QEI unit 0. 8 QEI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:5 reserved RO 0 SSI0 Reset Control Reset control for SSI unit 0. 4 SSI0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0 UART2 Reset Control Reset control for UART unit 2. 2 UART2 R/W 0 UART1 Reset Control Reset control for UART unit 1. 1 UART1 R/W 0 UART0 Reset Control Reset control for UART unit 0. 0 UART0 R/W 0 November 30, 2007 117 Preliminary LM3S6952 Microcontroller Register 29: Software Reset Control 2 (SRCR2), offset 0x048 Writes to this register are masked by the bits in the Device Capabilities 4 (DC4) register. Software Reset Control 2 (SRCR2) Base 0x400F.E000 Offset 0x048 Type R/W, reset 0x00000000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved EPHY0 reserved EMAC0 reserved Type RO R/W RO R/W RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPIOG GPIOF GPIOE GPIOD GPIOC GPIOB GPIOA Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31 reserved RO 0 PHY0 Reset Control Reset control for Ethernet PHY unit 0. 30 EPHY0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 29 reserved RO 0 MAC0 Reset Control Reset control for Ethernet MAC unit 0. 28 EMAC0 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:7 reserved RO 0 Port G Reset Control Reset control for GPIO Port G. 6 GPIOG R/W 0 Port F Reset Control Reset control for GPIO Port F. 5 GPIOF R/W 0 Port E Reset Control Reset control for GPIO Port E. 4 GPIOE R/W 0 Port D Reset Control Reset control for GPIO Port D. 3 GPIOD R/W 0 Port C Reset Control Reset control for GPIO Port C. 2 GPIOC R/W 0 Port B Reset Control Reset control for GPIO Port B. 1 GPIOB R/W 0 118 November 30, 2007 Preliminary System Control Bit/Field Name Type Reset Description Port A Reset Control Reset control for GPIO Port A. 0 GPIOA R/W 0 November 30, 2007 119 Preliminary LM3S6952 Microcontroller 7 Hibernation Module The Hibernation Module manages removal and restoration of power to the rest of the microcontroller to provide a means for reducing power consumption. When the processor and peripherals are idle, power can be completely removed with only the Hibernation Module remaining powered. Power can be restored based on an external signal, or at a certain time using the built-in real-time clock (RTC). The Hibernation module can be independently supplied from a battery or an auxiliary power supply. The Hibernation module has the following features: ■ Power-switching logic to discrete external regulator ■ Dedicated pin for waking from an external signal ■ Low-battery detection, signaling, and interrupt generation ■ 32-bit real-time counter (RTC) ■ Two 32-bit RTC match registers for timed wake-up and interrupt generation ■ Clock source from a 32.768-kHz external oscillator or a 4.194304-MHz crystal ■ RTC predivider trim for making fine adjustments to the clock rate ■ 64 32-bit words of non-volatile memory ■ Programmable interrupts for RTC match, external wake, and low battery events 120 November 30, 2007 Preliminary Hibernation Module 7.1 Block Diagram Figure 7-1. Hibernation Module Block Diagram HIBIM HIBRIS HIBMIS HIBIC HIBRTCT Pre-Divider /128 XOSC0 XOSC1 HIBCTL.CLK32EN HIBCTL.CLKSEL HIBRTCC HIBRTCLD HIBRTCM0 HIBRTCM1 RTC Interrupts Power Sequence Logic MATCH0/1 WAKE Interrupts to CPU Low Battery Detect LOWBAT VDD VBAT HIB HIBCTL.LOWBATEN HIBCTL.PWRCUT HIBCTL.EXTWEN HIBCTL.RTCWEN HIBCTL.VABORT Non-Volatile Memory HIBDATA 7.2 Functional Description The Hibernation module controls the power to the processor with an enable signal (HIB) that signals an external voltage regulator to turn off. The Hibernation module power is determined dynamically. The supply voltage of the Hibernation module is the larger of the main voltage source (VDD) or the battery/auxilliary voltage source (VBAT). A voting circuit indicates the larger and an internal power switch selects the appropriate voltage source. The Hibernation module also has a separate clock source to maintain a real-time clock (RTC). Once in hibernation, the module signals an external voltage regulator to turn back on the power when an external pin (WAKE) is asserted, or when the internal RTC reaches a certain value. The Hibernation module can also detect when the battery voltage is low, and optionally prevent hibernation when this occurs. Power-up from a power cut to code execution is defined as the regulator turn-on time (specifed at tHIB_TO_VDD maximum) plus the normal chip POR (see “Hibernation Module” on page 543). 7.2.1 Register Access Timing Because the Hibernation module has an independent clocking domain, certain registers must be written only with a timing gap between accesses. The delay time is tHIB_REG_WRITE, therefore software must guarantee that a delay of tHIB_REG_WRITE is inserted between back-to-back writes to certain Hibernation registers, or between a write followed by a read to those same registers. There is no November 30, 2007 121 Preliminary LM3S6952 Microcontroller restriction on timing for back-to-back reads from the Hibernation module. Refer to “Register Descriptions” on page 126 for details about which registers are subject to this timing restriction. 7.2.2 Clock Source The Hibernation module must be clocked by an external source, even if the RTC feature will not be used. An external oscillator or crystal can be used for this purpose. To use a crystal, a 4.194304-MHz crystal is connected to the XOSC0 and XOSC1 pins. This clock signal is divided by 128 internally to produce the 32.768-kHz clock reference. To use a more precise clock source, a 32.768-kHz oscillator can be connected to the XOSC0 pin. The clock source is enabled by setting the CLK32EN bit of the HIBCTL register. The type of clock source is selected by setting the CLKSEL bit to 0 for a 4.194304-MHz clock source, and to 1 for a 32.768-kHz clock source. If the bit is set to 0, the input clock is divided by 128, resulting in a 32.768-kHz clock source. If a crystal is used for the clock source, the software must leave a delay of tXOSC_SETTLE after setting the CLK32EN bit and before any other accesses to the Hibernation module registers. The delay allows the crystal to power up and stabilize. If an oscillator is used for the clock source, no delay is needed. 7.2.3 Battery Management The Hibernation module can be independently powered by a battery or an auxiliary power source. The module can monitor the voltage level of the battery and detect when the voltage becomes too low. When this happens, an interrupt can be generated. The module can also be configured so that it will not go into Hibernate mode if the battery voltage is too low. Note that the Hibernation module draws power from whichever source (VBAT or VDD) has the higher voltage. Therefore, it is important to design the circuit to ensure that VDD is higher that VBAT under nominal conditions or else the Hibernation module draws power from the battery even when VDD is available. The Hibernation module can be configured to detect a low battery condition by setting the LOWBATEN bit of the HIBCTL register. In this configuration, the LOWBAT bit of the HIBRIS register will be set when the battery level is low. If the VABORT bit is also set, then the module is prevented from entering Hibernation mode when a low battery is detected. The module can also be configured to generate an interrupt for the low-battery condition (see “Interrupts and Status” on page 123). 7.2.4 Real-Time Clock The Hibernation module includes a 32-bit counter that increments once per second with a proper clock source and configuration (see “Clock Source” on page 122). The 32.768-kHz clock signal is fed into a predivider register which counts down the 32.768-kHz clock ticks to achieve a once per second clock rate for the RTC. The rate can be adjusted to compensate for inaccuracies in the clock source by using the predivider trim register. This register has a nominal value of 0x7FFF, and is used for one second out of every 64 seconds to divide the input clock. This allows the software to make fine corrections to the clock rate by adjusting the predivider trim register up or down from 0x7FFF. The predivider trim should be adjusted up from 0x7FFF in order to slow down the RTC rate, and down from 0x7FFF in order to speed up the RTC rate. The Hibernation module includes two 32-bit match registers that are compared to the value of the RTC counter. The match registers can be used to wake the processor from hibernation mode, or to generate an interrupt to the processor if it is not in hibernation. The RTC must be enabled with the RTCEN bit of the HIBCTL register. The value of the RTC can be set at any time by writing to the HIBRTCLD register. The predivider trim can be adjusted by reading and writing the HIBRTCT register. The predivider uses this register once every 64 seconds to adjust 122 November 30, 2007 Preliminary Hibernation Module the clock rate. The two match registers can be set by writing to the HIBRTCM0 and HIBRTCM1 registers. The RTC can be configured to generate interrupts by using the interrupt registers (see “Interrupts and Status” on page 123). 7.2.5 Non-Volatile Memory The Hibernation module contains 64 32-bit words of memory which are retained during hibernation. This memory is powered from the battery or auxiliary power supply during hibernation. The processor software can save state information in this memory prior to hibernation, and can then recover the state upon waking. The non-volatile memory can be accessed through the HIBDATA registers. 7.2.6 Power Control The Hibernation module controls power to the processor through the use of the HIB pin, which is intended to be connected to the enable signal of the external regulator(s) providing 3.3 V and/or 2.5 V to the microcontroller. When the HIB signal is asserted by the Hibernation module, the external regulator is turned off and no longer powers the microcontroller. The Hibernation module remains powered from the VBAT supply, which could be a battery or an auxiliary power source. Hibernation mode is initiated by the microcontroller setting the HIBREQ bit of the HIBCTL register. Prior to doing this, a wake-up condition must be configured, either from the external WAKE pin, or by using an RTC match. The Hibernation module is configured to wake from the external WAKE pin by setting the PINWEN bit of the HIBCTL register. It is configured to wake from RTC match by setting the RTCWEN bit. Either one or both of these bits can be set prior to going into hibernation. The WAKE pin includes a weak internal pull-up. Note that both the HIB and WAKE pins use the Hibernation module's internal power supply as the logic 1 reference. When the Hibernation module wakes, the microcontroller will see a normal power-on reset. It can detect that the power-on was due to a wake from hibernation by examining the raw interrupt status register (see “Interrupts and Status” on page 123) and by looking for state data in the non-volatile memory (see “Non-Volatile Memory” on page 123). When the HIB signal deasserts, enabling the external regulator, the external regulator must reach the operating voltage within tHIB_TO_VDD. 7.2.7 Interrupts and Status The Hibernation module can generate interrupts when the following conditions occur: ■ Assertion of WAKE pin ■ RTC match ■ Low battery detected All of the interrupts are ORed together before being sent to the interrupt controller, so the Hibernate module can only generate a single interrupt request to the controller at any given time. The software interrupt handler can service multiple interrupt events by reading the HIBMIS register. Software can also read the status of the Hibernation module at any time by reading the HIBRIS register which shows all of the pending events. This register can be used at power-on to see if a wake condition is pending, which indicates to the software that a hibernation wake occurred. The events that can trigger an interrupt are configured by setting the appropriate bits in the HIBIM register. Pending interrupts can be cleared by writing the corresponding bit in the HIBIC register. November 30, 2007 123 Preliminary LM3S6952 Microcontroller 7.3 Initialization and Configuration The Hibernation module can be configured in several different combinations. The following sections show the recommended programming sequence for various scenarios. The examples below assume that a 32.768-kHz oscillator is used, and thus always show bit 2 (CLKSEL) of the HIBCTL register set to 1. If a 4.194304-MHz crystal is used instead, then the CLKSEL bit remains cleared. Because the Hibernation module runs at 32 kHz and is asynchronous to the rest of the system, software must allow a delay of tHIB_REG_WRITE after writes to certain registers (see “Register Access Timing” on page 121). The registers that require a delay are denoted with a footnote in Table 7-1 on page 125. 7.3.1 Initialization The clock source must be enabled first, even if the RTC will not be used. If a 4.194304-MHz crystal is used, perform the following steps: 1. Write 0x40 to the HIBCTL register at offset 0x10 to enable the crystal and select the divide-by-128 input path. 2. Wait for a time of tXOSC_SETTLE for the crystal to power up and stabilize before performing any other operations with the Hibernation module. If a 32.678-kHz oscillator is used, then perform the following steps: 1. Write 0x44 to the HIBCTL register at offset 0x10 to enable the oscillator input. 2. No delay is necessary. The above is only necessary when the entire system is initialized for the first time. If the processor is powered due to a wake from hibernation, then the Hibernation module has already been powered up and the above steps are not necessary. The software can detect that the Hibernation module and clock are already powered by examining the CLK32EN bit of the HIBCTL register. 7.3.2 RTC Match Functionality (No Hibernation) The following steps are needed to use the RTC match functionality of the Hibernation module: 1. Write the required RTC match value to one of the HIBRTCMn registers at offset 0x004 or 0x008. 2. Write the required RTC load value to the HIBRTCLD register at offset 0x00C. 3. Set the required RTC match interrupt mask in the RTCALT0 and RTCALT1 bits (bits 1:0) in the HIBIM register at offset 0x014. 4. Write 0x0000.0041 to the HIBCTL register at offset 0x010 to enable the RTC to begin counting. 7.3.3 RTC Match/Wake-Up from Hibernation The following steps are needed to use the RTC match and wake-up functionality of the Hibernation module: 1. Write the required RTC match value to the HIBRTCMn registers at offset 0x004 or 0x008. 2. Write the required RTC load value to the HIBRTCLD register at offset 0x00C. 3. Write any data to be retained during power cut to the HIBDATA register at offsets 0x030-0x12C. 124 November 30, 2007 Preliminary Hibernation Module 4. Set the RTC Match Wake-Up and start the hibernation sequence by writing 0x0000.004F to the HIBCTL register at offset 0x010. 7.3.4 External Wake-Up from Hibernation The following steps are needed to use the Hibernation module with the external WAKE pin as the wake-up source for the microcontroller: 1. Write any data to be retained during power cut to the HIBDATA register at offsets 0x030-0x12C. 2. Enable the external wake and start the hibernation sequence by writing 0x0000.0056 to the HIBCTL register at offset 0x010. 7.3.5 RTC/External Wake-Up from Hibernation 1. Write the required RTC match value to the HIBRTCMn registers at offset 0x004 or 0x008. 2. Write the required RTC load value to the HIBRTCLD register at offset 0x00C. 3. Write any data to be retained during power cut to the HIBDATA register at offsets 0x030-0x12C. 4. Set the RTC Match/External Wake-Up and start the hibernation sequence by writing 0x0000.005F to the HIBCTL register at offset 0x010. 7.4 Register Map Table 7-1 on page 125 lists the Hibernation registers. All addresses given are relative to the Hibernation Module base address at 0x400F.C000. Note: HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the Hibernation module clock domain and require a delay of tHIB_REG_WRITE between write accesses. See “Register Access Timing” on page 121. Table 7-1. Hibernation Module Register Map See Offset Name Type Reset Description page 0x000 HIBRTCC RO 0x0000.0000 Hibernation RTC Counter 127 0x004 HIBRTCM0 R/W 0xFFFF.FFFF Hibernation RTC Match 0 128 0x008 HIBRTCM1 R/W 0xFFFF.FFFF Hibernation RTC Match 1 129 0x00C HIBRTCLD R/W 0xFFFF.FFFF Hibernation RTC Load 130 0x010 HIBCTL R/W 0x0000.0000 Hibernation Control 131 0x014 HIBIM R/W 0x0000.0000 Hibernation Interrupt Mask 133 0x018 HIBRIS RO 0x0000.0000 Hibernation Raw Interrupt Status 134 0x01C HIBMIS RO 0x0000.0000 Hibernation Masked Interrupt Status 135 0x020 HIBIC R/W1C 0x0000.0000 Hibernation Interrupt Clear 136 0x024 HIBRTCT R/W 0x0000.7FFF Hibernation RTC Trim 137 0x030- HIBDATA R/W 0x0000.0000 Hibernation Data 138 0x12C November 30, 2007 125 Preliminary LM3S6952 Microcontroller 7.5 Register Descriptions The remainder of this section lists and describes the Hibernation module registers, in numerical order by address offset. 126 November 30, 2007 Preliminary Hibernation Module Register 1: Hibernation RTC Counter (HIBRTCC), offset 0x000 This register is the current 32-bit value of the RTC counter. Hibernation RTC Counter (HIBRTCC) Base 0x400F.C000 Offset 0x000 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RTCC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RTCC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description RTC Counter A read returns the 32-bit counter value. This register is read-only. To change the value, use the HIBRTCLD register. 31:0 RTCC RO 0x0000.0000 November 30, 2007 127 Preliminary LM3S6952 Microcontroller Register 2: Hibernation RTC Match 0 (HIBRTCM0), offset 0x004 This register is the 32-bit match 0 register for the RTC counter. Hibernation RTC Match 0 (HIBRTCM0) Base 0x400F.C000 Offset 0x004 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RTCM0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RTCM0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description RTC Match 0 A write loads the value into the RTC match register. A read returns the current match value. 31:0 RTCM0 R/W 0xFFFF.FFFF 128 November 30, 2007 Preliminary Hibernation Module Register 3: Hibernation RTC Match 1 (HIBRTCM1), offset 0x008 This register is the 32-bit match 1 register for the RTC counter. Hibernation RTC Match 1 (HIBRTCM1) Base 0x400F.C000 Offset 0x008 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RTCM1 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RTCM1 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description RTC Match 1 A write loads the value into the RTC match register. A read returns the current match value. 31:0 RTCM1 R/W 0xFFFF.FFFF November 30, 2007 129 Preliminary LM3S6952 Microcontroller Register 4: Hibernation RTC Load (HIBRTCLD), offset 0x00C This register is the 32-bit value loaded into the RTC counter. Hibernation RTC Load (HIBRTCLD) Base 0x400F.C000 Offset 0x00C Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RTCLD Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RTCLD Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description RTC Load A write loads the current value into the RTC counter (RTCC). A read returns the 32-bit load value. 31:0 RTCLD R/W 0xFFFF.FFFF 130 November 30, 2007 Preliminary Hibernation Module Register 5: Hibernation Control (HIBCTL), offset 0x010 This register is the control register for the Hibernation module. Hibernation Control (HIBCTL) Base 0x400F.C000 Offset 0x010 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved VABORT CLK32EN LOWBATEN PINWEN RTCWEN CLKSEL HIBREQ RTCEN Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Power Cut Abort Enable 0: Power cut occurs during a low-battery alert 1: Power cut is aborted 7 VABORT R/W 0 32-kHz Oscillator Enable 0: Disabled 1: Enabled This bit must be enabled to use the Hibernation module. If a crystal is used, then software should wait 20 ms after setting this bit to allow the crystal to power up and stabilize. 6 CLK32EN R/W 0 Low Battery Monitoring Enable 0: Disabled 1: Enabled When set, low battery voltage detection is enabled. 5 LOWBATEN R/W 0 External WAKE Pin Enable 0: Disabled 1: Enabled When set, an external event on the WAKE pin will re-power the device. 4 PINWEN R/W 0 RTC Wake-up Enable 0: Disabled 1: Enabled When set, an RTC match event (RTCM0 or RTCM1) will re-power the device based on the RTC counter value matching the corresponding match register 0 or 1. 3 RTCWEN R/W 0 November 30, 2007 131 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Hibernation Module Clock Select 0: Use Divide by 128 output. Use this value for a 4-MHz crystal. 1: Use raw output. Use this value for a 32-kHz oscillator. 2 CLKSEL R/W 0 Hibernation Request 0: Disabled 1: Hibernation initiated After a wake-up event, this bit is cleared by hardware. 1 HIBREQ R/W 0 RTC Timer Enable 0: Disabled 1: Enabled 0 RTCEN R/W 0 132 November 30, 2007 Preliminary Hibernation Module Register 6: Hibernation Interrupt Mask (HIBIM), offset 0x014 This register is the interrupt mask register for the Hibernation module interrupt sources. Hibernation Interrupt Mask (HIBIM) Base 0x400F.C000 Offset 0x014 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved EXTW LOWBAT RTCALT1 RTCALT0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x000.0000 External Wake-Up Interrupt Mask 0: Masked 1: Unmasked 3 EXTW R/W 0 Low Battery Voltage Interrupt Mask 0: Masked 1: Unmasked 2 LOWBAT R/W 0 RTC Alert1 Interrupt Mask 0: Masked 1: Unmasked 1 RTCALT1 R/W 0 RTC Alert0 Interrupt Mask 0: Masked 1: Unmasked 0 RTCALT0 R/W 0 November 30, 2007 133 Preliminary LM3S6952 Microcontroller Register 7: Hibernation Raw Interrupt Status (HIBRIS), offset 0x018 This register is the raw interrupt status for the Hibernation module interrupt sources. Hibernation Raw Interrupt Status (HIBRIS) Base 0x400F.C000 Offset 0x018 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved EXTW LOWBAT RTCALT1 RTCALT0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x000.0000 3 EXTW RO 0 External Wake-Up Raw Interrupt Status 2 LOWBAT RO 0 Low Battery Voltage Raw Interrupt Status 1 RTCALT1 RO 0 RTC Alert1 Raw Interrupt Status 0 RTCALT0 RO 0 RTC Alert0 Raw Interrupt Status 134 November 30, 2007 Preliminary Hibernation Module Register 8: Hibernation Masked Interrupt Status (HIBMIS), offset 0x01C This register is the masked interrupt status for the Hibernation module interrupt sources. Hibernation Masked Interrupt Status (HIBMIS) Base 0x400F.C000 Offset 0x01C Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved EXTW LOWBAT RTCALT1 RTCALT0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x000.0000 3 EXTW RO 0 External Wake-Up Masked Interrupt Status 2 LOWBAT RO 0 Low Battery Voltage Masked Interrupt Status 1 RTCALT1 RO 0 RTC Alert1 Masked Interrupt Status 0 RTCALT0 RO 0 RTC Alert0 Masked Interrupt Status November 30, 2007 135 Preliminary LM3S6952 Microcontroller Register 9: Hibernation Interrupt Clear (HIBIC), offset 0x020 This register is the interrupt write-one-to-clear register for the Hibernation module interrupt sources. Hibernation Interrupt Clear (HIBIC) Base 0x400F.C000 Offset 0x020 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved EXTW LOWBAT RTCALT1 RTCALT0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x000.0000 External Wake-Up Masked Interrupt Clear Reads return an indeterminate value. 3 EXTW R/W1C 0 Low Battery Voltage Masked Interrupt Clear Reads return an indeterminate value. 2 LOWBAT R/W1C 0 RTC Alert1 Masked Interrupt Clear Reads return an indeterminate value. 1 RTCALT1 R/W1C 0 RTC Alert0 Masked Interrupt Clear Reads return an indeterminate value. 0 RTCALT0 R/W1C 0 136 November 30, 2007 Preliminary Hibernation Module Register 10: Hibernation RTC Trim (HIBRTCT), offset 0x024 This register contains the value that is used to trim the RTC clock predivider. It represents the computed underflow value that is used during the trim cycle. It is represented as 0x7FFF ± N clock cycles. Hibernation RTC Trim (HIBRTCT) Base 0x400F.C000 Offset 0x024 Type R/W, reset 0x0000.7FFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TRIM Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0000 RTC Trim Value This value is loaded into the RTC predivider every 64 seconds. It is used to adjust the RTC rate to account for drift and inaccuracy in the clock source. The compensation is made by software by adjusting the default value of 0x7FFF up or down. 15:0 TRIM R/W 0x7FFF November 30, 2007 137 Preliminary LM3S6952 Microcontroller Register 11: Hibernation Data (HIBDATA), offset 0x030-0x12C This address space is implemented as a 64x32-bit memory (256 bytes). It can be loaded by the system processor in order to store any non-volatile state data and will not lose power during a power cut operation. Hibernation Data (HIBDATA) Base 0x400F.C000 Offset 0x030-0x12C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RTD Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RTD Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description 31:0 RTD R/W 0x0000.0000 Hibernation Module NV Registers[63:0] 138 November 30, 2007 Preliminary Hibernation Module 8 Internal Memory The LM3S6952 microcontroller comes with 64 KB of bit-banded SRAM and 256 KB of flash memory. The flash controller provides a user-friendly interface, making flash programming a simple task. Flash protection can be applied to the flash memory on a 2-KB block basis. 8.1 Block Diagram Figure 8-1. Flash Block Diagram Flash Control FMA FCMISC FCIM FCRIS FMC FMD Flash Timing USECRL Flash Protection FMPREn FMPPEn Flash Array SRAM Array Bridge Cortex-M3 ICode DCode System Bus APB User Registers USER_REG0 USER_REG1 USER_DBG 8.2 Functional Description This section describes the functionality of both the flash and SRAM memories. 8.2.1 SRAM Memory The internal SRAM of the Stellaris® devices is located at address 0x2000.0000 of the device memory map. To reduce the number of time consuming read-modify-write (RMW) operations, ARM has introduced bit-banding technology in the Cortex-M3 processor. With a bit-band-enabled processor, certain regions in the memory map (SRAM and peripheral space) can use address aliases to access individual bits in a single, atomic operation. The bit-band alias is calculated by using the formula: November 30, 2007 139 Preliminary LM3S6952 Microcontroller bit-band alias = bit-band base + (byte offset * 32) + (bit number * 4) For example, if bit 3 at address 0x2000.1000 is to be modified, the bit-band alias is calculated as: 0x2200.0000 + (0x1000 * 32) + (3 * 4) = 0x2202.000C With the alias address calculated, an instruction performing a read/write to address 0x2202.000C allows direct access to only bit 3 of the byte at address 0x2000.1000. For details about bit-banding, please refer to Chapter 4, “Memory Map” in the ARM® Cortex™-M3 Technical Reference Manual. 8.2.2 Flash Memory The flash is organized as a set of 1-KB blocks that can be individually erased. Erasing a block causes the entire contents of the block to be reset to all 1s. An individual 32-bit word can be programmed to change bits that are currently 1 to a 0. These blocks are paired into a set of 2-KB blocks that can be individually protected. The protection allows blocks to be marked as read-only or execute-only, providing different levels of code protection. Read-only blocks cannot be erased or programmed, protecting the contents of those blocks from being modified. Execute-only blocks cannot be erased or programmed, and can only be read by the controller instruction fetch mechanism, protecting the contents of those blocks from being read by either the controller or by a debugger. See also “Serial Flash Loader” on page 551 for a preprogrammed flash-resident utility used to download code to the flash memory of a device without the use of a debug interface. 8.2.2.1 Flash Memory Timing The timing for the flash is automatically handled by the flash controller. However, in order to do so, it must know the clock rate of the system in order to time its internal signals properly. The number of clock cycles per microsecond must be provided to the flash controller for it to accomplish this timing. It is software's responsibility to keep the flash controller updated with this information via the USec Reload (USECRL) register. On reset, the USECRL register is loaded with a value that configures the flash timing so that it works with the maximum clock rate of the part. If software changes the system operating frequency, the new operating frequency minus 1 (in MHz) must be loaded into USECRL before any flash modifications are attempted. For example, if the device is operating at a speed of 20 MHz, a value of 0x13 (20-1) must be written to the USECRL register. 8.2.2.2 Flash Memory Protection The user is provided two forms of flash protection per 2-KB flash blocks in four pairs of 32-bit wide registers. The protection policy for each form is controlled by individual bits (per policy per block) in the FMPPEn and FMPREn registers. ■ Flash Memory Protection Program Enable (FMPPEn): If set, the block may be programmed (written) or erased. If cleared, the block may not be changed. ■ Flash Memory Protection Read Enable (FMPREn): If set, the block may be executed or read by software or debuggers. If cleared, the block may only be executed. The contents of the memory block are prohibited from being accessed as data and traversing the DCode bus. The policies may be combined as shown in Table 8-1 on page 141. 140 November 30, 2007 Preliminary Internal Memory Table 8-1. Flash Protection Policy Combinations FMPPEn FMPREn Protection Execute-only protection. The block may only be executed and may not be written or erased. This mode is used to protect code. 0 0 1 0 The block may be written, erased or executed, but not read. This combination is unlikely to be used. Read-only protection. The block may be read or executed but may not be written or erased. This mode is used to lock the block from further modification while allowing any read or execute access. 0 1 1 1 No protection. The block may be written, erased, executed or read. An access that attempts to program or erase a PE-protected block is prohibited. A controller interrupt may be optionally generated (by setting the AMASK bit in the FIM register) to alert software developers of poorly behaving software during the development and debug phases. An access that attempts to read an RE-protected block is prohibited. Such accesses return data filled with all 0s. A controller interrupt may be optionally generated to alert software developers of poorly behaving software during the development and debug phases. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This implements a policy of open access and programmability. The register bits may be changed by writing the specific register bit. The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. Details on programming these bits are discussed in “Nonvolatile Register Programming” on page 142. 8.3 Flash Memory Initialization and Configuration 8.3.1 Flash Programming The Stellaris® devices provide a user-friendly interface for flash programming. All erase/program operations are handled via three registers: FMA, FMD, and FMC. 8.3.1.1 To program a 32-bit word 1. Write source data to the FMD register. 2. Write the target address to the FMA register. 3. Write the flash write key and the WRITE bit (a value of 0xA442.0001) to the FMC register. 4. Poll the FMC register until the WRITE bit is cleared. 8.3.1.2 To perform an erase of a 1-KB page 1. Write the page address to the FMA register. 2. Write the flash write key and the ERASE bit (a value of 0xA442.0002) to the FMC register. 3. Poll the FMC register until the ERASE bit is cleared. 8.3.1.3 To perform a mass erase of the flash 1. Write the flash write key and the MERASE bit (a value of 0xA442.0004) to the FMC register. 2. Poll the FMC register until the MERASE bit is cleared. November 30, 2007 141 Preliminary LM3S6952 Microcontroller 8.3.2 Nonvolatile Register Programming This section discusses how to update registers that are resident within the flash memory itself. These registers exist in a separate space from the main flash array and are not affected by an ERASE or MASS ERASE operation. These nonvolatile registers are updated by using the COMT bit in the FMC register to activate a write operation. For the USER_DBG register, the data to be written must be loaded into the FMD register before it is "committed". All other registers are R/W and can have their operation tried before committing them to nonvolatile memory. Important: These registers can only have bits changed from 1 to 0 by the user and there is no mechanism for the user to erase them back to a 1 value. In addition, the USER_REG0, USER_REG1, and USER_DBG use bit 31 (NW) of their respective registers to indicate that they are available for user write. These three registers can only be written once whereas the flash protection registers may be written multiple times. Table 8-2 on page 142 provides the FMA address required for commitment of each of the registers and the source of the data to be written when the COMT bit of the FMC register is written with a value of 0xA442.0008. After writing the COMT bit, the user may poll the FMC register to wait for the commit operation to complete. Table 8-2. Flash Resident Registersa Register to be Committed FMA Value Data Source FMPRE0 0x0000.0000 FMPRE0 FMPRE1 0x0000.0002 FMPRE1 FMPRE2 0x0000.0004 FMPRE2 FMPRE3 0x0000.0008 FMPRE3 FMPPE0 0x0000.0001 FMPPE0 FMPPE1 0x0000.0003 FMPPE1 FMPPE2 0x0000.0005 FMPPE2 FMPPE3 0x0000.0007 FMPPE3 USER_REG0 0x8000.0000 USER_REG0 USER_REG1 0x8000.0001 USER_REG1 USER_DBG 0x7510.0000 FMD a. Which FMPREn and FMPPEn registers are available depend on the flash size of your particular Stellaris® device. 8.4 Register Map Table 8-3 on page 142 lists the Flash memory and control registers. The offset listed is a hexadecimal increment to the register's address. The FMA, FMD, FMC, FCRIS, FCIM, and FCMISC registers are relative to the Flash control base address of 0x400F.D000. The FMPREn, FMPPEn, USECRL, USER_DBG, and USER_REGn registers are relative to the System Control base address of 0x400F.E000. Table 8-3. Flash Register Map See Offset Name Type Reset Description page Flash Control Offset 0x000 FMA R/W 0x0000.0000 Flash Memory Address 144 142 November 30, 2007 Preliminary Internal Memory See Offset Name Type Reset Description page 0x004 FMD R/W 0x0000.0000 Flash Memory Data 145 0x008 FMC R/W 0x0000.0000 Flash Memory Control 146 0x00C FCRIS RO 0x0000.0000 Flash Controller Raw Interrupt Status 148 0x010 FCIM R/W 0x0000.0000 Flash Controller Interrupt Mask 149 0x014 FCMISC R/W1C 0x0000.0000 Flash Controller Masked Interrupt Status and Clear 150 System Control Offset 0x130 FMPRE0 R/W 0xFFFF.FFFF Flash Memory Protection Read Enable 0 152 0x200 FMPRE0 R/W 0xFFFF.FFFF Flash Memory Protection Read Enable 0 152 0x134 FMPPE0 R/W 0xFFFF.FFFF Flash Memory Protection Program Enable 0 153 0x400 FMPPE0 R/W 0xFFFF.FFFF Flash Memory Protection Program Enable 0 153 0x140 USECRL R/W 0x31 USec Reload 151 0x1D0 USER_DBG R/W 0xFFFF.FFFE User Debug 154 0x1E0 USER_REG0 R/W 0xFFFF.FFFF User Register 0 155 0x1E4 USER_REG1 R/W 0xFFFF.FFFF User Register 1 156 0x204 FMPRE1 R/W 0xFFFF.FFFF Flash Memory Protection Read Enable 1 157 0x208 FMPRE2 R/W 0xFFFF.FFFF Flash Memory Protection Read Enable 2 158 0x20C FMPRE3 R/W 0xFFFF.FFFF Flash Memory Protection Read Enable 3 159 0x404 FMPPE1 R/W 0xFFFF.FFFF Flash Memory Protection Program Enable 1 160 0x408 FMPPE2 R/W 0xFFFF.FFFF Flash Memory Protection Program Enable 2 161 0x40C FMPPE3 R/W 0xFFFF.FFFF Flash Memory Protection Program Enable 3 162 8.5 Flash Register Descriptions (Flash Control Offset) The remainder of this section lists and describes the Flash Memory registers, in numerical order by address offset. Registers in this section are relative to the Flash control base address of 0x400F.D000. November 30, 2007 143 Preliminary LM3S6952 Microcontroller Register 1: Flash Memory Address (FMA), offset 0x000 During a write operation, this register contains a 4-byte-aligned address and specifies where the data is written. During erase operations, this register contains a 1 KB-aligned address and specifies which page is erased. Note that the alignment requirements must be met by software or the results of the operation are unpredictable. Flash Memory Address (FMA) Base 0x400F.D000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved OFFSET Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 OFFSET Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:18 reserved RO 0x0 Address Offset Address offset in flash where operation is performed, except for nonvolatile registers (see “Nonvolatile Register Programming” on page 142 for details on values for this field). 17:0 OFFSET R/W 0x0 144 November 30, 2007 Preliminary Internal Memory Register 2: Flash Memory Data (FMD), offset 0x004 This register contains the data to be written during the programming cycle or read during the read cycle. Note that the contents of this register are undefined for a read access of an execute-only block. This register is not used during the erase cycles. Flash Memory Data (FMD) Base 0x400F.D000 Offset 0x004 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Data Value Data value for write operation. 31:0 DATA R/W 0x0 November 30, 2007 145 Preliminary LM3S6952 Microcontroller Register 3: Flash Memory Control (FMC), offset 0x008 When this register is written, the flash controller initiates the appropriate access cycle for the location specified by the Flash Memory Address (FMA) register (see page 144). If the access is a write access, the data contained in the Flash Memory Data (FMD) register (see page 145) is written. This is the final register written and initiates the memory operation. There are four control bits in the lower byte of this register that, when set, initiate the memory operation. The most used of these register bits are the ERASE and WRITE bits. It is a programming error to write multiple control bits and the results of such an operation are unpredictable. Flash Memory Control (FMC) Base 0x400F.D000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 WRKEY Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved COMT MERASE ERASE WRITE Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Flash Write Key This field contains a write key, which is used to minimize the incidence of accidental flash writes. The value 0xA442 must be written into this field for a write to occur. Writes to the FMC register without this WRKEY value are ignored. A read of this field returns the value 0. 31:16 WRKEY WO 0x0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:4 reserved RO 0x0 Commit Register Value Commit (write) of register value to nonvolatile storage. A write of 0 has no effect on the state of this bit. If read, the state of the previous commit access is provided. If the previous commit access is complete, a 0 is returned; otherwise, if the commit access is not complete, a 1 is returned. This can take up to 50 μs. 3 COMT R/W 0 Mass Erase Flash Memory If this bit is set, the flash main memory of the device is all erased. A write of 0 has no effect on the state of this bit. If read, the state of the previous mass erase access is provided. If the previous mass erase access is complete, a 0 is returned; otherwise, if the previous mass erase access is not complete, a 1 is returned. This can take up to 250 ms. 2 MERASE R/W 0 146 November 30, 2007 Preliminary Internal Memory Bit/Field Name Type Reset Description Erase a Page of Flash Memory If this bit is set, the page of flash main memory as specified by the contents of FMA is erased. A write of 0 has no effect on the state of this bit. If read, the state of the previous erase access is provided. If the previous erase access is complete, a 0 is returned; otherwise, if the previous erase access is not complete, a 1 is returned. This can take up to 25 ms. 1 ERASE R/W 0 Write a Word into Flash Memory If this bit is set, the data stored in FMD is written into the location as specified by the contents of FMA. A write of 0 has no effect on the state of this bit. If read, the state of the previous write update is provided. If the previous write access is complete, a 0 is returned; otherwise, if the write access is not complete, a 1 is returned. This can take up to 50 μs. 0 WRITE R/W 0 November 30, 2007 147 Preliminary LM3S6952 Microcontroller Register 4: Flash Controller Raw Interrupt Status (FCRIS), offset 0x00C This register indicates that the flash controller has an interrupt condition. An interrupt is only signaled if the corresponding FCIM register bit is set. Flash Controller Raw Interrupt Status (FCRIS) Base 0x400F.D000 Offset 0x00C Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PRIS ARIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Programming Raw Interrupt Status This bit indicates the current state of the programming cycle. If set, the programming cycle completed; if cleared, the programming cycle has not completed. Programming cycles are either write or erase actions generated through the Flash Memory Control (FMC) register bits (see page 146). 1 PRIS RO 0 Access Raw Interrupt Status This bit indicates if the flash was improperly accessed. If set, the program tried to access the flash counter to the policy as set in the Flash Memory Protection Read Enable (FMPREn) and Flash Memory Protection Program Enable (FMPPEn) registers. Otherwise, no access has tried to improperly access the flash. 0 ARIS RO 0 148 November 30, 2007 Preliminary Internal Memory Register 5: Flash Controller Interrupt Mask (FCIM), offset 0x010 This register controls whether the flash controller generates interrupts to the controller. Flash Controller Interrupt Mask (FCIM) Base 0x400F.D000 Offset 0x010 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PMASK AMASK Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Programming Interrupt Mask This bit controls the reporting of the programming raw interrupt status to the controller. If set, a programming-generated interrupt is promoted to the controller. Otherwise, interrupts are recorded but suppressed from the controller. 1 PMASK R/W 0 Access Interrupt Mask This bit controls the reporting of the access raw interrupt status to the controller. If set, an access-generated interrupt is promoted to the controller. Otherwise, interrupts are recorded but suppressed from the controller. 0 AMASK R/W 0 November 30, 2007 149 Preliminary LM3S6952 Microcontroller Register 6: Flash Controller Masked Interrupt Status and Clear (FCMISC), offset 0x014 This register provides two functions. First, it reports the cause of an interrupt by indicating which interrupt source or sources are signalling the interrupt. Second, it serves as the method to clear the interrupt reporting. Flash Controller Masked Interrupt Status and Clear (FCMISC) Base 0x400F.D000 Offset 0x014 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PMISC AMISC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Programming Masked Interrupt Status and Clear This bit indicates whether an interrupt was signaled because a programming cycle completed and was not masked. This bit is cleared by writing a 1. The PRIS bit in the FCRIS register (see page 148) is also cleared when the PMISC bit is cleared. 1 PMISC R/W1C 0 Access Masked Interrupt Status and Clear This bit indicates whether an interrupt was signaled because an improper access was attempted and was not masked. This bit is cleared by writing a 1. The ARIS bit in the FCRIS register is also cleared when the AMISC bit is cleared. 0 AMISC R/W1C 0 8.6 Flash Register Descriptions (System Control Offset) The remainder of this section lists and describes the Flash Memory registers, in numerical order by address offset. Registers in this section are relative to the System Control base address of 0x400F.E000. 150 November 30, 2007 Preliminary Internal Memory Register 7: USec Reload (USECRL), offset 0x140 Note: Offset is relative to System Control base address of 0x400F.E000 This register is provided as a means of creating a 1-μs tick divider reload value for the flash controller. The internal flash has specific minimum and maximum requirements on the length of time the high voltage write pulse can be applied. It is required that this register contain the operating frequency (in MHz -1) whenever the flash is being erased or programmed. The user is required to change this value if the clocking conditions are changed for a flash erase/program operation. USec Reload (USECRL) Base 0x400F.E000 Offset 0x140 Type R/W, reset 0x31 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved USEC Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Microsecond Reload Value MHz -1 of the controller clock when the flash is being erased or programmed. USEC should be set to 0x31 (50 MHz) whenever the flash is being erased or programmed. 7:0 USEC R/W 0x31 November 30, 2007 151 Preliminary LM3S6952 Microcontroller Register 8: Flash Memory Protection Read Enable 0 (FMPRE0), offset 0x130 and 0x200 Note: This register is aliased for backwards compatability. Note: Offset is relative to System Control base address of 0x400FE000. This register stores the read-only protection bits for each 2-KB flash block (FMPPEn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Read Enable 0 (FMPRE0) Base 0x400F.D000 Offset 0x130 and 0x200 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Read Enable Enables 2-KB flash blocks to be executed or read. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 READ_ENABLE R/W 0xFFFFFFFF 152 November 30, 2007 Preliminary Internal Memory Register 9: Flash Memory Protection Program Enable 0 (FMPPE0), offset 0x134 and 0x400 Note: This register is aliased for backwards compatability. Note: Offset is relative to System Control base address of 0x400FE000. This register stores the execute-only protection bits for each 2-KB flash block (FMPREn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Program Enable 0 (FMPPE0) Base 0x400F.D000 Offset 0x134 and 0x400 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Programming Enable Configures 2-KB flash blocks to be execute only. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 PROG_ENABLE R/W 0xFFFFFFFF November 30, 2007 153 Preliminary LM3S6952 Microcontroller Register 10: User Debug (USER_DBG), offset 0x1D0 Note: Offset is relative to System Control base address of 0x400FE000. This register provides a write-once mechanism to disable external debugger access to the device in addition to 27 additional bits of user-defined data. The DBG0 bit (bit 0) is set to 0 from the factory and the DBG1 bit (bit 1) is set to 1, which enables external debuggers. Changing the DBG1 bit to 0 disables any external debugger access to the device permanently, starting with the next power-up cycle of the device. The NOTWRITTEN bit (bit 31) indicates that the register is available to be written and is controlled through hardware to ensure that the register is only written once. User Debug (USER_DBG) Base 0x400F.E000 Offset 0x1D0 Type R/W, reset 0xFFFF.FFFE 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 NW DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DATA DBG1 DBG0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 Bit/Field Name Type Reset Description User Debug Not Written Specifies that this 32-bit dword has not been written. 31 NW R/W 1 User Data Contains the user data value. This field is initialized to all 1s and can only be written once. 30:2 DATA R/W 0x1FFFFFFF Debug Control 1 The DBG1 bit must be 1 and DBG0 must be 0 for debug to be available. 1 DBG1 R/W 1 Debug Control 0 The DBG1 bit must be 1 and DBG0 must be 0 for debug to be available. 0 DBG0 R/W 0 154 November 30, 2007 Preliminary Internal Memory Register 11: User Register 0 (USER_REG0), offset 0x1E0 Note: Offset is relative to System Control base address of 0x400FE000. This register provides 31 bits of user-defined data that is non-volatile and can only be written once. Bit 31 indicates that the register is available to be written and is controlled through hardware to ensure that the register is only written once. The write-once characteristics of this register are useful for keeping static information like communication addresses that need to be unique per part and would otherwise require an external EEPROM or other non-volatile device. User Register 0 (USER_REG0) Base 0x400F.E000 Offset 0x1E0 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 NW DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Not Written Specifies that this 32-bit dword has not been written. 31 NW R/W 1 User Data Contains the user data value. This field is initialized to all 1s and can only be written once. 30:0 DATA R/W 0x7FFFFFFF November 30, 2007 155 Preliminary LM3S6952 Microcontroller Register 12: User Register 1 (USER_REG1), offset 0x1E4 Note: Offset is relative to System Control base address of 0x400FE000. This register provides 31 bits of user-defined data that is non-volatile and can only be written once. Bit 31 indicates that the register is available to be written and is controlled through hardware to ensure that the register is only written once. The write-once characteristics of this register are useful for keeping static information like communication addresses that need to be unique per part and would otherwise require an external EEPROM or other non-volatile device. User Register 1 (USER_REG1) Base 0x400F.E000 Offset 0x1E4 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 NW DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Not Written Specifies that this 32-bit dword has not been written. 31 NW R/W 1 User Data Contains the user data value. This field is initialized to all 1s and can only be written once. 30:0 DATA R/W 0x7FFFFFFF 156 November 30, 2007 Preliminary Internal Memory Register 13: Flash Memory Protection Read Enable 1 (FMPRE1), offset 0x204 Note: Offset is relative to System Control base address of 0x400FE000. This register stores the read-only protection bits for each 2-KB flash block (FMPPEn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Read Enable 1 (FMPRE1) Base 0x400F.E000 Offset 0x204 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Read Enable Enables 2-KB flash blocks to be executed or read. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 READ_ENABLE R/W 0xFFFFFFFF November 30, 2007 157 Preliminary LM3S6952 Microcontroller Register 14: Flash Memory Protection Read Enable 2 (FMPRE2), offset 0x208 Note: Offset is relative to System Control base address of 0x400FE000. This register stores the read-only protection bits for each 2-KB flash block (FMPPEn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Read Enable 2 (FMPRE2) Base 0x400F.E000 Offset 0x208 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Read Enable Enables 2-KB flash blocks to be executed or read. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 READ_ENABLE R/W 0xFFFFFFFF 158 November 30, 2007 Preliminary Internal Memory Register 15: Flash Memory Protection Read Enable 3 (FMPRE3), offset 0x20C Note: Offset is relative to System Control base address of 0x400FE000. This register stores the read-only protection bits for each 2-KB flash block (FMPPEn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Read Enable 3 (FMPRE3) Base 0x400F.E000 Offset 0x20C Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 READ_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Read Enable Enables 2-KB flash blocks to be executed or read. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 READ_ENABLE R/W 0xFFFFFFFF November 30, 2007 159 Preliminary LM3S6952 Microcontroller Register 16: Flash Memory Protection Program Enable 1 (FMPPE1), offset 0x404 Note: Offset is relative to System Control base address of 0x400FE000. This register stores the execute-only protection bits for each 2-KB flash block (FMPREn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Program Enable 1 (FMPPE1) Base 0x400F.E000 Offset 0x404 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Programming Enable Configures 2-KB flash blocks to be execute only. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 PROG_ENABLE R/W 0xFFFFFFFF 160 November 30, 2007 Preliminary Internal Memory Register 17: Flash Memory Protection Program Enable 2 (FMPPE2), offset 0x408 Note: Offset is relative to System Control base address of 0x400FE000. This register stores the execute-only protection bits for each 2-KB flash block (FMPREn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Program Enable 2 (FMPPE2) Base 0x400F.E000 Offset 0x408 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Programming Enable Configures 2-KB flash blocks to be execute only. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 PROG_ENABLE R/W 0xFFFFFFFF November 30, 2007 161 Preliminary LM3S6952 Microcontroller Register 18: Flash Memory Protection Program Enable 3 (FMPPE3), offset 0x40C Note: Offset is relative to System Control base address of 0x400FE000. This register stores the execute-only protection bits for each 2-KB flash block (FMPREn stores the execute-only bits). This register is loaded during the power-on reset sequence. The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented banks. This achieves a policy of open access and programmability. The register bits may be changed by writing the specific register bit. However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it may be restored by executing a power-on reset sequence. For additional information, see the "Flash Memory Protection" section. Flash Memory Protection Program Enable 3 (FMPPE3) Base 0x400F.E000 Offset 0x40C Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 PROG_ENABLE Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Flash Programming Enable Configures 2-KB flash blocks to be execute only. The policies may be combined as shown in the table “Flash Protection Policy Combinations”. Value Description 0xFFFFFFFF Enables 256 KB of flash. 31:0 PROG_ENABLE R/W 0xFFFFFFFF 162 November 30, 2007 Preliminary Internal Memory 9 General-Purpose Input/Outputs (GPIOs) The GPIO module is composed of seven physical GPIO blocks, each corresponding to an individual GPIO port (Port A, Port B, Port C, Port D, Port E, Port F, and Port G, ). The GPIO module is FiRM-compliant and supports 6-43 programmable input/output pins, depending on the peripherals being used. The GPIO module has the following features: ■ Programmable control for GPIO interrupts – Interrupt generation masking – Edge-triggered on rising, falling, or both – Level-sensitive on High or Low values ■ 5-V-tolerant input/outputs ■ Bit masking in both read and write operations through address lines ■ Programmable control for GPIO pad configuration – Weak pull-up or pull-down resistors – 2-mA, 4-mA, and 8-mA pad drive – Slew rate control for the 8-mA drive – Open drain enables – Digital input enables 9.1 Functional Description Important: All GPIO pins are tri-stated by default (GPIOAFSEL=0, GPIODEN=0, GPIOPDR=0, and GPIOPUR=0), with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). The JTAG/SWD pins default to their JTAG/SWD functionality (GPIOAFSEL=1, GPIODEN=1 and GPIOPUR=1). A Power-On-Reset (POR) or asserting RST puts both groups of pins back to their default state. Each GPIO port is a separate hardware instantiation of the same physical block (see Figure 9-1 on page 164). The LM3S6952 microcontroller contains seven ports and thus seven of these physical GPIO blocks. November 30, 2007 163 Preliminary LM3S6952 Microcontroller Figure 9-1. GPIO Port Block Diagram Alternate Input Alternate Output Alternate Output Enable Interrupt GPIO Input GPIO Output GPIO Output Enable Pad Output Pad Output Enable Package I/O Pin GPIODATA GPIODIR Data Control GPIOIS GPIOIBE GPIOIEV GPIOIM GPIORIS GPIOMIS GPIOICR Interrupt Control GPIODR2R GPIODR4R GPIODR8R GPIOSLR GPIOPUR GPIOPDR GPIOODR GPIODEN Pad Control GPIOPeriphID0 GPIOPeriphID1 GPIOPeriphID2 GPIOPeriphID3 GPIOPeriphID4 GPIOPeriphID5 GPIOPeriphID6 GPIOPeriphID7 GPIOPCellID0 GPIOPCellID1 GPIOPCellID2 GPIOPCellID3 Identification Registers GPIOAFSEL Mode Control DEMUX MUX MUX Digital I/O Pad Pad Input GPIOLOCK Commit Control GPIOCR 9.1.1 Data Control The data control registers allow software to configure the operational modes of the GPIOs. The data direction register configures the GPIO as an input or an output while the data register either captures incoming data or drives it out to the pads. 9.1.1.1 Data Direction Operation The GPIO Direction (GPIODIR) register (see page 171) is used to configure each individual pin as an input or output. When the data direction bit is set to 0, the GPIO is configured as an input and the corresponding data register bit will capture and store the value on the GPIO port. When the data direction bit is set to 1, the GPIO is configured as an output and the corresponding data register bit will be driven out on the GPIO port. 9.1.1.2 Data Register Operation To aid in the efficiency of software, the GPIO ports allow for the modification of individual bits in the GPIO Data (GPIODATA) register (see page 170) by using bits [9:2] of the address bus as a mask. This allows software drivers to modify individual GPIO pins in a single instruction, without affecting the state of the other pins. This is in contrast to the "typical" method of doing a read-modify-write operation to set or clear an individual GPIO pin. To accommodate this feature, the GPIODATA register covers 256 locations in the memory map. During a write, if the address bit associated with that data bit is set to 1, the value of the GPIODATA register is altered. If it is cleared to 0, it is left unchanged. 164 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) For example, writing a value of 0xEB to the address GPIODATA + 0x098 would yield as shown in Figure 9-2 on page 165, where u is data unchanged by the write. Figure 9-2. GPIODATA Write Example 0 0 1 0 0 1 1 0 1 0 u u 1 u u 0 1 u 9 8 7 6 5 4 3 2 1 0 1 1 1 0 1 0 1 1 7 6 5 4 3 2 1 0 GPIODATA 0xEB 0x098 ADDR[9:2] During a read, if the address bit associated with the data bit is set to 1, the value is read. If the address bit associated with the data bit is set to 0, it is read as a zero, regardless of its actual value. For example, reading address GPIODATA + 0x0C4 yields as shown in Figure 9-3 on page 165. Figure 9-3. GPIODATA Read Example 0 0 1 1 0 0 0 1 0 0 0 0 1 1 0 0 0 0 9 8 7 6 5 4 3 2 1 0 1 0 1 1 1 1 1 0 7 6 5 4 3 2 1 0 Returned Value GPIODATA 0x0C4 ADDR[9:2] 9.1.2 Interrupt Control The interrupt capabilities of each GPIO port are controlled by a set of seven registers. With these registers, it is possible to select the source of the interrupt, its polarity, and the edge properties. When one or more GPIO inputs cause an interrupt, a single interrupt output is sent to the interrupt controller for the entire GPIO port. For edge-triggered interrupts, software must clear the interrupt to enable any further interrupts. For a level-sensitive interrupt, it is assumed that the external source holds the level constant for the interrupt to be recognized by the controller. Three registers are required to define the edge or sense that causes interrupts: ■ GPIO Interrupt Sense (GPIOIS) register (see page 172) ■ GPIO Interrupt Both Edges (GPIOIBE) register (see page 173) ■ GPIO Interrupt Event (GPIOIEV) register (see page 174) Interrupts are enabled/disabled via the GPIO Interrupt Mask (GPIOIM) register (see page 175). When an interrupt condition occurs, the state of the interrupt signal can be viewed in two locations: the GPIO Raw Interrupt Status (GPIORIS) and GPIO Masked Interrupt Status (GPIOMIS) registers (see page 176 and page 177). As the name implies, the GPIOMIS register only shows interrupt conditions that are allowed to be passed to the controller. The GPIORIS register indicates that a GPIO pin meets the conditions for an interrupt, but has not necessarily been sent to the controller. November 30, 2007 165 Preliminary LM3S6952 Microcontroller In addition to providing GPIO functionality, PB4 can also be used as an external trigger for the ADC. If PB4 is configured as a non-masked interrupt pin (GPIOIM is set to 1), not only is an interrupt for PortB generated, but an external trigger signal is sent to the ADC. If the ADC Event Multiplexer Select (ADCEMUX) register is configured to use the external trigger, an ADC conversion is initiated. If no other PortB pins are being used to generate interrupts, the ARM Integrated Nested Vectored Interrupt Controller (NVIC) Interrupt Set Enable (SETNA) register can disable the PortB interrupts and the ADC interrupt can be used to read back the converted data. Otherwise, the PortB interrupt handler needs to ignore and clear interrupts on B4, and wait for the ADC interrupt or the ADC interrupt needs to be disabled in the SETNA register and the PortB interrupt handler polls the ADC registers until the conversion is completed. Interrupts are cleared by writing a 1 to the GPIO Interrupt Clear (GPIOICR) register (see page 178). When programming the following interrupt control registers, the interrupts should be masked (GPIOIM set to 0). Writing any value to an interrupt control register (GPIOIS, GPIOIBE, or GPIOIEV) can generate a spurious interrupt if the corresponding bits are enabled. 9.1.3 Mode Control The GPIO pins can be controlled by either hardware or software. When hardware control is enabled via the GPIO Alternate Function Select (GPIOAFSEL) register (see page 179), the pin state is controlled by its alternate function (that is, the peripheral). Software control corresponds to GPIO mode, where the GPIODATA register is used to read/write the corresponding pins. 9.1.4 Commit Control The commit control registers provide a layer of protection against accidental programming of critical hardware peripherals. Writes to protected bits of the GPIO Alternate Function Select (GPIOAFSEL) register (see page 179) are not committed to storage unless the GPIO Lock (GPIOLOCK) register (see page 189) has been unlocked and the appropriate bits of the GPIO Commit (GPIOCR) register (see page 190) have been set to 1. 9.1.5 Pad Control The pad control registers allow for GPIO pad configuration by software based on the application requirements. The pad control registers include the GPIODR2R, GPIODR4R, GPIODR8R, GPIOODR, GPIOPUR, GPIOPDR, GPIOSLR, and GPIODEN registers. 9.1.6 Identification The identification registers configured at reset allow software to detect and identify the module as a GPIO block. The identification registers include the GPIOPeriphID0-GPIOPeriphID7 registers as well as the GPIOPCellID0-GPIOPCellID3 registers. 9.2 Initialization and Configuration To use the GPIO, the peripheral clock must be enabled by setting the appropriate GPIO Port bit field (GPIOn) in the RCGC2 register. On reset, all GPIO pins (except for the five JTAG pins) are configured out of reset to be undriven (tristate): GPIOAFSEL=0, GPIODEN=0, GPIOPDR=0, and GPIOPUR=0. Table 9-1 on page 167 shows all possible configurations of the GPIO pads and the control register settings required to achieve them. Table 9-2 on page 167 shows how a rising edge interrupt would be configured for pin 2 of a GPIO port. 166 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Table 9-1. GPIO Pad Configuration Examples Configuration GPIO Register Bit Valuea AFSEL DIR ODR DEN PUR PDR DR2R DR4R DR8R SLR Digital Input (GPIO) 0 0 0 1 ? ? X X X X Digital Output (GPIO) 0 1 0 1 ? ? ? ? ? ? Open Drain Input 0 0 1 1 X X X X X X (GPIO) Open Drain Output 0 1 1 1 X X ? ? ? ? (GPIO) Open Drain 1 X 1 1 X X ? ? ? ? Input/Output (I2C) Digital Input (Timer 1 X 0 1 ? ? X X X X CCP) Digital Input (QEI) 1 X 0 1 ? ? X X X X Digital Output (PWM) 1 X 0 1 ? ? ? ? ? ? Digital Output (Timer 1 X 0 1 ? ? ? ? ? ? PWM) Digital Input/Output 1 X 0 1 ? ? ? ? ? ? (SSI) Digital Input/Output 1 X 0 1 ? ? ? ? ? ? (UART) Analog Input 0 0 0 0 0 0 X X X X (Comparator) Digital Output 1 X 0 1 ? ? ? ? ? ? (Comparator) a. X=Ignored (don’t care bit) ?=Can be either 0 or 1, depending on the configuration Table 9-2. GPIO Interrupt Configuration Example Desired Pin 2 Bit Valuea Interrupt Event Trigger Register 7 6 5 4 3 2 1 0 0=edge X X X X X 0 X X 1=level GPIOIS 0=single X X X X X 0 X X edge 1=both edges GPIOIBE 0=Low level, X X X X X 1 X X or negative edge 1=High level, or positive edge GPIOIEV 0=masked 0 0 0 0 0 1 0 0 1=not masked GPIOIM a. X=Ignored (don’t care bit) November 30, 2007 167 Preliminary LM3S6952 Microcontroller 9.3 Register Map Table 9-3 on page 168 lists the GPIO registers. The offset listed is a hexadecimal increment to the register’s address, relative to that GPIO port’s base address: ■ GPIO Port A: 0x4000.4000 ■ GPIO Port B: 0x4000.5000 ■ GPIO Port C: 0x4000.6000 ■ GPIO Port D: 0x4000.7000 ■ GPIO Port E: 0x4002.4000 ■ GPIO Port F: 0x4002.5000 ■ GPIO Port G: 0x4002.6000 Important: The GPIO registers in this chapter are duplicated in each GPIO block, however, depending on the block, all eight bits may not be connected to a GPIO pad. In those cases, writing to those unconnected bits has no effect and reading those unconnected bits returns no meaningful data. Note: The default reset value for the GPIOAFSEL, GPIOPUR, and GPIODEN registers are 0x0000.0000 for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins default to JTAG/SWD functionality. Because of this, the default reset value of these registers for GPIO Port B is 0x0000.0080 while the default reset value for Port C is 0x0000.000F. The default register type for the GPIOCR register is RO for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins are currently the only GPIOs that are protected by the GPIOCR register. Because of this, the register type for GPIO Port B7 and GPIO Port C[3:0] is R/W. The default reset value for the GPIOCR register is 0x0000.00FF for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). To ensure that the JTAG port is not accidentally programmed as a GPIO, these five pins default to non-commitable. Because of this, the default reset value of GPIOCR for GPIO Port B is 0x0000.007F while the default reset value of GPIOCR for Port C is 0x0000.00F0. Table 9-3. GPIO Register Map See Offset Name Type Reset Description page 0x000 GPIODATA R/W 0x0000.0000 GPIO Data 170 0x400 GPIODIR R/W 0x0000.0000 GPIO Direction 171 0x404 GPIOIS R/W 0x0000.0000 GPIO Interrupt Sense 172 0x408 GPIOIBE R/W 0x0000.0000 GPIO Interrupt Both Edges 173 0x40C GPIOIEV R/W 0x0000.0000 GPIO Interrupt Event 174 0x410 GPIOIM R/W 0x0000.0000 GPIO Interrupt Mask 175 168 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) See Offset Name Type Reset Description page 0x414 GPIORIS RO 0x0000.0000 GPIO Raw Interrupt Status 176 0x418 GPIOMIS RO 0x0000.0000 GPIO Masked Interrupt Status 177 0x41C GPIOICR W1C 0x0000.0000 GPIO Interrupt Clear 178 0x420 GPIOAFSEL R/W - GPIO Alternate Function Select 179 0x500 GPIODR2R R/W 0x0000.00FF GPIO 2-mA Drive Select 181 0x504 GPIODR4R R/W 0x0000.0000 GPIO 4-mA Drive Select 182 0x508 GPIODR8R R/W 0x0000.0000 GPIO 8-mA Drive Select 183 0x50C GPIOODR R/W 0x0000.0000 GPIO Open Drain Select 184 0x510 GPIOPUR R/W - GPIO Pull-Up Select 185 0x514 GPIOPDR R/W 0x0000.0000 GPIO Pull-Down Select 186 0x518 GPIOSLR R/W 0x0000.0000 GPIO Slew Rate Control Select 187 0x51C GPIODEN R/W - GPIO Digital Enable 188 0x520 GPIOLOCK R/W 0x0000.0001 GPIO Lock 189 0x524 GPIOCR - - GPIO Commit 190 0xFD0 GPIOPeriphID4 RO 0x0000.0000 GPIO Peripheral Identification 4 192 0xFD4 GPIOPeriphID5 RO 0x0000.0000 GPIO Peripheral Identification 5 193 0xFD8 GPIOPeriphID6 RO 0x0000.0000 GPIO Peripheral Identification 6 194 0xFDC GPIOPeriphID7 RO 0x0000.0000 GPIO Peripheral Identification 7 195 0xFE0 GPIOPeriphID0 RO 0x0000.0061 GPIO Peripheral Identification 0 196 0xFE4 GPIOPeriphID1 RO 0x0000.0000 GPIO Peripheral Identification 1 197 0xFE8 GPIOPeriphID2 RO 0x0000.0018 GPIO Peripheral Identification 2 198 0xFEC GPIOPeriphID3 RO 0x0000.0001 GPIO Peripheral Identification 3 199 0xFF0 GPIOPCellID0 RO 0x0000.000D GPIO PrimeCell Identification 0 200 0xFF4 GPIOPCellID1 RO 0x0000.00F0 GPIO PrimeCell Identification 1 201 0xFF8 GPIOPCellID2 RO 0x0000.0005 GPIO PrimeCell Identification 2 202 0xFFC GPIOPCellID3 RO 0x0000.00B1 GPIO PrimeCell Identification 3 203 9.4 Register Descriptions The remainder of this section lists and describes the GPIO registers, in numerical order by address offset. November 30, 2007 169 Preliminary LM3S6952 Microcontroller Register 1: GPIO Data (GPIODATA), offset 0x000 The GPIODATA register is the data register. In software control mode, values written in the GPIODATA register are transferred onto the GPIO port pins if the respective pins have been configured as outputs through the GPIO Direction (GPIODIR) register (see page 171). In order to write to GPIODATA, the corresponding bits in the mask, resulting from the address bus bits [9:2], must be High. Otherwise, the bit values remain unchanged by the write. Similarly, the values read from this register are determined for each bit by the mask bit derived from the address used to access the data register, bits [9:2]. Bits that are 1 in the address mask cause the corresponding bits in GPIODATA to be read, and bits that are 0 in the address mask cause the corresponding bits in GPIODATA to be read as 0, regardless of their value. A read from GPIODATA returns the last bit value written if the respective pins are configured as outputs, or it returns the value on the corresponding input pin when these are configured as inputs. All bits are cleared by a reset. GPIO Data (GPIODATA) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DATA Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Data This register is virtually mapped to 256 locations in the address space. To facilitate the reading and writing of data to these registers by independent drivers, the data read from and the data written to the registers are masked by the eight address lines ipaddr[9:2]. Reads from this register return its current state. Writes to this register only affect bits that are not masked by ipaddr[9:2] and are configured as outputs. See “Data Register Operation” on page 164 for examples of reads and writes. 7:0 DATA R/W 0x00 170 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 2: GPIO Direction (GPIODIR), offset 0x400 The GPIODIR register is the data direction register. Bits set to 1 in the GPIODIR register configure the corresponding pin to be an output, while bits set to 0 configure the pins to be inputs. All bits are cleared by a reset, meaning all GPIO pins are inputs by default. GPIO Direction (GPIODIR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x400 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DIR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Data Direction The DIR values are defined as follows: Value Description 0 Pins are inputs. 1 Pins are outputs. 7:0 DIR R/W 0x00 November 30, 2007 171 Preliminary LM3S6952 Microcontroller Register 3: GPIO Interrupt Sense (GPIOIS), offset 0x404 The GPIOIS register is the interrupt sense register. Bits set to 1 in GPIOIS configure the corresponding pins to detect levels, while bits set to 0 configure the pins to detect edges. All bits are cleared by a reset. GPIO Interrupt Sense (GPIOIS) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x404 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IS Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Sense The IS values are defined as follows: Value Description 0 Edge on corresponding pin is detected (edge-sensitive). 1 Level on corresponding pin is detected (level-sensitive). 7:0 IS R/W 0x00 172 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 4: GPIO Interrupt Both Edges (GPIOIBE), offset 0x408 The GPIOIBE register is the interrupt both-edges register. When the corresponding bit in the GPIO Interrupt Sense (GPIOIS) register (see page 172) is set to detect edges, bits set to High in GPIOIBE configure the corresponding pin to detect both rising and falling edges, regardless of the corresponding bit in the GPIO Interrupt Event (GPIOIEV) register (see page 174). Clearing a bit configures the pin to be controlled by GPIOIEV. All bits are cleared by a reset. GPIO Interrupt Both Edges (GPIOIBE) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x408 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IBE Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Both Edges The IBE values are defined as follows: Value Description Interrupt generation is controlled by the GPIO Interrupt Event (GPIOIEV) register (see page 174). 0 1 Both edges on the corresponding pin trigger an interrupt. Note: Single edge is determined by the corresponding bit in GPIOIEV. 7:0 IBE R/W 0x00 November 30, 2007 173 Preliminary LM3S6952 Microcontroller Register 5: GPIO Interrupt Event (GPIOIEV), offset 0x40C The GPIOIEV register is the interrupt event register. Bits set to High in GPIOIEV configure the corresponding pin to detect rising edges or high levels, depending on the corresponding bit value in the GPIO Interrupt Sense (GPIOIS) register (see page 172). Clearing a bit configures the pin to detect falling edges or low levels, depending on the corresponding bit value in GPIOIS. All bits are cleared by a reset. GPIO Interrupt Event (GPIOIEV) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x40C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IEV Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Event The IEV values are defined as follows: Value Description Falling edge or Low levels on corresponding pins trigger interrupts. 0 Rising edge or High levels on corresponding pins trigger interrupts. 1 7:0 IEV R/W 0x00 174 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 6: GPIO Interrupt Mask (GPIOIM), offset 0x410 The GPIOIM register is the interrupt mask register. Bits set to High in GPIOIM allow the corresponding pins to trigger their individual interrupts and the combined GPIOINTR line. Clearing a bit disables interrupt triggering on that pin. All bits are cleared by a reset. GPIO Interrupt Mask (GPIOIM) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x410 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IME Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Mask Enable The IME values are defined as follows: Value Description 0 Corresponding pin interrupt is masked. 1 Corresponding pin interrupt is not masked. 7:0 IME R/W 0x00 November 30, 2007 175 Preliminary LM3S6952 Microcontroller Register 7: GPIO Raw Interrupt Status (GPIORIS), offset 0x414 The GPIORIS register is the raw interrupt status register. Bits read High in GPIORIS reflect the status of interrupt trigger conditions detected (raw, prior to masking), indicating that all the requirements have been met, before they are finally allowed to trigger by the GPIO Interrupt Mask (GPIOIM) register (see page 175). Bits read as zero indicate that corresponding input pins have not initiated an interrupt. All bits are cleared by a reset. GPIO Raw Interrupt Status (GPIORIS) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x414 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Raw Status Reflects the status of interrupt trigger condition detection on pins (raw, prior to masking). The RIS values are defined as follows: Value Description 0 Corresponding pin interrupt requirements not met. 1 Corresponding pin interrupt has met requirements. 7:0 RIS RO 0x00 176 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 8: GPIO Masked Interrupt Status (GPIOMIS), offset 0x418 The GPIOMIS register is the masked interrupt status register. Bits read High in GPIOMIS reflect the status of input lines triggering an interrupt. Bits read as Low indicate that either no interrupt has been generated, or the interrupt is masked. In addition to providing GPIO functionality, PB4 can also be used as an external trigger for the ADC. If PB4 is configured as a non-masked interrupt pin (GPIOIM is set to 1), not only is an interrupt for PortB generated, but an external trigger signal is sent to the ADC. If the ADC Event Multiplexer Select (ADCEMUX) register is configured to use the external trigger, an ADC conversion is initiated. If no other PortB pins are being used to generate interrupts, the ARM Integrated Nested Vectored Interrupt Controller (NVIC) Interrupt Set Enable (SETNA) register can disable the PortB interrupts and the ADC interrupt can be used to read back the converted data. Otherwise, the PortB interrupt handler needs to ignore and clear interrupts on B4, and wait for the ADC interrupt or the ADC interrupt needs to be disabled in the SETNA register and the PortB interrupt handler polls the ADC registers until the conversion is completed. GPIOMIS is the state of the interrupt after masking. GPIO Masked Interrupt Status (GPIOMIS) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x418 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Masked Interrupt Status Masked value of interrupt due to corresponding pin. The MIS values are defined as follows: Value Description 0 Corresponding GPIO line interrupt not active. 1 Corresponding GPIO line asserting interrupt. 7:0 MIS RO 0x00 November 30, 2007 177 Preliminary LM3S6952 Microcontroller Register 9: GPIO Interrupt Clear (GPIOICR), offset 0x41C The GPIOICR register is the interrupt clear register. Writing a 1 to a bit in this register clears the corresponding interrupt edge detection logic register. Writing a 0 has no effect. GPIO Interrupt Clear (GPIOICR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x41C Type W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IC Type RO RO RO RO RO RO RO RO W1C W1C W1C W1C W1C W1C W1C W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Interrupt Clear The IC values are defined as follows: Value Description 0 Corresponding interrupt is unaffected. 1 Corresponding interrupt is cleared. 7:0 IC W1C 0x00 178 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 10: GPIO Alternate Function Select (GPIOAFSEL), offset 0x420 The GPIOAFSEL register is the mode control select register. Writing a 1 to any bit in this register selects the hardware control for the corresponding GPIO line. All bits are cleared by a reset, therefore no GPIO line is set to hardware control by default. The commit control registers provide a layer of protection against accidental programming of critical hardware peripherals. Writes to protected bits of the GPIO Alternate Function Select (GPIOAFSEL) register (see page 179) are not committed to storage unless the GPIO Lock (GPIOLOCK) register (see page 189) has been unlocked and the appropriate bits of the GPIO Commit (GPIOCR) register (see page 190) have been set to 1. Important: All GPIO pins are tri-stated by default (GPIOAFSEL=0, GPIODEN=0, GPIOPDR=0, and GPIOPUR=0), with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). The JTAG/SWD pins default to their JTAG/SWD functionality (GPIOAFSEL=1, GPIODEN=1 and GPIOPUR=1). A Power-On-Reset (POR) or asserting RST puts both groups of pins back to their default state. Caution – If the JTAG pins are used as GPIOs in a design, PB7 and PC2 cannot have external pull-down resistors connected to both of them at the same time. If both pins are pulled Low during reset, the controller has unpredictable behavior. If this happens, remove one or both of the pull-down resistors, and apply RST or power-cycle the part. In addition, it is possible to create a software sequence that prevents the debugger from connecting to the Stellaris® microcontroller. If the program code loaded into flash immediately changes the JTAG pins to their GPIO functionality, the debugger may not have enough time to connect and halt the controller before the JTAG pin functionality switches. This may lock the debugger out of the part. This can be avoided with a software routine that restores JTAG functionality based on an external or software trigger. GPIO Alternate Function Select (GPIOAFSEL) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x420 Type R/W, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved AFSEL Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 November 30, 2007 179 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description GPIO Alternate Function Select The AFSEL values are defined as follows: Value Description 0 Software control of corresponding GPIO line (GPIO mode). Hardware control of corresponding GPIO line (alternate hardware function). 1 Note: The default reset value for the GPIOAFSEL, GPIOPUR, and GPIODEN registers are 0x0000.0000 for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins default to JTAG/SWD functionality. Because of this, the default reset value of these registers for GPIO Port B is 0x0000.0080 while the default reset value for Port C is 0x0000.000F. 7:0 AFSEL R/W - 180 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 11: GPIO 2-mA Drive Select (GPIODR2R), offset 0x500 The GPIODR2R register is the 2-mA drive control register. It allows for each GPIO signal in the port to be individually configured without affecting the other pads. When writing a DRV2 bit for a GPIO signal, the corresponding DRV4 bit in the GPIODR4R register and the DRV8 bit in the GPIODR8R register are automatically cleared by hardware. GPIO 2-mA Drive Select (GPIODR2R) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x500 Type R/W, reset 0x0000.00FF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DRV2 Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Output Pad 2-mA Drive Enable A write of 1 to either GPIODR4[n] or GPIODR8[n] clears the corresponding 2-mA enable bit. The change is effective on the second clock cycle after the write. 7:0 DRV2 R/W 0xFF November 30, 2007 181 Preliminary LM3S6952 Microcontroller Register 12: GPIO 4-mA Drive Select (GPIODR4R), offset 0x504 The GPIODR4R register is the 4-mA drive control register. It allows for each GPIO signal in the port to be individually configured without affecting the other pads. When writing the DRV4 bit for a GPIO signal, the corresponding DRV2 bit in the GPIODR2R register and the DRV8 bit in the GPIODR8R register are automatically cleared by hardware. GPIO 4-mA Drive Select (GPIODR4R) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x504 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DRV4 Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Output Pad 4-mA Drive Enable A write of 1 to either GPIODR2[n] or GPIODR8[n] clears the corresponding 4-mA enable bit. The change is effective on the second clock cycle after the write. 7:0 DRV4 R/W 0x00 182 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 13: GPIO 8-mA Drive Select (GPIODR8R), offset 0x508 The GPIODR8R register is the 8-mA drive control register. It allows for each GPIO signal in the port to be individually configured without affecting the other pads. When writing the DRV8 bit for a GPIO signal, the corresponding DRV2 bit in the GPIODR2R register and the DRV4 bit in the GPIODR4R register are automatically cleared by hardware. GPIO 8-mA Drive Select (GPIODR8R) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x508 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DRV8 Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Output Pad 8-mA Drive Enable A write of 1 to either GPIODR2[n] or GPIODR4[n] clears the corresponding 8-mA enable bit. The change is effective on the second clock cycle after the write. 7:0 DRV8 R/W 0x00 November 30, 2007 183 Preliminary LM3S6952 Microcontroller Register 14: GPIO Open Drain Select (GPIOODR), offset 0x50C The GPIOODR register is the open drain control register. Setting a bit in this register enables the open drain configuration of the corresponding GPIO pad. When open drain mode is enabled, the corresponding bit should also be set in the GPIO Digital Input Enable (GPIODEN) register (see page 188). Corresponding bits in the drive strength registers (GPIODR2R, GPIODR4R, GPIODR8R, and GPIOSLR ) can be set to achieve the desired rise and fall times. The GPIO acts as an open drain input if the corresponding bit in the GPIODIR register is set to 0; and as an open drain output when set to 1. When using the I2C module, the GPIO Alternate Function Select (GPIOAFSEL) register bit for PB2 and PB3 should be set to 1 (see examples in “Initialization and Configuration” on page 166). GPIO Open Drain Select (GPIOODR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x50C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved ODE Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Output Pad Open Drain Enable The ODE values are defined as follows: Value Description 0 Open drain configuration is disabled. 1 Open drain configuration is enabled. 7:0 ODE R/W 0x00 184 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 15: GPIO Pull-Up Select (GPIOPUR), offset 0x510 The GPIOPUR register is the pull-up control register. When a bit is set to 1, it enables a weak pull-up resistor on the corresponding GPIO signal. Setting a bit in GPIOPUR automatically clears the corresponding bit in the GPIO Pull-Down Select (GPIOPDR) register (see page 186). GPIO Pull-Up Select (GPIOPUR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x510 Type R/W, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PUE Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Pad Weak Pull-Up Enable A write of 1 to GPIOPDR[n] clears the corresponding GPIOPUR[n] enables. The change is effective on the second clock cycle after the write. Note: The default reset value for the GPIOAFSEL, GPIOPUR, and GPIODEN registers are 0x0000.0000 for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins default to JTAG/SWD functionality. Because of this, the default reset value of these registers for GPIO Port B is 0x0000.0080 while the default reset value for Port C is 0x0000.000F. 7:0 PUE R/W - November 30, 2007 185 Preliminary LM3S6952 Microcontroller Register 16: GPIO Pull-Down Select (GPIOPDR), offset 0x514 The GPIOPDR register is the pull-down control register. When a bit is set to 1, it enables a weak pull-down resistor on the corresponding GPIO signal. Setting a bit in GPIOPDR automatically clears the corresponding bit in the GPIO Pull-Up Select (GPIOPUR) register (see page 185). GPIO Pull-Down Select (GPIOPDR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x514 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PDE Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Pad Weak Pull-Down Enable A write of 1 to GPIOPUR[n] clears the corresponding GPIOPDR[n] enables. The change is effective on the second clock cycle after the write. 7:0 PDE R/W 0x00 186 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 17: GPIO Slew Rate Control Select (GPIOSLR), offset 0x518 The GPIOSLR register is the slew rate control register. Slew rate control is only available when using the 8-mA drive strength option via the GPIO 8-mA Drive Select (GPIODR8R) register (see page 183). GPIO Slew Rate Control Select (GPIOSLR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x518 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SRL Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Slew Rate Limit Enable (8-mA drive only) The SRL values are defined as follows: Value Description 0 Slew rate control disabled. 1 Slew rate control enabled. 7:0 SRL R/W 0x00 November 30, 2007 187 Preliminary LM3S6952 Microcontroller Register 18: GPIO Digital Enable (GPIODEN), offset 0x51C The GPIODEN register is the digital enable register. By default, with the exception of the GPIO signals used for JTAG/SWD function, all other GPIO signals are configured out of reset to be undriven (tristate). Their digital function is disabled; they do not drive a logic value on the pin and they do not allow the pin voltage into the GPIO receiver. To use the pin in a digital function (either GPIO or alternate function), the corresponding GPIODEN bit must be set. GPIO Digital Enable (GPIODEN) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x51C Type R/W, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DEN Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Digital Enable The DEN values are defined as follows: Value Description 0 Digital functions disabled. 1 Digital functions enabled. Note: The default reset value for the GPIOAFSEL, GPIOPUR, and GPIODEN registers are 0x0000.0000 for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins default to JTAG/SWD functionality. Because of this, the default reset value of these registers for GPIO Port B is 0x0000.0080 while the default reset value for Port C is 0x0000.000F. 7:0 DEN R/W - 188 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 19: GPIO Lock (GPIOLOCK), offset 0x520 The GPIOLOCK register enables write access to the GPIOCR register (see page 190). Writing 0x1ACCE551 to the GPIOLOCK register will unlock the GPIOCR register. Writing any other value to the GPIOLOCK register re-enables the locked state. Reading the GPIOLOCK register returns the lock status rather than the 32-bit value that was previously written. Therefore, when write accesses are disabled, or locked, reading the GPIOLOCK register returns 0x00000001. When write accesses are enabled, or unlocked, reading the GPIOLOCK register returns 0x00000000. GPIO Lock (GPIOLOCK) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x520 Type R/W, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 LOCK Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 LOCK Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description GPIO Lock A write of the value 0x1ACCE551 unlocks the GPIO Commit (GPIOCR) register for write access. A write of any other value reapplies the lock, preventing any register updates. A read of this register returns the following values: Value Description 0x0000.0001 locked 0x0000.0000 unlocked 31:0 LOCK R/W 0x0000.0001 November 30, 2007 189 Preliminary LM3S6952 Microcontroller Register 20: GPIO Commit (GPIOCR), offset 0x524 The GPIOCR register is the commit register. The value of the GPIOCR register determines which bits of the GPIOAFSEL register will be committed when a write to the GPIOAFSEL register is performed. If a bit in the GPIOCR register is a zero, the data being written to the corresponding bit in the GPIOAFSEL register will not be committed and will retain its previous value. If a bit in the GPIOCR register is a one, the data being written to the corresponding bit of the GPIOAFSEL register will be committed to the register and will reflect the new value. The contents of the GPIOCR register can only be modified if the GPIOLOCK register is unlocked. Writes to the GPIOCR register will be ignored if the GPIOLOCK register is locked. Important: This register is designed to prevent accidental programming of the GPIOAFSEL registers that control connectivity to the JTAG/SWD debug hardware. By initializing the bits of the GPIOCR register to 0 for PB7 and PC[3:0], the JTAG/SWD debug port can only be converted to GPIOs through a deliberate set of writes to the GPIOLOCK, GPIOCR, and GPIOAFSEL registers. Because this protection is currently only implemented on the JTAG/SWD pins on PB7 and PC[3:0], all of the other bits in the GPIOCR registers cannot be written with 0x0. These bits are hardwired to 0x1, ensuring that it is always possible to commit new values to the GPIOAFSEL register bits of these other pins. GPIO Commit (GPIOCR) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0x524 Type -, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CR Type RO RO RO RO RO RO RO RO - - - - - - - - Reset 0 0 0 0 0 0 0 0 - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 190 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Bit/Field Name Type Reset Description GPIO Commit On a bit-wise basis, any bit set allows the corresponding GPIOAFSEL bit to be set to its alternate function. Note: The default register type for the GPIOCR register is RO for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). These five pins are currently the only GPIOs that are protected by the GPIOCR register. Because of this, the register type for GPIO Port B7 and GPIO Port C[3:0] is R/W. The default reset value for the GPIOCR register is 0x0000.00FF for all GPIO pins, with the exception of the five JTAG/SWD pins (PB7 and PC[3:0]). To ensure that the JTAG port is not accidentally programmed as a GPIO, these five pins default to non-commitable. Because of this, the default reset value of GPIOCR for GPIO Port B is 0x0000.007F while the default reset value of GPIOCR for Port C is 0x0000.00F0. 7:0 CR - - November 30, 2007 191 Preliminary LM3S6952 Microcontroller Register 21: GPIO Peripheral Identification 4 (GPIOPeriphID4), offset 0xFD0 The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 4 (GPIOPeriphID4) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFD0 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID4 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID4 RO 0x00 GPIO Peripheral ID Register[7:0] 192 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 22: GPIO Peripheral Identification 5 (GPIOPeriphID5), offset 0xFD4 The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 5 (GPIOPeriphID5) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFD4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID5 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID5 RO 0x00 GPIO Peripheral ID Register[15:8] November 30, 2007 193 Preliminary LM3S6952 Microcontroller Register 23: GPIO Peripheral Identification 6 (GPIOPeriphID6), offset 0xFD8 The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 6 (GPIOPeriphID6) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFD8 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID6 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID6 RO 0x00 GPIO Peripheral ID Register[23:16] 194 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 24: GPIO Peripheral Identification 7 (GPIOPeriphID7), offset 0xFDC The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 7 (GPIOPeriphID7) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFDC Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID7 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID7 RO 0x00 GPIO Peripheral ID Register[31:24] November 30, 2007 195 Preliminary LM3S6952 Microcontroller Register 25: GPIO Peripheral Identification 0 (GPIOPeriphID0), offset 0xFE0 The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 0 (GPIOPeriphID0) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFE0 Type RO, reset 0x0000.0061 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Peripheral ID Register[7:0] Can be used by software to identify the presence of this peripheral. 7:0 PID0 RO 0x61 196 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 26: GPIO Peripheral Identification 1 (GPIOPeriphID1), offset 0xFE4 The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 1 (GPIOPeriphID1) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFE4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Peripheral ID Register[15:8] Can be used by software to identify the presence of this peripheral. 7:0 PID1 RO 0x00 November 30, 2007 197 Preliminary LM3S6952 Microcontroller Register 27: GPIO Peripheral Identification 2 (GPIOPeriphID2), offset 0xFE8 The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 2 (GPIOPeriphID2) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFE8 Type RO, reset 0x0000.0018 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Peripheral ID Register[23:16] Can be used by software to identify the presence of this peripheral. 7:0 PID2 RO 0x18 198 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 28: GPIO Peripheral Identification 3 (GPIOPeriphID3), offset 0xFEC The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register, used by software to identify the peripheral. GPIO Peripheral Identification 3 (GPIOPeriphID3) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFEC Type RO, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO Peripheral ID Register[31:24] Can be used by software to identify the presence of this peripheral. 7:0 PID3 RO 0x01 November 30, 2007 199 Preliminary LM3S6952 Microcontroller Register 29: GPIO PrimeCell Identification 0 (GPIOPCellID0), offset 0xFF0 The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide registers, that can conceptually be treated as one 32-bit register. The register is used as a standard cross-peripheral identification system. GPIO PrimeCell Identification 0 (GPIOPCellID0) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFF0 Type RO, reset 0x0000.000D 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO PrimeCell ID Register[7:0] Provides software a standard cross-peripheral identification system. 7:0 CID0 RO 0x0D 200 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 30: GPIO PrimeCell Identification 1 (GPIOPCellID1), offset 0xFF4 The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide registers, that can conceptually be treated as one 32-bit register. The register is used as a standard cross-peripheral identification system. GPIO PrimeCell Identification 1 (GPIOPCellID1) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFF4 Type RO, reset 0x0000.00F0 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO PrimeCell ID Register[15:8] Provides software a standard cross-peripheral identification system. 7:0 CID1 RO 0xF0 November 30, 2007 201 Preliminary LM3S6952 Microcontroller Register 31: GPIO PrimeCell Identification 2 (GPIOPCellID2), offset 0xFF8 The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide registers, that can conceptually be treated as one 32-bit register. The register is used as a standard cross-peripheral identification system. GPIO PrimeCell Identification 2 (GPIOPCellID2) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFF8 Type RO, reset 0x0000.0005 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO PrimeCell ID Register[23:16] Provides software a standard cross-peripheral identification system. 7:0 CID2 RO 0x05 202 November 30, 2007 Preliminary General-Purpose Input/Outputs (GPIOs) Register 32: GPIO PrimeCell Identification 3 (GPIOPCellID3), offset 0xFFC The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide registers, that can conceptually be treated as one 32-bit register. The register is used as a standard cross-peripheral identification system. GPIO PrimeCell Identification 3 (GPIOPCellID3) GPIO Port A base: 0x4000.4000 GPIO Port B base: 0x4000.5000 GPIO Port C base: 0x4000.6000 GPIO Port D base: 0x4000.7000 GPIO Port E base: 0x4002.4000 GPIO Port F base: 0x4002.5000 GPIO Port G base: 0x4002.6000 Offset 0xFFC Type RO, reset 0x0000.00B1 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPIO PrimeCell ID Register[31:24] Provides software a standard cross-peripheral identification system. 7:0 CID3 RO 0xB1 November 30, 2007 203 Preliminary LM3S6952 Microcontroller 10 General-Purpose Timers Programmable timers can be used to count or time external events that drive the Timer input pins. The Stellaris® General-Purpose Timer Module (GPTM) contains three GPTM blocks (Timer0, Timer1, and Timer 2). Each GPTM block provides two 16-bit timers/counters (referred to as TimerA and TimerB) that can be configured to operate independently as timers or event counters, or configured to operate as one 32-bit timer or one 32-bit Real-Time Clock (RTC). Timers can also be used to trigger analog-to-digital (ADC) conversions. The trigger signals from all of the general-purpose timers are ORed together before reaching the ADC module, so only one timer should be used to trigger ADC events. Note: Timer2 is an internal timer and can only be used to generate internal interrupts or trigger ADC events. The General-Purpose Timer Module is one timing resource available on the Stellaris® microcontrollers. Other timer resources include the System Timer (SysTick) (see “System Timer (SysTick)” on page 40) and the PWM timer in the PWM module (see “PWM Timer” on page 466). The following modes are supported: ■ 32-bit Timer modes – Programmable one-shot timer – Programmable periodic timer – Real-Time Clock using 32.768-KHz input clock – Software-controlled event stalling (excluding RTC mode) ■ 16-bit Timer modes – General-purpose timer function with an 8-bit prescaler (for one-shot and periodic modes only) – Programmable one-shot timer – Programmable periodic timer – Software-controlled event stalling ■ 16-bit Input Capture modes – Input edge count capture – Input edge time capture ■ 16-bit PWM mode – Simple PWM mode with software-programmable output inversion of the PWM signal 10.1 Block Diagram Note: In Figure 10-1 on page 205, the specific CCP pins available depend on the Stellaris® device. See Table 10-1 on page 205 for the available CCPs. 204 November 30, 2007 Preliminary General-Purpose Timers Figure 10-1. GPTM Module Block Diagram TA Comparator TB Comparator GPTMTBR GPTMAR Clock / Edge Detect RTC Divider Clock / Edge Detect TimerA Interrupt TimerB Interrupt System Clock 0x0000 (Down Counter Modes) 0x0000 (Down Counter Modes) 32 KHz or Even CCP Pin Odd CCP Pin En En TimerA Control GPTMTAPMR GPTMTAILR GPTMTAMATCHR GPTMTAPR GPTMTAMR TimerB Control GPTMTBPMR GPTMTBILR GPTMTBMATCHR GPTMTBPR GPTMTBMR Interrupt / Config GPTMCFG GPTMRIS GPTMICR GPTMMIS GPTMIMR GPTMCTL Table 10-1. Available CCP Pins Timer 16-Bit Up/Down Counter Even CCP Pin Odd CCP Pin Timer 0 TimerA CCP0 - TimerB - CCP1 Timer 1 TimerA CCP2 - TimerB - CCP3 Timer 2 TimerA - - TimerB - - 10.2 Functional Description The main components of each GPTM block are two free-running 16-bit up/down counters (referred to as TimerA and TimerB), two 16-bit match registers, two prescaler match registers, and two 16-bit load/initialization registers and their associated control functions. The exact functionality of each GPTM is controlled by software and configured through the register interface. Software configures the GPTM using the GPTM Configuration (GPTMCFG) register (see page 216), the GPTM TimerA Mode (GPTMTAMR) register (see page 217), and the GPTM TimerB Mode (GPTMTBMR) register (see page 219). When in one of the 32-bit modes, the timer can only act as a 32-bit timer. However, when configured in 16-bit mode, the GPTM can have its two 16-bit timers configured in any combination of the 16-bit modes. 10.2.1 GPTM Reset Conditions After reset has been applied to the GPTM module, the module is in an inactive state, and all control registers are cleared and in their default states. Counters TimerA and TimerB are initialized to 0xFFFF, along with their corresponding load registers: the GPTM TimerA Interval Load November 30, 2007 205 Preliminary LM3S6952 Microcontroller (GPTMTAILR) register (see page 230) and the GPTM TimerB Interval Load (GPTMTBILR) register (see page 231). The prescale counters are initialized to 0x00: the GPTM TimerA Prescale (GPTMTAPR) register (see page 234) and the GPTM TimerB Prescale (GPTMTBPR) register (see page 235). 10.2.2 32-Bit Timer Operating Modes This section describes the three GPTM 32-bit timer modes (One-Shot, Periodic, and RTC) and their configuration. The GPTM is placed into 32-bit mode by writing a 0 (One-Shot/Periodic 32-bit timer mode) or a 1 (RTC mode) to the GPTM Configuration (GPTMCFG) register. In both configurations, certain GPTM registers are concatenated to form pseudo 32-bit registers. These registers include: ■ GPTM TimerA Interval Load (GPTMTAILR) register [15:0], see page 230 ■ GPTM TimerB Interval Load (GPTMTBILR) register [15:0], see page 231 ■ GPTM TimerA (GPTMTAR) register [15:0], see page 238 ■ GPTM TimerB (GPTMTBR) register [15:0], see page 239 In the 32-bit modes, the GPTM translates a 32-bit write access to GPTMTAILR into a write access to both GPTMTAILR and GPTMTBILR. The resulting word ordering for such a write operation is: GPTMTBILR[15:0]:GPTMTAILR[15:0] Likewise, a read access to GPTMTAR returns the value: GPTMTBR[15:0]:GPTMTAR[15:0] 10.2.2.1 32-Bit One-Shot/Periodic Timer Mode In 32-bit one-shot and periodic timer modes, the concatenated versions of the TimerA and TimerB registers are configured as a 32-bit down-counter. The selection of one-shot or periodic mode is determined by the value written to the TAMR field of the GPTM TimerA Mode (GPTMTAMR) register (see page 217), and there is no need to write to the GPTM TimerB Mode (GPTMTBMR) register. When software writes the TAEN bit in the GPTM Control (GPTMCTL) register (see page 221), the timer begins counting down from its preloaded value. Once the 0x0000.0000 state is reached, the timer reloads its start value from the concatenated GPTMTAILR on the next cycle. If configured to be a one-shot timer, the timer stops counting and clears the TAEN bit in the GPTMCTL register. If configured as a periodic timer, it continues counting. In addition to reloading the count value, the GPTM generates interrupts and output triggers when it reaches the 0x0000000 state. The GPTM sets the TATORIS bit in the GPTM Raw Interrupt Status (GPTMRIS) register (see page 226), and holds it until it is cleared by writing the GPTM Interrupt Clear (GPTMICR) register (see page 228). If the time-out interrupt is enabled in the GPTM Interrupt Mask (GPTIMR) register (see page 224), the GPTM also sets the TATOMIS bit in the GPTM Masked Interrupt Status (GPTMMIS) register (see page 227). The output trigger is a one-clock-cycle pulse that is asserted when the counter hits the 0x0000.0000 state, and deasserted on the following clock cycle. It is enabled by setting the TAOTE bit in GPTMCTL, and can trigger SoC-level events such as ADC conversions. If software reloads the GPTMTAILR register while the counter is running, the counter loads the new value on the next clock cycle and continues counting from the new value. 206 November 30, 2007 Preliminary General-Purpose Timers If the TASTALL bit in the GPTMCTL register is asserted, the timer freezes counting until the signal is deasserted. 10.2.2.2 32-Bit Real-Time Clock Timer Mode In Real-Time Clock (RTC) mode, the concatenated versions of the TimerA and TimerB registers are configured as a 32-bit up-counter. When RTC mode is selected for the first time, the counter is loaded with a value of 0x0000.0001. All subsequent load values must be written to the GPTM TimerA Match (GPTMTAMATCHR) register (see page 232) by the controller. The input clock on the CCP0, CCP2, or CCP4 pins is required to be 32.768 KHz in RTC mode. The clock signal is then divided down to a 1 Hz rate and is passed along to the input of the 32-bit counter. When software writes the TAEN bit inthe GPTMCTL register, the counter starts counting up from its preloaded value of 0x0000.0001. When the current count value matches the preloaded value in the GPTMTAMATCHR register, it rolls over to a value of 0x0000.0000 and continues counting until either a hardware reset, or it is disabled by software (clearing the TAEN bit). When a match occurs, the GPTM asserts the RTCRIS bit in GPTMRIS. If the RTC interrupt is enabled in GPTIMR, the GPTM also sets the RTCMIS bit in GPTMISR and generates a controller interrupt. The status flags are cleared by writing the RTCCINT bit in GPTMICR. If the TASTALL and/or TBSTALL bits in the GPTMCTL register are set, the timer does not freeze if the RTCEN bit is set in GPTMCTL. 10.2.3 16-Bit Timer Operating Modes The GPTM is placed into global 16-bit mode by writing a value of 0x4 to the GPTM Configuration (GPTMCFG) register (see page 216). This section describes each of the GPTM 16-bit modes of operation. TimerA and TimerB have identical modes, so a single description is given using an n to reference both. 10.2.3.1 16-Bit One-Shot/Periodic Timer Mode In 16-bit one-shot and periodic timer modes, the timer is configured as a 16-bit down-counter with an optional 8-bit prescaler that effectively extends the counting range of the timer to 24 bits. The selection of one-shot or periodic mode is determined by the value written to the TnMR field of the GPTMTnMR register. The optional prescaler is loaded into the GPTM Timern Prescale (GPTMTnPR) register. When software writes the TnEN bit in the GPTMCTL register, the timer begins counting down from its preloaded value. Once the 0x0000 state is reached, the timer reloads its start value from GPTMTnILR and GPTMTnPR on the next cycle. If configured to be a one-shot timer, the timer stops counting and clears the TnEN bit in the GPTMCTL register. If configured as a periodic timer, it continues counting. In addition to reloading the count value, the timer generates interrupts and output triggers when it reaches the 0x0000 state. The GPTM sets the TnTORIS bit in the GPTMRIS register, and holds it until it is cleared by writing the GPTMICR register. If the time-out interrupt is enabled in GPTIMR, the GPTM also sets the TnTOMIS bit in GPTMISR and generates a controller interrupt. The output trigger is a one-clock-cycle pulse that is asserted when the counter hits the 0x0000 state, and deasserted on the following clock cycle. It is enabled by setting the TnOTE bit in the GPTMCTL register, and can trigger SoC-level events such as ADC conversions. If software reloads the GPTMTAILR register while the counter is running, the counter loads the new value on the next clock cycle and continues counting from the new value. November 30, 2007 207 Preliminary LM3S6952 Microcontroller If the TnSTALL bit in the GPTMCTL register is enabled, the timer freezes counting until the signal is deasserted. The following example shows a variety of configurations for a 16-bit free running timer while using the prescaler. All values assume a 50-MHz clock with Tc=20 ns (clock period). Table 10-2. 16-Bit Timer With Prescaler Configurations Prescale #Clock (T c)a Max Time Units 00000000 1 1.3107 mS 00000001 2 2.6214 mS 00000010 3 3.9321 mS ------------ -- -- -- 11111100 254 332.9229 mS 11111110 255 334.2336 mS 11111111 256 335.5443 mS a. Tc is the clock period. 10.2.3.2 16-Bit Input Edge Count Mode In Edge Count mode, the timer is configured as a down-counter capable of capturing three types of events: rising edge, falling edge, or both. To place the timer in Edge Count mode, the TnCMR bit of the GPTMTnMR register must be set to 0. The type of edge that the timer counts is determined by the TnEVENT fields of the GPTMCTL register. During initialization, the GPTM Timern Match (GPTMTnMATCHR) register is configured so that the difference between the value in the GPTMTnILR register and the GPTMTnMATCHR register equals the number of edge events that must be counted. When software writes the TnEN bit in the GPTM Control (GPTMCTL) register, the timer is enabled for event capture. Each input event on the CCP pin decrements the counter by 1 until the event count matches GPTMTnMATCHR. When the counts match, the GPTM asserts the CnMRIS bit in the GPTMRIS register (and the CnMMIS bit, if the interrupt is not masked). The counter is then reloaded using the value in GPTMTnILR, and stopped since the GPTM automatically clears the TnEN bit in the GPTMCTL register. Once the event count has been reached, all further events are ignored until TnEN is re-enabled by software. Figure 10-2 on page 209 shows how input edge count mode works. In this case, the timer start value is set to GPTMnILR =0x000A and the match value is set to GPTMnMATCHR =0x0006 so that four edge events are counted. The counter is configured to detect both edges of the input signal. Note that the last two edges are not counted since the timer automatically clears the TnEN bit after the current count matches the value in the GPTMnMR register. 208 November 30, 2007 Preliminary General-Purpose Timers Figure 10-2. 16-Bit Input Edge Count Mode Example 0x000A 0x0006 0x0007 0x0008 0x0009 Input Signal Timer stops, flags asserted Timer reload Count on next cycle Ignored Ignored 10.2.3.3 16-Bit Input Edge Time Mode Note: The prescaler is not available in 16-Bit Input Edge Time mode. In Edge Time mode, the timer is configured as a free-running down-counter initialized to the value loaded in the GPTMTnILR register (or 0xFFFF at reset). This mode allows for event capture of both rising and falling edges. The timer is placed into Edge Time mode by setting the TnCMR bit in the GPTMTnMR register, and the type of event that the timer captures is determined by the TnEVENT fields of the GPTMCnTL register. When software writes the TnEN bit in the GPTMCTL register, the timer is enabled for event capture. When the selected input event is detected, the current Tn counter value is captured in the GPTMTnR register and is available to be read by the controller. The GPTM then asserts the CnERIS bit (and the CnEMIS bit, if the interrupt is not masked). After an event has been captured, the timer does not stop counting. It continues to count until the TnEN bit is cleared. When the timer reaches the 0x0000 state, it is reloaded with the value from the GPTMnILR register. Figure 10-3 on page 210 shows how input edge timing mode works. In the diagram, it is assumed that the start value of the timer is the default value of 0xFFFF, and the timer is configured to capture rising edge events. Each time a rising edge event is detected, the current count value is loaded into the GPTMTnR register, and is held there until another rising edge is detected (at which point the new count value is loaded into GPTMTnR). November 30, 2007 209 Preliminary LM3S6952 Microcontroller Figure 10-3. 16-Bit Input Edge Time Mode Example GPTMTnR=Y Input Signal Time Count GPTMTnR=X GPTMTnR=Z Z X Y 0xFFFF 10.2.3.4 16-Bit PWM Mode The GPTM supports a simple PWM generation mode. In PWM mode, the timer is configured as a down-counter with a start value (and thus period) defined by GPTMTnILR. PWM mode is enabled with the GPTMTnMR register by setting the TnAMS bit to 0x1, the TnCMR bit to 0x0, and the TnMR field to 0x2. When software writes the TnEN bit in the GPTMCTL register, the counter begins counting down until it reaches the 0x0000 state. On the next counter cycle, the counter reloads its start value from GPTMTnILR (and GPTMTnPR if using a prescaler) and continues counting until disabled by software clearing the TnEN bit in the GPTMCTL register. No interrupts or status bits are asserted in PWM mode. The output PWM signal asserts when the counter is at the value of the GPTMTnILR register (its start state), and is deasserted when the counter value equals the value in the GPTM Timern Match Register (GPTMnMATCHR). Software has the capability of inverting the output PWM signal by setting the TnPWML bit in the GPTMCTL register. Figure 10-4 on page 211 shows how to generate an output PWM with a 1-ms period and a 66% duty cycle assuming a 50-MHz input clock and TnPWML =0 (duty cycle would be 33% for the TnPWML =1 configuration). For this example, the start value is GPTMnIRL=0xC350 and the match value is GPTMnMR=0x411A. 210 November 30, 2007 Preliminary General-Purpose Timers Figure 10-4. 16-Bit PWM Mode Example Output Signal Time Count GPTMTnR=GPTMnMR GPTMTnR=GPTMnMR 0xC350 0x411A TnPWML = 0 TnPWML = 1 TnEN set 10.3 Initialization and Configuration To use the general-purpose timers, the peripheral clock must be enabled by setting the TIMER0, TIMER1, and TIMER2 bits in the RCGC1 register. This section shows module initialization and configuration examples for each of the supported timer modes. 10.3.1 32-Bit One-Shot/Periodic Timer Mode The GPTM is configured for 32-bit One-Shot and Periodic modes by the following sequence: 1. Ensure the timer is disabled (the TAEN bit in the GPTMCTL register is cleared) before making any changes. 2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x0. 3. Set the TAMR field in the GPTM TimerA Mode Register (GPTMTAMR): a. Write a value of 0x1 for One-Shot mode. b. Write a value of 0x2 for Periodic mode. 4. Load the start value into the GPTM TimerA Interval Load Register (GPTMTAILR). 5. If interrupts are required, set the TATOIM bit in the GPTM Interrupt Mask Register (GPTMIMR). 6. Set the TAEN bit in the GPTMCTL register to enable the timer and start counting. November 30, 2007 211 Preliminary LM3S6952 Microcontroller 7. Poll the TATORIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled). In both cases, the status flags are cleared by writing a 1 to the TATOCINT bit of the GPTM Interrupt Clear Register (GPTMICR). In One-Shot mode, the timer stops counting after step 7 on page 212. To re-enable the timer, repeat the sequence. A timer configured in Periodic mode does not stop counting after it times out. 10.3.2 32-Bit Real-Time Clock (RTC) Mode To use the RTC mode, the timer must have a 32.768-KHz input signal on its CCP0, CCP2, or CCP4 pins. To enable the RTC feature, follow these steps: 1. Ensure the timer is disabled (the TAEN bit is cleared) before making any changes. 2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x1. 3. Write the desired match value to the GPTM TimerA Match Register (GPTMTAMATCHR). 4. Set/clear the RTCEN bit in the GPTM Control Register (GPTMCTL) as desired. 5. If interrupts are required, set the RTCIM bit in the GPTM Interrupt Mask Register (GPTMIMR). 6. Set the TAEN bit in the GPTMCTL register to enable the timer and start counting. When the timer count equals the value in the GPTMTAMATCHR register, the counter is re-loaded with 0x0000.0000 and begins counting. If an interrupt is enabled, it does not have to be cleared. 10.3.3 16-Bit One-Shot/Periodic Timer Mode A timer is configured for 16-bit One-Shot and Periodic modes by the following sequence: 1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes. 2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x4. 3. Set the TnMR field in the GPTM Timer Mode (GPTMTnMR) register: a. Write a value of 0x1 for One-Shot mode. b. Write a value of 0x2 for Periodic mode. 4. If a prescaler is to be used, write the prescale value to the GPTM Timern Prescale Register (GPTMTnPR). 5. Load the start value into the GPTM Timer Interval Load Register (GPTMTnILR). 6. If interrupts are required, set the TnTOIM bit in the GPTM Interrupt Mask Register (GPTMIMR). 7. Set the TnEN bit in the GPTM Control Register (GPTMCTL) to enable the timer and start counting. 8. Poll the TnTORIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled). In both cases, the status flags are cleared by writing a 1 to the TnTOCINT bit of the GPTM Interrupt Clear Register (GPTMICR). 212 November 30, 2007 Preliminary General-Purpose Timers In One-Shot mode, the timer stops counting after step 8 on page 212. To re-enable the timer, repeat the sequence. A timer configured in Periodic mode does not stop counting after it times out. 10.3.4 16-Bit Input Edge Count Mode A timer is configured to Input Edge Count mode by the following sequence: 1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes. 2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4. 3. In the GPTM Timer Mode (GPTMTnMR) register, write the TnCMR field to 0x0 and the TnMR field to 0x3. 4. Configure the type of event(s) that the timer captures by writing the TnEVENT field of the GPTM Control (GPTMCTL) register. 5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register. 6. Load the desired event count into the GPTM Timern Match (GPTMTnMATCHR) register. 7. If interrupts are required, set the CnMIM bit in the GPTM Interrupt Mask (GPTMIMR) register. 8. Set the TnEN bit in the GPTMCTL register to enable the timer and begin waiting for edge events. 9. Poll the CnMRIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled). In both cases, the status flags are cleared by writing a 1 to the CnMCINT bit of the GPTM Interrupt Clear (GPTMICR) register. In Input Edge Count Mode, the timer stops after the desired number of edge events has been detected. To re-enable the timer, ensure that the TnEN bit is cleared and repeat step 4 on page 213 through step 9 on page 213. 10.3.5 16-Bit Input Edge Timing Mode A timer is configured to Input Edge Timing mode by the following sequence: 1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes. 2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4. 3. In the GPTM Timer Mode (GPTMTnMR) register, write the TnCMR field to 0x1 and the TnMR field to 0x3. 4. Configure the type of event that the timer captures by writing the TnEVENT field of the GPTM Control (GPTMCTL) register. 5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register. 6. If interrupts are required, set the CnEIM bit in the GPTM Interrupt Mask (GPTMIMR) register. 7. Set the TnEN bit in the GPTM Control (GPTMCTL) register to enable the timer and start counting. 8. Poll the CnERIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled). In both cases, the status flags are cleared by writing a 1 to the CnECINT bit of the GPTM November 30, 2007 213 Preliminary LM3S6952 Microcontroller Interrupt Clear (GPTMICR) register. The time at which the event happened can be obtained by reading the GPTM Timern (GPTMTnR) register. In Input Edge Timing mode, the timer continues running after an edge event has been detected, but the timer interval can be changed at any time by writing the GPTMTnILR register. The change takes effect at the next cycle after the write. 10.3.6 16-Bit PWM Mode A timer is configured to PWM mode using the following sequence: 1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes. 2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4. 3. In the GPTM Timer Mode (GPTMTnMR) register, set the TnAMS bit to 0x1, the TnCMR bit to 0x0, and the TnMR field to 0x2. 4. Configure the output state of the PWM signal (whether or not it is inverted) in the TnEVENT field of the GPTM Control (GPTMCTL) register. 5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register. 6. Load the GPTM Timern Match (GPTMTnMATCHR) register with the desired value. 7. If a prescaler is going to be used, configure the GPTM Timern Prescale (GPTMTnPR) register and the GPTM Timern Prescale Match (GPTMTnPMR) register. 8. Set the TnEN bit in the GPTM Control (GPTMCTL) register to enable the timer and begin generation of the output PWM signal. In PWM Timing mode, the timer continues running after the PWM signal has been generated. The PWM period can be adjusted at any time by writing the GPTMTnILR register, and the change takes effect at the next cycle after the write. 10.4 Register Map Table 10-3 on page 214 lists the GPTM registers. The offset listed is a hexadecimal increment to the register’s address, relative to that timer’s base address: ■ Timer0: 0x4003.0000 ■ Timer1: 0x4003.1000 ■ Timer2: 0x4003.2000 Table 10-3. Timers Register Map See Offset Name Type Reset Description page 0x000 GPTMCFG R/W 0x0000.0000 GPTM Configuration 216 0x004 GPTMTAMR R/W 0x0000.0000 GPTM TimerA Mode 217 0x008 GPTMTBMR R/W 0x0000.0000 GPTM TimerB Mode 219 214 November 30, 2007 Preliminary General-Purpose Timers See Offset Name Type Reset Description page 0x00C GPTMCTL R/W 0x0000.0000 GPTM Control 221 0x018 GPTMIMR R/W 0x0000.0000 GPTM Interrupt Mask 224 0x01C GPTMRIS RO 0x0000.0000 GPTM Raw Interrupt Status 226 0x020 GPTMMIS RO 0x0000.0000 GPTM Masked Interrupt Status 227 0x024 GPTMICR W1C 0x0000.0000 GPTM Interrupt Clear 228 GPTM TimerA Interval Load 230 0x0000.FFFF (16-bit mode) 0xFFFF.FFFF (32-bit mode) 0x028 GPTMTAILR R/W 0x02C GPTMTBILR R/W 0x0000.FFFF GPTM TimerB Interval Load 231 GPTM TimerA Match 232 0x0000.FFFF (16-bit mode) 0xFFFF.FFFF (32-bit mode) 0x030 GPTMTAMATCHR R/W 0x034 GPTMTBMATCHR R/W 0x0000.FFFF GPTM TimerB Match 233 0x038 GPTMTAPR R/W 0x0000.0000 GPTM TimerA Prescale 234 0x03C GPTMTBPR R/W 0x0000.0000 GPTM TimerB Prescale 235 0x040 GPTMTAPMR R/W 0x0000.0000 GPTM TimerA Prescale Match 236 0x044 GPTMTBPMR R/W 0x0000.0000 GPTM TimerB Prescale Match 237 GPTM TimerA 238 0x0000.FFFF (16-bit mode) 0xFFFF.FFFF (32-bit mode) 0x048 GPTMTAR RO 0x04C GPTMTBR RO 0x0000.FFFF GPTM TimerB 239 10.5 Register Descriptions The remainder of this section lists and describes the GPTM registers, in numerical order by address offset. November 30, 2007 215 Preliminary LM3S6952 Microcontroller Register 1: GPTM Configuration (GPTMCFG), offset 0x000 This register configures the global operation of the GPTM module. The value written to this register determines whether the GPTM is in 32- or 16-bit mode. GPTM Configuration (GPTMCFG) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GPTMCFG Type RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 GPTM Configuration The GPTMCFG values are defined as follows: Value Description 0x0 32-bit timer configuration. 0x1 32-bit real-time clock (RTC) counter configuration. 0x2 Reserved. 0x3 Reserved. 16-bit timer configuration, function is controlled by bits 1:0 of GPTMTAMR and GPTMTBMR. 0x4-0x7 2:0 GPTMCFG R/W 0x0 216 November 30, 2007 Preliminary General-Purpose Timers Register 2: GPTM TimerA Mode (GPTMTAMR), offset 0x004 This register configures the GPTM based on the configuration selected in the GPTMCFG register. When in 16-bit PWM mode, set the TAAMS bit to 0x1, the TACMR bit to 0x0, and the TAMR field to 0x2. GPTM TimerA Mode (GPTMTAMR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x004 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TAAMS TACMR TAMR Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 GPTM TimerA Alternate Mode Select The TAAMS values are defined as follows: Value Description 0 Capture mode is enabled. 1 PWM mode is enabled. Note: To enable PWM mode, you must also clear the TACMR bit and set the TAMR field to 0x2. 3 TAAMS R/W 0 GPTM TimerA Capture Mode The TACMR values are defined as follows: Value Description 0 Edge-Count mode. 1 Edge-Time mode. 2 TACMR R/W 0 November 30, 2007 217 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description GPTM TimerA Mode The TAMR values are defined as follows: Value Description 0x0 Reserved. 0x1 One-Shot Timer mode. 0x2 Periodic Timer mode. 0x3 Capture mode. The Timer mode is based on the timer configuration defined by bits 2:0 in the GPTMCFG register (16-or 32-bit). In 16-bit timer configuration, TAMR controls the 16-bit timer modes for TimerA. In 32-bit timer configuration, this register controls the mode and the contents of GPTMTBMR are ignored. 1:0 TAMR R/W 0x0 218 November 30, 2007 Preliminary General-Purpose Timers Register 3: GPTM TimerB Mode (GPTMTBMR), offset 0x008 This register configures the GPTM based on the configuration selected in the GPTMCFG register. When in 16-bit PWM mode, set the TBAMS bit to 0x1, the TBCMR bit to 0x0, and the TBMR field to 0x2. GPTM TimerB Mode (GPTMTBMR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TBAMS TBCMR TBMR Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 GPTM TimerB Alternate Mode Select The TBAMS values are defined as follows: Value Description 0 Capture mode is enabled. 1 PWM mode is enabled. Note: To enable PWM mode, you must also clear the TBCMR bit and set the TBMR field to 0x2. 3 TBAMS R/W 0 GPTM TimerB Capture Mode The TBCMR values are defined as follows: Value Description 0 Edge-Count mode. 1 Edge-Time mode. 2 TBCMR R/W 0 November 30, 2007 219 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description GPTM TimerB Mode The TBMR values are defined as follows: Value Description 0x0 Reserved. 0x1 One-Shot Timer mode. 0x2 Periodic Timer mode. 0x3 Capture mode. The timer mode is based on the timer configuration defined by bits 2:0 in the GPTMCFG register. In 16-bit timer configuration, these bits control the 16-bit timer modes for TimerB. In 32-bit timer configuration, this register’s contents are ignored and GPTMTAMR is used. 1:0 TBMR R/W 0x0 220 November 30, 2007 Preliminary General-Purpose Timers Register 4: GPTM Control (GPTMCTL), offset 0x00C This register is used alongside the GPTMCFG and GMTMTnMR registers to fine-tune the timer configuration, and to enable other features such as timer stall and the output trigger. The output trigger can be used to initiate transfers on the ADC module. GPTM Control (GPTMCTL) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x00C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TBPWML TBOTE reserved TBEVENT TBSTALL TBEN reserved TAPWML TAOTE RTCEN TAEVENT TASTALL TAEN Type RO R/W R/W RO R/W R/W R/W R/W RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:15 reserved RO 0x00 GPTM TimerB PWM Output Level The TBPWML values are defined as follows: Value Description 0 Output is unaffected. 1 Output is inverted. 14 TBPWML R/W 0 GPTM TimerB Output Trigger Enable The TBOTE values are defined as follows: Value Description 0 The output TimerB trigger is disabled. 1 The output TimerB trigger is enabled. 13 TBOTE R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 12 reserved RO 0 November 30, 2007 221 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description GPTM TimerB Event Mode The TBEVENT values are defined as follows: Value Description 0x0 Positive edge. 0x1 Negative edge. 0x2 Reserved 0x3 Both edges. 11:10 TBEVENT R/W 0x0 GPTM TimerB Stall Enable The TBSTALL values are defined as follows: Value Description 0 TimerB stalling is disabled. 1 TimerB stalling is enabled. 9 TBSTALL R/W 0 GPTM TimerB Enable The TBEN values are defined as follows: Value Description 0 TimerB is disabled. TimerB is enabled and begins counting or the capture logic is enabled based on the GPTMCFG register. 1 8 TBEN R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7 reserved RO 0 GPTM TimerA PWM Output Level The TAPWML values are defined as follows: Value Description 0 Output is unaffected. 1 Output is inverted. 6 TAPWML R/W 0 GPTM TimerA Output Trigger Enable The TAOTE values are defined as follows: Value Description 0 The output TimerA trigger is disabled. 1 The output TimerA trigger is enabled. 5 TAOTE R/W 0 222 November 30, 2007 Preliminary General-Purpose Timers Bit/Field Name Type Reset Description GPTM RTC Enable The RTCEN values are defined as follows: Value Description 0 RTC counting is disabled. 1 RTC counting is enabled. 4 RTCEN R/W 0 GPTM TimerA Event Mode The TAEVENT values are defined as follows: Value Description 0x0 Positive edge. 0x1 Negative edge. 0x2 Reserved 0x3 Both edges. 3:2 TAEVENT R/W 0x0 GPTM TimerA Stall Enable The TASTALL values are defined as follows: Value Description 0 TimerA stalling is disabled. 1 TimerA stalling is enabled. 1 TASTALL R/W 0 GPTM TimerA Enable The TAEN values are defined as follows: Value Description 0 TimerA is disabled. TimerA is enabled and begins counting or the capture logic is enabled based on the GPTMCFG register. 1 0 TAEN R/W 0 November 30, 2007 223 Preliminary LM3S6952 Microcontroller Register 5: GPTM Interrupt Mask (GPTMIMR), offset 0x018 This register allows software to enable/disable GPTM controller-level interrupts. Writing a 1 enables the interrupt, while writing a 0 disables it. GPTM Interrupt Mask (GPTMIMR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x018 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CBEIM CBMIM TBTOIM reserved RTCIM CAEIM CAMIM TATOIM Type RO RO RO RO RO R/W R/W R/W RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 GPTM CaptureB Event Interrupt Mask The CBEIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 10 CBEIM R/W 0 GPTM CaptureB Match Interrupt Mask The CBMIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 9 CBMIM R/W 0 GPTM TimerB Time-Out Interrupt Mask The TBTOIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 8 TBTOIM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:4 reserved RO 0 224 November 30, 2007 Preliminary General-Purpose Timers Bit/Field Name Type Reset Description GPTM RTC Interrupt Mask The RTCIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 3 RTCIM R/W 0 GPTM CaptureA Event Interrupt Mask The CAEIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 2 CAEIM R/W 0 GPTM CaptureA Match Interrupt Mask The CAMIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 1 CAMIM R/W 0 GPTM TimerA Time-Out Interrupt Mask The TATOIM values are defined as follows: Value Description 0 Interrupt is disabled. 1 Interrupt is enabled. 0 TATOIM R/W 0 November 30, 2007 225 Preliminary LM3S6952 Microcontroller Register 6: GPTM Raw Interrupt Status (GPTMRIS), offset 0x01C This register shows the state of the GPTM's internal interrupt signal. These bits are set whether or not the interrupt is masked in the GPTMIMR register. Each bit can be cleared by writing a 1 to its corresponding bit in GPTMICR. GPTM Raw Interrupt Status (GPTMRIS) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x01C Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CBERIS CBMRIS TBTORIS reserved RTCRIS CAERIS CAMRIS TATORIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 GPTM CaptureB Event Raw Interrupt This is the CaptureB Event interrupt status prior to masking. 10 CBERIS RO 0 GPTM CaptureB Match Raw Interrupt This is the CaptureB Match interrupt status prior to masking. 9 CBMRIS RO 0 GPTM TimerB Time-Out Raw Interrupt This is the TimerB time-out interrupt status prior to masking. 8 TBTORIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:4 reserved RO 0x0 GPTM RTC Raw Interrupt This is the RTC Event interrupt status prior to masking. 3 RTCRIS RO 0 GPTM CaptureA Event Raw Interrupt This is the CaptureA Event interrupt status prior to masking. 2 CAERIS RO 0 GPTM CaptureA Match Raw Interrupt This is the CaptureA Match interrupt status prior to masking. 1 CAMRIS RO 0 GPTM TimerA Time-Out Raw Interrupt This the TimerA time-out interrupt status prior to masking. 0 TATORIS RO 0 226 November 30, 2007 Preliminary General-Purpose Timers Register 7: GPTM Masked Interrupt Status (GPTMMIS), offset 0x020 This register show the state of the GPTM's controller-level interrupt. If an interrupt is unmasked in GPTMIMR, and there is an event that causes the interrupt to be asserted, the corresponding bit is set in this register. All bits are cleared by writing a 1 to the corresponding bit in GPTMICR. GPTM Masked Interrupt Status (GPTMMIS) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x020 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CBEMIS CBMMIS TBTOMIS reserved RTCMIS CAEMIS CAMMIS TATOMIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 GPTM CaptureB Event Masked Interrupt This is the CaptureB event interrupt status after masking. 10 CBEMIS RO 0 GPTM CaptureB Match Masked Interrupt This is the CaptureB match interrupt status after masking. 9 CBMMIS RO 0 GPTM TimerB Time-Out Masked Interrupt This is the TimerB time-out interrupt status after masking. 8 TBTOMIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:4 reserved RO 0x0 GPTM RTC Masked Interrupt This is the RTC event interrupt status after masking. 3 RTCMIS RO 0 GPTM CaptureA Event Masked Interrupt This is the CaptureA event interrupt status after masking. 2 CAEMIS RO 0 GPTM CaptureA Match Masked Interrupt This is the CaptureA match interrupt status after masking. 1 CAMMIS RO 0 GPTM TimerA Time-Out Masked Interrupt This is the TimerA time-out interrupt status after masking. 0 TATOMIS RO 0 November 30, 2007 227 Preliminary LM3S6952 Microcontroller Register 8: GPTM Interrupt Clear (GPTMICR), offset 0x024 This register is used to clear the status bits in the GPTMRIS and GPTMMIS registers. Writing a 1 to a bit clears the corresponding bit in the GPTMRIS and GPTMMIS registers. GPTM Interrupt Clear (GPTMICR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x024 Type W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CBECINT CBMCINT TBTOCINT reserved RTCCINT CAECINT CAMCINT TATOCINT Type RO RO RO RO RO W1C W1C W1C RO RO RO RO W1C W1C W1C W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 GPTM CaptureB Event Interrupt Clear The CBECINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 10 CBECINT W1C 0 GPTM CaptureB Match Interrupt Clear The CBMCINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 9 CBMCINT W1C 0 GPTM TimerB Time-Out Interrupt Clear The TBTOCINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 8 TBTOCINT W1C 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:4 reserved RO 0x0 228 November 30, 2007 Preliminary General-Purpose Timers Bit/Field Name Type Reset Description GPTM RTC Interrupt Clear The RTCCINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 3 RTCCINT W1C 0 GPTM CaptureA Event Interrupt Clear The CAECINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 2 CAECINT W1C 0 GPTM CaptureA Match Raw Interrupt This is the CaptureA match interrupt status after masking. 1 CAMCINT W1C 0 GPTM TimerA Time-Out Raw Interrupt The TATOCINT values are defined as follows: Value Description 0 The interrupt is unaffected. 1 The interrupt is cleared. 0 TATOCINT W1C 0 November 30, 2007 229 Preliminary LM3S6952 Microcontroller Register 9: GPTM TimerA Interval Load (GPTMTAILR), offset 0x028 This register is used to load the starting count value into the timer. When GPTM is configured to one of the 32-bit modes, GPTMTAILR appears as a 32-bit register (the upper 16-bits correspond to the contents of the GPTM TimerB Interval Load (GPTMTBILR) register). In 16-bit mode, the upper 16 bits of this register read as 0s and have no effect on the state of GPTMTBILR. GPTM TimerA Interval Load (GPTMTAILR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x028 Type R/W, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode) 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 TAILRH Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 1 1 0 1 0 1 1 1 1 0 1 1 1 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TAILRL Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description GPTM TimerA Interval Load Register High When configured for 32-bit mode via the GPTMCFG register, the GPTM TimerB Interval Load (GPTMTBILR) register loads this value on a write. A read returns the current value of GPTMTBILR. In 16-bit mode, this field reads as 0 and does not have an effect on the state of GPTMTBILR. 0xFFFF (32-bit mode) 0x0000 (16-bit mode) 31:16 TAILRH R/W GPTM TimerA Interval Load Register Low For both 16- and 32-bit modes, writing this field loads the counter for TimerA. A read returns the current value of GPTMTAILR. 15:0 TAILRL R/W 0xFFFF 230 November 30, 2007 Preliminary General-Purpose Timers Register 10: GPTM TimerB Interval Load (GPTMTBILR), offset 0x02C This register is used to load the starting count value into TimerB. When the GPTM is configured to a 32-bit mode, GPTMTBILR returns the current value of TimerB and ignores writes. GPTM TimerB Interval Load (GPTMTBILR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x02C Type R/W, reset 0x0000.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TBILRL Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0000 GPTM TimerB Interval Load Register When the GPTM is not configured as a 32-bit timer, a write to this field updates GPTMTBILR. In 32-bit mode, writes are ignored, and reads return the current value of GPTMTBILR. 15:0 TBILRL R/W 0xFFFF November 30, 2007 231 Preliminary LM3S6952 Microcontroller Register 11: GPTM TimerA Match (GPTMTAMATCHR), offset 0x030 This register is used in 32-bit Real-Time Clock mode and 16-bit PWM and Input Edge Count modes. GPTM TimerA Match (GPTMTAMATCHR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x030 Type R/W, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode) 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 TAMRH Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 1 1 0 1 0 1 1 1 1 0 1 1 1 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TAMRL Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description GPTM TimerA Match Register High When configured for 32-bit Real-Time Clock (RTC) mode via the GPTMCFG register, this value is compared to the upper half of GPTMTAR, to determine match events. In 16-bit mode, this field reads as 0 and does not have an effect on the state of GPTMTBMATCHR. 0xFFFF (32-bit mode) 0x0000 (16-bit mode) 31:16 TAMRH R/W GPTM TimerA Match Register Low When configured for 32-bit Real-Time Clock (RTC) mode via the GPTMCFG register, this value is compared to the lower half of GPTMTAR, to determine match events. When configured for PWM mode, this value along with GPTMTAILR, determines the duty cycle of the output PWM signal. When configured for Edge Count mode, this value along with GPTMTAILR, determines how many edge events are counted. The total number of edge events counted is equal to the value in GPTMTAILR minus this value. 15:0 TAMRL R/W 0xFFFF 232 November 30, 2007 Preliminary General-Purpose Timers Register 12: GPTM TimerB Match (GPTMTBMATCHR), offset 0x034 This register is used in 32-bit Real-Time Clock mode and 16-bit PWM and Input Edge Count modes. GPTM TimerB Match (GPTMTBMATCHR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x034 Type R/W, reset 0x0000.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TBMRL Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0000 GPTM TimerB Match Register Low When configured for PWM mode, this value along with GPTMTBILR, determines the duty cycle of the output PWM signal. When configured for Edge Count mode, this value along with GPTMTBILR, determines how many edge events are counted. The total number of edge events counted is equal to the value in GPTMTBILR minus this value. 15:0 TBMRL R/W 0xFFFF November 30, 2007 233 Preliminary LM3S6952 Microcontroller Register 13: GPTM TimerA Prescale (GPTMTAPR), offset 0x038 This register allows software to extend the range of the 16-bit timers when operating in one-shot or periodic mode. GPTM TimerA Prescale (GPTMTAPR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x038 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TAPSR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPTM TimerA Prescale The register loads this value on a write. A read returns the current value of the register. Refer to Table 10-2 on page 208 for more details and an example. 7:0 TAPSR R/W 0x00 234 November 30, 2007 Preliminary General-Purpose Timers Register 14: GPTM TimerB Prescale (GPTMTBPR), offset 0x03C This register allows software to extend the range of the 16-bit timers when operating in one-shot or periodic mode. GPTM TimerB Prescale (GPTMTBPR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x03C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TBPSR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPTM TimerB Prescale The register loads this value on a write. A read returns the current value of this register. Refer to Table 10-2 on page 208 for more details and an example. 7:0 TBPSR R/W 0x00 November 30, 2007 235 Preliminary LM3S6952 Microcontroller Register 15: GPTM TimerA Prescale Match (GPTMTAPMR), offset 0x040 This register effectively extends the range of GPTMTAMATCHR to 24 bits when operating in 16-bit one-shot or periodic mode. GPTM TimerA Prescale Match (GPTMTAPMR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x040 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TAPSMR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPTM TimerA Prescale Match This value is used alongside GPTMTAMATCHR to detect timer match events while using a prescaler. 7:0 TAPSMR R/W 0x00 236 November 30, 2007 Preliminary General-Purpose Timers Register 16: GPTM TimerB Prescale Match (GPTMTBPMR), offset 0x044 This register effectively extends the range of GPTMTBMATCHR to 24 bits when operating in 16-bit one-shot or periodic mode. GPTM TimerB Prescale Match (GPTMTBPMR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x044 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TBPSMR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 GPTM TimerB Prescale Match This value is used alongside GPTMTBMATCHR to detect timer match events while using a prescaler. 7:0 TBPSMR R/W 0x00 November 30, 2007 237 Preliminary LM3S6952 Microcontroller Register 17: GPTM TimerA (GPTMTAR), offset 0x048 This register shows the current value of the TimerA counter in all cases except for Input Edge Count mode. When in this mode, this register contains the time at which the last edge event took place. GPTM TimerA (GPTMTAR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x048 Type RO, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode) 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 TARH Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 1 1 0 1 0 1 1 1 1 0 1 1 1 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TARL Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description GPTM TimerA Register High If the GPTMCFG is in a 32-bit mode, TimerB value is read. If the GPTMCFG is in a 16-bit mode, this is read as zero. 0xFFFF (32-bit mode) 0x0000 (16-bit mode) 31:16 TARH RO GPTM TimerA Register Low A read returns the current value of the GPTM TimerA Count Register, except in Input Edge Count mode, when it returns the timestamp from the last edge event. 15:0 TARL RO 0xFFFF 238 November 30, 2007 Preliminary General-Purpose Timers Register 18: GPTM TimerB (GPTMTBR), offset 0x04C This register shows the current value of the TimerB counter in all cases except for Input Edge Count mode. When in this mode, this register contains the time at which the last edge event took place. GPTM TimerB (GPTMTBR) Timer0 base: 0x4003.0000 Timer1 base: 0x4003.1000 Timer2 base: 0x4003.2000 Offset 0x04C Type RO, reset 0x0000.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TBRL Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0000 GPTM TimerB A read returns the current value of the GPTM TimerB Count Register, except in Input Edge Count mode, when it returns the timestamp from the last edge event. 15:0 TBRL RO 0xFFFF November 30, 2007 239 Preliminary LM3S6952 Microcontroller 11 Watchdog Timer A watchdog timer can generate nonmaskable interrupts (NMIs) or a reset when a time-out value is reached. The watchdog timer is used to regain control when a system has failed due to a software error or due to the failure of an external device to respond in the expected way. The Stellaris® Watchdog Timer module consists of a 32-bit down counter, a programmable load register, interrupt generation logic, a locking register, and user-enabled stalling. The Watchdog Timer can be configured to generate an interrupt to the controller on its first time-out, and to generate a reset signal on its second time-out. Once the Watchdog Timer has been configured, the lock register can be written to prevent the timer configuration from being inadvertently altered. 11.1 Block Diagram Figure 11-1. WDT Module Block Diagram Control / Clock / Interrupt Generation WDTCTL WDTICR WDTRIS WDTMIS WDTLOCK WDTTEST WDTLOAD WDTVALUE Comparator 32-Bit Down Counter 0x00000000 Interrupt System Clock Identification Registers WDTPCellID0 WDTPeriphID0 WDTPeriphID4 WDTPCellID1 WDTPeriphID1 WDTPeriphID5 WDTPCellID2 WDTPeriphID2 WDTPeriphID6 WDTPCellID3 WDTPeriphID3 WDTPeriphID7 11.2 Functional Description The Watchdog Timer module generates the first time-out signal when the 32-bit counter reaches the zero state after being enabled; enabling the counter also enables the watchdog timer interrupt. After the first time-out event, the 32-bit counter is re-loaded with the value of the Watchdog Timer Load (WDTLOAD) register, and the timer resumes counting down from that value. Once the 240 November 30, 2007 Preliminary Watchdog Timer Watchdog Timer has been configured, the Watchdog Timer Lock (WDTLOCK) register is written, which prevents the timer configuration from being inadvertently altered by software. If the timer counts down to its zero state again before the first time-out interrupt is cleared, and the reset signal has been enabled (via the WatchdogResetEnable function), the Watchdog timer asserts its reset signal to the system. If the interrupt is cleared before the 32-bit counter reaches its second time-out, the 32-bit counter is loaded with the value in the WDTLOAD register, and counting resumes from that value. If WDTLOAD is written with a new value while the Watchdog Timer counter is counting, then the counter is loaded with the new value and continues counting. Writing to WDTLOAD does not clear an active interrupt. An interrupt must be specifically cleared by writing to the Watchdog Interrupt Clear (WDTICR) register. The Watchdog module interrupt and reset generation can be enabled or disabled as required. When the interrupt is re-enabled, the 32-bit counter is preloaded with the load register value and not its last state. 11.3 Initialization and Configuration To use the WDT, its peripheral clock must be enabled by setting the WDT bit in the RCGC0 register. The Watchdog Timer is configured using the following sequence: 1. Load the WDTLOAD register with the desired timer load value. 2. If the Watchdog is configured to trigger system resets, set the RESEN bit in the WDTCTL register. 3. Set the INTEN bit in the WDTCTL register to enable the Watchdog and lock the control register. If software requires that all of the watchdog registers are locked, the Watchdog Timer module can be fully locked by writing any value to the WDTLOCK register. To unlock the Watchdog Timer, write a value of 0x1ACC.E551. 11.4 Register Map Table 11-1 on page 241 lists the Watchdog registers. The offset listed is a hexadecimal increment to the register’s address, relative to the Watchdog Timer base address of 0x4000.0000. Table 11-1. Watchdog Timer Register Map See Offset Name Type Reset Description page 0x000 WDTLOAD R/W 0xFFFF.FFFF Watchdog Load 243 0x004 WDTVALUE RO 0xFFFF.FFFF Watchdog Value 244 0x008 WDTCTL R/W 0x0000.0000 Watchdog Control 245 0x00C WDTICR WO - Watchdog Interrupt Clear 246 0x010 WDTRIS RO 0x0000.0000 Watchdog Raw Interrupt Status 247 0x014 WDTMIS RO 0x0000.0000 Watchdog Masked Interrupt Status 248 0x418 WDTTEST R/W 0x0000.0000 Watchdog Test 249 0xC00 WDTLOCK R/W 0x0000.0000 Watchdog Lock 250 November 30, 2007 241 Preliminary LM3S6952 Microcontroller See Offset Name Type Reset Description page 0xFD0 WDTPeriphID4 RO 0x0000.0000 Watchdog Peripheral Identification 4 251 0xFD4 WDTPeriphID5 RO 0x0000.0000 Watchdog Peripheral Identification 5 252 0xFD8 WDTPeriphID6 RO 0x0000.0000 Watchdog Peripheral Identification 6 253 0xFDC WDTPeriphID7 RO 0x0000.0000 Watchdog Peripheral Identification 7 254 0xFE0 WDTPeriphID0 RO 0x0000.0005 Watchdog Peripheral Identification 0 255 0xFE4 WDTPeriphID1 RO 0x0000.0018 Watchdog Peripheral Identification 1 256 0xFE8 WDTPeriphID2 RO 0x0000.0018 Watchdog Peripheral Identification 2 257 0xFEC WDTPeriphID3 RO 0x0000.0001 Watchdog Peripheral Identification 3 258 0xFF0 WDTPCellID0 RO 0x0000.000D Watchdog PrimeCell Identification 0 259 0xFF4 WDTPCellID1 RO 0x0000.00F0 Watchdog PrimeCell Identification 1 260 0xFF8 WDTPCellID2 RO 0x0000.0005 Watchdog PrimeCell Identification 2 261 0xFFC WDTPCellID3 RO 0x0000.00B1 Watchdog PrimeCell Identification 3 262 11.5 Register Descriptions The remainder of this section lists and describes the WDT registers, in numerical order by address offset. 242 November 30, 2007 Preliminary Watchdog Timer Register 1: Watchdog Load (WDTLOAD), offset 0x000 This register is the 32-bit interval value used by the 32-bit counter. When this register is written, the value is immediately loaded and the counter restarts counting down from the new value. If the WDTLOAD register is loaded with 0x0000.0000, an interrupt is immediately generated. Watchdog Load (WDTLOAD) Base 0x4000.0000 Offset 0x000 Type R/W, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 WDTLoad Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 WDTLoad Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description 31:0 WDTLoad R/W 0xFFFF.FFFF Watchdog Load Value November 30, 2007 243 Preliminary LM3S6952 Microcontroller Register 2: Watchdog Value (WDTVALUE), offset 0x004 This register contains the current count value of the timer. Watchdog Value (WDTVALUE) Base 0x4000.0000 Offset 0x004 Type RO, reset 0xFFFF.FFFF 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 WDTValue Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 WDTValue Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Watchdog Value Current value of the 32-bit down counter. 31:0 WDTValue RO 0xFFFF.FFFF 244 November 30, 2007 Preliminary Watchdog Timer Register 3: Watchdog Control (WDTCTL), offset 0x008 This register is the watchdog control register. The watchdog timer can be configured to generate a reset signal (on second time-out) or an interrupt on time-out. When the watchdog interrupt has been enabled, all subsequent writes to the control register are ignored. The only mechanism that can re-enable writes is a hardware reset. Watchdog Control (WDTCTL) Base 0x4000.0000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RESEN INTEN Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Watchdog Reset Enable The RESEN values are defined as follows: Value Description 0 Disabled. 1 Enable the Watchdog module reset output. 1 RESEN R/W 0 Watchdog Interrupt Enable The INTEN values are defined as follows: Value Description Interrupt event disabled (once this bit is set, it can only be cleared by a hardware reset). 0 1 Interrupt event enabled. Once enabled, all writes are ignored. 0 INTEN R/W 0 November 30, 2007 245 Preliminary LM3S6952 Microcontroller Register 4: Watchdog Interrupt Clear (WDTICR), offset 0x00C This register is the interrupt clear register. A write of any value to this register clears the Watchdog interrupt and reloads the 32-bit counter from the WDTLOAD register. Value for a read or reset is indeterminate. Watchdog Interrupt Clear (WDTICR) Base 0x4000.0000 Offset 0x00C Type WO, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 WDTIntClr Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset - - - - - - - - - - - - - - - - 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 WDTIntClr Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset - - - - - - - - - - - - - - - - Bit/Field Name Type Reset Description 31:0 WDTIntClr WO - Watchdog Interrupt Clear 246 November 30, 2007 Preliminary Watchdog Timer Register 5: Watchdog Raw Interrupt Status (WDTRIS), offset 0x010 This register is the raw interrupt status register. Watchdog interrupt events can be monitored via this register if the controller interrupt is masked. Watchdog Raw Interrupt Status (WDTRIS) Base 0x4000.0000 Offset 0x010 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved WDTRIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Watchdog Raw Interrupt Status Gives the raw interrupt state (prior to masking) of WDTINTR. 0 WDTRIS RO 0 November 30, 2007 247 Preliminary LM3S6952 Microcontroller Register 6: Watchdog Masked Interrupt Status (WDTMIS), offset 0x014 This register is the masked interrupt status register. The value of this register is the logical AND of the raw interrupt bit and the Watchdog interrupt enable bit. Watchdog Masked Interrupt Status (WDTMIS) Base 0x4000.0000 Offset 0x014 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved WDTMIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Watchdog Masked Interrupt Status Gives the masked interrupt state (after masking) of the WDTINTR interrupt. 0 WDTMIS RO 0 248 November 30, 2007 Preliminary Watchdog Timer Register 7: Watchdog Test (WDTTEST), offset 0x418 This register provides user-enabled stalling when the microcontroller asserts the CPU halt flag during debug. Watchdog Test (WDTTEST) Base 0x4000.0000 Offset 0x418 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved STALL reserved Type RO RO RO RO RO RO RO R/W RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:9 reserved RO 0x00 Watchdog Stall Enable When set to 1, if the Stellaris® microcontroller is stopped with a debugger, the watchdog timer stops counting. Once the microcontroller is restarted, the watchdog timer resumes counting. 8 STALL R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:0 reserved RO 0x00 November 30, 2007 249 Preliminary LM3S6952 Microcontroller Register 8: Watchdog Lock (WDTLOCK), offset 0xC00 Writing 0x1ACC.E551 to the WDTLOCK register enables write access to all other registers. Writing any other value to the WDTLOCK register re-enables the locked state for register writes to all the other registers. Reading the WDTLOCK register returns the lock status rather than the 32-bit value written. Therefore, when write accesses are disabled, reading the WDTLOCK register returns 0x0000.0001 (when locked; otherwise, the returned value is 0x0000.0000 (unlocked)). Watchdog Lock (WDTLOCK) Base 0x4000.0000 Offset 0xC00 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 WDTLock Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 WDTLock Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Watchdog Lock A write of the value 0x1ACC.E551 unlocks the watchdog registers for write access. A write of any other value reapplies the lock, preventing any register updates. A read of this register returns the following values: Value Description 0x0000.0001 Locked 0x0000.0000 Unlocked 31:0 WDTLock R/W 0x0000 250 November 30, 2007 Preliminary Watchdog Timer Register 9: Watchdog Peripheral Identification 4 (WDTPeriphID4), offset 0xFD0 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 4 (WDTPeriphID4) Base 0x4000.0000 Offset 0xFD0 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID4 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID4 RO 0x00 WDT Peripheral ID Register[7:0] November 30, 2007 251 Preliminary LM3S6952 Microcontroller Register 10: Watchdog Peripheral Identification 5 (WDTPeriphID5), offset 0xFD4 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 5 (WDTPeriphID5) Base 0x4000.0000 Offset 0xFD4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID5 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID5 RO 0x00 WDT Peripheral ID Register[15:8] 252 November 30, 2007 Preliminary Watchdog Timer Register 11: Watchdog Peripheral Identification 6 (WDTPeriphID6), offset 0xFD8 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 6 (WDTPeriphID6) Base 0x4000.0000 Offset 0xFD8 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID6 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID6 RO 0x00 WDT Peripheral ID Register[23:16] November 30, 2007 253 Preliminary LM3S6952 Microcontroller Register 12: Watchdog Peripheral Identification 7 (WDTPeriphID7), offset 0xFDC The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 7 (WDTPeriphID7) Base 0x4000.0000 Offset 0xFDC Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID7 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID7 RO 0x00 WDT Peripheral ID Register[31:24] 254 November 30, 2007 Preliminary Watchdog Timer Register 13: Watchdog Peripheral Identification 0 (WDTPeriphID0), offset 0xFE0 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 0 (WDTPeriphID0) Base 0x4000.0000 Offset 0xFE0 Type RO, reset 0x0000.0005 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID0 RO 0x05 Watchdog Peripheral ID Register[7:0] November 30, 2007 255 Preliminary LM3S6952 Microcontroller Register 14: Watchdog Peripheral Identification 1 (WDTPeriphID1), offset 0xFE4 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 1 (WDTPeriphID1) Base 0x4000.0000 Offset 0xFE4 Type RO, reset 0x0000.0018 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID1 RO 0x18 Watchdog Peripheral ID Register[15:8] 256 November 30, 2007 Preliminary Watchdog Timer Register 15: Watchdog Peripheral Identification 2 (WDTPeriphID2), offset 0xFE8 The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 2 (WDTPeriphID2) Base 0x4000.0000 Offset 0xFE8 Type RO, reset 0x0000.0018 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID2 RO 0x18 Watchdog Peripheral ID Register[23:16] November 30, 2007 257 Preliminary LM3S6952 Microcontroller Register 16: Watchdog Peripheral Identification 3 (WDTPeriphID3), offset 0xFEC The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog Peripheral Identification 3 (WDTPeriphID3) Base 0x4000.0000 Offset 0xFEC Type RO, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 PID3 RO 0x01 Watchdog Peripheral ID Register[31:24] 258 November 30, 2007 Preliminary Watchdog Timer Register 17: Watchdog PrimeCell Identification 0 (WDTPCellID0), offset 0xFF0 The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog PrimeCell Identification 0 (WDTPCellID0) Base 0x4000.0000 Offset 0xFF0 Type RO, reset 0x0000.000D 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 CID0 RO 0x0D Watchdog PrimeCell ID Register[7:0] November 30, 2007 259 Preliminary LM3S6952 Microcontroller Register 18: Watchdog PrimeCell Identification 1 (WDTPCellID1), offset 0xFF4 The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog PrimeCell Identification 1 (WDTPCellID1) Base 0x4000.0000 Offset 0xFF4 Type RO, reset 0x0000.00F0 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 CID1 RO 0xF0 Watchdog PrimeCell ID Register[15:8] 260 November 30, 2007 Preliminary Watchdog Timer Register 19: Watchdog PrimeCell Identification 2 (WDTPCellID2), offset 0xFF8 The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog PrimeCell Identification 2 (WDTPCellID2) Base 0x4000.0000 Offset 0xFF8 Type RO, reset 0x0000.0005 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 CID2 RO 0x05 Watchdog PrimeCell ID Register[23:16] November 30, 2007 261 Preliminary LM3S6952 Microcontroller Register 20: Watchdog PrimeCell Identification 3 (WDTPCellID3 ), offset 0xFFC The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset value. Watchdog PrimeCell Identification 3 (WDTPCellID3) Base 0x4000.0000 Offset 0xFFC Type RO, reset 0x0000.00B1 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 7:0 CID3 RO 0xB1 Watchdog PrimeCell ID Register[31:24] 262 November 30, 2007 Preliminary Watchdog Timer 12 Analog-to-Digital Converter (ADC) An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a discrete digital number. The Stellaris® ADC module features 10-bit conversion resolution and supports three input channels, plus an internal temperature sensor. The ADC module contains a programmable sequencer which allows for the sampling of multiple analog input sources without controller intervention. Each sample sequence provides flexible programming with fully configurable input source, trigger events, interrupt generation, and sequence priority. The Stellaris® ADC provides the following features: ■ Three analog input channels ■ Single-ended and differential-input configurations ■ Internal temperature sensor ■ Sample rate of 500 thousand samples/second ■ Four programmable sample conversion sequences from one to eight entries long, with corresponding conversion result FIFOs ■ Flexible trigger control – Controller (software) – Timers – Analog Comparators – PWM – GPIO ■ Hardware averaging of up to 64 samples for improved accuracy November 30, 2007 263 Preliminary LM3S6952 Microcontroller 12.1 Block Diagram Figure 12-1. ADC Module Block Diagram Analog-to-Digital Converter ADCSSFIFO0 ADCSSFIFO1 ADCSSFIFO2 ADCSSFIFO3 FIFO Block ADCSSFSTAT0 ADCSSCTL0 ADCSSMUX0 Sample Sequencer 0 ADCSSFSTAT1 ADCSSCTL1 ADCSSMUX1 Sample Sequencer 1 ADCSSFSTAT2 ADCSSCTL2 ADCSSMUX2 Sample Sequencer 2 ADCSSFSTAT3 ADCSSCTL3 ADCSSMUX3 Sample Sequencer 3 ADCUSTAT ADCOSTAT ADCACTSS Control/Status ADCSSPRI ADCISC ADCRIS ADCIM Interrupt Control SS0 Interrupt Analog Inputs SS1 Interrupt SS2 Interrupt SS3 Interrupt ADCEMUX ADCPSSI Trigger Events SS0 SS1 SS2 SS3 Comparator GPIO (PB4) Timer PWM Comparator GPIO (PB4) Timer PWM Comparator GPIO (PB4) Timer PWM Comparator GPIO (PB4) Timer PWM Hardware Averager ADCSAC 12.2 Functional Description The Stellaris® ADC collects sample data by using a programmable sequence-based approach instead of the traditional single or double-sampling approach found on many ADC modules. Each sample sequence is a fully programmed series of consecutive (back-to-back) samples, allowing the ADC to collect data from multiple input sources without having to be re-configured or serviced by the controller. The programming of each sample in the sample sequence includes parameters such as the input source and mode (differential versus single-ended input), interrupt generation on sample completion, and the indicator for the last sample in the sequence. 12.2.1 Sample Sequencers The sampling control and data capture is handled by the Sample Sequencers. All of the sequencers are identical in implementation except for the number of samples that can be captured and the depth of the FIFO. Table 12-1 on page 264 shows the maximum number of samples that each Sequencer can capture and its corresponding FIFO depth. In this implementation, each FIFO entry is a 32-bit word, with the lower 10 bits containing the conversion result. Table 12-1. Samples and FIFO Depth of Sequencers Sequencer Number of Samples Depth of FIFO SS3 1 1 SS2 4 4 SS1 4 4 SS0 8 8 264 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) For a given sample sequence, each sample is defined by two 4-bit nibbles in the ADC Sample Sequence Input Multiplexer Select (ADCSSMUXn) and ADC Sample Sequence Control (ADCSSCTLn) registers, where "n" corresponds to the sequence number. The ADCSSMUXn nibbles select the input pin, while the ADCSSCTLn nibbles contain the sample control bits corresponding to parameters such as temperature sensor selection, interrupt enable, end of sequence, and differential input mode. Sample Sequencers are enabled by setting the respective ASENn bit in the ADC Active Sample Sequencer (ADCACTSS) register, but can be configured before being enabled. When configuring a sample sequence, multiple uses of the same input pin within the same sequence is allowed. In the ADCSSCTLn register, the Interrupt Enable (IE) bits can be set for any combination of samples, allowing interrupts to be generated after every sample in the sequence if necessary. Also, the END bit can be set at any point within a sample sequence. For example, if Sequencer 0 is used, the END bit can be set in the nibble associated with the fifth sample, allowing Sequencer 0 to complete execution of the sample sequence after the fifth sample. After a sample sequence completes execution, the result data can be retrieved from the ADC Sample Sequence Result FIFO (ADCSSFIFOn) registers. The FIFOs are simple circular buffers that read a single address to "pop" result data. For software debug purposes, the positions of the FIFO head and tail pointers are visible in the ADC Sample Sequence FIFO Status (ADCSSFSTATn) registers along with FULL and EMPTY status flags. Overflow and underflow conditions are monitored using the ADCOSTAT and ADCUSTAT registers. 12.2.2 Module Control Outside of the Sample Sequencers, the remainder of the control logic is responsible for tasks such as interrupt generation, sequence prioritization, and trigger configuration. Most of the ADC control logic runs at the ADC clock rate of 14-18 MHz. The internal ADC divider is configured automatically by hardware when the system XTAL is selected. The automatic clock divider configuration targets 16.667 MHz operation for all Stellaris® devices. 12.2.2.1 Interrupts The Sample Sequencers dictate the events that cause interrupts, but they don't have control over whether the interrupt is actually sent to the interrupt controller. The ADC module's interrupt signal is controlled by the state of the MASK bits in the ADC Interrupt Mask (ADCIM) register. Interrupt status can be viewed at two locations: the ADC Raw Interrupt Status (ADCRIS) register, which shows the raw status of a Sample Sequencer's interrupt signal, and the ADC Interrupt Status and Clear (ADCISC) register, which shows the logical AND of the ADCRIS register’s INR bit and the ADCIM register’s MASK bits. Interrupts are cleared by writing a 1 to the corresponding IN bit in ADCISC. 12.2.2.2 Prioritization When sampling events (triggers) happen concurrently, they are prioritized for processing by the values in the ADC Sample Sequencer Priority (ADCSSPRI) register. Valid priority values are in the range of 0-3, with 0 being the highest priority and 3 being the lowest. Multiple active Sample Sequencer units with the same priority do not provide consistent results, so software must ensure that all active Sample Sequencer units have a unique priority value. 12.2.2.3 Sampling Events Sample triggering for each Sample Sequencer is defined in the ADC Event Multiplexer Select (ADCEMUX) register. The external peripheral triggering sources vary by Stellaris® family member, November 30, 2007 265 Preliminary LM3S6952 Microcontroller but all devices share the "Controller" and "Always" triggers. Software can initiate sampling by setting the CH bits in the ADC Processor Sample Sequence Initiate (ADCPSSI) register. When using the "Always" trigger, care must be taken. If a sequence's priority is too high, it is possible to starve other lower priority sequences. 12.2.3 Hardware Sample Averaging Circuit Higher precision results can be generated using the hardware averaging circuit, however, the improved results are at the cost of throughput. Up to 64 samples can be accumulated and averaged to form a single data entry in the sequencer FIFO. Throughput is decreased proportionally to the number of samples in the averaging calculation. For example, if the averaging circuit is configured to average 16 samples, the throughput is decreased by a factor of 16. By default the averaging circuit is off and all data from the converter passes through to the sequencer FIFO. The averaging hardware is controlled by the ADC Sample Averaging Control (ADCSAC) register (see page 281). There is a single averaging circuit and all input channels receive the same amount of averaging whether they are single-ended or differential. 12.2.4 Analog-to-Digital Converter The converter itself generates a 10-bit output value for selected analog input. Special analog pads are used to minimize the distortion on the input. 12.2.5 Test Modes There is a user-available test mode that allows for loopback operation within the digital portion of the ADC module. This can be useful for debugging software without having to provide actual analog stimulus. This mode is available through the ADC Test Mode Loopback (ADCTMLB) register (see page 294). 12.2.6 Internal Temperature Sensor The internal temperature sensor provides an analog temperature reading as well as a reference voltage. The voltage at the output terminal SENSO is given by the following equation: SENSO = 2.7 - ((T + 55) / 75) This relation is shown in Figure 12-2 on page 267. 266 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Figure 12-2. Internal Temperature Sensor Characteristic 12.3 Initialization and Configuration In order for the ADC module to be used, the PLL must be enabled and using a supported crystal frequency (see the RCC register). Using unsupported frequencies can cause faulty operation in the ADC module. 12.3.1 Module Initialization Initialization of the ADC module is a simple process with very few steps. The main steps include enabling the clock to the ADC and reconfiguring the Sample Sequencer priorities (if needed). The initialization sequence for the ADC is as follows: 1. Enable the ADC clock by writing a value of 0x0001.0000 to the RCGC1 register (see page 100). 2. If required by the application, reconfigure the Sample Sequencer priorities in the ADCSSPRI register. The default configuration has Sample Sequencer 0 with the highest priority, and Sample Sequencer 3 as the lowest priority. 12.3.2 Sample Sequencer Configuration Configuration of the Sample Sequencers is slightly more complex than the module initialization since each sample sequence is completely programmable. The configuration for each Sample Sequencer should be as follows: 1. Ensure that the Sample Sequencer is disabled by writing a 0 to the corresponding ASEN bit in the ADCACTSS register. Programming of the Sample Sequencers is allowed without having them enabled. Disabling the Sequencer during programming prevents erroneous execution if a trigger event were to occur during the configuration process. 2. Configure the trigger event for the Sample Sequencer in the ADCEMUX register. 3. For each sample in the sample sequence, configure the corresponding input source in the ADCSSMUXn register. November 30, 2007 267 Preliminary LM3S6952 Microcontroller 4. For each sample in the sample sequence, configure the sample control bits in the corresponding nibble in the ADCSSCTLn register. When programming the last nibble, ensure that the END bit is set. Failure to set the END bit causes unpredictable behavior. 5. If interrupts are to be used, write a 1 to the corresponding MASK bit in the ADCIM register. 6. Enable the Sample Sequencer logic by writing a 1 to the corresponding ASEN bit in the ADCACTSS register. 12.4 Register Map Table 12-2 on page 268 lists the ADC registers. The offset listed is a hexadecimal increment to the register’s address, relative to the ADC base address of 0x4003.8000. Table 12-2. ADC Register Map See Offset Name Type Reset Description page 0x000 ADCACTSS R/W 0x0000.0000 ADC Active Sample Sequencer 270 0x004 ADCRIS RO 0x0000.0000 ADC Raw Interrupt Status 271 0x008 ADCIM R/W 0x0000.0000 ADC Interrupt Mask 272 0x00C ADCISC R/W1C 0x0000.0000 ADC Interrupt Status and Clear 273 0x010 ADCOSTAT R/W1C 0x0000.0000 ADC Overflow Status 274 0x014 ADCEMUX R/W 0x0000.0000 ADC Event Multiplexer Select 275 0x018 ADCUSTAT R/W1C 0x0000.0000 ADC Underflow Status 278 0x020 ADCSSPRI R/W 0x0000.3210 ADC Sample Sequencer Priority 279 0x028 ADCPSSI WO - ADC Processor Sample Sequence Initiate 280 0x030 ADCSAC R/W 0x0000.0000 ADC Sample Averaging Control 281 0x040 ADCSSMUX0 R/W 0x0000.0000 ADC Sample Sequence Input Multiplexer Select 0 282 0x044 ADCSSCTL0 R/W 0x0000.0000 ADC Sample Sequence Control 0 284 0x048 ADCSSFIFO0 RO 0x0000.0000 ADC Sample Sequence Result FIFO 0 287 0x04C ADCSSFSTAT0 RO 0x0000.0100 ADC Sample Sequence FIFO 0 Status 288 0x060 ADCSSMUX1 R/W 0x0000.0000 ADC Sample Sequence Input Multiplexer Select 1 289 0x064 ADCSSCTL1 R/W 0x0000.0000 ADC Sample Sequence Control 1 290 0x068 ADCSSFIFO1 RO 0x0000.0000 ADC Sample Sequence Result FIFO 1 287 0x06C ADCSSFSTAT1 RO 0x0000.0100 ADC Sample Sequence FIFO 1 Status 288 0x080 ADCSSMUX2 R/W 0x0000.0000 ADC Sample Sequence Input Multiplexer Select 2 289 0x084 ADCSSCTL2 R/W 0x0000.0000 ADC Sample Sequence Control 2 290 0x088 ADCSSFIFO2 RO 0x0000.0000 ADC Sample Sequence Result FIFO 2 287 0x08C ADCSSFSTAT2 RO 0x0000.0100 ADC Sample Sequence FIFO 2 Status 288 0x0A0 ADCSSMUX3 R/W 0x0000.0000 ADC Sample Sequence Input Multiplexer Select 3 292 268 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) See Offset Name Type Reset Description page 0x0A4 ADCSSCTL3 R/W 0x0000.0002 ADC Sample Sequence Control 3 293 0x0A8 ADCSSFIFO3 RO 0x0000.0000 ADC Sample Sequence Result FIFO 3 287 0x0AC ADCSSFSTAT3 RO 0x0000.0100 ADC Sample Sequence FIFO 3 Status 288 0x100 ADCTMLB R/W 0x0000.0000 ADC Test Mode Loopback 294 12.5 Register Descriptions The remainder of this section lists and describes the ADC registers, in numerical order by address offset. November 30, 2007 269 Preliminary LM3S6952 Microcontroller Register 1: ADC Active Sample Sequencer (ADCACTSS), offset 0x000 This register controls the activation of the Sample Sequencers. Each Sample Sequencer can be enabled/disabled independently. ADC Active Sample Sequencer (ADCACTSS) Base 0x4003.8000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved ASEN3 ASEN2 ASEN1 ASEN0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 ADC SS3 Enable Specifies whether Sample Sequencer 3 is enabled. If set, the sample sequence logic for Sequencer 3 is active. Otherwise, the Sequencer is inactive. 3 ASEN3 R/W 0 ADC SS2 Enable Specifies whether Sample Sequencer 2 is enabled. If set, the sample sequence logic for Sequencer 2 is active. Otherwise, the Sequencer is inactive. 2 ASEN2 R/W 0 ADC SS1 Enable Specifies whether Sample Sequencer 1 is enabled. If set, the sample sequence logic for Sequencer 1 is active. Otherwise, the Sequencer is inactive. 1 ASEN1 R/W 0 ADC SS0 Enable Specifies whether Sample Sequencer 0 is enabled. If set, the sample sequence logic for Sequencer 0 is active. Otherwise, the Sequencer is inactive. 0 ASEN0 R/W 0 270 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 2: ADC Raw Interrupt Status (ADCRIS), offset 0x004 This register shows the status of the raw interrupt signal of each Sample Sequencer. These bits may be polled by software to look for interrupt conditions without having to generate controller interrupts. ADC Raw Interrupt Status (ADCRIS) Base 0x4003.8000 Offset 0x004 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved INR3 INR2 INR1 INR0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SS3 Raw Interrupt Status Set by hardware when a sample with its respective ADCSSCTL3 IE bit has completed conversion. This bit is cleared by writing a 1 to the ADCISC IN3 bit. 3 INR3 RO 0 SS2 Raw Interrupt Status Set by hardware when a sample with its respective ADCSSCTL2 IE bit has completed conversion. This bit is cleared by writing a 1 to the ADCISC IN2 bit. 2 INR2 RO 0 SS1 Raw Interrupt Status Set by hardware when a sample with its respective ADCSSCTL1 IE bit has completed conversion. This bit is cleared by writing a 1 to the ADCISC IN1 bit. 1 INR1 RO 0 SS0 Raw Interrupt Status Set by hardware when a sample with its respective ADCSSCTL0 IE bit has completed conversion. This bit is cleared by writing a 1 to the ADCISC IN0 bit. 0 INR0 RO 0 November 30, 2007 271 Preliminary LM3S6952 Microcontroller Register 3: ADC Interrupt Mask (ADCIM), offset 0x008 This register controls whether the Sample Sequencer raw interrupt signals are promoted to controller interrupts. The raw interrupt signal for each Sample Sequencer can be masked independently. ADC Interrupt Mask (ADCIM) Base 0x4003.8000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MASK3 MASK2 MASK1 MASK0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SS3 Interrupt Mask Specifies whether the raw interrupt signal from Sample Sequencer 3 (ADCRIS register INR3 bit) is promoted to a controller interrupt. If set, the raw interrupt signal is promoted to a controller interrupt. Otherwise, it is not. 3 MASK3 R/W 0 SS2 Interrupt Mask Specifies whether the raw interrupt signal from Sample Sequencer 2 (ADCRIS register INR2 bit) is promoted to a controller interrupt. If set, the raw interrupt signal is promoted to a controller interrupt. Otherwise, it is not. 2 MASK2 R/W 0 SS1 Interrupt Mask Specifies whether the raw interrupt signal from Sample Sequencer 1 (ADCRIS register INR1 bit) is promoted to a controller interrupt. If set, the raw interrupt signal is promoted to a controller interrupt. Otherwise, it is not. 1 MASK1 R/W 0 SS0 Interrupt Mask Specifies whether the raw interrupt signal from Sample Sequencer 0 (ADCRIS register INR0 bit) is promoted to a controller interrupt. If set, the raw interrupt signal is promoted to a controller interrupt. Otherwise, it is not. 0 MASK0 R/W 0 272 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 4: ADC Interrupt Status and Clear (ADCISC), offset 0x00C This register provides the mechanism for clearing interrupt conditions, and shows the status of controller interrupts generated by the Sample Sequencers. When read, each bit field is the logical AND of the respective INR and MASK bits. Interrupts are cleared by writing a 1 to the corresponding bit position. If software is polling the ADCRIS instead of generating interrupts, the INR bits are still cleared via the ADCISC register, even if the IN bit is not set. ADC Interrupt Status and Clear (ADCISC) Base 0x4003.8000 Offset 0x00C Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IN3 IN2 IN1 IN0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SS3 Interrupt Status and Clear This bit is set by hardware when the MASK3 and INR3 bits are both 1, providing a level-based interrupt to the controller. It is cleared by writing a 1, and also clears the INR3 bit. 3 IN3 R/W1C 0 SS2 Interrupt Status and Clear This bit is set by hardware when the MASK2 and INR2 bits are both 1, providing a level based interrupt to the controller. It is cleared by writing a 1, and also clears the INR2 bit. 2 IN2 R/W1C 0 SS1 Interrupt Status and Clear This bit is set by hardware when the MASK1 and INR1 bits are both 1, providing a level based interrupt to the controller. It is cleared by writing a 1, and also clears the INR1 bit. 1 IN1 R/W1C 0 SS0 Interrupt Status and Clear This bit is set by hardware when the MASK0 and INR0 bits are both 1, providing a level based interrupt to the controller. It is cleared by writing a 1, and also clears the INR0 bit. 0 IN0 R/W1C 0 November 30, 2007 273 Preliminary LM3S6952 Microcontroller Register 5: ADC Overflow Status (ADCOSTAT), offset 0x010 This register indicates overflow conditions in the Sample Sequencer FIFOs. Once the overflow condition has been handled by software, the condition can be cleared by writing a 1 to the corresponding bit position. ADC Overflow Status (ADCOSTAT) Base 0x4003.8000 Offset 0x010 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OV3 OV2 OV1 OV0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SS3 FIFO Overflow This bit specifies that the FIFO for Sample Sequencer 3 has hit an overflow condition where the FIFO is full and a write was requested. When an overflow is detected, the most recent write is dropped and this bit is set by hardware to indicate the occurrence of dropped data. This bit is cleared by writing a 1. 3 OV3 R/W1C 0 SS2 FIFO Overflow This bit specifies that the FIFO for Sample Sequencer 2 has hit an overflow condition where the FIFO is full and a write was requested. When an overflow is detected, the most recent write is dropped and this bit is set by hardware to indicate the occurrence of dropped data. This bit is cleared by writing a 1. 2 OV2 R/W1C 0 SS1 FIFO Overflow This bit specifies that the FIFO for Sample Sequencer 1 has hit an overflow condition where the FIFO is full and a write was requested. When an overflow is detected, the most recent write is dropped and this bit is set by hardware to indicate the occurrence of dropped data. This bit is cleared by writing a 1. 1 OV1 R/W1C 0 SS0 FIFO Overflow This bit specifies that the FIFO for Sample Sequencer 0 has hit an overflow condition where the FIFO is full and a write was requested. When an overflow is detected, the most recent write is dropped and this bit is set by hardware to indicate the occurrence of dropped data. This bit is cleared by writing a 1. 0 OV0 R/W1C 0 274 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 6: ADC Event Multiplexer Select (ADCEMUX), offset 0x014 The ADCEMUX selects the event (trigger) that initiates sampling for each Sample Sequencer. Each Sample Sequencer can be configured with a unique trigger source. ADC Event Multiplexer Select (ADCEMUX) Base 0x4003.8000 Offset 0x014 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 EM3 EM2 EM1 EM0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x00 SS3 Trigger Select This field selects the trigger source for Sample Sequencer 3. The valid configurations for this field are: Value Event 0x0 Controller (default) 0x1 Analog Comparator 0 0x2 Analog Comparator 1 0x3 Analog Comparator 2 0x4 External (GPIO PB4) 0x5 Timer 0x6 PWM0 0x7 PWM1 0x8 PWM2 0x9-0xE reserved 0xF Always (continuously sample) 15:12 EM3 R/W 0x00 November 30, 2007 275 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description SS2 Trigger Select This field selects the trigger source for Sample Sequencer 2. The valid configurations for this field are: Value Event 0x0 Controller (default) 0x1 Analog Comparator 0 0x2 Analog Comparator 1 0x3 Analog Comparator 2 0x4 External (GPIO PB4) 0x5 Timer 0x6 PWM0 0x7 PWM1 0x8 PWM2 0x9-0xE reserved 0xF Always (continuously sample) 11:8 EM2 R/W 0x00 SS1 Trigger Select This field selects the trigger source for Sample Sequencer 1. The valid configurations for this field are: Value Event 0x0 Controller (default) 0x1 Analog Comparator 0 0x2 Analog Comparator 1 0x3 Analog Comparator 2 0x4 External (GPIO PB4) 0x5 Timer 0x6 PWM0 0x7 PWM1 0x8 PWM2 0x9-0xE reserved 0xF Always (continuously sample) 7:4 EM1 R/W 0x00 276 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Bit/Field Name Type Reset Description SS0 Trigger Select This field selects the trigger source for Sample Sequencer 0. The valid configurations for this field are: Value Event 0x0 Controller (default) 0x1 Analog Comparator 0 0x2 Analog Comparator 1 0x3 Analog Comparator 2 0x4 External (GPIO PB4) 0x5 Timer 0x6 PWM0 0x7 PWM1 0x8 PWM2 0x9-0xE reserved 0xF Always (continuously sample) 3:0 EM0 R/W 0x00 November 30, 2007 277 Preliminary LM3S6952 Microcontroller Register 7: ADC Underflow Status (ADCUSTAT), offset 0x018 This register indicates underflow conditions in the Sample Sequencer FIFOs. The corresponding underflow condition can be cleared by writing a 1 to the relevant bit position. ADC Underflow Status (ADCUSTAT) Base 0x4003.8000 Offset 0x018 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved UV3 UV2 UV1 UV0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SS3 FIFO Underflow This bit specifies that the FIFO for Sample Sequencer 3 has hit an underflow condition where the FIFO is empty and a read was requested. The problematic read does not move the FIFO pointers, and 0s are returned. This bit is cleared by writing a 1. 3 UV3 R/W1C 0 SS2 FIFO Underflow This bit specifies that the FIFO for Sample Sequencer 2 has hit an underflow condition where the FIFO is empty and a read was requested. The problematic read does not move the FIFO pointers, and 0s are returned. This bit is cleared by writing a 1. 2 UV2 R/W1C 0 SS1 FIFO Underflow This bit specifies that the FIFO for Sample Sequencer 1 has hit an underflow condition where the FIFO is empty and a read was requested. The problematic read does not move the FIFO pointers, and 0s are returned. This bit is cleared by writing a 1. 1 UV1 R/W1C 0 SS0 FIFO Underflow This bit specifies that the FIFO for Sample Sequencer 0 has hit an underflow condition where the FIFO is empty and a read was requested. The problematic read does not move the FIFO pointers, and 0s are returned. This bit is cleared by writing a 1. 0 UV0 R/W1C 0 278 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 8: ADC Sample Sequencer Priority (ADCSSPRI), offset 0x020 This register sets the priority for each of the Sample Sequencers. Out of reset, Sequencer 0 has the highest priority, and sample sequence 3 has the lowest priority. When reconfiguring sequence priorities, each sequence must have a unique priority or the ADC behavior is inconsistent. ADC Sample Sequencer Priority (ADCSSPRI) Base 0x4003.8000 Offset 0x020 Type R/W, reset 0x0000.3210 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SS3 reserved SS2 reserved SS1 reserved SS0 Type RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W Reset 0 0 1 1 0 0 1 0 0 0 0 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:14 reserved RO 0x00 SS3 Priority The SS3 field contains a binary-encoded value that specifies the priority encoding of Sample Sequencer 3. A priority encoding of 0 is highest and 3 is lowest. The priorities assigned to the Sequencers must be uniquely mapped. ADC behavior is not consistent if two or more fields are equal. 13:12 SS3 R/W 0x3 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:10 reserved RO 0x0 SS2 Priority The SS2 field contains a binary-encoded value that specifies the priority encoding of Sample Sequencer 2. 9:8 SS2 R/W 0x2 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:6 reserved RO 0x0 SS1 Priority The SS1 field contains a binary-encoded value that specifies the priority encoding of Sample Sequencer 1. 5:4 SS1 R/W 0x1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:2 reserved RO 0x0 SS0 Priority The SS0 field contains a binary-encoded value that specifies the priority encoding of Sample Sequencer 0. 1:0 SS0 R/W 0x0 November 30, 2007 279 Preliminary LM3S6952 Microcontroller Register 9: ADC Processor Sample Sequence Initiate (ADCPSSI), offset 0x028 This register provides a mechanism for application software to initiate sampling in the Sample Sequencers. Sample sequences can be initiated individually or in any combination. When multiple sequences are triggered simultaneously, the priority encodings in ADCSSPRI dictate execution order. ADC Processor Sample Sequence Initiate (ADCPSSI) Base 0x4003.8000 Offset 0x028 Type WO, reset - 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset - - - - - - - - - - - - - - - - 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SS3 SS2 SS1 SS0 Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset - - - - - - - - - - - - - - - - Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved WO - SS3 Initiate Only a write by software is valid; a read of the register returns no meaningful data. When set by software, sampling is triggered on Sample Sequencer 3, assuming the Sequencer is enabled in the ADCACTSS register. 3 SS3 WO - SS2 Initiate Only a write by software is valid; a read of the register returns no meaningful data. When set by software, sampling is triggered on Sample Sequencer 2, assuming the Sequencer is enabled in the ADCACTSS register. 2 SS2 WO - SS1 Initiate Only a write by software is valid; a read of the register returns no meaningful data. When set by software, sampling is triggered on Sample Sequencer 1, assuming the Sequencer is enabled in the ADCACTSS register. 1 SS1 WO - SS0 Initiate Only a write by software is valid; a read of the register returns no meaningful data. When set by software, sampling is triggered on Sample Sequencer 0, assuming the Sequencer is enabled in the ADCACTSS register. 0 SS0 WO - 280 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 10: ADC Sample Averaging Control (ADCSAC), offset 0x030 This register controls the amount of hardware averaging applied to conversion results. The final conversion result stored in the FIFO is averaged from 2 AVG consecutive ADC samples at the specified ADC speed. If AVG is 0, the sample is passed directly through without any averaging. If AVG=6, then 64 consecutive ADC samples are averaged to generate one result in the sequencer FIFO. An AVG = 7 provides unpredictable results. ADC Sample Averaging Control (ADCSAC) Base 0x4003.8000 Offset 0x030 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved AVG Type RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 Hardware Averaging Control Specifies the amount of hardware averaging that will be applied to ADC samples. The AVG field can be any value between 0 and 6. Entering a value of 7 creates unpredictable results. Value Description 0x0 No hardware oversampling 0x1 2x hardware oversampling 0x2 4x hardware oversampling 0x3 8x hardware oversampling 0x4 16x hardware oversampling 0x5 32x hardware oversampling 0x6 64x hardware oversampling 0x7 Reserved 2:0 AVG R/W 0x0 November 30, 2007 281 Preliminary LM3S6952 Microcontroller Register 11: ADC Sample Sequence Input Multiplexer Select 0 (ADCSSMUX0), offset 0x040 This register defines the analog input configuration for each sample in a sequence executed with Sample Sequencer 0. This register is 32-bits wide and contains information for eight possible samples. ADC Sample Sequence Input Multiplexer Select 0 (ADCSSMUX0) Base 0x4003.8000 Offset 0x040 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved MUX7 reserved MUX6 reserved MUX5 reserved MUX4 Type RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MUX3 reserved MUX2 reserved MUX1 reserved MUX0 Type RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:30 reserved RO 0 8th Sample Input Select The MUX7 field is used during the eighth sample of a sequence executed with the Sample Sequencer. It specifies which of the analog inputs is sampled for the analog-to-digital conversion. The value set here indicates the corresponding pin, for example, a value of 1 indicates the input is ADC1. 29:28 MUX7 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 27:26 reserved RO 0 7th Sample Input Select The MUX6 field is used during the seventh sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 25:24 MUX6 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 23:22 reserved RO 0 6th Sample Input Select The MUX5 field is used during the sixth sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 21:20 MUX5 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 19:18 reserved RO 0 282 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Bit/Field Name Type Reset Description 5th Sample Input Select The MUX4 field is used during the fifth sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 17:16 MUX4 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:14 reserved RO 0 4th Sample Input Select The MUX3 field is used during the fourth sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 13:12 MUX3 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:10 reserved RO 0 3rd Sample Input Select The MUX2 field is used during the third sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 9:8 MUX2 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:6 reserved RO 0 2nd Sample Input Select The MUX1 field is used during the second sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 5:4 MUX1 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:2 reserved RO 0 1st Sample Input Select The MUX0 field is used during the first sample of a sequence executed with the Sample Sequencer and specifies which of the analog inputs is sampled for the analog-to-digital conversion. 1:0 MUX0 R/W 0 November 30, 2007 283 Preliminary LM3S6952 Microcontroller Register 12: ADC Sample Sequence Control 0 (ADCSSCTL0), offset 0x044 This register contains the configuration information for each sample for a sequence executed with Sample Sequencer 0. When configuring a sample sequence, the END bit must be set at some point, whether it be after the first sample, last sample, or any sample in between. This register is 32-bits wide and contains information for eight possible samples. ADC Sample Sequence Control 0 (ADCSSCTL0) Base 0x4003.8000 Offset 0x044 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 TS7 IE7 END7 D7 TS6 IE6 END6 D6 TS5 IE5 END5 D5 TS4 IE4 END4 D4 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TS3 IE3 END3 D3 TS2 IE2 END2 D2 TS1 IE1 END1 D1 TS0 IE0 END0 D0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description 8th Sample Temp Sensor Select The TS7 bit is used during the eighth sample of the sample sequence and specifies the input source of the sample. If set, the temperature sensor is read. Otherwise, the input pin specified by the ADCSSMUX register is read. 31 TS7 R/W 0 8th Sample Interrupt Enable The IE7 bit is used during the eighth sample of the sample sequence and specifies whether the raw interrupt signal (INR0 bit) is asserted at the end of the sample's conversion. If the MASK0 bit in the ADCIM register is set, the interrupt is promoted to a controller-level interrupt. When this bit is set, the raw interrupt is asserted, otherwise it is not. It is legal to have multiple samples within a sequence generate interrupts. 30 IE7 R/W 0 8th Sample is End of Sequence The END7 bit indicates that this is the last sample of the sequence. It is possible to end the sequence on any sample position. Samples defined after the sample containing a set END are not requested for conversion even though the fields may be non-zero. It is required that software write the END bit somewhere within the sequence. (Sample Sequencer 3, which only has a single sample in the sequence, is hardwired to have the END0 bit set.) Setting this bit indicates that this sample is the last in the sequence. 29 END7 R/W 0 8th Sample Diff Input Select The D7 bit indicates that the analog input is to be differentially sampled. The corresponding ADCSSMUXx nibble must be set to the pair number "i", where the paired inputs are "2i and 2i+1". The temperature sensor does not have a differential option. When set, the analog inputs are differentially sampled. 28 D7 R/W 0 7th Sample Temp Sensor Select Same definition as TS7 but used during the seventh sample. 27 TS6 R/W 0 284 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Bit/Field Name Type Reset Description 7th Sample Interrupt Enable Same definition as IE7 but used during the seventh sample. 26 IE6 R/W 0 7th Sample is End of Sequence Same definition as END7 but used during the seventh sample. 25 END6 R/W 0 7th Sample Diff Input Select Same definition as D7 but used during the seventh sample. 24 D6 R/W 0 6th Sample Temp Sensor Select Same definition as TS7 but used during the sixth sample. 23 TS5 R/W 0 6th Sample Interrupt Enable Same definition as IE7 but used during the sixth sample. 22 IE5 R/W 0 6th Sample is End of Sequence Same definition as END7 but used during the sixth sample. 21 END5 R/W 0 6th Sample Diff Input Select Same definition as D7 but used during the sixth sample. 20 D5 R/W 0 5th Sample Temp Sensor Select Same definition as TS7 but used during the fifth sample. 19 TS4 R/W 0 5th Sample Interrupt Enable Same definition as IE7 but used during the fifth sample. 18 IE4 R/W 0 5th Sample is End of Sequence Same definition as END7 but used during the fifth sample. 17 END4 R/W 0 5th Sample Diff Input Select Same definition as D7 but used during the fifth sample. 16 D4 R/W 0 4th Sample Temp Sensor Select Same definition as TS7 but used during the fourth sample. 15 TS3 R/W 0 4th Sample Interrupt Enable Same definition as IE7 but used during the fourth sample. 14 IE3 R/W 0 4th Sample is End of Sequence Same definition as END7 but used during the fourth sample. 13 END3 R/W 0 4th Sample Diff Input Select Same definition as D7 but used during the fourth sample. 12 D3 R/W 0 3rd Sample Temp Sensor Select Same definition as TS7 but used during the third sample. 11 TS2 R/W 0 November 30, 2007 285 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description 3rd Sample Interrupt Enable Same definition as IE7 but used during the third sample. 10 IE2 R/W 0 3rd Sample is End of Sequence Same definition as END7 but used during the third sample. 9 END2 R/W 0 3rd Sample Diff Input Select Same definition as D7 but used during the third sample. 8 D2 R/W 0 2nd Sample Temp Sensor Select Same definition as TS7 but used during the second sample. 7 TS1 R/W 0 2nd Sample Interrupt Enable Same definition as IE7 but used during the second sample. 6 IE1 R/W 0 2nd Sample is End of Sequence Same definition as END7 but used during the second sample. 5 END1 R/W 0 2nd Sample Diff Input Select Same definition as D7 but used during the second sample. 4 D1 R/W 0 1st Sample Temp Sensor Select Same definition as TS7 but used during the first sample. 3 TS0 R/W 0 1st Sample Interrupt Enable Same definition as IE7 but used during the first sample. 2 IE0 R/W 0 1st Sample is End of Sequence Same definition as END7 but used during the first sample. Since this sequencer has only one entry, this bit must be set. 1 END0 R/W 0 1st Sample Diff Input Select Same definition as D7 but used during the first sample. 0 D0 R/W 0 286 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 13: ADC Sample Sequence Result FIFO 0 (ADCSSFIFO0), offset 0x048 Register 14: ADC Sample Sequence Result FIFO 1 (ADCSSFIFO1), offset 0x068 Register 15: ADC Sample Sequence Result FIFO 2 (ADCSSFIFO2), offset 0x088 Register 16: ADC Sample Sequence Result FIFO 3 (ADCSSFIFO3), offset 0x0A8 This register contains the conversion results for samples collected with the Sample Sequencer (the ADCSSFIFO0 register is used for Sample Sequencer 0, ADCSSFIFO1 for Sequencer 1, ADCSSFIFO2 for Sequencer 2, and ADCSSFIFO3 for Sequencer 3). Reads of this register return conversion result data in the order sample 0, sample 1, and so on, until the FIFO is empty. If the FIFO is not properly handled by software, overflow and underflow conditions are registered in the ADCOSTAT and ADCUSTAT registers. ADC Sample Sequence Result FIFO 0 (ADCSSFIFO0) Base 0x4003.8000 Offset 0x048 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DATA Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:10 reserved RO 0x00 9:0 DATA RO 0x00 Conversion Result Data November 30, 2007 287 Preliminary LM3S6952 Microcontroller Register 17: ADC Sample Sequence FIFO 0 Status (ADCSSFSTAT0), offset 0x04C Register 18: ADC Sample Sequence FIFO 1 Status (ADCSSFSTAT1), offset 0x06C Register 19: ADC Sample Sequence FIFO 2 Status (ADCSSFSTAT2), offset 0x08C Register 20: ADC Sample Sequence FIFO 3 Status (ADCSSFSTAT3), offset 0x0AC This register provides a window into the Sample Sequencer, providing full/empty status information as well as the positions of the head and tail pointers. The reset value of 0x100 indicates an empty FIFO. The ADCSSFSTAT0 register provides status on FIF0, ADCSSFSTAT1 on FIFO1, ADCSSFSTAT2 on FIFO2, and ADCSSFSTAT3 on FIFO3. ADC Sample Sequence FIFO 0 Status (ADCSSFSTAT0) Base 0x4003.8000 Offset 0x04C Type RO, reset 0x0000.0100 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved FULL reserved EMPTY HPTR TPTR Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:13 reserved RO 0x00 FIFO Full When set, indicates that the FIFO is currently full. 12 FULL RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:9 reserved RO 0x00 FIFO Empty When set, indicates that the FIFO is currently empty. 8 EMPTY RO 1 FIFO Head Pointer This field contains the current "head" pointer index for the FIFO, that is, the next entry to be written. 7:4 HPTR RO 0x00 FIFO Tail Pointer This field contains the current "tail" pointer index for the FIFO, that is, the next entry to be read. 3:0 TPTR RO 0x00 288 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 21: ADC Sample Sequence Input Multiplexer Select 1 (ADCSSMUX1), offset 0x060 Register 22: ADC Sample Sequence Input Multiplexer Select 2 (ADCSSMUX2), offset 0x080 This register defines the analog input configuration for each sample in a sequence executed with Sample Sequencer 1 or 2. These registers are 16-bits wide and contain information for four possible samples. See the ADCSSMUX0 register on page 282 for detailed bit descriptions. ADC Sample Sequence Input Multiplexer Select 1 (ADCSSMUX1) Base 0x4003.8000 Offset 0x060 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MUX3 reserved MUX2 reserved MUX1 reserved MUX0 Type RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:14 reserved RO 0x00 13:12 MUX3 R/W 0 4th Sample Input Select Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 11:10 reserved RO 0 9:8 MUX2 R/W 0 3rd Sample Input Select Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:6 reserved RO 0 5:4 MUX1 R/W 0 2nd Sample Input Select Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:2 reserved RO 0 1:0 MUX0 R/W 0 1st Sample Input Select November 30, 2007 289 Preliminary LM3S6952 Microcontroller Register 23: ADC Sample Sequence Control 1 (ADCSSCTL1), offset 0x064 Register 24: ADC Sample Sequence Control 2 (ADCSSCTL2), offset 0x084 These registers contain the configuration information for each sample for a sequence executed with Sample Sequencer 1 or 2. When configuring a sample sequence, the END bit must be set at some point, whether it be after the first sample, last sample, or any sample in between. This register is 16-bits wide and contains information for four possible samples. See the ADCSSCTL0 register on page 284 for detailed bit descriptions. ADC Sample Sequence Control 1 (ADCSSCTL1) Base 0x4003.8000 Offset 0x064 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TS3 IE3 END3 D3 TS2 IE2 END2 D2 TS1 IE1 END1 D1 TS0 IE0 END0 D0 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x00 4th Sample Temp Sensor Select Same definition as TS7 but used during the fourth sample. 15 TS3 R/W 0 4th Sample Interrupt Enable Same definition as IE7 but used during the fourth sample. 14 IE3 R/W 0 4th Sample is End of Sequence Same definition as END7 but used during the fourth sample. 13 END3 R/W 0 4th Sample Diff Input Select Same definition as D7 but used during the fourth sample. 12 D3 R/W 0 3rd Sample Temp Sensor Select Same definition as TS7 but used during the third sample. 11 TS2 R/W 0 3rd Sample Interrupt Enable Same definition as IE7 but used during the third sample. 10 IE2 R/W 0 3rd Sample is End of Sequence Same definition as END7 but used during the third sample. 9 END2 R/W 0 3rd Sample Diff Input Select Same definition as D7 but used during the third sample. 8 D2 R/W 0 290 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Bit/Field Name Type Reset Description 2nd Sample Temp Sensor Select Same definition as TS7 but used during the second sample. 7 TS1 R/W 0 2nd Sample Interrupt Enable Same definition as IE7 but used during the second sample. 6 IE1 R/W 0 2nd Sample is End of Sequence Same definition as END7 but used during the second sample. 5 END1 R/W 0 2nd Sample Diff Input Select Same definition as D7 but used during the second sample. 4 D1 R/W 0 1st Sample Temp Sensor Select Same definition as TS7 but used during the first sample. 3 TS0 R/W 0 1st Sample Interrupt Enable Same definition as IE7 but used during the first sample. 2 IE0 R/W 0 1st Sample is End of Sequence Same definition as END7 but used during the first sample. Since this sequencer has only one entry, this bit must be set. 1 END0 R/W 0 1st Sample Diff Input Select Same definition as D7 but used during the first sample. 0 D0 R/W 0 November 30, 2007 291 Preliminary LM3S6952 Microcontroller Register 25: ADC Sample Sequence Input Multiplexer Select 3 (ADCSSMUX3), offset 0x0A0 This register defines the analog input configuration for each sample in a sequence executed with Sample Sequencer 3. This register is 4-bits wide and contains information for one possible sample. See the ADCSSMUX0 register on page 282 for detailed bit descriptions. ADC Sample Sequence Input Multiplexer Select 3 (ADCSSMUX3) Base 0x4003.8000 Offset 0x0A0 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MUX0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 1:0 MUX0 R/W 0 1st Sample Input Select 292 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Register 26: ADC Sample Sequence Control 3 (ADCSSCTL3), offset 0x0A4 This register contains the configuration information for each sample for a sequence executed with Sample Sequencer 3. The END bit is always set since there is only one sample in this sequencer. This register is 4-bits wide and contains information for one possible sample. See the ADCSSCTL0 register on page 284 for detailed bit descriptions. ADC Sample Sequence Control 3 (ADCSSCTL3) Base 0x4003.8000 Offset 0x0A4 Type R/W, reset 0x0000.0002 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TS0 IE0 END0 D0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 1st Sample Temp Sensor Select Same definition as TS7 but used during the first sample. 3 TS0 R/W 0 1st Sample Interrupt Enable Same definition as IE7 but used during the first sample. 2 IE0 R/W 0 1st Sample is End of Sequence Same definition as END7 but used during the first sample. Since this sequencer has only one entry, this bit must be set. 1 END0 R/W 1 1st Sample Diff Input Select Same definition as D7 but used during the first sample. 0 D0 R/W 0 November 30, 2007 293 Preliminary LM3S6952 Microcontroller Register 27: ADC Test Mode Loopback (ADCTMLB), offset 0x100 This register provides loopback operation within the digital logic of the ADC, which can be useful in debugging software without having to provide actual analog stimulus. This test mode is entered by writing a value of 0x0000.0001 to this register. When data is read from the FIFO in loopback mode, the read-only portion of this register is returned. Read-Only Register ADC Test Mode Loopback (ADCTMLB) Base 0x4003.8000 Offset 0x100 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CNT CONT DIFF TS MUX Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:10 reserved RO 0x00 Continuous Sample Counter Continuous sample counter that is initialized to 0 and counts each sample as it processed. This helps provide a unique value for the data received. 9:6 CNT RO 0x0 Continuation Sample Indicator When set, indicates that this is a continuation sample. For example, if two sequencers were to run back-to-back, this indicates that the controller kept continuously sampling at full rate. 5 CONT RO 0 Differential Sample Indicator When set, indicates that this is a differential sample. 4 DIFF RO 0 Temp Sensor Sample Indicator When set, indicates that this is a temperature sensor sample. 3 TS RO 0 Analog Input Indicator Indicates which analog input is to be sampled. 2:0 MUX RO 0x0 294 November 30, 2007 Preliminary Analog-to-Digital Converter (ADC) Write-Only Register ADC Test Mode Loopback (ADCTMLB) Base 0x4003.8000 Offset 0x100 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved LB Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Loopback Mode Enable When set, forces a loopback within the digital block to provide information on input and unique numbering. The 10-bit loopback data is defined as shown in the read for bits 9:0 above. 0 LB WO 0 November 30, 2007 295 Preliminary LM3S6952 Microcontroller 13 Universal Asynchronous Receivers/Transmitters (UARTs) The Stellaris® Universal Asynchronous Receiver/Transmitter (UART) provides fully programmable, 16C550-type serial interface characteristics. The LM3S6952 controller is equipped with three UART modules. Each UART has the following features: ■ Separate transmit and receive FIFOs ■ Programmable FIFO length, including 1-byte deep operation providing conventional double-buffered interface ■ FIFO trigger levels of 1/8, 1/4, 1/2, 3/4, and 7/8 ■ Programmable baud-rate generator allowing rates up to 3.125 Mbps ■ Standard asynchronous communication bits for start, stop, and parity ■ False start bit detection ■ Line-break generation and detection ■ Fully programmable serial interface characteristics: – 5, 6, 7, or 8 data bits – Even, odd, stick, or no-parity bit generation/detection – 1 or 2 stop bit generation ■ IrDA serial-IR (SIR) encoder/decoder providing: – Programmable use of IrDA Serial InfraRed (SIR) or UART input/output – Support of IrDA SIR encoder/decoder functions for data rates up to 115.2 Kbps half-duplex – Support of normal 3/16 and low-power (1.41-2.23 μs) bit durations – Programmable internal clock generator enabling division of reference clock by 1 to 256 for low-power mode bit duration 296 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) 13.1 Block Diagram Figure 13-1. UART Module Block Diagram Receiver Transmitter System Clock Control / Status UARTRSR/ECR UARTFR UARTLCRH UARTCTL UARTILPR Interrupt Control UARTIFLS UARTIM UARTMIS UARTRIS UARTICR Baud Rate Generator UARTIBRD UARTFBRD Identification Registers UARTPCellID0 UARTPCellID1 UARTPCellID2 UARTPCellID3 UARTPeriphID0 UARTPeriphID1 UARTPeriphID2 UARTPeriphID3 UART PeriphID4 UARTPeriphID5 UARTPeriphID6 UARTPeriphID7 UARTDR TXFIFO 16x8 ... RXFIFO 16x8 ... Interrupt UnTx UnRx 13.2 Functional Description Each Stellaris® UART performs the functions of parallel-to-serial and serial-to-parallel conversions. It is similar in functionality to a 16C550 UART, but is not register compatible. The UART is configured for transmit and/or receive via the TXE and RXE bits of the UART Control (UARTCTL) register (see page 315). Transmit and receive are both enabled out of reset. Before any control registers are programmed, the UART must be disabled by clearing the UARTEN bit in UARTCTL. If the UART is disabled during a TX or RX operation, the current transaction is completed prior to the UART stopping. The UART peripheral also includes a serial IR (SIR) encoder/decoder block that can be connected to an infrared transceiver to implement an IrDA SIR physical layer. The SIR function is programmed using the UARTCTL register. 13.2.1 Transmit/Receive Logic The transmit logic performs parallel-to-serial conversion on the data read from the transmit FIFO. The control logic outputs the serial bit stream beginning with a start bit, and followed by the data November 30, 2007 297 Preliminary LM3S6952 Microcontroller bits (LSB first), parity bit, and the stop bits according to the programmed configuration in the control registers. See Figure 13-2 on page 298 for details. The receive logic performs serial-to-parallel conversion on the received bit stream after a valid start pulse has been detected. Overrun, parity, frame error checking, and line-break detection are also performed, and their status accompanies the data that is written to the receive FIFO. Figure 13-2. UART Character Frame 1 0 5-8 data bits LSB MSB Parity bit if enabled 1-2 stop bits UnTX n Start 13.2.2 Baud-Rate Generation The baud-rate divisor is a 22-bit number consisting of a 16-bit integer and a 6-bit fractional part. The number formed by these two values is used by the baud-rate generator to determine the bit period. Having a fractional baud-rate divider allows the UART to generate all the standard baud rates. The 16-bit integer is loaded through the UART Integer Baud-Rate Divisor (UARTIBRD) register (see page 311) and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate Divisor (UARTFBRD) register (see page 312). The baud-rate divisor (BRD) has the following relationship to the system clock (where BRDI is the integer part of the BRD and BRDF is the fractional part, separated by a decimal place.): BRD = BRDI + BRDF = SysClk / (16 * Baud Rate) The 6-bit fractional number (that is to be loaded into the DIVFRAC bit field in the UARTFBRD register) can be calculated by taking the fractional part of the baud-rate divisor, multiplying it by 64, and adding 0.5 to account for rounding errors: UARTFBRD[DIVFRAC] = integer(BRDF * 64 + 0.5) The UART generates an internal baud-rate reference clock at 16x the baud-rate (referred to as Baud16). This reference clock is divided by 16 to generate the transmit clock, and is used for error detection during receive operations. Along with the UART Line Control, High Byte (UARTLCRH) register (see page 313), the UARTIBRD and UARTFBRD registers form an internal 30-bit register. This internal register is only updated when a write operation to UARTLCRH is performed, so any changes to the baud-rate divisor must be followed by a write to the UARTLCRH register for the changes to take effect. To update the baud-rate registers, there are four possible sequences: ■ UARTIBRD write, UARTFBRD write, and UARTLCRH write ■ UARTFBRD write, UARTIBRD write, and UARTLCRH write ■ UARTIBRD write and UARTLCRH write ■ UARTFBRD write and UARTLCRH write 298 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) 13.2.3 Data Transmission Data received or transmitted is stored in two 16-byte FIFOs, though the receive FIFO has an extra four bits per character for status information. For transmission, data is written into the transmit FIFO. If the UART is enabled, it causes a data frame to start transmitting with the parameters indicated in the UARTLCRH register. Data continues to be transmitted until there is no data left in the transmit FIFO. The BUSY bit in the UART Flag (UARTFR) register (see page 308) is asserted as soon as data is written to the transmit FIFO (that is, if the FIFO is non-empty) and remains asserted while data is being transmitted. The BUSY bit is negated only when the transmit FIFO is empty, and the last character has been transmitted from the shift register, including the stop bits. The UART can indicate that it is busy even though the UART may no longer be enabled. When the receiver is idle (the UnRx is continuously 1) and the data input goes Low (a start bit has been received), the receive counter begins running and data is sampled on the eighth cycle of Baud16 (described in “Transmit/Receive Logic” on page 297). The start bit is valid if UnRx is still low on the eighth cycle of Baud16, otherwise a false start bit is detected and it is ignored. Start bit errors can be viewed in the UART Receive Status (UARTRSR) register (see page 306). If the start bit was valid, successive data bits are sampled on every 16th cycle of Baud16 (that is, one bit period later) according to the programmed length of the data characters. The parity bit is then checked if parity mode was enabled. Data length and parity are defined in the UARTLCRH register. Lastly, a valid stop bit is confirmed if UnRx is High, otherwise a framing error has occurred. When a full word is received, the data is stored in the receive FIFO, with any error bits associated with that word. 13.2.4 Serial IR (SIR) The UART peripheral includes an IrDA serial-IR (SIR) encoder/decoder block. The IrDA SIR block provides functionality that converts between an asynchronous UART data stream, and half-duplex serial SIR interface. No analog processing is performed on-chip. The role of the SIR block is to provide a digital encoded output, and decoded input to the UART. The UART signal pins can be connected to an infrared transceiver to implement an IrDA SIR physical layer link. The SIR block has two modes of operation: ■ In normal IrDA mode, a zero logic level is transmitted as high pulse of 3/16th duration of the selected baud rate bit period on the output pin, while logic one levels are transmitted as a static LOW signal. These levels control the driver of an infrared transmitter, sending a pulse of light for each zero. On the reception side, the incoming light pulses energize the photo transistor base of the receiver, pulling its output LOW. This drives the UART input pin LOW. ■ In low-power IrDA mode, the width of the transmitted infrared pulse is set to three times the period of the internally generated IrLPBaud16 signal (1.63 μs, assuming a nominal 1.8432 MHz frequency) by changing the appropriate bit in the UARTCR register. Figure 13-3 on page 300 shows the UART transmit and receive signals, with and without IrDA modulation. November 30, 2007 299 Preliminary LM3S6952 Microcontroller Figure 13-3. IrDA Data Modulation 0 1 0 1 0 0 1 1 0 1 Data bits 0 1 0 1 0 0 1 1 0 1 Start Data bits bit Start Stop Bit period Bit period 3 16 UnTx UnTx with IrDA UnRx with IrDA UnRx Stop bit In both normal and low-power IrDA modes: ■ During transmission, the UART data bit is used as the base for encoding ■ During reception, the decoded bits are transferred to the UART receive logic The IrDA SIR physical layer specifies a half-duplex communication link, with a minimum 10 ms delay between transmission and reception. This delay must be generated by software because it is not automatically supported by the UART. The delay is required because the infrared receiver electronics might become biased, or even saturated from the optical power coupled from the adjacent transmitter LED. This delay is known as latency, or receiver setup time. 13.2.5 FIFO Operation The UART has two 16-entry FIFOs; one for transmit and one for receive. Both FIFOs are accessed via the UART Data (UARTDR) register (see page 304). Read operations of the UARTDR register return a 12-bit value consisting of 8 data bits and 4 error flags while write operations place 8-bit data in the transmit FIFO. Out of reset, both FIFOs are disabled and act as 1-byte-deep holding registers. The FIFOs are enabled by setting the FEN bit in UARTLCRH (page 313). FIFO status can be monitored via the UART Flag (UARTFR) register (see page 308) and the UART Receive Status (UARTRSR) register. Hardware monitors empty, full and overrun conditions. The UARTFR register contains empty and full flags (TXFE, TXFF, RXFE, and RXFF bits) and the UARTRSR register shows overrun status via the OE bit. The trigger points at which the FIFOs generate interrupts is controlled via the UART Interrupt FIFO Level Select (UARTIFLS) register (see page 317). Both FIFOs can be individually configured to trigger interrupts at different levels. Available configurations include 1/8, ¼, ½, ¾, and 7/8. For example, if the ¼ option is selected for the receive FIFO, the UART generates a receive interrupt after 4 data bytes are received. Out of reset, both FIFOs are configured to trigger an interrupt at the ½ mark. 13.2.6 Interrupts The UART can generate interrupts when the following conditions are observed: ■ Overrun Error ■ Break Error 300 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) ■ Parity Error ■ Framing Error ■ Receive Timeout ■ Transmit (when condition defined in the TXIFLSEL bit in the UARTIFLS register is met) ■ Receive (when condition defined in the RXIFLSEL bit in the UARTIFLS register is met) All of the interrupt events are ORed together before being sent to the interrupt controller, so the UART can only generate a single interrupt request to the controller at any given time. Software can service multiple interrupt events in a single interrupt service routine by reading the UART Masked Interrupt Status (UARTMIS) register (see page 322). The interrupt events that can trigger a controller-level interrupt are defined in the UART Interrupt Mask (UARTIM ) register (see page 319) by setting the corresponding IM bit to 1. If interrupts are not used, the raw interrupt status is always visible via the UART Raw Interrupt Status (UARTRIS) register (see page 321). Interrupts are always cleared (for both the UARTMIS and UARTRIS registers) by setting the corresponding bit in the UART Interrupt Clear (UARTICR) register (see page 323). The receive timeout interrupt is asserted when the receive FIFO is not empty, and no further data is received over a 32-bit period. The receive timeout interrupt is cleared either when the FIFO becomes empty through reading all the data (or by reading the holding register), or when a 1 is written to the corresponding bit in the UARTICR register. 13.2.7 Loopback Operation The UART can be placed into an internal loopback mode for diagnostic or debug work. This is accomplished by setting the LBE bit in the UARTCTL register (see page 315). In loopback mode, data transmitted on UnTx is received on the UnRx input. 13.2.8 IrDA SIR block The IrDA SIR block contains an IrDA serial IR (SIR) protocol encoder/decoder. When enabled, the SIR block uses the UnTx and UnRx pins for the SIR protocol, which should be connected to an IR transceiver. The SIR block can receive and transmit, but it is only half-duplex so it cannot do both at the same time. Transmission must be stopped before data can be received. The IrDA SIR physical layer specifies a minimum 10-ms delay between transmission and reception. 13.3 Initialization and Configuration To use the UARTs, the peripheral clock must be enabled by setting the UART0, UART1, or UART2 bits in the RCGC1 register. This section discusses the steps that are required for using a UART module. For this example, the system clock is assumed to be 20 MHz and the desired UART configuration is: ■ 115200 baud rate ■ Data length of 8 bits ■ One stop bit November 30, 2007 301 Preliminary LM3S6952 Microcontroller ■ No parity ■ FIFOs disabled ■ No interrupts The first thing to consider when programming the UART is the baud-rate divisor (BRD), since the UARTIBRD and UARTFBRD registers must be written before the UARTLCRH register. Using the equation described in “Baud-Rate Generation” on page 298, the BRD can be calculated: BRD = 20,000,000 / (16 * 115,200) = 10.8507 which means that the DIVINT field of the UARTIBRD register (see page 311) should be set to 10. The value to be loaded into the UARTFBRD register (see page 312) is calculated by the equation: UARTFBRD[DIVFRAC] = integer(0.8507 * 64 + 0.5) = 54 With the BRD values in hand, the UART configuration is written to the module in the following order: 1. Disable the UART by clearing the UARTEN bit in the UARTCTL register. 2. Write the integer portion of the BRD to the UARTIBRD register. 3. Write the fractional portion of the BRD to the UARTFBRD register. 4. Write the desired serial parameters to the UARTLCRH register (in this case, a value of 0x0000.0060). 5. Enable the UART by setting the UARTEN bit in the UARTCTL register. 13.4 Register Map Table 13-1 on page 302 lists the UART registers. The offset listed is a hexadecimal increment to the register’s address, relative to that UART’s base address: ■ UART0: 0x4000.C000 ■ UART1: 0x4000.D000 ■ UART2: 0x4000.E000 Note: The UART must be disabled (see the UARTEN bit in the UARTCTL register on page 315) before any of the control registers are reprogrammed. When the UART is disabled during a TX or RX operation, the current transaction is completed prior to the UART stopping. Table 13-1. UART Register Map See Offset Name Type Reset Description page 0x000 UARTDR R/W 0x0000.0000 UART Data 304 0x004 UARTRSR/UARTECR R/W 0x0000.0000 UART Receive Status/Error Clear 306 0x018 UARTFR RO 0x0000.0090 UART Flag 308 0x020 UARTILPR R/W 0x0000.0000 UART IrDA Low-Power Register 310 302 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) See Offset Name Type Reset Description page 0x024 UARTIBRD R/W 0x0000.0000 UART Integer Baud-Rate Divisor 311 0x028 UARTFBRD R/W 0x0000.0000 UART Fractional Baud-Rate Divisor 312 0x02C UARTLCRH R/W 0x0000.0000 UART Line Control 313 0x030 UARTCTL R/W 0x0000.0300 UART Control 315 0x034 UARTIFLS R/W 0x0000.0012 UART Interrupt FIFO Level Select 317 0x038 UARTIM R/W 0x0000.0000 UART Interrupt Mask 319 0x03C UARTRIS RO 0x0000.000F UART Raw Interrupt Status 321 0x040 UARTMIS RO 0x0000.0000 UART Masked Interrupt Status 322 0x044 UARTICR W1C 0x0000.0000 UART Interrupt Clear 323 0xFD0 UARTPeriphID4 RO 0x0000.0000 UART Peripheral Identification 4 325 0xFD4 UARTPeriphID5 RO 0x0000.0000 UART Peripheral Identification 5 326 0xFD8 UARTPeriphID6 RO 0x0000.0000 UART Peripheral Identification 6 327 0xFDC UARTPeriphID7 RO 0x0000.0000 UART Peripheral Identification 7 328 0xFE0 UARTPeriphID0 RO 0x0000.0011 UART Peripheral Identification 0 329 0xFE4 UARTPeriphID1 RO 0x0000.0000 UART Peripheral Identification 1 330 0xFE8 UARTPeriphID2 RO 0x0000.0018 UART Peripheral Identification 2 331 0xFEC UARTPeriphID3 RO 0x0000.0001 UART Peripheral Identification 3 332 0xFF0 UARTPCellID0 RO 0x0000.000D UART PrimeCell Identification 0 333 0xFF4 UARTPCellID1 RO 0x0000.00F0 UART PrimeCell Identification 1 334 0xFF8 UARTPCellID2 RO 0x0000.0005 UART PrimeCell Identification 2 335 0xFFC UARTPCellID3 RO 0x0000.00B1 UART PrimeCell Identification 3 336 13.5 Register Descriptions The remainder of this section lists and describes the UART registers, in numerical order by address offset. November 30, 2007 303 Preliminary LM3S6952 Microcontroller Register 1: UART Data (UARTDR), offset 0x000 This register is the data register (the interface to the FIFOs). When FIFOs are enabled, data written to this location is pushed onto the transmit FIFO. If FIFOs are disabled, data is stored in the transmitter holding register (the bottom word of the transmit FIFO). A write to this register initiates a transmission from the UART. For received data, if the FIFO is enabled, the data byte and the 4-bit status (break, frame, parity, and overrun) is pushed onto the 12-bit wide receive FIFO. If FIFOs are disabled, the data byte and status are stored in the receiving holding register (the bottom word of the receive FIFO). The received data can be retrieved by reading this register. UART Data (UARTDR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OE BE PE FE DATA Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:12 reserved RO 0 UART Overrun Error The OE values are defined as follows: Value Description 0 There has been no data loss due to a FIFO overrun. New data was received when the FIFO was full, resulting in data loss. 1 11 OE RO 0 UART Break Error This bit is set to 1 when a break condition is detected, indicating that the receive data input was held Low for longer than a full-word transmission time (defined as start, data, parity, and stop bits). In FIFO mode, this error is associated with the character at the top of the FIFO. When a break occurs, only one 0 character is loaded into the FIFO. The next character is only enabled after the received data input goes to a 1 (marking state) and the next valid start bit is received. 10 BE RO 0 304 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Bit/Field Name Type Reset Description UART Parity Error This bit is set to 1 when the parity of the received data character does not match the parity defined by bits 2 and 7 of the UARTLCRH register. In FIFO mode, this error is associated with the character at the top of the FIFO. 9 PE RO 0 UART Framing Error This bit is set to 1 when the received character does not have a valid stop bit (a valid stop bit is 1). 8 FE RO 0 Data Transmitted or Received When written, the data that is to be transmitted via the UART. When read, the data that was received by the UART. 7:0 DATA R/W 0 November 30, 2007 305 Preliminary LM3S6952 Microcontroller Register 2: UART Receive Status/Error Clear (UARTRSR/UARTECR), offset 0x004 The UARTRSR/UARTECR register is the receive status register/error clear register. In addition to the UARTDR register, receive status can also be read from the UARTRSR register. If the status is read from this register, then the status information corresponds to the entry read from UARTDR prior to reading UARTRSR. The status information for overrun is set immediately when an overrun condition occurs. The UARTRSR register cannot be written. A write of any value to the UARTECR register clears the framing, parity, break, and overrun errors. All the bits are cleared to 0 on reset. Read-Only Receive Status (UARTRSR) Register UART Receive Status/Error Clear (UARTRSR/UARTECR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x004 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OE BE PE FE Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0 UART Overrun Error When this bit is set to 1, data is received and the FIFO is already full. This bit is cleared to 0 by a write to UARTECR. The FIFO contents remain valid since no further data is written when the FIFO is full, only the contents of the shift register are overwritten. The CPU must now read the data in order to empty the FIFO. 3 OE RO 0 UART Break Error This bit is set to 1 when a break condition is detected, indicating that the received data input was held Low for longer than a full-word transmission time (defined as start, data, parity, and stop bits). This bit is cleared to 0 by a write to UARTECR. In FIFO mode, this error is associated with the character at the top of the FIFO. When a break occurs, only one 0 character is loaded into the FIFO. The next character is only enabled after the receive data input goes to a 1 (marking state) and the next valid start bit is received. 2 BE RO 0 306 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Bit/Field Name Type Reset Description UART Parity Error This bit is set to 1 when the parity of the received data character does not match the parity defined by bits 2 and 7 of the UARTLCRH register. This bit is cleared to 0 by a write to UARTECR. 1 PE RO 0 UART Framing Error This bit is set to 1 when the received character does not have a valid stop bit (a valid stop bit is 1). This bit is cleared to 0 by a write to UARTECR. In FIFO mode, this error is associated with the character at the top of the FIFO. 0 FE RO 0 Write-Only Error Clear (UARTECR) Register UART Receive Status/Error Clear (UARTRSR/UARTECR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x004 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DATA Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved WO 0 Error Clear A write to this register of any data clears the framing, parity, break, and overrun flags. 7:0 DATA WO 0 November 30, 2007 307 Preliminary LM3S6952 Microcontroller Register 3: UART Flag (UARTFR), offset 0x018 The UARTFR register is the flag register. After reset, the TXFF, RXFF, and BUSY bits are 0, and TXFE and RXFE bits are 1. UART Flag (UARTFR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x018 Type RO, reset 0x0000.0090 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TXFE RXFF TXFF RXFE BUSY reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0 UART Transmit FIFO Empty The meaning of this bit depends on the state of the FEN bit in the UARTLCRH register. If the FIFO is disabled (FEN is 0), this bit is set when the transmit holding register is empty. If the FIFO is enabled (FEN is 1), this bit is set when the transmit FIFO is empty. 7 TXFE RO 1 UART Receive FIFO Full The meaning of this bit depends on the state of the FEN bit in the UARTLCRH register. If the FIFO is disabled, this bit is set when the receive holding register is full. If the FIFO is enabled, this bit is set when the receive FIFO is full. 6 RXFF RO 0 UART Transmit FIFO Full The meaning of this bit depends on the state of the FEN bit in the UARTLCRH register. If the FIFO is disabled, this bit is set when the transmit holding register is full. If the FIFO is enabled, this bit is set when the transmit FIFO is full. 5 TXFF RO 0 308 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Bit/Field Name Type Reset Description UART Receive FIFO Empty The meaning of this bit depends on the state of the FEN bit in the UARTLCRH register. If the FIFO is disabled, this bit is set when the receive holding register is empty. If the FIFO is enabled, this bit is set when the receive FIFO is empty. 4 RXFE RO 1 UART Busy When this bit is 1, the UART is busy transmitting data. This bit remains set until the complete byte, including all stop bits, has been sent from the shift register. This bit is set as soon as the transmit FIFO becomes non-empty (regardless of whether UART is enabled). 3 BUSY RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2:0 reserved RO 0 November 30, 2007 309 Preliminary LM3S6952 Microcontroller Register 4: UART IrDA Low-Power Register (UARTILPR), offset 0x020 The UARTILPR register is an 8-bit read/write register that stores the low-power counter divisor value used to generate the IrLPBaud16 signal by dividing down the system clock (SysClk). All the bits are cleared to 0 when reset. The IrLPBaud16 internal signal is generated by dividing down the UARTCLK signal according to the low-power divisor value written to UARTILPR. The low-power divisor value is calculated as follows: ILPDVSR = SysClk / FIrLPBaud16 where FIrLPBaud16 is nominally 1.8432 MHz. IrLPBaud16 is an internal signal used for SIR pulse generation when low-power mode is used. You must choose the divisor so that 1.42 MHz < FIrLPBaud16 < 2.12 MHz, which results in a low-power pulse duration of 1.41–2.11 μs (three times the period of IrLPBaud16). The minimum frequency of IrLPBaud16 ensures that pulses less than one period of IrLPBaud16 are rejected, but that pulses greater than 1.4 μs are accepted as valid pulses. Note: Zero is an illegal value. Programming a zero value results in no IrLPBaud16 pulses being generated. UART IrDA Low-Power Register (UARTILPR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x020 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved ILPDVSR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0 IrDA Low-Power Divisor This is an 8-bit low-power divisor value. 7:0 ILPDVSR R/W 0x00 310 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 5: UART Integer Baud-Rate Divisor (UARTIBRD), offset 0x024 The UARTIBRD register is the integer part of the baud-rate divisor value. All the bits are cleared on reset. The minimum possible divide ratio is 1 (when UARTIBRD=0), in which case the UARTFBRD register is ignored. When changing the UARTIBRD register, the new value does not take effect until transmission/reception of the current character is complete. Any changes to the baud-rate divisor must be followed by a write to the UARTLCRH register. See “Baud-Rate Generation” on page 298 for configuration details. UART Integer Baud-Rate Divisor (UARTIBRD) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x024 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DIVINT Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0 15:0 DIVINT R/W 0x0000 Integer Baud-Rate Divisor November 30, 2007 311 Preliminary LM3S6952 Microcontroller Register 6: UART Fractional Baud-Rate Divisor (UARTFBRD), offset 0x028 The UARTFBRD register is the fractional part of the baud-rate divisor value. All the bits are cleared on reset. When changing the UARTFBRD register, the new value does not take effect until transmission/reception of the current character is complete. Any changes to the baud-rate divisor must be followed by a write to the UARTLCRH register. See “Baud-Rate Generation” on page 298 for configuration details. UART Fractional Baud-Rate Divisor (UARTFBRD) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x028 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DIVFRAC Type RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0x00 5:0 DIVFRAC R/W 0x000 Fractional Baud-Rate Divisor 312 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 7: UART Line Control (UARTLCRH), offset 0x02C The UARTLCRH register is the line control register. Serial parameters such as data length, parity, and stop bit selection are implemented in this register. When updating the baud-rate divisor (UARTIBRD and/or UARTIFRD), the UARTLCRH register must also be written. The write strobe for the baud-rate divisor registers is tied to the UARTLCRH register. UART Line Control (UARTLCRH) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x02C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SPS WLEN FEN STP2 EPS PEN BRK Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0 UART Stick Parity Select When bits 1, 2, and 7 of UARTLCRH are set, the parity bit is transmitted and checked as a 0. When bits 1 and 7 are set and 2 is cleared, the parity bit is transmitted and checked as a 1. When this bit is cleared, stick parity is disabled. 7 SPS R/W 0 UART Word Length The bits indicate the number of data bits transmitted or received in a frame as follows: Value Description 0x3 8 bits 0x2 7 bits 0x1 6 bits 0x0 5 bits (default) 6:5 WLEN R/W 0 UART Enable FIFOs If this bit is set to 1, transmit and receive FIFO buffers are enabled (FIFO mode). When cleared to 0, FIFOs are disabled (Character mode). The FIFOs become 1-byte-deep holding registers. 4 FEN R/W 0 November 30, 2007 313 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART Two Stop Bits Select If this bit is set to 1, two stop bits are transmitted at the end of a frame. The receive logic does not check for two stop bits being received. 3 STP2 R/W 0 UART Even Parity Select If this bit is set to 1, even parity generation and checking is performed during transmission and reception, which checks for an even number of 1s in data and parity bits. When cleared to 0, then odd parity is performed, which checks for an odd number of 1s. This bit has no effect when parity is disabled by the PEN bit. 2 EPS R/W 0 UART Parity Enable If this bit is set to 1, parity checking and generation is enabled; otherwise, parity is disabled and no parity bit is added to the data frame. 1 PEN R/W 0 UART Send Break If this bit is set to 1, a Low level is continually output on the UnTX output, after completing transmission of the current character. For the proper execution of the break command, the software must set this bit for at least two frames (character periods). For normal use, this bit must be cleared to 0. 0 BRK R/W 0 314 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 8: UART Control (UARTCTL), offset 0x030 The UARTCTL register is the control register. All the bits are cleared on reset except for the Transmit Enable (TXE) and Receive Enable (RXE) bits, which are set to 1. To enable the UART module, the UARTEN bit must be set to 1. If software requires a configuration change in the module, the UARTEN bit must be cleared before the configuration changes are written. If the UART is disabled during a transmit or receive operation, the current transaction is completed prior to the UART stopping. UART Control (UARTCTL) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x030 Type R/W, reset 0x0000.0300 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RXE TXE LBE reserved SIRLP SIREN UARTEN Type RO RO RO RO RO RO R/W R/W R/W RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:10 reserved RO 0 UART Receive Enable If this bit is set to 1, the receive section of the UART is enabled. When the UART is disabled in the middle of a receive, it completes the current character before stopping. Note: To enable reception, the UARTEN bit must also be set. 9 RXE R/W 1 UART Transmit Enable If this bit is set to 1, the transmit section of the UART is enabled. When the UART is disabled in the middle of a transmission, it completes the current character before stopping. Note: To enable transmission, the UARTEN bit must also be set. 8 TXE R/W 1 UART Loop Back Enable If this bit is set to 1, the UnTX path is fed through the UnRX path. 7 LBE R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 6:3 reserved RO 0 November 30, 2007 315 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART SIR Low Power Mode This bit selects the IrDA encoding mode. If this bit is cleared to 0, low-level bits are transmitted as an active High pulse with a width of 3/16th of the bit period. If this bit is set to 1, low-level bits are transmitted with a pulse width which is 3 times the period of the IrLPBaud16 input signal, regardless of the selected bit rate. Setting this bit uses less power, but might reduce transmission distances. See page 310 for more information. 2 SIRLP R/W 0 UART SIR Enable If this bit is set to 1, the IrDA SIR block is enabled, and the UART will transmit and receive data using SIR protocol. 1 SIREN R/W 0 UART Enable If this bit is set to 1, the UART is enabled. When the UART is disabled in the middle of transmission or reception, it completes the current character before stopping. 0 UARTEN R/W 0 316 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 9: UART Interrupt FIFO Level Select (UARTIFLS), offset 0x034 The UARTIFLS register is the interrupt FIFO level select register. You can use this register to define the FIFO level at which the TXRIS and RXRIS bits in the UARTRIS register are triggered. The interrupts are generated based on a transition through a level rather than being based on the level. That is, the interrupts are generated when the fill level progresses through the trigger level. For example, if the receive trigger level is set to the half-way mark, the interrupt is triggered as the module is receiving the 9th character. Out of reset, the TXIFLSEL and RXIFLSEL bits are configured so that the FIFOs trigger an interrupt at the half-way mark. UART Interrupt FIFO Level Select (UARTIFLS) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x034 Type R/W, reset 0x0000.0012 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RXIFLSEL TXIFLSEL Type RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0x00 UART Receive Interrupt FIFO Level Select The trigger points for the receive interrupt are as follows: Value Description 0x0 RX FIFO ≥ 1/8 full 0x1 RX FIFO ≥ ¼ full 0x2 RX FIFO ≥ ½ full (default) 0x3 RX FIFO ≥ ¾ full 0x4 RX FIFO ≥ 7/8 full 0x5-0x7 Reserved 5:3 RXIFLSEL R/W 0x2 November 30, 2007 317 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART Transmit Interrupt FIFO Level Select The trigger points for the transmit interrupt are as follows: Value Description 0x0 TX FIFO ≤ 1/8 full 0x1 TX FIFO ≤ ¼ full 0x2 TX FIFO ≤ ½ full (default) 0x3 TX FIFO ≤ ¾ full 0x4 TX FIFO ≤ 7/8 full 0x5-0x7 Reserved 2:0 TXIFLSEL R/W 0x2 318 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 10: UART Interrupt Mask (UARTIM), offset 0x038 The UARTIM register is the interrupt mask set/clear register. On a read, this register gives the current value of the mask on the relevant interrupt. Writing a 1 to a bit allows the corresponding raw interrupt signal to be routed to the interrupt controller. Writing a 0 prevents the raw interrupt signal from being sent to the interrupt controller. UART Interrupt Mask (UARTIM) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x038 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OEIM BEIM PEIM FEIM RTIM TXIM RXIM reserved Type RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 UART Overrun Error Interrupt Mask On a read, the current mask for the OEIM interrupt is returned. Setting this bit to 1 promotes the OEIM interrupt to the interrupt controller. 10 OEIM R/W 0 UART Break Error Interrupt Mask On a read, the current mask for the BEIM interrupt is returned. Setting this bit to 1 promotes the BEIM interrupt to the interrupt controller. 9 BEIM R/W 0 UART Parity Error Interrupt Mask On a read, the current mask for the PEIM interrupt is returned. Setting this bit to 1 promotes the PEIM interrupt to the interrupt controller. 8 PEIM R/W 0 UART Framing Error Interrupt Mask On a read, the current mask for the FEIM interrupt is returned. Setting this bit to 1 promotes the FEIM interrupt to the interrupt controller. 7 FEIM R/W 0 UART Receive Time-Out Interrupt Mask On a read, the current mask for the RTIM interrupt is returned. Setting this bit to 1 promotes the RTIM interrupt to the interrupt controller. 6 RTIM R/W 0 UART Transmit Interrupt Mask On a read, the current mask for the TXIM interrupt is returned. Setting this bit to 1 promotes the TXIM interrupt to the interrupt controller. 5 TXIM R/W 0 November 30, 2007 319 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description UART Receive Interrupt Mask On a read, the current mask for the RXIM interrupt is returned. Setting this bit to 1 promotes the RXIM interrupt to the interrupt controller. 4 RXIM R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0x00 320 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 11: UART Raw Interrupt Status (UARTRIS), offset 0x03C The UARTRIS register is the raw interrupt status register. On a read, this register gives the current raw status value of the corresponding interrupt. A write has no effect. UART Raw Interrupt Status (UARTRIS) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x03C Type RO, reset 0x0000.000F 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OERIS BERIS PERIS FERIS RTRIS TXRIS RXRIS reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 UART Overrun Error Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 10 OERIS RO 0 UART Break Error Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 9 BERIS RO 0 UART Parity Error Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 8 PERIS RO 0 UART Framing Error Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 7 FERIS RO 0 UART Receive Time-Out Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 6 RTRIS RO 0 UART Transmit Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 5 TXRIS RO 0 UART Receive Raw Interrupt Status Gives the raw interrupt state (prior to masking) of this interrupt. 4 RXRIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0xF November 30, 2007 321 Preliminary LM3S6952 Microcontroller Register 12: UART Masked Interrupt Status (UARTMIS), offset 0x040 The UARTMIS register is the masked interrupt status register. On a read, this register gives the current masked status value of the corresponding interrupt. A write has no effect. UART Masked Interrupt Status (UARTMIS) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x040 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OEMIS BEMIS PEMIS FEMIS RTMIS TXMIS RXMIS reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 UART Overrun Error Masked Interrupt Status Gives the masked interrupt state of this interrupt. 10 OEMIS RO 0 UART Break Error Masked Interrupt Status Gives the masked interrupt state of this interrupt. 9 BEMIS RO 0 UART Parity Error Masked Interrupt Status Gives the masked interrupt state of this interrupt. 8 PEMIS RO 0 UART Framing Error Masked Interrupt Status Gives the masked interrupt state of this interrupt. 7 FEMIS RO 0 UART Receive Time-Out Masked Interrupt Status Gives the masked interrupt state of this interrupt. 6 RTMIS RO 0 UART Transmit Masked Interrupt Status Gives the masked interrupt state of this interrupt. 5 TXMIS RO 0 UART Receive Masked Interrupt Status Gives the masked interrupt state of this interrupt. 4 RXMIS RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0 322 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 13: UART Interrupt Clear (UARTICR), offset 0x044 The UARTICR register is the interrupt clear register. On a write of 1, the corresponding interrupt (both raw interrupt and masked interrupt, if enabled) is cleared. A write of 0 has no effect. UART Interrupt Clear (UARTICR) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0x044 Type W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OEIC BEIC PEIC FEIC RTIC TXIC RXIC reserved Type RO RO RO RO RO W1C W1C W1C W1C W1C W1C W1C RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:11 reserved RO 0x00 Overrun Error Interrupt Clear The OEIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 10 OEIC W1C 0 Break Error Interrupt Clear The BEIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 9 BEIC W1C 0 Parity Error Interrupt Clear The PEIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 8 PEIC W1C 0 November 30, 2007 323 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Framing Error Interrupt Clear The FEIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 7 FEIC W1C 0 Receive Time-Out Interrupt Clear The RTIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 6 RTIC W1C 0 Transmit Interrupt Clear The TXIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 5 TXIC W1C 0 Receive Interrupt Clear The RXIC values are defined as follows: Value Description 0 No effect on the interrupt. 1 Clears interrupt. 4 RXIC W1C 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:0 reserved RO 0x00 324 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 14: UART Peripheral Identification 4 (UARTPeriphID4), offset 0xFD0 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 4 (UARTPeriphID4) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFD0 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID4 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[7:0] Can be used by software to identify the presence of this peripheral. 7:0 PID4 RO 0x0000 November 30, 2007 325 Preliminary LM3S6952 Microcontroller Register 15: UART Peripheral Identification 5 (UARTPeriphID5), offset 0xFD4 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 5 (UARTPeriphID5) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFD4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID5 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[15:8] Can be used by software to identify the presence of this peripheral. 7:0 PID5 RO 0x0000 326 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 16: UART Peripheral Identification 6 (UARTPeriphID6), offset 0xFD8 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 6 (UARTPeriphID6) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFD8 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID6 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[23:16] Can be used by software to identify the presence of this peripheral. 7:0 PID6 RO 0x0000 November 30, 2007 327 Preliminary LM3S6952 Microcontroller Register 17: UART Peripheral Identification 7 (UARTPeriphID7), offset 0xFDC The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 7 (UARTPeriphID7) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFDC Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID7 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0 UART Peripheral ID Register[31:24] Can be used by software to identify the presence of this peripheral. 7:0 PID7 RO 0x0000 328 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 18: UART Peripheral Identification 0 (UARTPeriphID0), offset 0xFE0 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 0 (UARTPeriphID0) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFE0 Type RO, reset 0x0000.0011 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[7:0] Can be used by software to identify the presence of this peripheral. 7:0 PID0 RO 0x11 November 30, 2007 329 Preliminary LM3S6952 Microcontroller Register 19: UART Peripheral Identification 1 (UARTPeriphID1), offset 0xFE4 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 1 (UARTPeriphID1) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFE4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[15:8] Can be used by software to identify the presence of this peripheral. 7:0 PID1 RO 0x00 330 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 20: UART Peripheral Identification 2 (UARTPeriphID2), offset 0xFE8 The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 2 (UARTPeriphID2) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFE8 Type RO, reset 0x0000.0018 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[23:16] Can be used by software to identify the presence of this peripheral. 7:0 PID2 RO 0x18 November 30, 2007 331 Preliminary LM3S6952 Microcontroller Register 21: UART Peripheral Identification 3 (UARTPeriphID3), offset 0xFEC The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the reset values. UART Peripheral Identification 3 (UARTPeriphID3) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFEC Type RO, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART Peripheral ID Register[31:24] Can be used by software to identify the presence of this peripheral. 7:0 PID3 RO 0x01 332 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 22: UART PrimeCell Identification 0 (UARTPCellID0), offset 0xFF0 The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset values. UART PrimeCell Identification 0 (UARTPCellID0) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFF0 Type RO, reset 0x0000.000D 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART PrimeCell ID Register[7:0] Provides software a standard cross-peripheral identification system. 7:0 CID0 RO 0x0D November 30, 2007 333 Preliminary LM3S6952 Microcontroller Register 23: UART PrimeCell Identification 1 (UARTPCellID1), offset 0xFF4 The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset values. UART PrimeCell Identification 1 (UARTPCellID1) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFF4 Type RO, reset 0x0000.00F0 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART PrimeCell ID Register[15:8] Provides software a standard cross-peripheral identification system. 7:0 CID1 RO 0xF0 334 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) Register 24: UART PrimeCell Identification 2 (UARTPCellID2), offset 0xFF8 The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset values. UART PrimeCell Identification 2 (UARTPCellID2) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFF8 Type RO, reset 0x0000.0005 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART PrimeCell ID Register[23:16] Provides software a standard cross-peripheral identification system. 7:0 CID2 RO 0x05 November 30, 2007 335 Preliminary LM3S6952 Microcontroller Register 25: UART PrimeCell Identification 3 (UARTPCellID3), offset 0xFFC The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset values. UART PrimeCell Identification 3 (UARTPCellID3) UART0 base: 0x4000.C000 UART1 base: 0x4000.D000 UART2 base: 0x4000.E000 Offset 0xFFC Type RO, reset 0x0000.00B1 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 UART PrimeCell ID Register[31:24] Provides software a standard cross-peripheral identification system. 7:0 CID3 RO 0xB1 336 November 30, 2007 Preliminary Universal Asynchronous Receivers/Transmitters (UARTs) 14 Synchronous Serial Interface (SSI) The Stellaris® Synchronous Serial Interface (SSI) is a master or slave interface for synchronous serial communication with peripheral devices that have either Freescale SPI, MICROWIRE, or Texas Instruments synchronous serial interfaces. The Stellaris® SSI module has the following features: ■ Master or slave operation ■ Programmable clock bit rate and prescale ■ Separate transmit and receive FIFOs, 16 bits wide, 8 locations deep ■ Programmable interface operation for Freescale SPI, MICROWIRE, or Texas Instruments synchronous serial interfaces ■ Programmable data frame size from 4 to 16 bits ■ Internal loopback test mode for diagnostic/debug testing 14.1 Block Diagram Figure 14-1. SSI Module Block Diagram Transmit/ Receive Logic Clock Prescaler SSICPSR Control / Status SSICR0 SSICR1 SSISR Interrupt Control SSIIM SSIMIS SSIRIS SSIICR SSIDR TxFIFO 8 x 16 ... RxFIFO 8 x 16 ... System Clock SSITx SSIRx SSIClk SSIFss Interrupt Identification Registers SSIPCellID0 SSIPeriphID0 SSIPeriphID4 SSIPCellID1 SSIPeriphID1 SSIPeriphID5 SSIPCellID2 SSIPeriphID2 SSIPeriphID6 SSIPCellID3 SSIPeriphID3 SSIPeriphID7 14.2 Functional Description The SSI performs serial-to-parallel conversion on data received from a peripheral device. The CPU accesses data, control, and status information. The transmit and receive paths are buffered with November 30, 2007 337 Preliminary LM3S6952 Microcontroller internal FIFO memories allowing up to eight 16-bit values to be stored independently in both transmit and receive modes. 14.2.1 Bit Rate Generation The SSI includes a programmable bit rate clock divider and prescaler to generate the serial output clock. Bit rates are supported to 2 MHz and higher, although maximum bit rate is determined by peripheral devices. The serial bit rate is derived by dividing down the 50-MHz input clock. The clock is first divided by an even prescale value CPSDVSR from 2 to 254, which is programmed in the SSI Clock Prescale (SSICPSR) register (see page 356). The clock is further divided by a value from 1 to 256, which is 1 + SCR, where SCR is the value programmed in the SSI Control0 (SSICR0) register (see page 349). The frequency of the output clock SSIClk is defined by: FSSIClk = FSysClk / (CPSDVSR * (1 + SCR)) Note that although the SSIClk transmit clock can theoretically be 25 MHz, the module may not be able to operate at that speed. For master mode, the system clock must be at least two times faster than the SSIClk. For slave mode, the system clock must be at least 12 times faster than the SSIClk. See “Synchronous Serial Interface (SSI)” on page 543 to view SSI timing parameters. 14.2.2 FIFO Operation 14.2.2.1 Transmit FIFO The common transmit FIFO is a 16-bit wide, 8-locations deep, first-in, first-out memory buffer. The CPU writes data to the FIFO by writing the SSI Data (SSIDR) register (see page 353), and data is stored in the FIFO until it is read out by the transmission logic. When configured as a master or a slave, parallel data is written into the transmit FIFO prior to serial conversion and transmission to the attached slave or master, respectively, through the SSITx pin. 14.2.2.2 Receive FIFO The common receive FIFO is a 16-bit wide, 8-locations deep, first-in, first-out memory buffer. Received data from the serial interface is stored in the buffer until read out by the CPU, which accesses the read FIFO by reading the SSIDR register. When configured as a master or slave, serial data received through the SSIRx pin is registered prior to parallel loading into the attached slave or master receive FIFO, respectively. 14.2.3 Interrupts The SSI can generate interrupts when the following conditions are observed: ■ Transmit FIFO service ■ Receive FIFO service ■ Receive FIFO time-out ■ Receive FIFO overrun All of the interrupt events are ORed together before being sent to the interrupt controller, so the SSI can only generate a single interrupt request to the controller at any given time. You can mask each 338 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) of the four individual maskable interrupts by setting the appropriate bits in the SSI Interrupt Mask (SSIIM) register (see page 357). Setting the appropriate mask bit to 1 enables the interrupt. Provision of the individual outputs, as well as a combined interrupt output, allows use of either a global interrupt service routine, or modular device drivers to handle interrupts. The transmit and receive dynamic dataflow interrupts have been separated from the status interrupts so that data can be read or written in response to the FIFO trigger levels. The status of the individual interrupt sources can be read from the SSI Raw Interrupt Status (SSIRIS) and SSI Masked Interrupt Status (SSIMIS) registers (see page 359 and page 360, respectively). 14.2.4 Frame Formats Each data frame is between 4 and 16 bits long, depending on the size of data programmed, and is transmitted starting with the MSB. There are three basic frame types that can be selected: ■ Texas Instruments synchronous serial ■ Freescale SPI ■ MICROWIRE For all three formats, the serial clock (SSIClk) is held inactive while the SSI is idle, and SSIClk transitions at the programmed frequency only during active transmission or reception of data. The idle state of SSIClk is utilized to provide a receive timeout indication that occurs when the receive FIFO still contains data after a timeout period. For Freescale SPI and MICROWIRE frame formats, the serial frame (SSIFss ) pin is active Low, and is asserted (pulled down) during the entire transmission of the frame. For Texas Instruments synchronous serial frame format, the SSIFss pin is pulsed for one serial clock period starting at its rising edge, prior to the transmission of each frame. For this frame format, both the SSI and the off-chip slave device drive their output data on the rising edge of SSIClk, and latch data from the other device on the falling edge. Unlike the full-duplex transmission of the other two frame formats, the MICROWIRE format uses a special master-slave messaging technique, which operates at half-duplex. In this mode, when a frame begins, an 8-bit control message is transmitted to the off-chip slave. During this transmit, no incoming data is received by the SSI. After the message has been sent, the off-chip slave decodes it and, after waiting one serial clock after the last bit of the 8-bit control message has been sent, responds with the requested data. The returned data can be 4 to 16 bits in length, making the total frame length anywhere from 13 to 25 bits. 14.2.4.1 Texas Instruments Synchronous Serial Frame Format Figure 14-2 on page 339 shows the Texas Instruments synchronous serial frame format for a single transmitted frame. Figure 14-2. TI Synchronous Serial Frame Format (Single Transfer) SSIClk 4 to 16 bits SSIFss SSITx/SSIRx MSB LSB November 30, 2007 339 Preliminary LM3S6952 Microcontroller In this mode, SSIClk and SSIFss are forced Low, and the transmit data line SSITx is tristated whenever the SSI is idle. Once the bottom entry of the transmit FIFO contains data, SSIFss is pulsed High for one SSIClk period. The value to be transmitted is also transferred from the transmit FIFO to the serial shift register of the transmit logic. On the next rising edge of SSIClk, the MSB of the 4 to 16-bit data frame is shifted out on the SSITx pin. Likewise, the MSB of the received data is shifted onto the SSIRx pin by the off-chip serial slave device. Both the SSI and the off-chip serial slave device then clock each data bit into their serial shifter on the falling edge of each SSIClk. The received data is transferred from the serial shifter to the receive FIFO on the first rising edge of SSIClk after the LSB has been latched. Figure 14-3 on page 340 shows the Texas Instruments synchronous serial frame format when back-to-back frames are transmitted. Figure 14-3. TI Synchronous Serial Frame Format (Continuous Transfer) MSB LSB 4 to 16 bits SSIClk SSIFss SSITx/SSIRx 14.2.4.2 Freescale SPI Frame Format The Freescale SPI interface is a four-wire interface where the SSIFss signal behaves as a slave select. The main feature of the Freescale SPI format is that the inactive state and phase of the SSIClk signal are programmable through the SPO and SPH bits within the SSISCR0 control register. SPO Clock Polarity Bit When the SPO clock polarity control bit is Low, it produces a steady state Low value on the SSIClk pin. If the SPO bit is High, a steady state High value is placed on the SSIClk pin when data is not being transferred. SPH Phase Control Bit The SPH phase control bit selects the clock edge that captures data and allows it to change state. It has the most impact on the first bit transmitted by either allowing or not allowing a clock transition before the first data capture edge. When the SPH phase control bit is Low, data is captured on the first clock edge transition. If the SPH bit is High, data is captured on the second clock edge transition. 14.2.4.3 Freescale SPI Frame Format with SPO=0 and SPH=0 Single and continuous transmission signal sequences for Freescale SPI format with SPO=0 and SPH=0 are shown in Figure 14-4 on page 341 and Figure 14-5 on page 341. 340 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Figure 14-4. Freescale SPI Format (Single Transfer) with SPO=0 and SPH=0 4 to 16 bits SSIClk SSIFss SSIRx Q SSITx MSB MSB LSB LSB Note: Q is undefined. Figure 14-5. Freescale SPI Format (Continuous Transfer) with SPO=0 and SPH=0 SSIClk SSIFss SSIRx LSB SSITx MSB LSB 4 to 16 bits LSB MSB MSB MSB LSB In this configuration, during idle periods: ■ SSIClk is forced Low ■ SSIFss is forced High ■ The transmit data line SSITx is arbitrarily forced Low ■ When the SSI is configured as a master, it enables the SSIClk pad ■ When the SSI is configured as a slave, it disables the SSIClk pad If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSIFss master signal being driven Low. This causes slave data to be enabled onto the SSIRx input line of the master. The master SSITx output pad is enabled. One half SSIClk period later, valid master data is transferred to the SSITx pin. Now that both the master and slave data have been set, the SSIClk master clock pin goes High after one further half SSIClk period. The data is now captured on the rising and propagated on the falling edges of the SSIClk signal. In the case of a single word transmission, after all bits of the data word have been transferred, the SSIFss line is returned to its idle High state one SSIClk period after the last bit has been captured. However, in the case of continuous back-to-back transmissions, the SSIFss signal must be pulsed High between each data word transfer. This is because the slave select pin freezes the data in its serial peripheral register and does not allow it to be altered if the SPH bit is logic zero. Therefore, the master device must raise the SSIFss pin of the slave device between each data transfer to enable the serial peripheral data write. On completion of the continuous transfer, the SSIFss pin is returned to its idle state one SSIClk period after the last bit has been captured. November 30, 2007 341 Preliminary LM3S6952 Microcontroller 14.2.4.4 Freescale SPI Frame Format with SPO=0 and SPH=1 The transfer signal sequence for Freescale SPI format with SPO=0 and SPH=1 is shown in Figure 14-6 on page 342, which covers both single and continuous transfers. Figure 14-6. Freescale SPI Frame Format with SPO=0 and SPH=1 4 to 16 bits SSIClk SSIFss SSIRx SSITx Q MSB Q MSB LSB LSB Note: Q is undefined. In this configuration, during idle periods: ■ SSIClk is forced Low ■ SSIFss is forced High ■ The transmit data line SSITx is arbitrarily forced Low ■ When the SSI is configured as a master, it enables the SSIClk pad ■ When the SSI is configured as a slave, it disables the SSIClk pad If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSIFss master signal being driven Low. The master SSITx output is enabled. After a further one half SSIClk period, both master and slave valid data is enabled onto their respective transmission lines. At the same time, the SSIClk is enabled with a rising edge transition. Data is then captured on the falling edges and propagated on the rising edges of the SSIClk signal. In the case of a single word transfer, after all bits have been transferred, the SSIFss line is returned to its idle High state one SSIClk period after the last bit has been captured. For continuous back-to-back transfers, the SSIFss pin is held Low between successive data words and termination is the same as that of the single word transfer. 14.2.4.5 Freescale SPI Frame Format with SPO=1 and SPH=0 Single and continuous transmission signal sequences for Freescale SPI format with SPO=1 and SPH=0 are shown in Figure 14-7 on page 343 and Figure 14-8 on page 343. 342 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Figure 14-7. Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0 4 to 16 bits SSIClk SSIFss SSIRx SSITx MSB Q MSB LSB LSB Note: Q is undefined. Figure 14-8. Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0 SSIClk SSIFss SSITx/SSIRx MSB LSB 4 to 16 bits LSB MSB In this configuration, during idle periods: ■ SSIClk is forced High ■ SSIFss is forced High ■ The transmit data line SSITx is arbitrarily forced Low ■ When the SSI is configured as a master, it enables the SSIClk pad ■ When the SSI is configured as a slave, it disables the SSIClk pad If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSIFss master signal being driven Low, which causes slave data to be immediately transferred onto the SSIRx line of the master. The master SSITx output pad is enabled. One half period later, valid master data is transferred to the SSITx line. Now that both the master and slave data have been set, the SSIClk master clock pin becomes Low after one further half SSIClk period. This means that data is captured on the falling edges and propagated on the rising edges of the SSIClk signal. In the case of a single word transmission, after all bits of the data word are transferred, the SSIFss line is returned to its idle High state one SSIClk period after the last bit has been captured. However, in the case of continuous back-to-back transmissions, the SSIFss signal must be pulsed High between each data word transfer. This is because the slave select pin freezes the data in its serial peripheral register and does not allow it to be altered if the SPH bit is logic zero. Therefore, the master device must raise the SSIFss pin of the slave device between each data transfer to enable the serial peripheral data write. On completion of the continuous transfer, the SSIFss pin is returned to its idle state one SSIClk period after the last bit has been captured. November 30, 2007 343 Preliminary LM3S6952 Microcontroller 14.2.4.6 Freescale SPI Frame Format with SPO=1 and SPH=1 The transfer signal sequence for Freescale SPI format with SPO=1 and SPH=1 is shown in Figure 14-9 on page 344, which covers both single and continuous transfers. Figure 14-9. Freescale SPI Frame Format with SPO=1 and SPH=1 4 to 16 bits SSIClk SSIFss SSIRx SSITx Q Q MSB MSB LSB LSB Note: Q is undefined. In this configuration, during idle periods: ■ SSIClk is forced High ■ SSIFss is forced High ■ The transmit data line SSITx is arbitrarily forced Low ■ When the SSI is configured as a master, it enables the SSIClk pad ■ When the SSI is configured as a slave, it disables the SSIClk pad If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is signified by the SSIFss master signal being driven Low. The master SSITx output pad is enabled. After a further one-half SSIClk period, both master and slave data are enabled onto their respective transmission lines. At the same time, SSIClk is enabled with a falling edge transition. Data is then captured on the rising edges and propagated on the falling edges of the SSIClk signal. After all bits have been transferred, in the case of a single word transmission, the SSIFss line is returned to its idle high state one SSIClk period after the last bit has been captured. For continuous back-to-back transmissions, the SSIFss pin remains in its active Low state, until the final bit of the last word has been captured, and then returns to its idle state as described above. For continuous back-to-back transfers, the SSIFss pin is held Low between successive data words and termination is the same as that of the single word transfer. 14.2.4.7 MICROWIRE Frame Format Figure 14-10 on page 345 shows the MICROWIRE frame format, again for a single frame. Figure 14-11 on page 346 shows the same format when back-to-back frames are transmitted. 344 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Figure 14-10. MICROWIRE Frame Format (Single Frame) SSIClk SSIFss SSIRx MSB LSB 4 to 16 bits output data 0 SSITx MSB LSB 8-bit control MICROWIRE format is very similar to SPI format, except that transmission is half-duplex instead of full-duplex, using a master-slave message passing technique. Each serial transmission begins with an 8-bit control word that is transmitted from the SSI to the off-chip slave device. During this transmission, no incoming data is received by the SSI. After the message has been sent, the off-chip slave decodes it and, after waiting one serial clock after the last bit of the 8-bit control message has been sent, responds with the required data. The returned data is 4 to 16 bits in length, making the total frame length anywhere from 13 to 25 bits. In this configuration, during idle periods: ■ SSIClk is forced Low ■ SSIFss is forced High ■ The transmit data line SSITx is arbitrarily forced Low A transmission is triggered by writing a control byte to the transmit FIFO. The falling edge of SSIFss causes the value contained in the bottom entry of the transmit FIFO to be transferred to the serial shift register of the transmit logic, and the MSB of the 8-bit control frame to be shifted out onto the SSITx pin. SSIFss remains Low for the duration of the frame transmission. The SSIRx pin remains tristated during this transmission. The off-chip serial slave device latches each control bit into its serial shifter on the rising edge of each SSIClk. After the last bit is latched by the slave device, the control byte is decoded during a one clock wait-state, and the slave responds by transmitting data back to the SSI. Each bit is driven onto the SSIRx line on the falling edge of SSIClk. The SSI in turn latches each bit on the rising edge of SSIClk. At the end of the frame, for single transfers, the SSIFss signal is pulled High one clock period after the last bit has been latched in the receive serial shifter, which causes the data to be transferred to the receive FIFO. Note: The off-chip slave device can tristate the receive line either on the falling edge of SSIClk after the LSB has been latched by the receive shifter, or when the SSIFss pin goes High. For continuous transfers, data transmission begins and ends in the same manner as a single transfer. However, the SSIFss line is continuously asserted (held Low) and transmission of data occurs back-to-back. The control byte of the next frame follows directly after the LSB of the received data from the current frame. Each of the received values is transferred from the receive shifter on the falling edge of SSIClk, after the LSB of the frame has been latched into the SSI. November 30, 2007 345 Preliminary LM3S6952 Microcontroller Figure 14-11. MICROWIRE Frame Format (Continuous Transfer) 8-bit control SSIClk SSIFss SSIRx MSB LSB 4 to 16 bits output data 0 SSITx LSB MSB LSB MSB In the MICROWIRE mode, the SSI slave samples the first bit of receive data on the rising edge of SSIClk after SSIFss has gone Low. Masters that drive a free-running SSIClk must ensure that the SSIFss signal has sufficient setup and hold margins with respect to the rising edge of SSIClk. Figure 14-12 on page 346 illustrates these setup and hold time requirements. With respect to the SSIClk rising edge on which the first bit of receive data is to be sampled by the SSI slave, SSIFss must have a setup of at least two times the period of SSIClk on which the SSI operates. With respect to the SSIClk rising edge previous to this edge, SSIFss must have a hold of at least one SSIClk period. Figure 14-12. MICROWIRE Frame Format, SSIFss Input Setup and Hold Requirements SSIClk SSIFss SSIRx First RX data to be sampled by SSI slave tSetup=(2*tSSIClk) tHold=tSSIClk 14.3 Initialization and Configuration To use the SSI, its peripheral clock must be enabled by setting the SSI bit in the RCGC1 register. For each of the frame formats, the SSI is configured using the following steps: 1. Ensure that the SSE bit in the SSICR1 register is disabled before making any configuration changes. 2. Select whether the SSI is a master or slave: a. For master operations, set the SSICR1 register to 0x0000.0000. b. For slave mode (output enabled), set the SSICR1 register to 0x0000.0004. c. For slave mode (output disabled), set the SSICR1 register to 0x0000.000C. 3. Configure the clock prescale divisor by writing the SSICPSR register. 346 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) 4. Write the SSICR0 register with the following configuration: ■ Serial clock rate (SCR) ■ Desired clock phase/polarity, if using Freescale SPI mode (SPH and SPO) ■ The protocol mode: Freescale SPI, TI SSF, MICROWIRE (FRF) ■ The data size (DSS) 5. Enable the SSI by setting the SSE bit in the SSICR1 register. As an example, assume the SSI must be configured to operate with the following parameters: ■ Master operation ■ Freescale SPI mode (SPO=1, SPH=1) ■ 1 Mbps bit rate ■ 8 data bits Assuming the system clock is 20 MHz, the bit rate calculation would be: FSSIClk = FSysClk / (CPSDVSR * (1 + SCR)) 1x106 = 20x106 / (CPSDVSR * (1 + SCR)) In this case, if CPSDVSR=2, SCR must be 9. The configuration sequence would be as follows: 1. Ensure that the SSE bit in the SSICR1 register is disabled. 2. Write the SSICR1 register with a value of 0x0000.0000. 3. Write the SSICPSR register with a value of 0x0000.0002. 4. Write the SSICR0 register with a value of 0x0000.09C7. 5. The SSI is then enabled by setting the SSE bit in the SSICR1 register to 1. 14.4 Register Map Table 14-1 on page 347 lists the SSI registers. The offset listed is a hexadecimal increment to the register’s address, relative to that SSI module’s base address: ■ SSI0: 0x4000.8000 Note: The SSI must be disabled (see the SSE bit in the SSICR1 register) before any of the control registers are reprogrammed. Table 14-1. SSI Register Map See Offset Name Type Reset Description page 0x000 SSICR0 R/W 0x0000.0000 SSI Control 0 349 November 30, 2007 347 Preliminary LM3S6952 Microcontroller See Offset Name Type Reset Description page 0x004 SSICR1 R/W 0x0000.0000 SSI Control 1 351 0x008 SSIDR R/W 0x0000.0000 SSI Data 353 0x00C SSISR RO 0x0000.0003 SSI Status 354 0x010 SSICPSR R/W 0x0000.0000 SSI Clock Prescale 356 0x014 SSIIM R/W 0x0000.0000 SSI Interrupt Mask 357 0x018 SSIRIS RO 0x0000.0008 SSI Raw Interrupt Status 359 0x01C SSIMIS RO 0x0000.0000 SSI Masked Interrupt Status 360 0x020 SSIICR W1C 0x0000.0000 SSI Interrupt Clear 361 0xFD0 SSIPeriphID4 RO 0x0000.0000 SSI Peripheral Identification 4 362 0xFD4 SSIPeriphID5 RO 0x0000.0000 SSI Peripheral Identification 5 363 0xFD8 SSIPeriphID6 RO 0x0000.0000 SSI Peripheral Identification 6 364 0xFDC SSIPeriphID7 RO 0x0000.0000 SSI Peripheral Identification 7 365 0xFE0 SSIPeriphID0 RO 0x0000.0022 SSI Peripheral Identification 0 366 0xFE4 SSIPeriphID1 RO 0x0000.0000 SSI Peripheral Identification 1 367 0xFE8 SSIPeriphID2 RO 0x0000.0018 SSI Peripheral Identification 2 368 0xFEC SSIPeriphID3 RO 0x0000.0001 SSI Peripheral Identification 3 369 0xFF0 SSIPCellID0 RO 0x0000.000D SSI PrimeCell Identification 0 370 0xFF4 SSIPCellID1 RO 0x0000.00F0 SSI PrimeCell Identification 1 371 0xFF8 SSIPCellID2 RO 0x0000.0005 SSI PrimeCell Identification 2 372 0xFFC SSIPCellID3 RO 0x0000.00B1 SSI PrimeCell Identification 3 373 14.5 Register Descriptions The remainder of this section lists and describes the SSI registers, in numerical order by address offset. 348 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 1: SSI Control 0 (SSICR0), offset 0x000 SSICR0 is control register 0 and contains bit fields that control various functions within the SSI module. Functionality such as protocol mode, clock rate, and data size are configured in this register. SSI Control 0 (SSICR0) SSI0 base: 0x4000.8000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 SCR SPH SPO FRF DSS Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x00 SSI Serial Clock Rate The value SCR is used to generate the transmit and receive bit rate of the SSI. The bit rate is: BR=FSSIClk/(CPSDVSR * (1 + SCR)) where CPSDVSR is an even value from 2-254 programmed in the SSICPSR register, and SCR is a value from 0-255. 15:8 SCR R/W 0x0000 SSI Serial Clock Phase This bit is only applicable to the Freescale SPI Format. The SPH control bit selects the clock edge that captures data and allows it to change state. It has the most impact on the first bit transmitted by either allowing or not allowing a clock transition before the first data capture edge. When the SPH bit is 0, data is captured on the first clock edge transition. If SPH is 1, data is captured on the second clock edge transition. 7 SPH R/W 0 SSI Serial Clock Polarity This bit is only applicable to the Freescale SPI Format. When the SPO bit is 0, it produces a steady state Low value on the SSIClk pin. If SPO is 1, a steady state High value is placed on the SSIClk pin when data is not being transferred. 6 SPO R/W 0 November 30, 2007 349 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description SSI Frame Format Select The FRF values are defined as follows: Value Frame Format 0x0 Freescale SPI Frame Format 0x1 Texas Intruments Synchronous Serial Frame Format 0x2 MICROWIRE Frame Format 0x3 Reserved 5:4 FRF R/W 0x0 SSI Data Size Select The DSS values are defined as follows: Value Data Size 0x0-0x2 Reserved 0x3 4-bit data 0x4 5-bit data 0x5 6-bit data 0x6 7-bit data 0x7 8-bit data 0x8 9-bit data 0x9 10-bit data 0xA 11-bit data 0xB 12-bit data 0xC 13-bit data 0xD 14-bit data 0xE 15-bit data 0xF 16-bit data 3:0 DSS R/W 0x00 350 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 2: SSI Control 1 (SSICR1), offset 0x004 SSICR1 is control register 1 and contains bit fields that control various functions within the SSI module. Master and slave mode functionality is controlled by this register. SSI Control 1 (SSICR1) SSI0 base: 0x4000.8000 Offset 0x004 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SOD MS SSE LBM Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SSI Slave Mode Output Disable This bit is relevant only in the Slave mode (MS=1). In multiple-slave systems, it is possible for the SSI master to broadcast a message to all slaves in the system while ensuring that only one slave drives data onto the serial output line. In such systems, the TXD lines from multiple slaves could be tied together. To operate in such a system, the SOD bit can be configured so that the SSI slave does not drive the SSITx pin. The SOD values are defined as follows: Value Description 0 SSI can drive SSITx output in Slave Output mode. 1 SSI must not drive the SSITx output in Slave mode. 3 SOD R/W 0 SSI Master/Slave Select This bit selects Master or Slave mode and can be modified only when SSI is disabled (SSE=0). The MS values are defined as follows: Value Description 0 Device configured as a master. 1 Device configured as a slave. 2 MS R/W 0 November 30, 2007 351 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description SSI Synchronous Serial Port Enable Setting this bit enables SSI operation. The SSE values are defined as follows: Value Description 0 SSI operation disabled. 1 SSI operation enabled. Note: This bit must be set to 0 before any control registers are reprogrammed. 1 SSE R/W 0 SSI Loopback Mode Setting this bit enables Loopback Test mode. The LBM values are defined as follows: Value Description 0 Normal serial port operation enabled. Output of the transmit serial shift register is connected internally to the input of the receive serial shift register. 1 0 LBM R/W 0 352 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 3: SSI Data (SSIDR), offset 0x008 SSIDR is the data register and is 16-bits wide. When SSIDR is read, the entry in the receive FIFO (pointed to by the current FIFO read pointer) is accessed. As data values are removed by the SSI receive logic from the incoming data frame, they are placed into the entry in the receive FIFO (pointed to by the current FIFO write pointer). When SSIDR is written to, the entry in the transmit FIFO (pointed to by the write pointer) is written to. Data values are removed from the transmit FIFO one value at a time by the transmit logic. It is loaded into the transmit serial shifter, then serially shifted out onto the SSITx pin at the programmed bit rate. When a data size of less than 16 bits is selected, the user must right-justify data written to the transmit FIFO. The transmit logic ignores the unused bits. Received data less than 16 bits is automatically right-justified in the receive buffer. When the SSI is programmed for MICROWIRE frame format, the default size for transmit data is eight bits (the most significant byte is ignored). The receive data size is controlled by the programmer. The transmit FIFO and the receive FIFO are not cleared even when the SSE bit in the SSICR1 register is set to zero. This allows the software to fill the transmit FIFO before enabling the SSI. SSI Data (SSIDR) SSI0 base: 0x4000.8000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 DATA Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0000 SSI Receive/Transmit Data A read operation reads the receive FIFO. A write operation writes the transmit FIFO. Software must right-justify data when the SSI is programmed for a data size that is less than 16 bits. Unused bits at the top are ignored by the transmit logic. The receive logic automatically right-justifies the data. 15:0 DATA R/W 0x0000 November 30, 2007 353 Preliminary LM3S6952 Microcontroller Register 4: SSI Status (SSISR), offset 0x00C SSISR is a status register that contains bits that indicate the FIFO fill status and the SSI busy status. SSI Status (SSISR) SSI0 base: 0x4000.8000 Offset 0x00C Type RO, reset 0x0000.0003 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved BSY RFF RNE TNF TFE Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO R0 Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:5 reserved RO 0x00 SSI Busy Bit The BSY values are defined as follows: Value Description 0 SSI is idle. SSI is currently transmitting and/or receiving a frame, or the transmit FIFO is not empty. 1 4 BSY RO 0 SSI Receive FIFO Full The RFF values are defined as follows: Value Description 0 Receive FIFO is not full. 1 Receive FIFO is full. 3 RFF RO 0 SSI Receive FIFO Not Empty The RNE values are defined as follows: Value Description 0 Receive FIFO is empty. 1 Receive FIFO is not empty. 2 RNE RO 0 SSI Transmit FIFO Not Full The TNF values are defined as follows: Value Description 0 Transmit FIFO is full. 1 Transmit FIFO is not full. 1 TNF RO 1 354 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Bit/Field Name Type Reset Description SSI Transmit FIFO Empty The TFE values are defined as follows: Value Description 0 Transmit FIFO is not empty. 1 Transmit FIFO is empty. 0 TFE R0 1 November 30, 2007 355 Preliminary LM3S6952 Microcontroller Register 5: SSI Clock Prescale (SSICPSR), offset 0x010 SSICPSR is the clock prescale register and specifies the division factor by which the system clock must be internally divided before further use. The value programmed into this register must be an even number between 2 and 254. The least-significant bit of the programmed number is hard-coded to zero. If an odd number is written to this register, data read back from this register has the least-significant bit as zero. SSI Clock Prescale (SSICPSR) SSI0 base: 0x4000.8000 Offset 0x010 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CPSDVSR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Clock Prescale Divisor This value must be an even number from 2 to 254, depending on the frequency of SSIClk. The LSB always returns 0 on reads. 7:0 CPSDVSR R/W 0x00 356 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 6: SSI Interrupt Mask (SSIIM), offset 0x014 The SSIIM register is the interrupt mask set or clear register. It is a read/write register and all bits are cleared to 0 on reset. On a read, this register gives the current value of the mask on the relevant interrupt. A write of 1 to the particular bit sets the mask, enabling the interrupt to be read. A write of 0 clears the corresponding mask. SSI Interrupt Mask (SSIIM) SSI0 base: 0x4000.8000 Offset 0x014 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TXIM RXIM RTIM RORIM Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SSI Transmit FIFO Interrupt Mask The TXIM values are defined as follows: Value Description 0 TX FIFO half-full or less condition interrupt is masked. 1 TX FIFO half-full or less condition interrupt is not masked. 3 TXIM R/W 0 SSI Receive FIFO Interrupt Mask The RXIM values are defined as follows: Value Description 0 RX FIFO half-full or more condition interrupt is masked. 1 RX FIFO half-full or more condition interrupt is not masked. 2 RXIM R/W 0 SSI Receive Time-Out Interrupt Mask The RTIM values are defined as follows: Value Description 0 RX FIFO time-out interrupt is masked. 1 RX FIFO time-out interrupt is not masked. 1 RTIM R/W 0 November 30, 2007 357 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description SSI Receive Overrun Interrupt Mask The RORIM values are defined as follows: Value Description 0 RX FIFO overrun interrupt is masked. 1 RX FIFO overrun interrupt is not masked. 0 RORIM R/W 0 358 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 7: SSI Raw Interrupt Status (SSIRIS), offset 0x018 The SSIRIS register is the raw interrupt status register. On a read, this register gives the current raw status value of the corresponding interrupt prior to masking. A write has no effect. SSI Raw Interrupt Status (SSIRIS) SSI0 base: 0x4000.8000 Offset 0x018 Type RO, reset 0x0000.0008 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TXRIS RXRIS RTRIS RORRIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 SSI Transmit FIFO Raw Interrupt Status Indicates that the transmit FIFO is half full or less, when set. 3 TXRIS RO 1 SSI Receive FIFO Raw Interrupt Status Indicates that the receive FIFO is half full or more, when set. 2 RXRIS RO 0 SSI Receive Time-Out Raw Interrupt Status Indicates that the receive time-out has occurred, when set. 1 RTRIS RO 0 SSI Receive Overrun Raw Interrupt Status Indicates that the receive FIFO has overflowed, when set. 0 RORRIS RO 0 November 30, 2007 359 Preliminary LM3S6952 Microcontroller Register 8: SSI Masked Interrupt Status (SSIMIS), offset 0x01C The SSIMIS register is the masked interrupt status register. On a read, this register gives the current masked status value of the corresponding interrupt. A write has no effect. SSI Masked Interrupt Status (SSIMIS) SSI0 base: 0x4000.8000 Offset 0x01C Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TXMIS RXMIS RTMIS RORMIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0 SSI Transmit FIFO Masked Interrupt Status Indicates that the transmit FIFO is half full or less, when set. 3 TXMIS RO 0 SSI Receive FIFO Masked Interrupt Status Indicates that the receive FIFO is half full or more, when set. 2 RXMIS RO 0 SSI Receive Time-Out Masked Interrupt Status Indicates that the receive time-out has occurred, when set. 1 RTMIS RO 0 SSI Receive Overrun Masked Interrupt Status Indicates that the receive FIFO has overflowed, when set. 0 RORMIS RO 0 360 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 9: SSI Interrupt Clear (SSIICR), offset 0x020 The SSIICR register is the interrupt clear register. On a write of 1, the corresponding interrupt is cleared. A write of 0 has no effect. SSI Interrupt Clear (SSIICR) SSI0 base: 0x4000.8000 Offset 0x020 Type W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RTIC RORIC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO W1C W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 SSI Receive Time-Out Interrupt Clear The RTIC values are defined as follows: Value Description 0 No effect on interrupt. 1 Clears interrupt. 1 RTIC W1C 0 SSI Receive Overrun Interrupt Clear The RORIC values are defined as follows: Value Description 0 No effect on interrupt. 1 Clears interrupt. 0 RORIC W1C 0 November 30, 2007 361 Preliminary LM3S6952 Microcontroller Register 10: SSI Peripheral Identification 4 (SSIPeriphID4), offset 0xFD0 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 4 (SSIPeriphID4) SSI0 base: 0x4000.8000 Offset 0xFD0 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID4 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register[7:0] Can be used by software to identify the presence of this peripheral. 7:0 PID4 RO 0x00 362 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 11: SSI Peripheral Identification 5 (SSIPeriphID5), offset 0xFD4 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 5 (SSIPeriphID5) SSI0 base: 0x4000.8000 Offset 0xFD4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID5 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register[15:8] Can be used by software to identify the presence of this peripheral. 7:0 PID5 RO 0x00 November 30, 2007 363 Preliminary LM3S6952 Microcontroller Register 12: SSI Peripheral Identification 6 (SSIPeriphID6), offset 0xFD8 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 6 (SSIPeriphID6) SSI0 base: 0x4000.8000 Offset 0xFD8 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID6 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register[23:16] Can be used by software to identify the presence of this peripheral. 7:0 PID6 RO 0x00 364 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 13: SSI Peripheral Identification 7 (SSIPeriphID7), offset 0xFDC The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 7 (SSIPeriphID7) SSI0 base: 0x4000.8000 Offset 0xFDC Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID7 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register[31:24] Can be used by software to identify the presence of this peripheral. 7:0 PID7 RO 0x00 November 30, 2007 365 Preliminary LM3S6952 Microcontroller Register 14: SSI Peripheral Identification 0 (SSIPeriphID0), offset 0xFE0 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 0 (SSIPeriphID0) SSI0 base: 0x4000.8000 Offset 0xFE0 Type RO, reset 0x0000.0022 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0 SSI Peripheral ID Register[7:0] Can be used by software to identify the presence of this peripheral. 7:0 PID0 RO 0x22 366 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 15: SSI Peripheral Identification 1 (SSIPeriphID1), offset 0xFE4 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 1 (SSIPeriphID1) SSI0 base: 0x4000.8000 Offset 0xFE4 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register [15:8] Can be used by software to identify the presence of this peripheral. 7:0 PID1 RO 0x00 November 30, 2007 367 Preliminary LM3S6952 Microcontroller Register 16: SSI Peripheral Identification 2 (SSIPeriphID2), offset 0xFE8 The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 2 (SSIPeriphID2) SSI0 base: 0x4000.8000 Offset 0xFE8 Type RO, reset 0x0000.0018 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register [23:16] Can be used by software to identify the presence of this peripheral. 7:0 PID2 RO 0x18 368 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 17: SSI Peripheral Identification 3 (SSIPeriphID3), offset 0xFEC The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset value. SSI Peripheral Identification 3 (SSIPeriphID3) SSI0 base: 0x4000.8000 Offset 0xFEC Type RO, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI Peripheral ID Register [31:24] Can be used by software to identify the presence of this peripheral. 7:0 PID3 RO 0x01 November 30, 2007 369 Preliminary LM3S6952 Microcontroller Register 18: SSI PrimeCell Identification 0 (SSIPCellID0), offset 0xFF0 The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset value. SSI PrimeCell Identification 0 (SSIPCellID0) SSI0 base: 0x4000.8000 Offset 0xFF0 Type RO, reset 0x0000.000D 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI PrimeCell ID Register [7:0] Provides software a standard cross-peripheral identification system. 7:0 CID0 RO 0x0D 370 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 19: SSI PrimeCell Identification 1 (SSIPCellID1), offset 0xFF4 The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset value. SSI PrimeCell Identification 1 (SSIPCellID1) SSI0 base: 0x4000.8000 Offset 0xFF4 Type RO, reset 0x0000.00F0 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID1 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI PrimeCell ID Register [15:8] Provides software a standard cross-peripheral identification system. 7:0 CID1 RO 0xF0 November 30, 2007 371 Preliminary LM3S6952 Microcontroller Register 20: SSI PrimeCell Identification 2 (SSIPCellID2), offset 0xFF8 The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset value. SSI PrimeCell Identification 2 (SSIPCellID2) SSI0 base: 0x4000.8000 Offset 0xFF8 Type RO, reset 0x0000.0005 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID2 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI PrimeCell ID Register [23:16] Provides software a standard cross-peripheral identification system. 7:0 CID2 RO 0x05 372 November 30, 2007 Preliminary Synchronous Serial Interface (SSI) Register 21: SSI PrimeCell Identification 3 (SSIPCellID3), offset 0xFFC The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset value. SSI PrimeCell Identification 3 (SSIPCellID3) SSI0 base: 0x4000.8000 Offset 0xFFC Type RO, reset 0x0000.00B1 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved CID3 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SSI PrimeCell ID Register [31:24] Provides software a standard cross-peripheral identification system. 7:0 CID3 RO 0xB1 November 30, 2007 373 Preliminary LM3S6952 Microcontroller 15 Inter-Integrated Circuit (I2C) Interface The Inter-Integrated Circuit (I2C) bus provides bi-directional data transfer through a two-wire design (a serial data line SDA and a serial clock line SCL), and interfaces to external I2C devices such as serial memory (RAMs and ROMs), networking devices, LCDs, tone generators, and so on. The I2C bus may also be used for system testing and diagnostic purposes in product development and manufacture. The LM3S6952 microcontroller includes one I2C module, providing the ability to interact (both send and receive) with other I2C devices on the bus. Devices on the I2C bus can be designated as either a master or a slave. The Stellaris® I2C module supports both sending and receiving data as either a master or a slave, and also supports the simultaneous operation as both a master and a slave. There are a total of four I2C modes: Master Transmit, Master Receive, Slave Transmit, and Slave Receive. The Stellaris® I2C module can operate at two speeds: Standard (100 Kbps) and Fast (400 Kbps). Both the I2C master and slave can generate interrupts; the I2C master generates interrupts when a transmit or receive operation completes (or aborts due to an error) and the I2C slave generates interrupts when data has been sent or requested by a master. 15.1 Block Diagram Figure 15-1. I2C Block Diagram I2C I/O Select I2C Master Core Interrupt I2C Slave Core I2CSCL I2CSDA I2CSDA I2CSCL I2CSDA I2CSCL I2CMSA I2CMCS I2CMDR I2CMTPR I2CMIMR I2CMRIS I2CMICR I2CMCR I2CSOAR I2CSCSR I2CSDR I2CSIM I2CSRIS I2CSMIS I2CMMIS I2CSICR I2C Control 15.2 Functional Description The I2C module is comprised of both master and slave functions which are implemented as separate peripherals. For proper operation, the SDA and SCL pins must be connected to bi-directional open-drain pads. A typical I2C bus configuration is shown in Figure 15-2 on page 375. See “I2C” on page 539 for I2C timing diagrams. 374 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Figure 15-2. I2C Bus Configuration RPUP StellarisTM I2CSCL I2CSDA RPUP 3rd Party Device with I2C Interface SCL SDA I2C Bus SCL SDA 3rd Party Device with I2C Interface SCL SDA 15.2.1 I2C Bus Functional Overview The I2C bus uses only two signals: SDA and SCL, named I2CSDA and I2CSCL on Stellaris® microcontrollers. SDA is the bi-directional serial data line and SCL is the bi-directional serial clock line. The bus is considered idle when both lines are high. Every transaction on the I2C bus is nine bits long, consisting of eight data bits and a single acknowledge bit. The number of bytes per transfer (defined as the time between a valid START and STOP condition, described in “START and STOP Conditions” on page 375) is unrestricted, but each byte has to be followed by an acknowledge bit, and data must be transferred MSB first. When a receiver cannot receive another complete byte, it can hold the clock line SCL Low and force the transmitter into a wait state. The data transfer continues when the receiver releases the clock SCL. 15.2.1.1 START and STOP Conditions The protocol of the I2C bus defines two states to begin and end a transaction: START and STOP. A high-to-low transition on the SDA line while the SCL is high is defined as a START condition, and a low-to-high transition on the SDA line while SCL is high is defined as a STOP condition. The bus is considered busy after a START condition and free after a STOP condition. See Figure 15-3 on page 375. Figure 15-3. START and STOP Conditions START condition SDA SCL STOP condition SDA SCL 15.2.1.2 Data Format with 7-Bit Address Data transfers follow the format shown in Figure 15-4 on page 376. After the START condition, a slave address is sent. This address is 7-bits long followed by an eighth bit, which is a data direction bit (R/S bit in the I2CMSA register). A zero indicates a transmit operation (send), and a one indicates a request for data (receive). A data transfer is always terminated by a STOP condition generated by the master, however, a master can initiate communications with another device on the bus by generating a repeated START condition and addressing another slave without first generating a STOP condition. Various combinations of receive/send formats are then possible within a single transfer. November 30, 2007 375 Preliminary LM3S6952 Microcontroller Figure 15-4. Complete Data Transfer with a 7-Bit Address Slave address Data SDA MSB LSB R/S ACK MSB LSB ACK SCL 1 2 7 8 9 1 2 7 8 9 The first seven bits of the first byte make up the slave address (see Figure 15-5 on page 376). The eighth bit determines the direction of the message. A zero in the R/S position of the first byte means that the master will write (send) data to the selected slave, and a one in this position means that the master will receive data from the slave. Figure 15-5. R/S Bit in First Byte R/S LSB Slave address MSB 15.2.1.3 Data Validity The data on the SDA line must be stable during the high period of the clock, and the data line can only change when SCL is low (see Figure 15-6 on page 376). Figure 15-6. Data Validity During Bit Transfer on the I2C Bus Change of data allowed Dataline stable SDA SCL 15.2.1.4 Acknowledge All bus transactions have a required acknowledge clock cycle that is generated by the master. During the acknowledge cycle, the transmitter (which can be the master or slave) releases the SDA line. To acknowledge the transaction, the receiver must pull down SDA during the acknowledge clock cycle. The data sent out by the receiver during the acknowledge cycle must comply with the data validity requirements described in “Data Validity” on page 376. When a slave receiver does not acknowledge the slave address, SDA must be left high by the slave so that the master can generate a STOP condition and abort the current transfer. If the master device is acting as a receiver during a transfer, it is responsible for acknowledging each transfer made by the slave. Since the master controls the number of bytes in the transfer, it signals the end of data to the slave transmitter by not generating an acknowledge on the last data byte. The slave transmitter must then release SDA to allow the master to generate the STOP or a repeated START condition. 376 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface 15.2.1.5 Arbitration A master may start a transfer only if the bus is idle. It's possible for two or more masters to generate a START condition within minimum hold time of the START condition. In these situations, an arbitration scheme takes place on the SDA line, while SCL is high. During arbitration, the first of the competing master devices to place a '1' (high) on SDA while another master transmits a '0' (low) will switch off its data output stage and retire until the bus is idle again. Arbitration can take place over several bits. Its first stage is a comparison of address bits, and if both masters are trying to address the same device, arbitration continues on to the comparison of data bits. 15.2.2 Available Speed Modes The I2C clock rate is determined by the parameters: CLK_PRD, TIMER_PRD, SCL_LP, and SCL_HP. where: CLK_PRD is the system clock period SCL_LP is the low phase of SCL (fixed at 6) SCL_HP is the high phase of SCL (fixed at 4) TIMER_PRD is the programmed value in the I2C Master Timer Period (I2CMTPR) register (see page 394). The I2C clock period is calculated as follows: SCL_PERIOD = 2*(1 + TIMER_PRD)*(SCL_LP + SCL_HP)*CLK_PRD For example: CLK_PRD = 50 ns TIMER_PRD = 2 SCL_LP=6 SCL_HP=4 yields a SCL frequency of: 1/T = 333 Khz Table 15-1 on page 377 gives examples of timer period, system clock, and speed mode (Standard or Fast). Table 15-1. Examples of I2C Master Timer Period versus Speed Mode System Clock Timer Period Standard Mode Timer Period Fast Mode 4 Mhz 0x01 100 Kbps - - 6 Mhz 0x02 100 Kbps - - 12.5 Mhz 0x06 89 Kbps 0x01 312 Kbps 16.7 Mhz 0x08 93 Kbps 0x02 278 Kbps 20 Mhz 0x09 100 Kbps 0x02 333 Kbps 25 Mhz 0x0C 96.2 Kbps 0x03 312 Kbps 33Mhz 0x10 97.1 Kbps 0x04 330 Kbps 40Mhz 0x13 100 Kbps 0x04 400 Kbps November 30, 2007 377 Preliminary LM3S6952 Microcontroller System Clock Timer Period Standard Mode Timer Period Fast Mode 50Mhz 0x18 100 Kbps 0x06 357 Kbps 15.2.3 Interrupts The I2C can generate interrupts when the following conditions are observed: ■ Master transaction completed ■ Master transaction error ■ Slave transaction received ■ Slave transaction requested There is a separate interrupt signal for the I2C master and I2C modules. While both modules can generate interrupts for multiple conditions, only a single interrupt signal is sent to the interrupt controller. 15.2.3.1 I2C Master Interrupts The I2C master module generates an interrupt when a transaction completes (either transmit or receive), or when an error occurs during a transaction. To enable the I2C master interrupt, software must write a '1' to the I2C Master Interrupt Mask (I2CMIMR) register. When an interrupt condition is met, software must check the ERROR bit in the I2C Master Control/Status (I2CMCS) register to verify that an error didn't occur during the last transaction. An error condition is asserted if the last transaction wasn't acknowledge by the slave or if the master was forced to give up ownership of the bus due to a lost arbitration round with another master. If an error is not detected, the application can proceed with the transfer. The interrupt is cleared by writing a '1' to the I2C Master Interrupt Clear (I2CMICR) register. If the application doesn't require the use of interrupts, the raw interrupt status is always visible via the I2C Master Raw Interrupt Status (I2CMRIS) register. 15.2.3.2 I2C Slave Interrupts The slave module generates interrupts as it receives requests from an I2C master. To enable the I2C slave interrupt, write a '1' to the I2C Slave Interrupt Mask (I2CSIMR) register. Software determines whether the module should write (transmit) or read (receive) data from the I2C Slave Data (I2CSDR) register, by checking the RREQ and TREQ bits of the I2C Slave Control/Status (I2CSCSR) register. If the slave module is in receive mode and the first byte of a transfer is received, the FBR bit is set along with the RREQ bit. The interrupt is cleared by writing a '1' to the I2C Slave Interrupt Clear (I2CSICR) register. If the application doesn't require the use of interrupts, the raw interrupt status is always visible via the I2C Slave Raw Interrupt Status (I2CSRIS) register. 15.2.4 Loopback Operation The I2C modules can be placed into an internal loopback mode for diagnostic or debug work. This is accomplished by setting the LPBK bit in the I2C Master Configuration (I2CMCR) register. In loopback mode, the SDA and SCL signals from the master and slave modules are tied together. 378 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface 15.2.5 Command Sequence Flow Charts This section details the steps required to perform the various I2C transfer types in both master and slave mode. 15.2.5.1 I2C Master Command Sequences The figures that follow show the command sequences available for the I2C master. Figure 15-7. Master Single SEND Idle Write Slave Address to I2CMSA Write data to I2CMDR Read I2CMCS Sequence may be omitted in a Single Master system BUSBSY bit=0? NO Write ---0-111 to I2CMCS YES Read I2CMCS BUSY bit=0? ERROR bit=0? YES Error Service Idle YES NO NO November 30, 2007 379 Preliminary LM3S6952 Microcontroller Figure 15-8. Master Single RECEIVE Idle Write Slave Address to I2CMSA Read I2CMCS Sequence may be omitted in a Single Master system BUSBSY bit=0? NO Write ---00111 to I2CMCS YES Read I2CMCS BUSY bit=0? ERROR bit=0? YES Error Service Idle NO NO Read data from I2CMDR YES 380 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Figure 15-9. Master Burst SEND Idle Write Slave Address to I2CMSA Write data to I2CMDR Read I2CMCS BUSBSY bit=0? YES Write ---0-011 to I2CMCS NO Read I2CMCS BUSY bit=0? YES ERROR bit=0? YES Write data to ARBLST bit=1? I2CMDR Write ---0-100 to Index=n? I2CMCS NO Error Service Idle YES Write ---0-001 to I2CMCS Write ---0-101 to I2CMCS YES Read I2CMCS BUSY bit=0? ERROR bit=0? YES NO Idle YES Error Service NO NO NO NO Sequence may be omitted in a Single Master system November 30, 2007 381 Preliminary LM3S6952 Microcontroller Figure 15-10. Master Burst RECEIVE Idle Write Slave Address to I2CMSA Read I2CMCS BUSBSY bit=0? NO Write ---01011 to I2CMCS YES Read I2CMCS BUSY bit=0? NO ERROR bit=0? YES ARBLST bit=1? Write ---0-100 to I2CMCS NO Error Service YES Idle Read data from I2CMDR Index=m-1? Write ---00101 to I2CMCS YES Idle Read data from Error Service I2CMDR ERROR bit=0? YES Write ---01001 to I2CMCS Read I2CMCS BUSY bit=0? NO YES Sequence may be omitted in a Single Master system NO NO NO 382 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Figure 15-11. Master Burst RECEIVE after Burst SEND Idle Master operates in Master Transmit mode STOP condition is not generated Write Slave Address to I2CMSA Write ---01011 to I2CMCS Master operates in Master Receive mode Idle Repeated START condition is generated with changing data direction November 30, 2007 383 Preliminary LM3S6952 Microcontroller Figure 15-12. Master Burst SEND after Burst RECEIVE Idle Master operates in Master Receive mode STOP condition is not generated Write Slave Address to I2CMSA Write ---0-011 to I2CMCS Master operates in Master Transmit mode Idle Repeated START condition is generated with changing data direction 15.2.5.2 I2C Slave Command Sequences Figure 15-13 on page 385 presents the command sequence available for the I2C slave. 384 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Figure 15-13. Slave Command Sequence Idle Write OWN Slave Address to I2CSOAR Write -------1 to I2CSCSR Read I2CSCSR RREQ bit=1? Read data from I2CSDR YES TREQ bit=1? NO Write data to I2CSDR YES NO FBR is also valid 15.3 Initialization and Configuration The following example shows how to configure the I2C module to send a single byte as a master. This assumes the system clock is 20 MHz. 1. Enable the I2C clock by writing a value of 0x0000.1000 to the RCGC1 register in the System Control module. 2. Enable the clock to the appropriate GPIO module via the RCGC2 register in the System Control module. 3. In the GPIO module, enable the appropriate pins for their alternate function using the GPIOAFSEL register. Also, be sure to enable the same pins for Open Drain operation. 4. Initialize the I2C Master by writing the I2CMCR register with a value of 0x0000.0020. 5. Set the desired SCL clock speed of 100 Kbps by writing the I2CMTPR register with the correct value. The value written to the I2CMTPR register represents the number of system clock periods in one SCL clock period. The TPR value is determined by the following equation: November 30, 2007 385 Preliminary LM3S6952 Microcontroller TPR = (System Clock / (2 * (SCL_LP + SCL_HP) * SCL_CLK)) - 1; TPR = (20MHz / (2 * (6 + 4) * 100000)) - 1; TPR = 9 Write the I2CMTPR register with the value of 0x0000.0009. 6. Specify the slave address of the master and that the next operation will be a Send by writing the I2CMSA register with a value of 0x0000.0076. This sets the slave address to 0x3B. 7. Place data (byte) to be sent in the data register by writing the I2CMDR register with the desired data. 8. Initiate a single byte send of the data from Master to Slave by writing the I2CMCS register with a value of 0x0000.0007 (STOP, START, RUN). 9. Wait until the transmission completes by polling the I2CMCS register’s BUSBSY bit until it has been cleared. 15.4 I2C Register Map Table 15-2 on page 386 lists the I2C registers. All addresses given are relative to the I2C base addresses for the master and slave: ■ I2C Master 0: 0x4002.0000 ■ I2C Slave 0: 0x4002.0800 Table 15-2. Inter-Integrated Circuit (I2C) Interface Register Map See Offset Name Type Reset Description page I2C Master 0x000 I2CMSA R/W 0x0000.0000 I2C Master Slave Address 388 0x004 I2CMCS R/W 0x0000.0000 I2C Master Control/Status 389 0x008 I2CMDR R/W 0x0000.0000 I2C Master Data 393 0x00C I2CMTPR R/W 0x0000.0001 I2C Master Timer Period 394 0x010 I2CMIMR R/W 0x0000.0000 I2C Master Interrupt Mask 395 0x014 I2CMRIS RO 0x0000.0000 I2C Master Raw Interrupt Status 396 0x018 I2CMMIS RO 0x0000.0000 I2C Master Masked Interrupt Status 397 0x01C I2CMICR WO 0x0000.0000 I2C Master Interrupt Clear 398 0x020 I2CMCR R/W 0x0000.0000 I2C Master Configuration 399 I2C Slave 0x000 I2CSOAR R/W 0x0000.0000 I2C Slave Own Address 401 0x004 I2CSCSR RO 0x0000.0000 I2C Slave Control/Status 402 0x008 I2CSDR R/W 0x0000.0000 I2C Slave Data 404 0x00C I2CSIMR R/W 0x0000.0000 I2C Slave Interrupt Mask 405 386 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface See Offset Name Type Reset Description page 0x010 I2CSRIS RO 0x0000.0000 I2C Slave Raw Interrupt Status 406 0x014 I2CSMIS RO 0x0000.0000 I2C Slave Masked Interrupt Status 407 0x018 I2CSICR WO 0x0000.0000 I2C Slave Interrupt Clear 408 15.5 Register Descriptions (I2C Master) The remainder of this section lists and describes the I2C master registers, in numerical order by address offset. See also “Register Descriptions (I2C Slave)” on page 400. November 30, 2007 387 Preliminary LM3S6952 Microcontroller Register 1: I2C Master Slave Address (I2CMSA), offset 0x000 This register consists of eight bits: seven address bits (A6-A0), and a Receive/Send bit, which determines if the next operation is a Receive (High), or Send (Low). I2C Master Slave Address (I2CMSA) I2C Master 0 base: 0x4002.0000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SA R/S Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 I2C Slave Address This field specifies bits A6 through A0 of the slave address. 7:1 SA R/W 0 Receive/Send The R/S bit specifies if the next operation is a Receive (High) or Send (Low). Value Description 0 Send. 1 Receive. 0 R/S R/W 0 388 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 2: I2C Master Control/Status (I2CMCS), offset 0x004 This register accesses four control bits when written, and accesses seven status bits when read. The status register consists of seven bits, which when read determine the state of the I2C bus controller. The control register consists of four bits: the RUN, START, STOP, and ACK bits. The START bit causes the generation of the START, or REPEATED START condition. The STOP bit determines if the cycle stops at the end of the data cycle, or continues on to a burst. To generate a single send cycle, the I2C Master Slave Address (I2CMSA) register is written with the desired address, the R/S bit is set to 0, and the Control register is written with ACK=X (0 or 1), STOP=1, START=1, and RUN=1 to perform the operation and stop. When the operation is completed (or aborted due an error), the interrupt pin becomes active and the data may be read from the I2CMDR register. When the I2C module operates in Master receiver mode, the ACK bit must be set normally to logic 1. This causes the I2C bus controller to send an acknowledge automatically after each byte. This bit must be reset when the I2C bus controller requires no further data to be sent from the slave transmitter. Read-Only Status Register I2C Master Control/Status (I2CMCS) I2C Master 0 base: 0x4002.0000 Offset 0x004 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved BUSBSY IDLE ARBLST DATACK ADRACK ERROR BUSY Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0x00 Bus Busy This bit specifies the state of the I2C bus. If set, the bus is busy; otherwise, the bus is idle. The bit changes based on the START and STOP conditions. 6 BUSBSY RO 0 I2C Idle This bit specifies the I2C controller state. If set, the controller is idle; otherwise the controller is not idle. 5 IDLE RO 0 Arbitration Lost This bit specifies the result of bus arbitration. If set, the controller lost arbitration; otherwise, the controller won arbitration. 4 ARBLST RO 0 November 30, 2007 389 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Acknowledge Data This bit specifies the result of the last data operation. If set, the transmitted data was not acknowledged; otherwise, the data was acknowledged. 3 DATACK RO 0 Acknowledge Address This bit specifies the result of the last address operation. If set, the transmitted address was not acknowledged; otherwise, the address was acknowledged. 2 ADRACK RO 0 Error This bit specifies the result of the last bus operation. If set, an error occurred on the last operation; otherwise, no error was detected. The error can be from the slave address not being acknowledged, the transmit data not being acknowledged, or because the controller lost arbitration. 1 ERROR RO 0 I2C Busy This bit specifies the state of the controller. If set, the controller is busy; otherwise, the controller is idle. When the BUSY bit is set, the other status bits are not valid. 0 BUSY RO 0 Write-Only Control Register I2C Master Control/Status (I2CMCS) I2C Master 0 base: 0x4002.0000 Offset 0x004 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved ACK STOP START RUN Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved WO 0x00 Data Acknowledge Enable When set, causes received data byte to be acknowledged automatically by the master. See field decoding in Table 15-3 on page 391. 3 ACK WO 0 Generate STOP When set, causes the generation of the STOP condition. See field decoding in Table 15-3 on page 391. 2 STOP WO 0 390 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Bit/Field Name Type Reset Description Generate START When set, causes the generation of a START or repeated START condition. See field decoding in Table 15-3 on page 391. 1 START WO 0 I2C Master Enable When set, allows the master to send or receive data. See field decoding in Table 15-3 on page 391. 0 RUN WO 0 Table 15-3. Write Field Decoding for I2CMCS[3:0] Field (Sheet 1 of 3) Current I2CMSA[0] I2CMCS[3:0] Description State R/S ACK STOP START RUN START condition followed by SEND (master goes to the Master Transmit state). Idle 0 Xa 0 1 1 START condition followed by a SEND and STOP condition (master remains in Idle state). 0 X 1 1 1 START condition followed by RECEIVE operation with negative ACK (master goes to the Master Receive state). 1 0 0 1 1 START condition followed by RECEIVE and STOP condition (master remains in Idle state). 1 0 1 1 1 START condition followed by RECEIVE (master goes to the Master Receive state). 1 1 0 1 1 1 1 1 1 1 Illegal. All other combinations not listed are non-operations. NOP. SEND operation (master remains in Master Transmit state). Master X X 0 0 1 Transmit X X 1 0 0 STOP condition (master goes to Idle state). SEND followed by STOP condition (master goes to Idle state). X X 1 0 1 Repeated START condition followed by a SEND (master remains in Master Transmit state). 0 X 0 1 1 Repeated START condition followed by SEND and STOP condition (master goes to Idle state). 0 X 1 1 1 Repeated START condition followed by a RECEIVE operation with a negative ACK (master goes to Master Receive state). 1 0 0 1 1 Repeated START condition followed by a SEND and STOP condition (master goes to Idle state). 1 0 1 1 1 Repeated START condition followed by RECEIVE (master goes to Master Receive state). 1 1 0 1 1 1 1 1 1 1 Illegal. All other combinations not listed are non-operations. NOP. November 30, 2007 391 Preliminary LM3S6952 Microcontroller Current I2CMSA[0] I2CMCS[3:0] Description State R/S ACK STOP START RUN RECEIVE operation with negative ACK (master remains in Master Receive state). Master X 0 0 0 1 Receive X X 1 0 0 STOP condition (master goes to Idle state).b RECEIVE followed by STOP condition (master goes to Idle state). X 0 1 0 1 RECEIVE operation (master remains in Master Receive state). X 1 0 0 1 X 1 1 0 1 Illegal. Repeated START condition followed by RECEIVE operation with a negative ACK (master remains in Master Receive state). 1 0 0 1 1 Repeated START condition followed by RECEIVE and STOP condition (master goes to Idle state). 1 0 1 1 1 Repeated START condition followed by RECEIVE (master remains in Master Receive state). 1 1 0 1 1 Repeated START condition followed by SEND (master goes to Master Transmit state). 0 X 0 1 1 Repeated START condition followed by SEND and STOP condition (master goes to Idle state). 0 X 1 1 1 All other combinations not listed are non-operations. NOP. a. An X in a table cell indicates the bit can be 0 or 1. b. In Master Receive mode, a STOP condition should be generated only after a Data Negative Acknowledge executed by the master or an Address Negative Acknowledge executed by the slave. 392 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 3: I2C Master Data (I2CMDR), offset 0x008 This register contains the data to be transmitted when in the Master Transmit state, and the data received when in the Master Receive state. I2C Master Data (I2CMDR) I2C Master 0 base: 0x4002.0000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DATA Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Data Transferred Data transferred during transaction. 7:0 DATA R/W 0x00 November 30, 2007 393 Preliminary LM3S6952 Microcontroller Register 4: I2C Master Timer Period (I2CMTPR), offset 0x00C This register specifies the period of the SCL clock. I2C Master Timer Period (I2CMTPR) I2C Master 0 base: 0x4002.0000 Offset 0x00C Type R/W, reset 0x0000.0001 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TPR Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 SCL Clock Period This field specifies the period of the SCL clock. SCL_PRD = 2*(1 + TPR)*(SCL_LP + SCL_HP)*CLK_PRD where: SCL_PRD is the SCL line period (I2C clock). TPR is the Timer Period register value (range of 1 to 255). SCL_LP is the SCL Low period (fixed at 6). SCL_HP is the SCL High period (fixed at 4). 7:0 TPR R/W 0x1 394 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 5: I2C Master Interrupt Mask (I2CMIMR), offset 0x010 This register controls whether a raw interrupt is promoted to a controller interrupt. I2C Master Interrupt Mask (I2CMIMR) I2C Master 0 base: 0x4002.0000 Offset 0x010 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IM Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Interrupt Mask This bit controls whether a raw interrupt is promoted to a controller interrupt. If set, the interrupt is not masked and the interrupt is promoted; otherwise, the interrupt is masked. 0 IM R/W 0 November 30, 2007 395 Preliminary LM3S6952 Microcontroller Register 6: I2C Master Raw Interrupt Status (I2CMRIS), offset 0x014 This register specifies whether an interrupt is pending. I2C Master Raw Interrupt Status (I2CMRIS) I2C Master 0 base: 0x4002.0000 Offset 0x014 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Raw Interrupt Status This bit specifies the raw interrupt state (prior to masking) of the I2C master block. If set, an interrupt is pending; otherwise, an interrupt is not pending. 0 RIS RO 0 396 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 7: I2C Master Masked Interrupt Status (I2CMMIS), offset 0x018 This register specifies whether an interrupt was signaled. I2C Master Masked Interrupt Status (I2CMMIS) I2C Master 0 base: 0x4002.0000 Offset 0x018 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Masked Interrupt Status This bit specifies the raw interrupt state (after masking) of the I2C master block. If set, an interrupt was signaled; otherwise, an interrupt has not been generated since the bit was last cleared. 0 MIS RO 0 November 30, 2007 397 Preliminary LM3S6952 Microcontroller Register 8: I2C Master Interrupt Clear (I2CMICR), offset 0x01C This register clears the raw interrupt. I2C Master Interrupt Clear (I2CMICR) I2C Master 0 base: 0x4002.0000 Offset 0x01C Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Interrupt Clear This bit controls the clearing of the raw interrupt. A write of 1 clears the interrupt; otherwise, a write of 0 has no affect on the interrupt state. A read of this register returns no meaningful data. 0 IC WO 0 398 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 9: I2C Master Configuration (I2CMCR), offset 0x020 This register configures the mode (Master or Slave) and sets the interface for test mode loopback. I2C Master Configuration (I2CMCR) I2C Master 0 base: 0x4002.0000 Offset 0x020 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved SFE MFE reserved LPBK Type RO RO RO RO RO RO RO RO RO RO R/W R/W RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0x00 I2C Slave Function Enable This bit specifies whether the interface may operate in Slave mode. If set, Slave mode is enabled; otherwise, Slave mode is disabled. 5 SFE R/W 0 I2C Master Function Enable This bit specifies whether the interface may operate in Master mode. If set, Master mode is enabled; otherwise, Master mode is disabled and the interface clock is disabled. 4 MFE R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:1 reserved RO 0x00 I2C Loopback This bit specifies whether the interface is operating normally or in Loopback mode. If set, the device is put in a test mode loopback configuration; otherwise, the device operates normally. 0 LPBK R/W 0 November 30, 2007 399 Preliminary LM3S6952 Microcontroller 15.6 Register Descriptions (I2C Slave) The remainder of this section lists and describes the I2C slave registers, in numerical order by address offset. See also “Register Descriptions (I2C Master)” on page 387. 400 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 10: I2C Slave Own Address (I2CSOAR), offset 0x000 This register consists of seven address bits that identify the Stellaris® I2C device on the I2C bus. I2C Slave Own Address (I2CSOAR) I2C Slave 0 base: 0x4002.0800 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OAR Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0x00 I2C Slave Own Address This field specifies bits A6 through A0 of the slave address. 6:0 OAR R/W 0x00 November 30, 2007 401 Preliminary LM3S6952 Microcontroller Register 11: I2C Slave Control/Status (I2CSCSR), offset 0x004 This register accesses one control bit when written, and three status bits when read. The read-only Status register consists of three bits: the FBR, RREQ, and TREQ bits. The First Byte Received (FBR) bit is set only after the Stellaris® device detects its own slave address and receives the first data byte from the I2C master. The Receive Request (RREQ) bit indicates that the Stellaris® I2C device has received a data byte from an I2C master. Read one data byte from the I2C Slave Data (I2CSDR) register to clear the RREQ bit. The Transmit Request (TREQ) bit indicates that the Stellaris® I2C device is addressed as a Slave Transmitter. Write one data byte into the I2C Slave Data (I2CSDR) register to clear the TREQ bit. The write-only Control register consists of one bit: the DA bit. The DA bit enables and disables the Stellaris® I2C slave operation. Read-Only Status Register I2C Slave Control/Status (I2CSCSR) I2C Slave 0 base: 0x4002.0800 Offset 0x004 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved FBR TREQ RREQ Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 First Byte Received Indicates that the first byte following the slave’s own address is received. This bit is only valid when the RREQ bit is set, and is automatically cleared when data has been read from the I2CSDR register. Note: This bit is not used for slave transmit operations. 2 FBR RO 0 Transmit Request This bit specifies the state of the I2C slave with regards to outstanding transmit requests. If set, the I2C unit has been addressed as a slave transmitter and uses clock stretching to delay the master until data has been written to the I2CSDR register. Otherwise, there is no outstanding transmit request. 1 TREQ RO 0 Receive Request This bit specifies the status of the I2C slave with regards to outstanding receive requests. If set, the I2C unit has outstanding receive data from the I2C master and uses clock stretching to delay the master until the data has been read from the I2CSDR register. Otherwise, no receive data is outstanding. 0 RREQ RO 0 402 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Write-Only Control Register I2C Slave Control/Status (I2CSCSR) I2C Slave 0 base: 0x4002.0800 Offset 0x004 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DA Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Device Active Value Description 0 Disables the I2C slave operation. 1 Enables the I2C slave operation. 0 DA WO 0 November 30, 2007 403 Preliminary LM3S6952 Microcontroller Register 12: I2C Slave Data (I2CSDR), offset 0x008 This register contains the data to be transmitted when in the Slave Transmit state, and the data received when in the Slave Receive state. I2C Slave Data (I2CSDR) I2C Slave 0 base: 0x4002.0800 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DATA Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x00 Data for Transfer This field contains the data for transfer during a slave receive or transmit operation. 7:0 DATA R/W 0x0 404 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 13: I2C Slave Interrupt Mask (I2CSIMR), offset 0x00C This register controls whether a raw interrupt is promoted to a controller interrupt. I2C Slave Interrupt Mask (I2CSIMR) I2C Slave 0 base: 0x4002.0800 Offset 0x00C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IM Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Interrupt Mask This bit controls whether a raw interrupt is promoted to a controller interrupt. If set, the interrupt is not masked and the interrupt is promoted; otherwise, the interrupt is masked. 0 IM R/W 0 November 30, 2007 405 Preliminary LM3S6952 Microcontroller Register 14: I2C Slave Raw Interrupt Status (I2CSRIS), offset 0x010 This register specifies whether an interrupt is pending. I2C Slave Raw Interrupt Status (I2CSRIS) I2C Slave 0 base: 0x4002.0800 Offset 0x010 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Raw Interrupt Status This bit specifies the raw interrupt state (prior to masking) of the I2C slave block. If set, an interrupt is pending; otherwise, an interrupt is not pending. 0 RIS RO 0 406 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface Register 15: I2C Slave Masked Interrupt Status (I2CSMIS), offset 0x014 This register specifies whether an interrupt was signaled. I2C Slave Masked Interrupt Status (I2CSMIS) I2C Slave 0 base: 0x4002.0800 Offset 0x014 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved MIS Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Masked Interrupt Status This bit specifies the raw interrupt state (after masking) of the I2C slave block. If set, an interrupt was signaled; otherwise, an interrupt has not been generated since the bit was last cleared. 0 MIS RO 0 November 30, 2007 407 Preliminary LM3S6952 Microcontroller Register 16: I2C Slave Interrupt Clear (I2CSICR), offset 0x018 This register clears the raw interrupt. I2C Slave Interrupt Clear (I2CSICR) I2C Slave 0 base: 0x4002.0800 Offset 0x018 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IC Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x00 Clear Interrupt This bit controls the clearing of the raw interrupt. A write of 1 clears the interrupt; otherwise a write of 0 has no affect on the interrupt state. A read of this register returns no meaningful data. 0 IC WO 0 408 November 30, 2007 Preliminary Inter-Integrated Circuit (I2C) Interface 16 Ethernet Controller The Stellaris® Ethernet Controller consists of a fully integrated media access controller (MAC) and network physical (PHY) interface device. The Ethernet Controller conforms to IEEE 802.3 specifications and fully supports 10BASE-T and 100BASE-TX standards. The Ethernet Controller module has the following features: ■ Conforms to the IEEE 802.3-2002 specification – 10BASE-T/100BASE-TX IEEE-802.3 compliant. Requires only a dual 1:1 isolation transformer interface to the line – 10BASE-T/100BASE-TX ENDEC, 100BASE-TX scrambler/descrambler – Full-featured auto-negotiation ■ Multiple operational modes – Full- and half-duplex 100 Mbps – Full- and half-duplex 10 Mbps – Power-saving and power-down modes ■ Highly configurable – Programmable MAC address – LED activity selection – Promiscuous mode support – CRC error-rejection control – User-configurable interrupts ■ Physical media manipulation – Automatic MDI/MDI-X cross-over correction – Register-programmable transmit amplitude – Automatic polarity correction and 10BASE-T signal reception November 30, 2007 409 Preliminary LM3S6952 Microcontroller 16.1 Block Diagram Figure 16-1. Ethernet Controller Block Diagram MACISR MACIACK MACIMR Interrupt Control MACRCR MACNPR Receive Control MACTCR MACITHR MACTRR Transmit Control Transmit FIFO Receive FIFO MACIAR0 MACIAR1 Individual Address MACMDTX MACMCR MACMDVR MACMAR MACMDRX MII Control MACDR Data Access TXOP TXON RXIP RXIN XTLP XTLN MDIX Clock Reference Transmit Encoding Pulse Shaping Receive Decoding Clock Recovery Auto Negotiation Carrier Sense MR3 MR0 MR1 MR2 MR4 Media Independent Interface Management Register Set MR5 MR18 MR6 MR16 MR17 MR19 MR23 MR24 Collision Detect System Clock Interrupt 16.2 Functional Description As shown in Figure 16-2 on page 410, the Ethernet Controller is functionally divided into two layers or modules: the Media Access Controller (MAC) layer and the Network Physical (PHY) layer. These correspond to the OSI model layers 2 and 1. The primary interface to the Ethernet Controller is a simple bus interface to the MAC layer. The MAC layer provides transmit and receive processing for Ethernet frames. The MAC layer also provides the interface to the PHY module via an internal Media Independent Interface (MII). Figure 16-2. Ethernet Controller Cortex M3 Media Access Controller MAC (Layer 2) Physical Layer Entity PHY (Layer 1) Magnetics RJ45 Ethernet Controller 16.2.1 Internal MII Operation For the MII management interface to function properly, the MDIO signal must be connected through a 10k Ω pull-up resistor to the +3.3 V supply. Failure to connect this pull-up resistor will prevent management transactions on this internal MII to function. Note that it is possible for data transmission across the MII to still function since the PHY layer will auto-negotiate the link parameters by default. 410 November 30, 2007 Preliminary Ethernet Controller For the MII management interface to function properly, the internal clock must be divided down from the system clock to a frequency no greater than 2.5 MHz. The MACMDV register contains the divider used for scaling down the system clock. See page 430 for more details about the use of this register. 16.2.2 PHY Configuration/Operation The Physical Layer (PHY) in the Ethernet Controller includes integrated ENDECs, scrambler/descrambler, dual-speed clock recovery, and full-featured auto-negotiation functions. The transmitter includes an on-chip pulse shaper and a low-power line driver. The receiver has an adaptive equalizer and a baseline restoration circuit required for accurate clock and data recovery. The transceiver interfaces to Category-5 unshielded twisted pair (Cat-5 UTP) cabling for 100BASE-TX applications, and Category-3 unshielded twisted pair (Cat-3 UTP) for 10BASE-T applications. The Ethernet Controller is connected to the line media via dual 1:1 isolation transformers. No external filter is required. 16.2.2.1 Clock Selection The PHY has an on-chip crystal oscillator which can also be driven by an external oscillator. In this mode of operation, a 25-MHz crystal should be connected between the XTALPPHY and XTALNPHY pins. Alternatively, an external 25-MHz clock input can be connected to the XTALPPHY pin. In this mode of operation, a crystal is not required and the XTALNPHY pin must be tied to ground. 16.2.2.2 Auto-Negotiation The PHY supports the auto-negotiation functions of Clause 28 of the IEEE 802.3 standard for 10/100 Mbps operation over copper wiring. This function can be enabled via register settings. The auto-negotiation function defaults to On and the ANEGEN bit in the MR0 register is High after reset. Software can disable the auto-negotiation function by writing to the ANEGEN bit. The contents of the MR4 register are sent to the PHY’s link partner during auto-negotiation via fast-link pulse coding. Once auto-negotiation is complete, the DPLX and RATE bits in the MR18 register reflect the actual speed and duplex that was chosen. If auto-negotiation fails to establish a link for any reason, the ANEGF bit in the MR18 register reflects this and auto-negotiation restarts from the beginning. Writing a 1 to the RANEG bit in the MR0 register also causes auto-negotiation to restart. 16.2.2.3 Polarity Correction The PHY is capable of either automatic or manual polarity reversal for 10BASE-T and auto-negotiation functions. Bits 4 and 5 (RVSPOL and APOL) in the MR16 register control this feature. The default is automatic mode, where APOL is Low and RVSPOL indicates if the detection circuitry has inverted the input signal. To enter manual mode, APOL should be set High and RVSPOL then controls the signal polarity. 16.2.2.4 MDI/MDI-X Configuration The PHY supports the automatic MDI/MDI-X configuration as defined in IEEE 802.3-2002 specification. This eliminates the need for cross-over cables when connecting to another device, such as a hub. The algorithm is controlled via settings in the MR24 register. Refer to page 452 for additional details about these settings. 16.2.2.5 LED Indicators The PHY supports two LED signals that can be used to indicate various states of operation of the Ethernet Controller. These signals are mapped to the LED0 and LED1 pins. By default, these pins are configured as GPIO signals (PF3 and PF2). For the PHY layer to drive these signals, they must be reconfigured to their hardware function. See “General-Purpose Input/Outputs (GPIOs)” on page November 30, 2007 411 Preliminary LM3S6952 Microcontroller 163 for additional details. The function of these pins is programmable via the PHY layer MR23 register. Refer to page 451 for additonal details on how to program these LED functions. 16.2.3 MAC Configuration/Operation 16.2.3.1 Ethernet Frame Format Ethernet data is carried by Ethernet frames. The basic frame format is shown in Figure 16-3 on page 412. Figure 16-3. Ethernet Frame Preamble SFD Destination Address Source Address Length/ Type Data FCS 7 Bytes 6 Bytes 6 Bytes 2 Bytes 1 Byte 4 Bytes 46 - 1500 Bytes The seven fields of the frame are transmitted from left to right. The bits within the frame are transmitted from least to most significant bit. ■ Preamble The Preamble field is used by the physical layer signaling circuitry to synchronize with the received frame’s timing. The preamble is 7 octets long. ■ Start Frame Delimiter (SFD) The SFD field follows the preamble pattern and indicates the start of the frame. Its value is 1010.1011. ■ Destination Address (DA) This field specifies destination addresses for which the frame is intended. The LSB of the DA determines whether the address is an individual (0), or group/multicast (1) address. ■ Source Address (SA) The source address field identifies the station from which the frame was initiated. ■ Length/Type Field The meaning of this field depends on its numeric value. The first of two octets is most significant. This field can be interpreted as length or type code. The maximum length of the data field is 1500 octets. If the value of the Length/Type field is less than or equal to 1500 decimal, it indicates the number of MAC client data octets. If the value of this field is greater than or equal to 1536 decimal, then it is type interpretation. The meaning of the Length/Type field when the value is between 1500 and 1536 decimal is unspecified by the standard. The MAC module assumes type interpretation if the value of the Length/Type field is greater than 1500 decimal. ■ Data The data field is a sequence of 0 to 1500 octets. Full data transparency is provided so any values can appear in this field. A minimum frame size is required to properly meet the IEEE standard. If necessary, the data field is extended by appending extra bits (a pad). The pad field can have a size of 0 to 46 octets. The sum of the data and pad lengths must be a minimum of 46 octets. The MAC module automatically inserts pads if required, though it can be disabled by a register 412 November 30, 2007 Preliminary Ethernet Controller write. For the MAC module core, data sent/received can be larger than 1500 bytes, and no Frame Too Long error is reported. Instead, a FIFO Overrun error is reported when the frame received is too large to fit into the Ethernet Controller’s RAM. ■ Frame Check Sequence (FCS) The frame check sequence carries the cyclic redundancy check (CRC) value. The value of this field is computed over destination address, source address, length/type, data, and pad fields using the CRC-32 algorithm. The MAC module computes the FCS value one nibble at a time. For transmitted frames, this field is automatically inserted by the MAC layer, unless disabled by the CRC bit in the MACTCTL register. For received frames, this field is automatically checked. If the FCS does not pass, the frame will not be placed in the RX FIFO, unless the FCS check is disabled by the BADCRC bit in the MACRCTL register. 16.2.3.2 MAC Layer FIFOs For Ethernet frame transmission, a 2 KB TX FIFO is provided that can be used to store a single frame. While the IEEE 802.3 specification limits the size of an Ethernet frame's payload section to 1500 Bytes, the Ethernet Controller places no such limit. The full buffer can be used, for a payload of up to 2032 bytes. For Ethernet frame reception, a 2-KB RX FIFO is provided that can be used to store multiple frames, up to a maximum of 31 frames. If a frame is received and there is insufficient space in the RX FIFO, an overflow error will be indicated. For details regarding the TX and RX FIFO layout, refer to Table 16-1 on page 413. Please note the following difference between TX and RX FIFO layout. For the TX FIFO, the Data Length field in the first FIFO word refers to the Ethernet frame data payload, as shown in the 5th to nth FIFO positions. For the RX FIFO, the Frame Length field is the total length of the received Ethernet frame, including the FCS and Frame Length bytes. Also note that if FCS generation is disabled with the CRC bit in the MACTCTL register, the last word in the FIFO must be the FCS bytes for the frame that has been written to the FIFO. Also note that if the length of the data payload section is not a multiple of 4, the FCS field will overlap words in the FIFO. However, for the RX FIFO, the beginning of the next frame will always be on a word boundary. Table 16-1. TX & RX FIFO Organization FIFO Word Read/Write Word Bit Fields TX FIFO (Write) RX FIFO (Read) Sequence 1st 7:0 Data Length LSB Frame Length LSB 15:8 Data Length MSB Frame Length MSB 23:16 DA oct 1 31:24 DA oct 2 2nd 7:0 DA oct 3 15:8 DA oct 4 23:16 DA oct 5 31:24 DA oct 6 3rd 7:0 SA oct 1 15:8 SA oct 2 23:16 SA oct 3 31:24 SA oct 4 November 30, 2007 413 Preliminary LM3S6952 Microcontroller FIFO Word Read/Write Word Bit Fields TX FIFO (Write) RX FIFO (Read) Sequence 4th 7:0 SA oct 5 15:8 SA oct 6 23:16 Len/Type MSB 31:24 Len/Type LSB 5th to nth 7:0 data oct n 15:8 data oct n+1 23:16 data oct n+2 31:24 data oct n+3 FCS 1 (if the CRC bit in FCS 1 MACCTL is 0) last 7:0 FCS 2 (if the CRC bit in FCS 2 MACCTL is 0) 15:8 FCS 3 (if the CRC bit in FCS 3 MACCTL is 0) 23:16 FCS 4 (if the CRC bit in FCS 4 MACCTL is 0) 31:24 16.2.3.3 Ethernet Transmission Options The Ethernet Controller can automatically generate and insert the Frame Check Sequence (FCS) at the end of the transmit frame. This is controlled by the CRC bit in the MACTCTL register. For test purposes, in order to generate a frame with an invalid CRC, this feature can be disabled. The IEEE 802.3 specification requires that the Ethernet frame payload section be a minimum of 46 bytes. The Ethernet Controller can be configured to automatically pad the data section if the payload data section loaded into the FIFO is less than the minimum 46 bytes. This feature is controlled by the PADEN bit in the MACTCTL register. At the MAC layer, the transmitter can be configured for both full-duplex and half-duplex operation by using the DUPLEX bit in the MACTCTL register. 16.2.3.4 Ethernet Reception Options Using the BADCRC bit in the MACRCTL register, the Ethernet Controller can be configured to reject incoming Ethernet frames with an invalid FCS field. The Ethernet receiver can also be configured for Promiscuous and Multicast modes using the PRMS and AMUL fields in the MACRCTL register. If these modes are not enabled, only Ethernet frames with a broadcast address, or frames matching the MAC address programmed into the MACIA0 and MACIA1 register will be placed into the RX FIFO. 16.2.4 Interrupts The Ethernet Controller can generate an interrupt for one or more of the following conditions: ■ A frame has been received into an empty RX FIFO ■ A frame transmission error has occurred ■ A frame has been transmitted successfully ■ A frame has been received with no room in the RX FIFO (overrun) 414 November 30, 2007 Preliminary Ethernet Controller ■ A frame has been received with one or more error conditions (for example, FCS failed) ■ An MII management transaction between the MAC and PHY layers has completed ■ One or more of the following PHY layer conditions occurs: – Auto-Negotiate Complete – Remote Fault – Link Status Change – Link Partner Acknowledge – Parallel Detect Fault – Page Received – Receive Error – Jabber Event Detected 16.3 Initialization and Configuration To use the Ethernet Controller, the peripheral must be enabled by setting the EPHY0 and EMAC0 bits in the RCGC2 register. The following steps can then be used to configure the Ethernet Controller for basic operation. 1. Program the MACDIV register to obtain a 2.5 MHz clock (or less) on the internal MII. Assuming a 20-MHz system clock, the MACDIV value would be 4. 2. Program the MACIA0 and MACIA1 register for address filtering. 3. Program the MACTCTL register for Auto CRC generation, padding, and full-duplex operation using a value of 0x16. 4. Program the MACRCTL register to reject frames with bad FCS using a value of 0x08. 5. Enable both the Transmitter and Receive by setting the LSB in both the MACTCTL and MACRCTL registers. 6. To transmit a frame, write the frame into the TX FIFO using the MACDATA register. Then set the NEWTX bit in the MACTR register to initiate the transmit process. When the NEWTX bit has been cleared, the TX FIFO will be available for the next transmit frame. 7. To receive a frame, wait for the NPR field in the MACNP register to be non-zero. Then begin reading the frame from the RX FIFO by using the MACDATA register. When the frame (including the FCS field) has been read, the NPR field should decrement by one. When there are no more frames in the RX FIFO, the NPR field will read 0. 16.4 Ethernet Register Map Table 16-2 on page 416 lists the Ethernet MAC registers. All addresses given are relative to the Ethernet MAC base address of 0x4004.8000. November 30, 2007 415 Preliminary LM3S6952 Microcontroller The IEEE 802.3 standard specifies a register set for controlling and gathering status from the PHY. The registers are collectively known as the MII Management registers and are detailed in Section 22.2.4 of the IEEE 802.3 specification. Table 16-2 on page 416 also lists these MII Management registers. All addresses given are absolute and are written directly to the REGADR field of the MACMCTL register. The format of registers 0 to 15 are defined by the IEEE specification and are common to all PHY implementations. The only variance allowed is for features that may or may not be supported by a specific PHY. Registers 16 to 31 are vendor-specific registers, used to support features that are specific to a vendors PHY implementation. Vendor-specific registers not listed are reserved. Table 16-2. Ethernet Register Map See Offset Name Type Reset Description page Ethernet MAC 0x000 MACRIS RO 0x0000.0000 Ethernet MAC Raw Interrupt Status 418 0x000 MACIACK W1C 0x0000.0000 Ethernet MAC Interrupt Acknowledge 420 0x004 MACIM R/W 0x0000.007F Ethernet MAC Interrupt Mask 421 0x008 MACRCTL R/W 0x0000.0008 Ethernet MAC Receive Control 422 0x00C MACTCTL R/W 0x0000.0000 Ethernet MAC Transmit Control 423 0x010 MACDATA R/W 0x0000.0000 Ethernet MAC Data 424 0x014 MACIA0 R/W 0x0000.0000 Ethernet MAC Individual Address 0 426 0x018 MACIA1 R/W 0x0000.0000 Ethernet MAC Individual Address 1 427 0x01C MACTHR R/W 0x0000.003F Ethernet MAC Threshold 428 0x020 MACMCTL R/W 0x0000.0000 Ethernet MAC Management Control 429 0x024 MACMDV R/W 0x0000.0080 Ethernet MAC Management Divider 430 0x02C MACMTXD R/W 0x0000.0000 Ethernet MAC Management Transmit Data 431 0x030 MACMRXD R/W 0x0000.0000 Ethernet MAC Management Receive Data 432 0x034 MACNP RO 0x0000.0000 Ethernet MAC Number of Packets 433 0x038 MACTR R/W 0x0000.0000 Ethernet MAC Transmission Request 434 MII Management - MR0 R/W 0x3100 Ethernet PHY Management Register 0 – Control 435 - MR1 RO 0x7849 Ethernet PHY Management Register 1 – Status 437 Ethernet PHY Management Register 2 – PHY Identifier 439 - MR2 RO 0x000E 1 Ethernet PHY Management Register 3 – PHY Identifier 440 - MR3 RO 0x7237 2 Ethernet PHYManagement Register 4 – Auto-Negotiation 441 - MR4 R/W 0x01E1 Advertisement Ethernet PHYManagement Register 5 – Auto-Negotiation 443 - MR5 RO 0x0000 Link Partner Base Page Ability 416 November 30, 2007 Preliminary Ethernet Controller See Offset Name Type Reset Description page Ethernet PHYManagement Register 6 – Auto-Negotiation 444 - MR6 RO 0x0000 Expansion Ethernet PHY Management Register 16 – 445 - MR16 R/W 0x0140 Vendor-Specific Ethernet PHY Management Register 17 – Interrupt 447 - MR17 R/W 0x0000 Control/Status - MR18 RO 0x0000 Ethernet PHY Management Register 18 – Diagnostic 449 Ethernet PHY Management Register 19 – Transceiver 450 - MR19 R/W 0x4000 Control Ethernet PHY Management Register 23 – LED 451 - MR23 R/W 0x0010 Configuration Ethernet PHY Management Register 24 –MDI/MDIX 452 - MR24 R/W 0x00C0 Control 16.5 Ethernet MAC Register Descriptions The remainder of this section lists and describes the Ethernet MAC registers, in numerical order by address offset. Also see “MII Management Register Descriptions” on page 434. November 30, 2007 417 Preliminary LM3S6952 Microcontroller Register 1: Ethernet MAC Raw Interrupt Status (MACRIS), offset 0x000 The MACRIS register is the interrupt status register. On a read, this register gives the current status value of the corresponding interrupt prior to masking. Ethernet MAC Raw Interrupt Status (MACRIS) Base 0x4004.8000 Offset 0x000 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PHYINT MDINT RXER FOV TXEMP TXER RXINT Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0x0 PHY Interrupt When set, indicates that an enabled interrupt in the PHY layer has occured. MR17 in the PHY must be read to determine the specific PHY event that triggered this interrupt. 6 PHYINT RO 0x0 MII Transaction Complete When set, indicates that a transaction (read or write) on the MII interface has completed successfully. 5 MDINT RO 0x0 Receive Error This bit indicates that an error was encountered on the receiver. The possible errors that can cause this interrupt bit to be set are: ■ A receive error occurs during the reception of a frame (100 Mb/s only). ■ The frame is not an integer number of bytes (dribble bits) due to an alignment error. ■ The CRC of the frame does not pass the FCS check. ■ The length/type field is inconsistent with the frame data size when interpreted as a length field. 4 RXER RO 0x0 FIFO Overrrun When set, indicates that an overrun was encountered on the receive FIFO. 3 FOV RO 0x0 Transmit FIFO Empty When set, indicates that the packet was transmitted and that the TX FIFO is empty. 2 TXEMP RO 0x0 418 November 30, 2007 Preliminary Ethernet Controller Bit/Field Name Type Reset Description Transmit Error When set, indicates that an error was encountered on the transmitter. The possible errors that can cause this interrupt bit to be set are: ■ The data length field stored in the TX FIFO exceeds 2032. The frame is not sent when this error occurs. ■ The retransmission attempts during the backoff process have exceeded the maximum limit of 16. 1 TXER RO 0x0 Packet Received When set, indicates that at least one packet has been received and is stored in the receiver FIFO. 0 RXINT RO 0x0 November 30, 2007 419 Preliminary LM3S6952 Microcontroller Register 2: Ethernet MAC Interrupt Acknowledge (MACIACK), offset 0x000 A write of a 1 to any bit position of this register clears the corresponding interrupt bit in the Ethernet MAC Raw Interrupt Status (MACRIS) register. Ethernet MAC Interrupt Acknowledge (MACIACK) Base 0x4004.8000 Offset 0x000 Type W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PHYINT MDINT RXER FOV TXEMP TXER RXINT Type RO RO RO RO RO RO RO RO RO W1C W1C W1C W1C W1C W1C W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0x0 Clear PHY Interrupt A write of a 1 clears the PHYINT interrupt read from the MACRIS register. 6 PHYINT W1C 0x0 Clear MII Transaction Complete A write of a 1 clears the MDINT interrupt read from the MACRIS register. 5 MDINT W1C 0x0 Clear Receive Error A write of a 1 clears the RXER interrupt read from the MACRIS register. 4 RXER W1C 0x0 Clear FIFO Overrun A write of a 1 clears the FOV interrupt read from the MACRIS register. 3 FOV W1C 0x0 Clear Transmit FIFO Empty A write of a 1 clears the TXEMP interrupt read from the MACRIS register. 2 TXEMP W1C 0x0 Clear Transmit Error A write of a 1 clears the TXER interrupt read from the MACRIS register and resets the TX FIFO write pointer. 1 TXER W1C 0x0 Clear Packet Received A write of a 1 clears the RXINT interrupt read from the MACRIS register. 0 RXINT W1C 0x0 420 November 30, 2007 Preliminary Ethernet Controller Register 3: Ethernet MAC Interrupt Mask (MACIM), offset 0x004 This register allows software to enable/disable Ethernet MAC interrupts. Writing a 0 disables the interrupt, while writing a 1 enables it. Ethernet MAC Interrupt Mask (MACIM) Base 0x4004.8000 Offset 0x004 Type R/W, reset 0x0000.007F 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PHYINTM MDINTM RXERM FOVM TXEMPM TXERM RXINTM Type RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:7 reserved RO 0x0 Mask PHY Interrupt This bit masks the PHYINT bit in the MACRIS register from being asserted. 6 PHYINTM R/W 1 Mask MII Transaction Complete This bit masks the MDINT bit in the MACRIS register from being asserted. 5 MDINTM R/W 1 Mask Receive Error This bit masks the RXER bit in the MACRIS register from being asserted. 4 RXERM R/W 1 Mask FIFO Overrrun This bit masks the FOV bit in the MACRIS register from being asserted. 3 FOVM R/W 1 Mask Transmit FIFO Empty This bit masks the TXEMP bit in the MACRIS register from being asserted. 2 TXEMPM R/W 1 Mask Transmit Error This bit masks the TXER bit in the MACRIS register from being asserted. 1 TXERM R/W 1 Mask Packet Received This bit masks the RXINT bit in the MACRIS register from being asserted. 0 RXINTM R/W 1 November 30, 2007 421 Preliminary LM3S6952 Microcontroller Register 4: Ethernet MAC Receive Control (MACRCTL), offset 0x008 This register enables software to configure the receive module and control the types of frames that are received from the physical medium. It is important to note that when the receive module is enabled, all valid frames with a broadcast address of FF-FF-FF-FF-FF-FF in the Destination Address field will be received and stored in the RX FIFO, even if the AMUL bit is not set. Ethernet MAC Receive Control (MACRCTL) Base 0x4004.8000 Offset 0x008 Type R/W, reset 0x0000.0008 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved RSTFIFO BADCRC PRMS AMUL RXEN Type RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:5 reserved RO 0x0 Clear Receive FIFO When set, clears the receive FIFO. This should be done when software initialization is performed. It is recommended that the receiver be disabled (RXEN = 0), and then the reset initiated (RSTFIFO = 1). This sequence will flush and reset the RX FIFO. 4 RSTFIFO R/W 0x0 Enable Reject Bad CRC The BADCRC bit enables the rejection of frames with an incorrectly calculated CRC. 3 BADCRC R/W 0x1 Enable Promiscuous Mode The PRMS bit enables Promiscuous mode, which accepts all valid frames, regardless of the Destination Address. 2 PRMS R/W 0x0 Enable Multicast Frames The AMUL bit enables the reception of multicast frames from the physical medium. 1 AMUL R/W 0x0 Enable Receiver The RXEN bit enables the Ethernet receiver. When this bit is Low, the receiver is disabled and all frames on the physical medium are ignored. 0 RXEN R/W 0x0 422 November 30, 2007 Preliminary Ethernet Controller Register 5: Ethernet MAC Transmit Control (MACTCTL), offset 0x00C This register enables software to configure the transmit module, and control frames are placed onto the physical medium. Ethernet MAC Transmit Control (MACTCTL) Base 0x4004.8000 Offset 0x00C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DUPLEX reserved CRC PADEN TXEN Type RO RO RO RO RO RO RO RO RO RO RO R/W RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:5 reserved RO 0x0 Enable Duplex Mode When set, enables Duplex mode, allowing simultaneous transmission and reception. 4 DUPLEX R/W 0x0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3 reserved RO 0x0 Enable CRC Generation When set, enables the automatic generation of the CRC and the placement at the end of the packet. If this bit is not set, the frames placed in the TX FIFO will be sent exactly as they are written into the FIFO. 2 CRC R/W 0x0 Enable Packet Padding When set, enables the automatic padding of packets that do not meet the minimum frame size. 1 PADEN R/W 0x0 Enable Transmitter When set, enables the transmitter. When this bit is 0, the transmitter is disabled. 0 TXEN R/W 0x0 November 30, 2007 423 Preliminary LM3S6952 Microcontroller Register 6: Ethernet MAC Data (MACDATA), offset 0x010 This register enables software to access the TX and RX FIFOs. Reads from this register return the data stored in the RX FIFO from the location indicated by the read pointer. Writes to this register store the data in the TX FIFO at the location indicated by the write pointer. The write pointer is then auto-incremented to the next TX FIFO location. There is no mechanism for randomly accessing bytes in either the RX or TX FIFOs. Data must be read from the RX FIFO sequentially and stored in a buffer for further processing. Once a read has been performed, the data in the FIFO cannot be re-read. Data must be written to the TX FIFO sequentially. If an error is made in placing the frame into the TX FIFO, the write pointer can be reset to the start of the TX FIFO by writing the TXER bit of the MACIACK register and then the data re-written. Read-Only Register Ethernet MAC Data (MACDATA) Base 0x4004.8000 Offset 0x010 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 RXDATA Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RXDATA Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Receive FIFO Data The RXDATA bits represent the next four bytes of data stored in the RX FIFO. 31:0 RXDATA RO 0x0 Write-Only Register Ethernet MAC Data (MACDATA) Base 0x4004.8000 Offset 0x010 Type WO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 TXDATA Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TXDATA Type WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO WO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 424 November 30, 2007 Preliminary Ethernet Controller Bit/Field Name Type Reset Description Transmit FIFO Data The TXDATA bits represent the next four bytes of data to place in the TX FIFO for transmission. 31:0 TXDATA WO 0x0 November 30, 2007 425 Preliminary LM3S6952 Microcontroller Register 7: Ethernet MAC Individual Address 0 (MACIA0), offset 0x014 This register enables software to program the first four bytes of the hardware MAC address of the Network Interface Card (NIC). (The last two bytes are in MACIA1). The 6-byte IAR is compared against the incoming Destination Address fields to determine whether the frame should be received. Ethernet MAC Individual Address 0 (MACIA0) Base 0x4004.8000 Offset 0x014 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 MACOCT4 MACOCT3 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MACOCT2 MACOCT1 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description MAC Address Octet 4 The MACOCT4 bits represent the fourth octet of the MAC address used to uniquely identify each Ethernet Controller. 31:24 MACOCT4 R/W 0x0 MAC Address Octet 3 The MACOCT3 bits represent the third octet of the MAC address used to uniquely identify each Ethernet Controller. 23:16 MACOCT3 R/W 0x0 MAC Address Octet 2 The MACOCT2 bits represent the second octet of the MAC address used to uniquely identify each Ethernet Controller. 15:8 MACOCT2 R/W 0x0 MAC Address Octet 1 The MACOCT1 bits represent the first octet of the MAC address used to uniquely identify each Ethernet Controller. 7:0 MACOCT1 R/W 0x0 426 November 30, 2007 Preliminary Ethernet Controller Register 8: Ethernet MAC Individual Address 1 (MACIA1), offset 0x018 This register enables software to program the last two bytes of the hardware MAC address of the Network Interface Card (NIC). (The first four bytes are in MACIA0). The 6-byte IAR is compared against the incoming Destination Address fields to determine whether the frame should be received. Ethernet MAC Individual Address 1 (MACIA1) Base 0x4004.8000 Offset 0x018 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MACOCT6 MACOCT5 Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0 MAC Address Octet 6 The MACOCT6 bits represent the sixth octet of the MAC address used to uniquely identify each Ethernet Controller. 15:8 MACOCT6 R/W 0x0 MAC Address Octet 5 The MACOCT5 bits represent the fifth octet of the MAC address used to uniquely identify each Ethernet Controller. 7:0 MACOCT5 R/W 0x0 November 30, 2007 427 Preliminary LM3S6952 Microcontroller Register 9: Ethernet MAC Threshold (MACTHR), offset 0x01C This register enables software to set the threshold level at which the transmission of the frame begins. If the THRESH bits are set to 0x3F, which is the reset value, transmission does not start until the NEWTX bit is set in the MACTR register. This effectively disables the early transmission feature. Writing the THRESH bits to any value besides all 1s enables the early transmission feature. Once the byte count of data in the TX FIFO reaches this level, transmission of the frame begins. When THRESH is set to all 0s, transmission of the frame begins after 4 bytes (a single write) are stored in the TX FIFO. Each increment of the THRESH bit field waits for an additional 32 bytes of data (eight writes) to be stored in the TX FIFO. Therefore, a value of 0x01 would wait for 36 bytes of data to be written while a value of 0x02 would wait for 68 bytes to be written. In general, early transmission starts when: Number of Bytes >= 4 (THRESH x 8 + 1) Reaching the threshold level has the same effect as setting the NEWTX bit in the MACTR register. Transmission of the frame begins and then the number of bytes indicated by the Data Length field is sent out on the physical medium. Because under-run checking is not performed, it is possible that the tail pointer may reach and pass the write pointer in the TX FIFO. This causes indeterminate values to be written to the physical medium rather than the end of the frame. Therefore, sufficient bus bandwidth for writing to the TX FIFO must be guaranteed by the software. If a frame smaller than the threshold level needs to be sent, the NEWTX bit in the MACTR register must be set with an explicit write. This initiates the transmission of the frame even though the threshold limit has not been reached. If the threshold level is set too small, it is possible for the transmitter to underrun. If this occurs, the transmit frame is aborted, and a transmit error occurs. Ethernet MAC Threshold (MACTHR) Base 0x4004.8000 Offset 0x01C Type R/W, reset 0x0000.003F 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved THRESH Type RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0x0 Threshold Value The THRESH bits represent the early transmit threshold. Once the amount of data in the TX FIFO exceeds this value, transmission of the packet begins. 5:0 THRESH R/W 0x3F 428 November 30, 2007 Preliminary Ethernet Controller Register 10: Ethernet MAC Management Control (MACMCTL), offset 0x020 This register enables software to control the transfer of data to and from the MII Management registers in the Ethernet PHY. The address, name, type, reset configuration, and functional description of each of these registers can be found in Table 16-2 on page 416 and in “MII Management Register Descriptions” on page 434. In order to initiate a read transaction from the MII Management registers, the WRITE bit must be written with a 0 during the same cycle that the START bit is written with a 1. In order to initiate a write transaction to the MII Management registers, the WRITE bit must be written with a 1 during the same cycle that the START bit is written with a 1. Ethernet MAC Management Control (MACMCTL) Base 0x4004.8000 Offset 0x020 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved REGADR reserved WRITE START Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x0 MII Register Address The REGADR bit field represents the MII Management register address for the next MII management interface transaction. 7:3 REGADR R/W 0x0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2 reserved RO 0x0 MII Register Transaction Type The WRITE bit represents the operation of the next MII management interface transaction. If WRITE is set, the next operation will be a write; otherwise, it will be a read. 1 WRITE R/W 0x0 MII Register Transaction Enable The START bit represents the initiation of the next MII management interface transaction. When a 1 is written to this bit, the MII register located at REGADR will be read (WRITE=0) or written (WRITE=1). 0 START R/W 0x0 November 30, 2007 429 Preliminary LM3S6952 Microcontroller Register 11: Ethernet MAC Management Divider (MACMDV), offset 0x024 This register enables software to set the clock divider for the Management Data Clock (MDC). This clock is used to synchronize read and write transactions between the system and the MII Management registers. The frequency of the MDC clock can be calculated from the following formula: Fmdc = Fipclk / (2 * (MACMDVR + 1 )) The clock divider must be written with a value that ensures that the MDC clock will not exceed a frequency of 2.5 MHz. Ethernet MAC Management Divider (MACMDV) Base 0x4004.8000 Offset 0x024 Type R/W, reset 0x0000.0080 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved DIV Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:8 reserved RO 0x0 Clock Divider The DIV bits are used to set the clock divider for the MDC clock used to transmit data between the MAC and PHY over the serial MII interface. 7:0 DIV R/W 0x80 430 November 30, 2007 Preliminary Ethernet Controller Register 12: Ethernet MAC Management Transmit Data (MACMTXD), offset 0x02C This register holds the next value to be written to the MII Management registers. Ethernet MAC Management Transmit Data (MACMTXD) Base 0x4004.8000 Offset 0x02C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MDTX Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0 MII Register Transmit Data The MDTX bits represent the data that will be written in the next MII management transaction. 15:0 MDTX R/W 0x0 November 30, 2007 431 Preliminary LM3S6952 Microcontroller Register 13: Ethernet MAC Management Receive Data (MACMRXD), offset 0x030 This register holds the last value read from the MII Management registers. Ethernet MAC Management Receive Data (MACMRXD) Base 0x4004.8000 Offset 0x030 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MDRX Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:16 reserved RO 0x0 MII Register Receive Data The MDRX bits represent the data that was read in the previous MII management transaction. 15:0 MDRX R/W 0x0 432 November 30, 2007 Preliminary Ethernet Controller Register 14: Ethernet MAC Number of Packets (MACNP), offset 0x034 This register holds the number of frames that are currently in the RX FIFO. When NPR is 0, there are no frames in the RX FIFO and the RXINT bit is not set. When NPR is any other value, there is at least one frame in the RX FIFO and the RXINT bit in the MACRIS register is set. Ethernet MAC Number of Packets (MACNP) Base 0x4004.8000 Offset 0x034 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved NPR Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:6 reserved RO 0x0 Number of Packets in Receive FIFO The NPR bits represent the number of packets stored in the RX FIFO. While the NPR field is greater than 0, the RXINT interrupt in the MACRIS register will be asserted. 5:0 NPR RO 0x0 November 30, 2007 433 Preliminary LM3S6952 Microcontroller Register 15: Ethernet MAC Transmission Request (MACTR), offset 0x038 This register enables software to initiate the transmission of the frame currently located in the TX FIFO to the physical medium. Once the frame has been transmitted to the medium from the TX FIFO or a transmission error has been encountered, the NEWTX bit is auto-cleared by the hardware. Ethernet MAC Transmission Request (MACTR) Base 0x4004.8000 Offset 0x038 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved NEWTX Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:1 reserved RO 0x0 New Transmission When set, the NEWTX bit initiates an Ethernet transmission once the packet has been placed in the TX FIFO. This bit is cleared once the transmission has been completed. If early transmission is being used (see the MACTHR register), this bit does not need to be set. 0 NEWTX R/W 0x0 16.6 MII Management Register Descriptions The IEEE 802.3 standard specifies a register set for controlling and gathering status from the PHY. The registers are collectively known as the MII Management registers. All addresses given are absolute. Addresses not listed are reserved. Also see “Ethernet MAC Register Descriptions” on page 417. 434 November 30, 2007 Preliminary Ethernet Controller Register 16: Ethernet PHY Management Register 0 – Control (MR0), address 0x00 This register enables software to configure the operation of the PHY. The default settings of these registers are designed to initialize the PHY to a normal operational mode without configuration. Ethernet PHY Management Register 0 – Control (MR0) Base 0x4004.8000 Address 0x00 Type R/W, reset 0x3100 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RESET LOOPBK SPEEDSL ANEGEN PWRDN ISO RANEG DUPLEX COLT reserved Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 1 1 0 0 0 1 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Reset Registers When set, resets the registers to their default state and reinitializes internal state machines. Once the reset operation has completed, this bit is cleared by hardware. 15 RESET R/W 0 Loopback Mode When set, enables the Loopback mode of operation. The receive circuitry is isolated from the physical medium and transmissions are sent back through the receive circuitry instead of the medium. 14 LOOPBK R/W 0 Speed Select 1: Enables the 100 Mb/s mode of operation (100BASE-TX). 0: Enables the 10 Mb/s mode of operation (10BASE-T). 13 SPEEDSL R/W 1 Auto-Negotiation Enable When set, enables the Auto-Negotiation process. 12 ANEGEN R/W 1 Power Down When set, places the PHY into a low-power consuming state. 11 PWRDN R/W 0 Isolate When set, isolates transmit and receive data paths and ignores all signaling on these buses. 10 ISO R/W 0 Restart Auto-Negotiation When set, restarts the Auto-Negotiation process. Once the restart has initiated, this bit is cleared by hardware. 9 RANEG R/W 0 Set Duplex Mode 1: Enables the Full-Duplex mode of operation. This bit can be set by software in a manual configuration process or by the Auto-Negotiation process. 0: Enables the Half-Duplex mode of operation. 8 DUPLEX R/W 1 November 30, 2007 435 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Collision Test When set, enables the Collision Test mode of operation. The COLT bit asserts after the initiation of a transmission and de-asserts once the transmission is halted. 7 COLT R/W 0 6:0 reserved R/W 0x00 Write as 0, ignore on read. 436 November 30, 2007 Preliminary Ethernet Controller Register 17: Ethernet PHY Management Register 1 – Status (MR1), address 0x01 This register enables software to determine the capabilities of the PHY and perform its initialization and operation appropriately. Ethernet PHY Management Register 1 – Status (MR1) Base 0x4004.8000 Address 0x01 Type RO, reset 0x7849 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved 100X_F 100X_H 10T_F 10T_H reserved MFPS ANEGC RFAULT ANEGA LINK JAB EXTD Type RO RO RO RO RO RO RO RO RO RO RO RC RO RO RC RO Reset 0 1 1 1 1 0 0 0 0 1 0 0 1 0 0 1 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15 reserved RO 0 100BASE-TX Full-Duplex Mode When set, indicates that the PHY is capable of supporting 100BASE-TX Full-Duplex mode. 14 100X_F RO 1 100BASE-TX Half-Duplex Mode When set, indicates that the PHY is capable of supporting 100BASE-TX Half-Duplex mode. 13 100X_H RO 1 10BASE-T Full-Duplex Mode When set, indicates that the PHY is capable of 10BASE-T Full-Duplex mode. 12 10T_F RO 1 10BASE-T Half-Duplex Mode When set, indicates that the PHY is capable of supporting 10BASE-T Half-Duplex mode. 11 10T_H RO 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 10:7 reserved RO 0 Management Frames with Preamble Suppressed When set, indicates that the Management Interface is capable of receiving management frames with the preamble suppressed. 6 MFPS RO 1 Auto-Negotiation Complete When set, indicates that the Auto-Negotiation process has been completed and that the extended registers defined by the Auto-Negotiation protocol are valid. 5 ANEGC RO 0 Remote Fault When set, indicates that a remote fault condition has been detected. This bit remains set until it is read, even if the condition no longer exists. 4 RFAULT RC 0 November 30, 2007 437 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Auto-Negotiation When set, indicates that the PHY has the ability to perform Auto-Negotiation. 3 ANEGA RO 1 Link Made When set, indicates that a valid link has been established by the PHY. 2 LINK RO 0 Jabber Condition When set, indicates that a jabber condition has been detected by the PHY. This bit remains set until it is read, even if the jabber condition no longer exists. 1 JAB RC 0 Extended Capabilities When set, indicates that the PHY provides an extended set of capabilities that can be accessed through the extended register set. 0 EXTD RO 1 438 November 30, 2007 Preliminary Ethernet Controller Register 18: Ethernet PHY Management Register 2 – PHY Identifier 1 (MR2), address 0x02 This register, along with MR3, provides a 32-bit value indicating the manufacturer, model, and revision information. Ethernet PHY Management Register 2 – PHY Identifier 1 (MR2) Base 0x4004.8000 Address 0x02 Type RO, reset 0x000E 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 OUI[21:6] Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 Bit/Field Name Type Reset Description Organizationally Unique Identifier[21:6] This field, along with the OUI[5:0] field in MR3, makes up the Organizationally Unique Identifier indicating the PHY manufacturer. 15:0 OUI[21:6] RO 0x000E November 30, 2007 439 Preliminary LM3S6952 Microcontroller Register 19: Ethernet PHY Management Register 3 – PHY Identifier 2 (MR3), address 0x03 This register, along with MR2, provides a 32-bit value indicating the manufacturer, model, and revision information. Ethernet PHY Management Register 3 – PHY Identifier 2 (MR3) Base 0x4004.8000 Address 0x03 Type RO, reset 0x7237 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 OUI[5:0] MN RN Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 1 1 1 0 0 1 0 0 0 1 1 0 1 1 1 Bit/Field Name Type Reset Description Organizationally Unique Identifier[5:0] This field, along with the OUI[21:6] field in MR2, makes up the Organizationally Unique Identifier indicating the PHY manufacturer. 15:10 OUI[5:0] RO 0x1C Model Number The MN field represents the Model Number of the PHY. 9:4 MN RO 0x23 Revision Number The RN field represents the Revision Number of the PHY. 3:0 RN RO 0x7 440 November 30, 2007 Preliminary Ethernet Controller Register 20: Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4), address 0x04 This register provides the advertised abilities of the PHY used during Auto-Negotiation. Bits 8:5 represent the Technology Ability Field bits. This field can be overwritten by software to Auto-Negotiate to an alternate common technology. Writing to this register has no effect until Auto-Negotiation is re-initiated. Ethernet PHY Management Register 4 – Auto-Negotiation Advertisement (MR4) Base 0x4004.8000 Address 0x04 Type R/W, reset 0x01E1 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NP reserved RF reserved A3 A2 A1 A0 S[4:0] Type RO RO R/W RO RO RO RO R/W R/W R/W R/W RO RO RO RO RO Reset 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 Bit/Field Name Type Reset Description Next Page When set, indicates the PHY is capable of Next Page exchanges to provide more detailed information on the PHY’s capabilities. 15 NP RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 14 reserved RO 0 Remote Fault When set, indicates to the link partner that a Remote Fault condition has been encountered. 13 RF R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 12:9 reserved RO 0 Technology Ability Field[3] When set, indicates that the PHY supports the 100Base-TX full-duplex signaling protocol. If software wants to ensure that this mode is not used, this bit can be written to 0 and Auto-Negotiation re-initiated with the RANEG bit in the MR0 register. 8 A3 R/W 1 Technology Ability Field[2] When set, indicates that the PHY supports the 100Base-T half-duplex signaling protocol. If software wants to ensure that this mode is not used, this bit can be written to 0 and Auto-Negotiation re-initiated. 7 A2 R/W 1 Technology Ability Field[1] When set, indicates that the PHY supports the 10Base-T full-duplex signaling protocol. If software wants to ensure that this mode is not used, this bit can be written to 0 and Auto-Negotiation re-initiated. 6 A1 R/W 1 Technology Ability Field[0] When set, indicates that the PHY supports the 10Base-T half-duplex signaling protocol. If software wants to ensure that this mode is not used, this bit can be written to 0 and Auto-Negotiation re-initiated. 5 A0 R/W 1 November 30, 2007 441 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Selector Field The S[4:0] field encodes 32 possible messages for communicating between PHYs. This field is hard-coded to 0x01, indicating that the Stellaris® PHY is IEEE 802.3 compliant. 4:0 S[4:0] RO 0x01 442 November 30, 2007 Preliminary Ethernet Controller Register 21: Ethernet PHY Management Register 5 – Auto-Negotiation Link Partner Base Page Ability (MR5), address 0x05 This register provides the advertised abilities of the link partner’s PHY that are received and stored during Auto-Negotiation. Ethernet PHY Management Register 5 – Auto-Negotiation Link Partner Base Page Ability (MR5) Base 0x4004.8000 Address 0x05 Type RO, reset 0x0000 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NP ACK RF A[7:0] S[4:0] Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Next Page When set, indicates that the link partner’s PHY is capable of Next page exchanges to provide more detailed information on the PHY’s capabilities. 15 NP RO 0 Acknowledge When set, indicates that the device has successfully received the link partner’s advertised abilities during Auto-Negotiation. 14 ACK RO 0 Remote Fault Used as a standard transport mechanism for transmitting simple fault information. 13 RF RO 0 Technology Ability Field The A[7:0] field encodes individual technologies that are supported by the PHY. See the MR4 register. 12:5 A[7:0] RO 0x00 Selector Field The S[4:0] field encodes possible messages for communicating between PHYs. Value Description 0x00 Reserved 0x01 IEEE Std 802.3 0x02 IEEE Std 802.9 ISLAN-16T 0x03 IEEE Std 802.5 0x04 IEEE Std 1394 0x05–0x1F Reserved 4:0 S[4:0] RO 0x00 November 30, 2007 443 Preliminary LM3S6952 Microcontroller Register 22: Ethernet PHY Management Register 6 – Auto-Negotiation Expansion (MR6), address 0x06 This register enables software to determine the Auto-Negotiation and Next Page capabilities of the PHY and the link partner after Auto-Negotiation. Ethernet PHY Management Register 6 – Auto-Negotiation Expansion (MR6) Base 0x4004.8000 Address 0x06 Type RO, reset 0x0000 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PDF LPNPA reserved PRX LPANEGA Type RO RO RO RO RO RO RO RO RO RO RO RC RO RO RC RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:5 reserved RO 0x000 Parallel Detection Fault When set, indicates that more than one technology has been detected at link up. This bit is cleared when read. 4 PDF RC 0 Link Partner is Next Page Able When set, indicates that the link partner is Next Page Able. 3 LPNPA RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 2 reserved RO 0x000 New Page Received When set, indicates that a New Page has been received from the link partner and stored in the appropriate location. This bit remains set until the register is read. 1 PRX RC 0 Link Partner is Auto-Negotiation Able When set, indicates that the Link partner is Auto-Negotiation Able. 0 LPANEGA RO 0 444 November 30, 2007 Preliminary Ethernet Controller Register 23: Ethernet PHY Management Register 16 – Vendor-Specific (MR16), address 0x10 This register enables software to configure the operation of vendor-specific modes of the PHY. Ethernet PHY Management Register 16 – Vendor-Specific (MR16) Base 0x4004.8000 Address 0x10 Type R/W, reset 0x0140 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 RPTR INPOL reserved TXHIM SQEI NL10 reserved APOL RVSPOL reserved PCSBP RXCC Type R/W R/W RO R/W R/W R/W RO RO RO RO R/W R/W RO RO R/W R/W Reset 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 Bit/Field Name Type Reset Description Repeater Mode When set, enables the repeater mode of operation. In this mode, full-duplex is not allowed and the Carrier Sense signal only responds to receive activity. If the PHY is configured to 10Base-T mode, the SQE test function is disabled. 15 RPTR R/W 0 Interrupt Polarity 1: Sets the polarity of the PHY interrupt to be active High. 0: Sets the polarity of the PHY interrupt to active Low. Important: Because the Media Access Controller expects active Low interrupts from the PHY, this bit must always be written with a 0 to ensure proper operation. 14 INPOL R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 13 reserved RO 0 Transmit High Impedance Mode When set, enables the transmitter High Impedance mode. In this mode, the TXOP and TXON transmitter pins are put into a high impedance state. The RXIP and RXIN pins remain fully functional. 12 TXHIM R/W 0 SQE Inhibit Testing When set, prohibits 10Base-T SQE testing. When 0, the SQE testing is performed by generating a Collision pulse following the completion of the transmission of a frame. 11 SQEI R/W 0 Natural Loopback Mode When set, enables the 10Base-T Natural Loopback mode. This causes the transmission data received by the PHY to be looped back onto the receive data path when 10Base-T mode is enabled. 10 NL10 R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 9:6 reserved RO 0x05 November 30, 2007 445 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Auto-Polarity Disable When set, disables the PHY’s auto-polarity function. If this bit is 0, the PHY automatically inverts the received signal due to a wrong polarity connection during Auto-Negotiation if the PHY is in 10Base-T mode. 5 APOL R/W 0 Receive Data Polarity This bit indicates whether the receive data pulses are being inverted. If the APOL bit is 0, then the RVSPOL bit is read-only and indicates whether the auto-polarity circuitry is reversing the polarity. In this case, a 1 in the RVSPOL bit indicates that the receive data is inverted while a 0 indicates that the receive data is not inverted. If the APOL bit is 1, then the RVSPOL bit is writable and software can force the receive data to be inverted. Setting RVSPOL to 1 forces the receive data to be inverted while a 0 does not invert the receive data. 4 RVSPOL R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 3:2 reserved RO 0 PCS Bypass When set, enables the bypass of the PCS and scrambling/descrambling functions in 100Base-TX mode. This mode is only valid when Auto-Negotiation is disabled and 100Base-T mode is enabled. 1 PCSBP R/W 0 Receive Clock Control When set, enables the Receive Clock Control power saving mode if the PHY is configured in 100Base-TX mode. This mode shuts down the receive clock when no data is being received from the physical medium to save power. This mode should not be used when PCSBP is enabled and is automatically disabled when the LOOPBK bit in the MR0 register is set. 0 RXCC R/W 0 446 November 30, 2007 Preliminary Ethernet Controller Register 24: Ethernet PHY Management Register 17 – Interrupt Control/Status (MR17), address 0x11 This register provides the means for controlling and observing the events, which trigger a PHY interrupt in the MACRIS register. This register can also be used in a polling mode via the MII Serial Interface as a means to observe key events within the PHY via one register address. Bits 0 through 7 are status bits, which are each set to logic 1 based on an event. These bits are cleared after the register is read. Bits 8 through 15 of this register, when set to logic 1, enable their corresponding bit in the lower byte to signal a PHY interrupt in the MACRIS register. Ethernet PHY Management Register 17 – Interrupt Control/Status (MR17) Base 0x4004.8000 Address 0x11 Type R/W, reset 0x0000 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 JABBER_IE RXER_IE PRX_IE PDF_IE LPACK_IELSCHG_IE RFAULT_IE ANEGCOMP_IE JABBER_INTRXER_INT PRX_INT PDF_INT LPACK_INT LSCHG_INT RFAULT_INT ANEGCOMP_INT Type R/W R/W R/W R/W R/W R/W R/W R/W RC RC RC RC RC RC RC RC Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Jabber Interrupt Enable When set, enables system interrupts when a Jabber condition is detected by the PHY. 15 JABBER_IE R/W 0 Receive Error Interrupt Enable When set, enables system interrupts when a receive error is detected by the PHY. 14 RXER_IE R/W 0 Page Received Interrupt Enable When set, enables system interrupts when a new page is received by the PHY. 13 PRX_IE R/W 0 Parallel Detection Fault Interrupt Enable When set, enables system interrupts when a Parallel Detection Fault is detected by the PHY. 12 PDF_IE R/W 0 LP Acknowledge Interrupt Enable When set, enables system interrupts when FLP bursts are received with the Acknowledge bit during Auto-Negotiation. 11 LPACK_IE R/W 0 Link Status Change Interrupt Enable When set, enables system interrupts when the Link Status changes from OK to FAIL. 10 LSCHG_IE R/W 0 Remote Fault Interrupt Enable When set, enables system interrupts when a Remote Fault condition is signaled by the link partner. 9 RFAULT_IE R/W 0 Auto-Negotiation Complete Interrupt Enable When set, enables system interrupts when the Auto-Negotiation sequence has completed successfully. 8 ANEGCOMP_IE R/W 0 November 30, 2007 447 Preliminary LM3S6952 Microcontroller Bit/Field Name Type Reset Description Jabber Event Interrupt When set, indicates that a Jabber event has been detected by the 10Base-T circuitry. 7 JABBER_INT RC 0 Receive Error Interrupt When set, indicates that a receive error has been detected by the PHY. 6 RXER_INT RC 0 Page Receive Interrupt When set, indicates that a new page has been received from the link partner during Auto-Negotiation. 5 PRX_INT RC 0 Parallel Detection Fault Interrupt When set, indicates that a Parallel Detection Fault has been detected by the PHY during the Auto-Negotiation process. 4 PDF_INT RC 0 LP Acknowledge Interrupt When set, indicates that an FLP burst has been received with the Acknowledge bit set during Auto-Negotiation. 3 LPACK_INT RC 0 Link Status Change Interrupt When set, indicates that the link status has changed from OK to FAIL. 2 LSCHG_INT RC 0 Remote Fault Interrupt When set, indicates that a Remote Fault condition has been signaled by the link partner. 1 RFAULT_INT RC 0 Auto-Negotiation Complete Interrupt When set, indicates that the Auto-Negotiation sequence has completed successfully. 0 ANEGCOMP_INT RC 0 448 November 30, 2007 Preliminary Ethernet Controller Register 25: Ethernet PHY Management Register 18 – Diagnostic (MR18), address 0x12 This register enables software to diagnose the results of the previous Auto-Negotiation. Ethernet PHY Management Register 18 – Diagnostic (MR18) Base 0x4004.8000 Address 0x12 Type RO, reset 0x0000 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved ANEGF DPLX RATE RXSD RX_LOCK reserved Type RO RO RO RC RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:13 reserved RO 0 Auto-Negotiation Failure When set, indicates that no common technology was found during Auto-Negotiation and has failed. This bit remains set until read. 12 ANEGF RC 0 Duplex Mode When set, indicates that Full-Duplex was the highest common denominator found during the Auto-Negotiation process. Otherwise, Half-Duplex was the highest common denominator found. 11 DPLX RO 0 Rate When set, indicates that 100Base-TX was the highest common denominator found during the Auto-Negotiation process. Otherwise, 10Base-TX was the highest common denominator found. 10 RATE RO 0 Receive Detection When set, indicates that receive signal detection has occurred (in 100Base-TX mode) or that Manchester-encoded data has been detected (in 10Base-T mode). 9 RXSD RO 0 Receive PLL Lock When set, indicates that the Receive PLL has locked onto the receive signal for the selected speed of operation (10Base-T or 100Base-TX). 8 RX_LOCK RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:0 reserved RO 00 November 30, 2007 449 Preliminary LM3S6952 Microcontroller Register 26: Ethernet PHY Management Register 19 – Transceiver Control (MR19), address 0x13 This register enables software to set the gain of the transmit output to compensate for transformer loss. Ethernet PHY Management Register 19 – Transceiver Control (MR19) Base 0x4004.8000 Address 0x13 Type R/W, reset 0x4000 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 TXO[1:0] reserved Type R/W R/W RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Transmit Amplitude Selection The TXO[1:0] field sets the transmit output amplitude to account for transmit transformer insertion loss. Value Description 0x0 Gain set for 0.0dB of insertion loss 0x1 Gain set for 0.4dB of insertion loss 0x2 Gain set for 0.8dB of insertion loss 0x3 Gain set for 1.2dB of insertion loss 15:14 TXO[1:0] R/W 1 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 13:0 reserved RO 0x0 450 November 30, 2007 Preliminary Ethernet Controller Register 27: Ethernet PHY Management Register 23 – LED Configuration (MR23), address 0x17 This register enables software to select the source that will cause the LEDs to toggle. Ethernet PHY Management Register 23 – LED Configuration (MR23) Base 0x4004.8000 Address 0x17 Type R/W, reset 0x0010 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved LED1[3:0] LED0[3:0] Type RO RO RO RO RO RO RO RO R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:8 reserved RO 0x0 LED1 Source The LED1 field selects the source that will toggle the LED1 signal. Value Description 0x0 Link OK 0x1 RX or TX Activity (Default LED1) 0x2 TX Activity 0x3 RX Activity 0x4 Collision 0x5 100BASE-TX mode 0x6 10BASE-T mode 0x7 Full-Duplex 0x8 Link OK & Blink=RX or TX Activity 7:4 LED1[3:0] R/W 1 LED0 Source The LED0 field selects the source that will toggle the LED0 signal. Value Description 0x0 Link OK (Default LED0) 0x1 RX or TX Activity 0x2 TX Activity 0x3 RX Activity 0x4 Collision 0x5 100BASE-TX mode 0x6 10BASE-T mode 0x7 Full-Duplex 0x8 Link OK & Blink=RX or TX Activity 3:0 LED0[3:0] R/W 0 November 30, 2007 451 Preliminary LM3S6952 Microcontroller Register 28: Ethernet PHY Management Register 24 –MDI/MDIX Control (MR24), address 0x18 This register enables software to control the behavior of the MDI/MDIX mux and its switching capabilities. Ethernet PHY Management Register 24 –MDI/MDIX Control (MR24) Base 0x4004.8000 Address 0x18 Type R/W, reset 0x00C0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PD_MODEAUTO_SW MDIX MDIX_CM MDIX_SD Type RO RO RO RO RO RO RO RO R/W R/W R/W RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 15:8 reserved RO 0x0 Parallel Detection Mode When set, enables the Parallel Detection mode and allows auto-switching to work when Auto-Negotiation is not enabled. 7 PD_MODE R/W 0 Auto-Switching Enable When set, enables Auto-Switching of the MDI/MDIX mux. 6 AUTO_SW R/W 0 Auto-Switching Configuration When set, indicates that the MDI/MDIX mux is in the crossover (MDIX) configuration. When 0, it indicates that the mux is in the pass-through (MDI) configuration. When the AUTO_SW bit is 1, the MDIX bit is read-only. When the AUTO_SW bit is 0, the MDIX bit is read/write and can be configured manually. 5 MDIX R/W 0 Auto-Switching Complete When set, indicates that the auto-switching sequence has completed. If 0, it indicates that the sequence has not completed or that auto-switching is disabled. 4 MDIX_CM RO 0 Auto-Switching Seed This field provides the initial seed for the switching algorithm. This seed directly affects the number of attempts [5,4] respectively to write bits [3:0]. A 0 sets the seed to 0x5. 3:0 MDIX_SD R/W 0 452 November 30, 2007 Preliminary Ethernet Controller 17 Analog Comparators An analog comparator is a peripheral that compares two analog voltages, and provides a logical output that signals the comparison result. The LM3S6952 controller provides three independent integrated analog comparators that can be configured to drive an output or generate an interrupt or ADC event. Note: Not all comparators have the option to drive an output pin. See the Comparator Operating Mode tables for more information. A comparator can compare a test voltage against any one of these voltages: ■ An individual external reference voltage ■ A shared single external reference voltage ■ A shared internal reference voltage The comparator can provide its output to a device pin, acting as a replacement for an analog comparator on the board, or it can be used to signal the application via interrupts or triggers to the ADC to cause it to start capturing a sample sequence. The interrupt generation and ADC triggering logic is separate. This means, for example, that an interrupt can be generated on a rising edge and the ADC triggered on a falling edge. November 30, 2007 453 Preliminary LM3S6952 Microcontroller 17.1 Block Diagram Figure 17-1. Analog Comparator Module Block Diagram interrupt C2+ C2- output +ve input (alternate) +ve input interrupt -ve input reference input Comparator 2 ACSTAT2 ACCTL2 interrupt C1- C1+ output +ve input (alternate) +ve input interrupt -ve input reference input Comparator 1 ACSTAT1 ACCTL1 C1o Voltage Ref ACREFCTL output +ve input (alternate) +ve input interrupt -ve input reference input Comparator 0 ACSTAT0 ACCTL0 C0+ internal bus interrupt C0- C0o trigger trigger trigger trigger trigger trigger 17.2 Functional Description Important: It is recommended that the Digital-Input enable (the GPIODEN bit in the GPIO module) for the analog input pin be disabled to prevent excessive current draw from the I/O pads. The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT. VIN- < VIN+, VOUT = 1 VIN- > VIN+, VOUT = 0 As shown in Figure 17-2 on page 455, the input source for VIN- is an external input. In addition to an external input, input sources for VIN+ can be the +ve input of comparator 0 or an internal reference. 454 November 30, 2007 Preliminary Analog Comparators Figure 17-2. Structure of Comparator Unit ACCTL ACSTAT IntGen 2 TrigGen 1 0 CINV output -ve input +ve input interrupt internal bus trigger +ve input (alternate) reference input A comparator is configured through two status/control registers (ACCTL and ACSTAT ). The internal reference is configured through one control register (ACREFCTL). Interrupt status and control is configured through three registers (ACMIS, ACRIS, and ACINTEN). The operating modes of the comparators are shown in the Comparator Operating Mode tables. Typically, the comparator output is used internally to generate controller interrupts. It may also be used to drive an external pin or generate an analog-to-digital converter (ADC) trigger. Important: Certain register bit values must be set before using the analog comparators. The proper pad configuration for the comparator input and output pins are described in the Comparator Operating Mode tables. Table 17-1. Comparator 0 Operating Modes ACCNTL0 Comparator 0 ASRCP VIN- VIN+ Output Interrupt ADCTrigger 00 C0- C0+ C0o yes yes 01 C0- C0+ C0o yes yes 10 C0- Vref C0o yes yes 11 C0- reserved C0o yes yes Table 17-2. Comparator 1 Operating Modes ACCNTL1 Comparator 1 ASRCP VIN- VIN+ Output Interrupt ADCTrigger 00 C1- C1o/C1+ C1o/C1+ yes yes 01 C1- C0+ C1o/C1+ yes yes 10 C1- Vref C1o/C1+ yes yes 11 C1- reserved C1o/C1+ yes yes November 30, 2007 455 Preliminary LM3S6952 Microcontroller Table 17-3. Comparator 2 Operating Modes ACCNTL2 Comparator 2 ASRCP VIN- VIN+ Output Interrupt ADCTrigger 00 C2- C2+ n/a yes yes 01 C2- C0+ n/a yes yes 10 C2- Vref n/a yes yes 11 C2- reserved n/a yes yes 17.2.1 Internal Reference Programming The structure of the internal reference is shown in Figure 17-3 on page 456. This is controlled by a single configuration register (ACREFCTL). Table 17-4 on page 456 shows the programming options to develop specific internal reference values, to compare an external voltage against a particular voltage generated internally. Figure 17-3. Comparator Internal Reference Structure 8R R R 8R R R ••• ••• 0 Decoder 15 14 1 AVDD EN internal reference VREF RNG Table 17-4. Internal Reference Voltage and ACREFCTL Field Values ACREFCTL Register Output Reference Voltage Based on VREF Field Value EN Bit Value RNG Bit Value 0 V (GND) for any value of VREF; however, it is recommended that RNG=1 and VREF=0 for the least noisy ground reference. EN=0 RNG=X 456 November 30, 2007 Preliminary Analog Comparators ACREFCTL Register Output Reference Voltage Based on VREF Field Value EN Bit Value RNG Bit Value Total resistance in ladder is 32 R. VREF AVDD R V REF RT = × ---------------- VREF AVDD (VREF + 8) 32 = × ------------------------------ VR EF = 0.825 + 0.103 VREF The range of internal reference in this mode is 0.825-2.37 V. EN=1 RNG=0 Total resistance in ladder is 24 R. VREF AVDD R V REF RT = × ---------------- VREF AVDD (VREF) 24 = × -------------------- VREF = 0.1375 x VREF The range of internal reference for this mode is 0.0-2.0625 V. RNG=1 17.3 Initialization and Configuration The following example shows how to configure an analog comparator to read back its output value from an internal register. 1. Enable the analog comparator 0 clock by writing a value of 0x0010.0000 to the RCGC1 register in the System Control module. 2. In the GPIO module, enable the GPIO port/pin associated with C0- as a GPIO input. 3. Configure the internal voltage reference to 1.65 V by writing the ACREFCTL register with the value 0x0000.030C. 4. Configure comparator 0 to use the internal voltage reference and to not invert the output on the C0o pin by writing the ACCTL0 register with the value of 0x0000.040C. 5. Delay for some time. 6. Read the comparator output value by reading the ACSTAT0 register’s OVAL value. Change the level of the signal input on C0- to see the OVAL value change. 17.4 Register Map Table 17-5 on page 458 lists the comparator registers. The offset listed is a hexadecimal increment to the register’s address, relative to the Analog Comparator base address of 0x4003.C000. November 30, 2007 457 Preliminary LM3S6952 Microcontroller Table 17-5. Analog Comparators Register Map See Offset Name Type Reset Description page 0x00 ACMIS R/W1C 0x0000.0000 Analog Comparator Masked Interrupt Status 459 0x04 ACRIS RO 0x0000.0000 Analog Comparator Raw Interrupt Status 460 0x08 ACINTEN R/W 0x0000.0000 Analog Comparator Interrupt Enable 461 0x10 ACREFCTL R/W 0x0000.0000 Analog Comparator Reference Voltage Control 462 0x20 ACSTAT0 RO 0x0000.0000 Analog Comparator Status 0 463 0x24 ACCTL0 R/W 0x0000.0000 Analog Comparator Control 0 464 0x40 ACSTAT1 RO 0x0000.0000 Analog Comparator Status 1 463 0x44 ACCTL1 R/W 0x0000.0000 Analog Comparator Control 1 464 0x60 ACSTAT2 RO 0x0000.0000 Analog Comparator Status 2 463 0x64 ACCTL2 R/W 0x0000.0000 Analog Comparator Control 2 464 17.5 Register Descriptions The remainder of this section lists and describes the Analog Comparator registers, in numerical order by address offset. 458 November 30, 2007 Preliminary Analog Comparators Register 1: Analog Comparator Masked Interrupt Status (ACMIS), offset 0x00 This register provides a summary of the interrupt status (masked) of the comparator. Analog Comparator Masked Interrupt Status (ACMIS) Base 0x4003.C000 Offset 0x00 Type R/W1C, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IN2 IN1 IN0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO R/W1C R/W1C R/W1C Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 Comparator 2 Masked Interrupt Status Gives the masked interrupt state of this interrupt. Write 1 to this bit to clear the pending interrupt. 2 IN2 R/W1C 0 Comparator 1 Masked Interrupt Status Gives the masked interrupt state of this interrupt. Write 1 to this bit to clear the pending interrupt. 1 IN1 R/W1C 0 Comparator 0 Masked Interrupt Status Gives the masked interrupt state of this interrupt. Write 1 to this bit to clear the pending interrupt. 0 IN0 R/W1C 0 November 30, 2007 459 Preliminary LM3S6952 Microcontroller Register 2: Analog Comparator Raw Interrupt Status (ACRIS), offset 0x04 This register provides a summary of the interrupt status (raw) of the comparator. Analog Comparator Raw Interrupt Status (ACRIS) Base 0x4003.C000 Offset 0x04 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IN2 IN1 IN0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 Comparator 2 Interrupt Status When set, indicates that an interrupt has been generated by comparator 2. 2 IN2 RO 0 Comparator 1 Interrupt Status When set, indicates that an interrupt has been generated by comparator 1. 1 IN1 RO 0 Comparator 0 Interrupt Status When set, indicates that an interrupt has been generated by comparator 0. 0 IN0 RO 0 460 November 30, 2007 Preliminary Analog Comparators Register 3: Analog Comparator Interrupt Enable (ACINTEN), offset 0x08 This register provides the interrupt enable for the comparator. Analog Comparator Interrupt Enable (ACINTEN) Base 0x4003.C000 Offset 0x08 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IN2 IN1 IN0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:3 reserved RO 0x00 Comparator 2 Interrupt Enable When set, enables the controller interrupt from the comparator 2 output 2 IN2 R/W 0 Comparator 1 Interrupt Enable When set, enables the controller interrupt from the comparator 1 output. 1 IN1 R/W 0 Comparator 0 Interrupt Enable When set, enables the controller interrupt from the comparator 0 output. 0 IN0 R/W 0 November 30, 2007 461 Preliminary LM3S6952 Microcontroller Register 4: Analog Comparator Reference Voltage Control (ACREFCTL), offset 0x10 This register specifies whether the resistor ladder is powered on as well as the range and tap. Analog Comparator Reference Voltage Control (ACREFCTL) Base 0x4003.C000 Offset 0x10 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved EN RNG reserved VREF Type RO RO RO RO RO RO R/W R/W RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:10 reserved RO 0x00 Resistor Ladder Enable The EN bit specifies whether the resistor ladder is powered on. If 0, the resistor ladder is unpowered. If 1, the resistor ladder is connected to the analog VDD. This bit is reset to 0 so that the internal reference consumes the least amount of power if not used and programmed. 9 EN R/W 0 Resistor Ladder Range The RNG bit specifies the range of the resistor ladder. If 0, the resistor ladder has a total resistance of 32 R. If 1, the resistor ladder has a total resistance of 24 R. 8 RNG R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 7:4 reserved RO 0x00 Resistor Ladder Voltage Ref The VREF bit field specifies the resistor ladder tap that is passed through an analog multiplexer. The voltage corresponding to the tap position is the internal reference voltage available for comparison. See Table 17-4 on page 456 for some output reference voltage examples. 3:0 VREF R/W 0x00 462 November 30, 2007 Preliminary Analog Comparators Register 5: Analog Comparator Status 0 (ACSTAT0), offset 0x20 Register 6: Analog Comparator Status 1 (ACSTAT1), offset 0x40 Register 7: Analog Comparator Status 2 (ACSTAT2), offset 0x60 These registers specify the current output value of the comparator. Analog Comparator Status 0 (ACSTAT0) Base 0x4003.C000 Offset 0x20 Type RO, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved OVAL reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Comparator Output Value The OVAL bit specifies the current output value of the comparator. 1 OVAL RO 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 November 30, 2007 463 Preliminary LM3S6952 Microcontroller Register 8: Analog Comparator Control 0 (ACCTL0), offset 0x24 Register 9: Analog Comparator Control 1 (ACCTL1), offset 0x44 Register 10: Analog Comparator Control 2 (ACCTL2), offset 0x64 These registers configure the comparator’s input and output. Analog Comparator Control 0 (ACCTL0) Base 0x4003.C000 Offset 0x24 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved TOEN ASRCP reserved TSLVAL TSEN ISLVAL ISEN CINV reserved Type RO RO RO RO R/W R/W R/W RO R/W R/W R/W R/W R/W R/W R/W RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:12 reserved RO 0x00 Trigger Output Enable The TOEN bit enables the ADC event transmission to the ADC. If 0, the event is suppressed and not sent to the ADC. If 1, the event is transmitted to the ADC. 11 TOEN R/W 0 Analog Source Positive The ASRCP field specifies the source of input voltage to the VIN+ terminal of the comparator. The encodings for this field are as follows: Value Function 0x0 Pin value 0x1 Pin value of C0+ 0x2 Internal voltage reference 0x3 Reserved 10:9 ASRCP R/W 0x00 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 8 reserved RO 0 Trigger Sense Level Value The TSLVAL bit specifies the sense value of the input that generates an ADC event if in Level Sense mode. If 0, an ADC event is generated if the comparator output is Low. Otherwise, an ADC event is generated if the comparator output is High. 7 TSLVAL R/W 0 464 November 30, 2007 Preliminary Analog Comparators Bit/Field Name Type Reset Description Trigger Sense The TSEN field specifies the sense of the comparator output that generates an ADC event. The sense conditioning is as follows: Value Function 0x0 Level sense, see TSLVAL 0x1 Falling edge 0x2 Rising edge 0x3 Either edge 6:5 TSEN R/W 0x0 Interrupt Sense Level Value The ISLVAL bit specifies the sense value of the input that generates an interrupt if in Level Sense mode. If 0, an interrupt is generated if the comparator output is Low. Otherwise, an interrupt is generated if the comparator output is High. 4 ISLVAL R/W 0 Interrupt Sense The ISEN field specifies the sense of the comparator output that generates an interrupt. The sense conditioning is as follows: Value Function 0x0 Level sense, see ISLVAL 0x1 Falling edge 0x2 Rising edge 0x3 Either edge 3:2 ISEN R/W 0x0 Comparator Output Invert The CINV bit conditionally inverts the output of the comparator. If 0, the output of the comparator is unchanged. If 1, the output of the comparator is inverted prior to being processed by hardware. 1 CINV R/W 0 Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 0 reserved RO 0 November 30, 2007 465 Preliminary LM3S6952 Microcontroller 18 Pulse Width Modulator (PWM) Pulse width modulation (PWM) is a powerful technique for digitally encoding analog signal levels. High-resolution counters are used to generate a square wave, and the duty cycle of the square wave is modulated to encode an analog signal. Typical applications include switching power supplies and motor control. The Stellaris® PWM module consists of two PWM generator blocks and a control block. Each PWM generator block contains one timer (16-bit down or up/down counter), two PWM comparators, a PWM signal generator, a dead-band generator, and an interrupt/ADC-trigger selector. The control block determines the polarity of the PWM signals, and which signals are passed through to the pins. Each PWM generator block produces two PWM signals that can either be independent signals (other than being based on the same timer and therefore having the same frequency) or a single pair of complementary signals with dead-band delays inserted. The output of the PWM generation blocks are managed by the output control block before being passed to the device pins. The Stellaris® PWM module provides a great deal of flexibility. It can generate simple PWM signals, such as those required by a simple charge pump. It can also generate paired PWM signals with dead-band delays, such as those required by a half-H bridge driver. 18.1 Block Diagram Figure 18-1 on page 466 provides a block diagram of a Stellaris® PWM module. The LM3S6952 controller contains two generator blocks (PWM0 and PWM1) and generates four independent PWM signals or two paired PWM signals with dead-band delays inserted. Figure 18-1. PWM Module Block Diagram Interrupt and Trigger Generate PWMnINTEN PWMnRIS PWMnISC PWM Clock Interrupt Dead-Band Generator PWMnDBCTL PWMnDBRISE PWMnDBFALL PWM Output Control PWMENABLE PWMINVERT PWMFAULT PWM Generator PWMnGENA PWMnGENB pwma pwmb Timer PWMnLOAD PWMnCOUNT Comparator A PWMnCMPA Comparator B PWMnCMPB zero load dir 16 cmpA cmpB Fault PWM Generator Block 18.2 Functional Description 18.2.1 PWM Timer The timer in each PWM generator runs in one of two modes: Count-Down mode or Count-Up/Down mode. In Count-Down mode, the timer counts from the load value to zero, goes back to the load value, and continues counting down. In Count-Up/Down mode, the timer counts from zero up to the load value, back down to zero, back up to the load value, and so on. Generally, Count-Down mode 466 November 30, 2007 Preliminary Pulse Width Modulator (PWM) is used for generating left- or right-aligned PWM signals, while the Count-Up/Down mode is used for generating center-aligned PWM signals. The timers output three signals that are used in the PWM generation process: the direction signal (this is always Low in Count-Down mode, but alternates between Low and High in Count-Up/Down mode), a single-clock-cycle-width High pulse when the counter is zero, and a single-clock-cycle-width High pulse when the counter is equal to the load value. Note that in Count-Down mode, the zero pulse is immediately followed by the load pulse. 18.2.2 PWM Comparators There are two comparators in each PWM generator that monitor the value of the counter; when either match the counter, they output a single-clock-cycle-width High pulse. When in Count-Up/Down mode, these comparators match both when counting up and when counting down; they are therefore qualified by the counter direction signal. These qualified pulses are used in the PWM generation process. If either comparator match value is greater than the counter load value, then that comparator never outputs a High pulse. Figure 18-2 on page 467 shows the behavior of the counter and the relationship of these pulses when the counter is in Count-Down mode. Figure 18-3 on page 468 shows the behavior of the counter and the relationship of these pulses when the counter is in Count-Up/Down mode. Figure 18-2. PWM Count-Down Mode Load Zero CompB CompA Load Zero B A Dir ADown BDown November 30, 2007 467 Preliminary LM3S6952 Microcontroller Figure 18-3. PWM Count-Up/Down Mode Load Zero CompB CompA Load Zero B A Dir BUp AUp ADown BDown 18.2.3 PWM Signal Generator The PWM generator takes these pulses (qualified by the direction signal), and generates two PWM signals. In Count-Down mode, there are four events that can affect the PWM signal: zero, load, match A down, and match B down. In Count-Up/Down mode, there are six events that can affect the PWM signal: zero, load, match A down, match A up, match B down, and match B up. The match A or match B events are ignored when they coincide with the zero or load events. If the match A and match B events coincide, the first signal, PWMA, is generated based only on the match A event, and the second signal, PWMB, is generated based only on the match B event. For each event, the effect on each output PWM signal is programmable: it can be left alone (ignoring the event), it can be toggled, it can be driven Low, or it can be driven High. These actions can be used to generate a pair of PWM signals of various positions and duty cycles, which do or do not overlap. Figure 18-4 on page 468 shows the use of Count-Up/Down mode to generate a pair of center-aligned, overlapped PWM signals that have different duty cycles. Figure 18-4. PWM Generation Example In Count-Up/Down Mode Load Zero CompB CompA PWMB PWMA In this example, the first generator is set to drive High on match A up, drive Low on match A down, and ignore the other four events. The second generator is set to drive High on match B up, drive Low on match B down, and ignore the other four events. Changing the value of comparator A 468 November 30, 2007 Preliminary Pulse Width Modulator (PWM) changes the duty cycle of the PWMA signal, and changing the value of comparator B changes the duty cycle of the PWMB signal. 18.2.4 Dead-Band Generator The two PWM signals produced by the PWM generator are passed to the dead-band generator. If disabled, the PWM signals simply pass through unmodified. If enabled, the second PWM signal is lost and two PWM signals are generated based on the first PWM signal. The first output PWM signal is the input signal with the rising edge delayed by a programmable amount. The second output PWM signal is the inversion of the input signal with a programmable delay added between the falling edge of the input signal and the rising edge of this new signal. This is therefore a pair of active High signals where one is always High, except for a programmable amount of time at transitions where both are Low. These signals are therefore suitable for driving a half-H bridge, with the dead-band delays preventing shoot-through current from damaging the power electronics. Figure 18-5 on page 469 shows the effect of the dead-band generator on an input PWM signal. Figure 18-5. PWM Dead-Band Generator Input PWMA PWMB Rising Edge Delay Falling Edge Delay 18.2.5 Interrupt/ADC-Trigger Selector The PWM generator also takes the same four (or six) counter events and uses them to generate an interrupt or an ADC trigger. Any of these events or a set of these events can be selected as a source for an interrupt; when any of the selected events occur, an interrupt is generated. Additionally, the same event, a different event, the same set of events, or a different set of events can be selected as a source for an ADC trigger; when any of these selected events occur, an ADC trigger pulse is generated. The selection of events allows the interrupt or ADC trigger to occur at a specific position within the PWM signal. Note that interrupts and ADC triggers are based on the raw events; delays in the PWM signal edges caused by the dead-band generator are not taken into account. 18.2.6 Synchronization Methods There is a global reset capability that can synchronously reset any or all of the counters in the PWM generators. If multiple PWM generators are configured with the same counter load value, this can be used to guarantee that they also have the same count value (this does imply that the PWM generators must be configured before they are synchronized). With this, more than two PWM signals can be produced with a known relationship between the edges of those signals since the counters always have the same values. The counter load values and comparator match values of the PWM generator can be updated in two ways. The first is immediate update mode, where a new value is used as soon as the counter reaches zero. By waiting for the counter to reach zero, a guaranteed behavior is defined, and overly short or overly long output PWM pulses are prevented. The other update method is synchronous, where the new value is not used until a global synchronized update signal is asserted, at which point the new value is used as soon as the counter reaches zero. This second mode allows multiple items in multiple PWM generators to be updated November 30, 2007 469 Preliminary LM3S6952 Microcontroller simultaneously without odd effects during the update; everything runs from the old values until a point at which they all run from the new values. The Update mode of the load and comparator match values can be individually configured in each PWM generator block. It typically makes sense to use the synchronous update mechanism across PWM generator blocks when the timers in those blocks are synchronized, though this is not required in order for this mechanism to function properly. 18.2.7 Fault Conditions There are two external conditions that affect the PWM block; the signal input on the Fault pin and the stalling of the controller by a debugger. There are two mechanisms available to handle such conditions: the output signals can be forced into an inactive state and/or the PWM timers can be stopped. Each output signal has a fault bit. If set, a fault input signal causes the corresponding output signal to go into the inactive state. If the inactive state is a safe condition for the signal to be in for an extended period of time, this keeps the output signal from driving the outside world in a dangerous manner during the fault condition. A fault condition can also generate a controller interrupt. Each PWM generator can also be configured to stop counting during a stall condition. The user can select for the counters to run until they reach zero then stop, or to continue counting and reloading. A stall condition does not generate a controller interrupt. 18.2.8 Output Control Block With each PWM generator block producing two raw PWM signals, the output control block takes care of the final conditioning of the PWM signals before they go to the pins. Via a single register, the set of PWM signals that are actually enabled to the pins can be modified; this can be used, for example, to perform commutation of a brushless DC motor with a single register write (and without modifying the individual PWM generators, which are modified by the feedback control loop). Similarly, fault control can disable any of the PWM signals as well. A final inversion can be applied to any of the PWM signals, making them active Low instead of the default active High. 18.3 Initialization and Configuration The following example shows how to initialize the PWM Generator 0 with a 25-KHz frequency, and with a 25% duty cycle on the PWM0 pin and a 75% duty cycle on the PWM1 pin. This example assumes the system clock is 20 MHz. 1. Enable the PWM clock by writing a value of 0x0010.0000 to the RCGC0 register in the System Control module. 2. Enable the clock to the appropriate GPIO module via the RCGC2 register in the System Control module. 3. In the GPIO module, enable the appropriate pins for their alternate function using the GPIOAFSEL register. 4. Configure the Run-Mode Clock Configuration (RCC) register in the System Control module to use the PWM divide (USEPWMDIV) and set the divider (PWMDIV) to divide by 2 (000). 5. Configure the PWM generator for countdown mode with immediate updates to the parameters. ■ Write the PWM0CTL register with a value of 0x0000.0000. ■ Write the PWM0GENA register with a value of 0x0000.008C. 470 November 30, 2007 Preliminary Pulse Width Modulator (PWM) ■ Write the PWM0GENB register with a value of 0x0000.080C. 6. Set the period. For a 25-KHz frequency, the period = 1/25,000, or 40 microseconds. The PWM clock source is 10 MHz; the system clock divided by 2. This translates to 400 clock ticks per period. Use this value to set the PWM0LOAD register. In Count-Down mode, set the Load field in the PWM0LOAD register to the requested period minus one. ■ Write the PWM0LOAD register with a value of 0x0000.018F. 7. Set the pulse width of the PWM0 pin for a 25% duty cycle. ■ Write the PWM0CMPA register with a value of 0x0000.012B. 8. Set the pulse width of the PWM1 pin for a 75% duty cycle. ■ Write the PWM0CMPB register with a value of 0x0000.0063. 9. Start the timers in PWM generator 0. ■ Write the PWM0CTL register with a value of 0x0000.0001. 10. Enable PWM outputs. ■ Write the PWMENABLE register with a value of 0x0000.0003. 18.4 Register Map Table 18-1 on page 471 lists the PWM registers. The offset listed is a hexadecimal increment to the register’s address, relative to the PWM base address of 0x4002.8000. Table 18-1. PWM Register Map See Offset Name Type Reset Description page 0x000 PWMCTL R/W 0x0000.0000 PWM Master Control 473 0x004 PWMSYNC R/W 0x0000.0000 PWM Time Base Sync 474 0x008 PWMENABLE R/W 0x0000.0000 PWM Output Enable 475 0x00C PWMINVERT R/W 0x0000.0000 PWM Output Inversion 476 0x010 PWMFAULT R/W 0x0000.0000 PWM Output Fault 477 0x014 PWMINTEN R/W 0x0000.0000 PWM Interrupt Enable 478 0x018 PWMRIS RO 0x0000.0000 PWM Raw Interrupt Status 479 0x01C PWMISC R/W1C 0x0000.0000 PWM Interrupt Status and Clear 480 0x020 PWMSTATUS RO 0x0000.0000 PWM Status 481 0x040 PWM0CTL R/W 0x0000.0000 PWM0 Control 482 0x044 PWM0INTEN R/W 0x0000.0000 PWM0 Interrupt and Trigger Enable 484 0x048 PWM0RIS RO 0x0000.0000 PWM0 Raw Interrupt Status 486 0x04C PWM0ISC R/W1C 0x0000.0000 PWM0 Interrupt Status and Clear 487 November 30, 2007 471 Preliminary LM3S6952 Microcontroller See Offset Name Type Reset Description page 0x050 PWM0LOAD R/W 0x0000.0000 PWM0 Load 488 0x054 PWM0COUNT RO 0x0000.0000 PWM0 Counter 489 0x058 PWM0CMPA R/W 0x0000.0000 PWM0 Compare A 490 0x05C PWM0CMPB R/W 0x0000.0000 PWM0 Compare B 491 0x060 PWM0GENA R/W 0x0000.0000 PWM0 Generator A Control 492 0x064 PWM0GENB R/W 0x0000.0000 PWM0 Generator B Control 495 0x068 PWM0DBCTL R/W 0x0000.0000 PWM0 Dead-Band Control 498 0x06C PWM0DBRISE R/W 0x0000.0000 PWM0 Dead-Band Rising-Edge Delay 499 0x070 PWM0DBFALL R/W 0x0000.0000 PWM0 Dead-Band Falling-Edge-Delay 500 0x080 PWM1CTL R/W 0x0000.0000 PWM1 Control 482 0x084 PWM1INTEN R/W 0x0000.0000 PWM1 Interrupt and Trigger Enable 484 0x088 PWM1RIS RO 0x0000.0000 PWM1 Raw Interrupt Status 486 0x08C PWM1ISC R/W1C 0x0000.0000 PWM1 Interrupt Status and Clear 487 0x090 PWM1LOAD R/W 0x0000.0000 PWM1 Load 488 0x094 PWM1COUNT RO 0x0000.0000 PWM1 Counter 489 0x098 PWM1CMPA R/W 0x0000.0000 PWM1 Compare A 490 0x09C PWM1CMPB R/W 0x0000.0000 PWM1 Compare B 491 0x0A0 PWM1GENA R/W 0x0000.0000 PWM1 Generator A Control 492 0x0A4 PWM1GENB R/W 0x0000.0000 PWM1 Generator B Control 495 0x0A8 PWM1DBCTL R/W 0x0000.0000 PWM1 Dead-Band Control 498 0x0AC PWM1DBRISE R/W 0x0000.0000 PWM1 Dead-Band Rising-Edge Delay 499 0x0B0 PWM1DBFALL R/W 0x0000.0000 PWM1 Dead-Band Falling-Edge-Delay 500 18.5 Register Descriptions The remainder of this section lists and describes the PWM registers, in numerical order by address offset. 472 November 30, 2007 Preliminary Pulse Width Modulator (PWM) Register 1: PWM Master Control (PWMCTL), offset 0x000 This register provides master control over the PWM generation blocks. PWM Master Control (PWMCTL) Base 0x4002.8000 Offset 0x000 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved GlobalSync1 GlobalSync0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Update PWM Generator 1 Same as GlobalSync0 but for PWM generator 1. 1 GlobalSync1 R/W 0 Update PWM Generator 0 Setting this bit causes any queued update to a load or comparator register in PWM generator 0 to be applied the next time the corresponding counter becomes zero. This bit automatically clears when the updates have completed; it cannot be cleared by software. 0 GlobalSync0 R/W 0 November 30, 2007 473 Preliminary LM3S6952 Microcontroller Register 2: PWM Time Base Sync (PWMSYNC), offset 0x004 This register provides a method to perform synchronization of the counters in the PWM generation blocks. Writing a bit in this register to 1 causes the specified counter to reset back to 0; writing multiple bits resets multiple counters simultaneously. The bits auto-clear after the reset has occurred; reading them back as zero indicates that the synchronization has completed. PWM Time Base Sync (PWMSYNC) Base 0x4002.8000 Offset 0x004 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved Sync1 Sync0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:2 reserved RO 0x00 Reset Generator 1 Counter Performs a reset of the PWM generator 1 counter. 1 Sync1 R/W 0 Reset Generator 0 Counter Performs a reset of the PWM generator 0 counter. 0 Sync0 R/W 0 474 November 30, 2007 Preliminary Pulse Width Modulator (PWM) Register 3: PWM Output Enable (PWMENABLE), offset 0x008 This register provides a master control of which generated PWM signals are output to device pins. By disabling a PWM output, the generation process can continue (for example, when the time bases are synchronized) without driving PWM signals to the pins. When bits in this register are set, the corresponding PWM signal is passed through to the output stage, which is controlled by the PWMINVERT register. When bits are not set, the PWM signal is replaced by a zero value which is also passed to the output stage. PWM Output Enable (PWMENABLE) Base 0x4002.8000 Offset 0x008 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PWM3En PWM2En PWM1En PWM0En Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 PWM3 Output Enable When set, allows the generated PWM3 signal to be passed to the device pin. 3 PWM3En R/W 0 PWM2 Output Enable When set, allows the generated PWM2 signal to be passed to the device pin. 2 PWM2En R/W 0 PWM1 Output Enable When set, allows the generated PWM1 signal to be passed to the device pin. 1 PWM1En R/W 0 PWM0 Output Enable When set, allows the generated PWM0 signal to be passed to the device pin. 0 PWM0En R/W 0 November 30, 2007 475 Preliminary LM3S6952 Microcontroller Register 4: PWM Output Inversion (PWMINVERT), offset 0x00C This register provides a master control of the polarity of the PWM signals on the device pins. The PWM signals generated by the PWM generator are active High; they can optionally be made active Low via this register. Disabled PWM channels are also passed through the output inverter (if so configured) so that inactive channels maintain the correct polarity. PWM Output Inversion (PWMINVERT) Base 0x4002.8000 Offset 0x00C Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved PWM3Inv PWM2Inv PWM1Inv PWM0Inv Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 Invert PWM3 Signal When set, the generated PWM3 signal is inverted. 3 PWM3Inv R/W 0 Invert PWM2 Signal When set, the generated PWM2 signal is inverted. 2 PWM2Inv R/W 0 Invert PWM1 Signal When set, the generated PWM1 signal is inverted. 1 PWM1Inv R/W 0 Invert PWM0 Signal When set, the generated PWM0 signal is inverted. 0 PWM0Inv R/W 0 476 November 30, 2007 Preliminary Pulse Width Modulator (PWM) Register 5: PWM Output Fault (PWMFAULT), offset 0x010 This register controls the behavior of the PWM outputs in the presence of fault conditions. Both the fault input and debug events are considered fault conditions. On a fault condition, each PWM signal can either be passed through unmodified or driven Low. For outputs that are configured for pass-through, the debug event handling on the corresponding PWM generator also determines if the PWM signal continues to be generated. Fault condition control happens before the output inverter, so PWM signals driven Low on fault are inverted if the channel is configured for inversion (therefore, the pin is driven High on a fault condition). PWM Output Fault (PWMFAULT) Base 0x4002.8000 Offset 0x010 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved Fault3 Fault2 Fault1 Fault0 Type RO RO RO RO RO RO RO RO RO RO RO RO R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Bit/Field Name Type Reset Description Software should not rely on the value of a reserved bit. To provide compatibility with future products, the value of a reserved bit should be preserved across a read-modify-write operation. 31:4 reserved RO 0x00 PWM3 Driven Low on Fault When set, the PWM3 output signal is driven Low on a fault condition. 3 Fault3 R/W 0 PWM2 Driven Low on Fault When set, the PWM2 output signal is driven Low on a fault condition. 2 Fault2 R/W 0 PWM1 Driven Low on Fault When set, the PWM1 output signal is driven Low on a fault condition. 1 Fault1 R/W 0 PWM0 Driven Low on Fault When set, the PWM0 output signal is driven Low on a fault condition. 0 Fault0 R/W 0 November 30, 2007 477 Preliminary LM3S6952 Microcontroller Register 6: PWM Interrupt Enable (PWMINTEN), offset 0x014 This register controls the global interrupt generation capabilities of the PWM module. The events that can cause an interrupt are the fault input and the individual interrupts from the PWM generators. PWM Interrupt Enable (PWMINTEN) Base 0x4002.8000 Offset 0x014 Type R/W, reset 0x0000.0000 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 reserved IntFault Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 reserved IntPWM1 IntPWM0 Type RO RO RO RO RO RO RO RO RO RO RO RO RO RO R/W R/