TI1 LM3S5737-IQC50-A0T Stellarisâ® lm3s5737 microcontroller Datasheet

TE X AS INS TRUM E NTS - P RO DUCTI O N D ATA
Stellaris® LM3S5737 Microcontroller
D ATA SH E E T
D S -LM3S 5737 - 111 0 7
C o p yri g h t © 2 0 07-2011
Te xa s In stru me n ts In co r porated
Copyright
Copyright © 2007-2011 Texas Instruments Incorporated All rights reserved. Stellaris® and StellarisWare® are registered trademarks of Texas Instruments
Incorporated. 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.
PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard
warranty. Production processing does not necessarily include testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor
products and disclaimers thereto appears at the end of this data sheet.
Texas Instruments Incorporated
108 Wild Basin, Suite 350
Austin, TX 78746
http://www.ti.com/stellaris
http://www-k.ext.ti.com/sc/technical-support/product-information-centers.htm
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Stellaris® LM3S5737 Microcontroller
Table of Contents
Revision History ............................................................................................................................. 25
About This Document .................................................................................................................... 31
Audience ..............................................................................................................................................
About This Manual ................................................................................................................................
Related Documents ...............................................................................................................................
Documentation Conventions ..................................................................................................................
31
31
31
32
1
Architectural Overview .......................................................................................... 34
1.1
1.2
1.3
1.4
1.4.1
1.4.2
1.4.3
1.4.4
1.4.5
1.4.6
1.4.7
1.4.8
Product Features ..........................................................................................................
Target Applications ........................................................................................................
High-Level Block Diagram .............................................................................................
Functional Overview ......................................................................................................
ARM Cortex™-M3 .........................................................................................................
Motor Control Peripherals ..............................................................................................
Analog Peripherals ........................................................................................................
Serial Communications Peripherals ................................................................................
System Peripherals .......................................................................................................
Memory Peripherals ......................................................................................................
Additional Features .......................................................................................................
Hardware Details ..........................................................................................................
34
42
43
45
45
46
46
47
48
49
50
50
2
The Cortex-M3 Processor ...................................................................................... 51
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
2.3
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.3.6
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.4.7
2.5
2.5.1
2.5.2
2.5.3
Block Diagram .............................................................................................................. 52
Overview ...................................................................................................................... 53
System-Level Interface .................................................................................................. 53
Integrated Configurable Debug ...................................................................................... 53
Trace Port Interface Unit (TPIU) ..................................................................................... 54
Cortex-M3 System Component Details ........................................................................... 54
Programming Model ...................................................................................................... 55
Processor Mode and Privilege Levels for Software Execution ........................................... 55
Stacks .......................................................................................................................... 55
Register Map ................................................................................................................ 56
Register Descriptions .................................................................................................... 57
Exceptions and Interrupts .............................................................................................. 70
Data Types ................................................................................................................... 70
Memory Model .............................................................................................................. 70
Memory Regions, Types and Attributes ........................................................................... 72
Memory System Ordering of Memory Accesses .............................................................. 72
Behavior of Memory Accesses ....................................................................................... 72
Software Ordering of Memory Accesses ......................................................................... 73
Bit-Banding ................................................................................................................... 74
Data Storage ................................................................................................................ 76
Synchronization Primitives ............................................................................................. 77
Exception Model ........................................................................................................... 78
Exception States ........................................................................................................... 79
Exception Types ............................................................................................................ 79
Exception Handlers ....................................................................................................... 82
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2.5.4
2.5.5
2.5.6
2.5.7
2.6
2.6.1
2.6.2
2.6.3
2.6.4
2.7
2.7.1
2.7.2
2.8
Vector Table .................................................................................................................. 82
Exception Priorities ....................................................................................................... 83
Interrupt Priority Grouping .............................................................................................. 84
Exception Entry and Return ........................................................................................... 84
Fault Handling .............................................................................................................. 86
Fault Types ................................................................................................................... 87
Fault Escalation and Hard Faults .................................................................................... 87
Fault Status Registers and Fault Address Registers ........................................................ 88
Lockup ......................................................................................................................... 88
Power Management ...................................................................................................... 88
Entering Sleep Modes ................................................................................................... 89
Wake Up from Sleep Mode ............................................................................................ 89
Instruction Set Summary ............................................................................................... 90
3
Cortex-M3 Peripherals ........................................................................................... 93
3.1
3.1.1
3.1.2
3.1.3
3.1.4
3.2
3.3
3.4
3.5
3.6
Functional Description ................................................................................................... 93
System Timer (SysTick) ................................................................................................. 93
Nested Vectored Interrupt Controller (NVIC) .................................................................... 94
System Control Block (SCB) .......................................................................................... 96
Memory Protection Unit (MPU) ....................................................................................... 96
Register Map .............................................................................................................. 101
System Timer (SysTick) Register Descriptions .............................................................. 103
NVIC Register Descriptions .......................................................................................... 107
System Control Block (SCB) Register Descriptions ........................................................ 120
Memory Protection Unit (MPU) Register Descriptions .................................................... 147
4
JTAG Interface ...................................................................................................... 157
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.4
4.5
4.5.1
4.5.2
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
JTAG Interface Pins .....................................................................................................
JTAG TAP Controller ...................................................................................................
Shift Registers ............................................................................................................
Operational Considerations ..........................................................................................
Initialization and Configuration .....................................................................................
Register Descriptions ..................................................................................................
Instruction Register (IR) ...............................................................................................
Data Registers ............................................................................................................
158
158
159
159
160
161
161
164
164
164
166
5
System Control ..................................................................................................... 169
5.1
5.2
5.2.1
5.2.2
5.2.3
5.2.4
5.2.5
5.2.6
5.3
5.4
5.5
Signal Description .......................................................................................................
Functional Description .................................................................................................
Device Identification ....................................................................................................
Reset Control ..............................................................................................................
Non-Maskable Interrupt ...............................................................................................
Power Control .............................................................................................................
Clock Control ..............................................................................................................
System Control ...........................................................................................................
Initialization and Configuration .....................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
4
169
169
169
169
173
174
174
180
181
181
183
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6
Hibernation Module .............................................................................................. 236
6.1
6.2
6.3
6.3.1
6.3.2
6.3.3
6.3.4
6.3.5
6.3.6
6.3.7
6.3.8
6.4
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
6.5
6.6
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
Register Access Timing ...............................................................................................
Clock Source ..............................................................................................................
Battery Management ...................................................................................................
Real-Time Clock ..........................................................................................................
Battery-Backed Memory ..............................................................................................
Power Control .............................................................................................................
Initiating Hibernate ......................................................................................................
Interrupts and Status ...................................................................................................
Initialization and Configuration .....................................................................................
Initialization .................................................................................................................
RTC Match Functionality (No Hibernation) ....................................................................
RTC Match/Wake-Up from Hibernation .........................................................................
External Wake-Up from Hibernation ..............................................................................
RTC/External Wake-Up from Hibernation ......................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
237
237
238
238
238
240
240
240
241
241
241
242
242
242
242
243
243
243
244
7
Internal Memory ................................................................................................... 258
7.1
7.2
7.2.1
7.2.2
7.2.3
7.3
7.3.1
7.3.2
7.4
7.5
7.6
7.7
Block Diagram ............................................................................................................ 258
Functional Description ................................................................................................. 258
SRAM Memory ............................................................................................................ 258
ROM Memory ............................................................................................................. 259
Flash Memory ............................................................................................................. 259
Flash Memory Initialization and Configuration ............................................................... 261
Flash Programming ..................................................................................................... 261
Nonvolatile Register Programming ............................................................................... 261
Register Map .............................................................................................................. 262
ROM Register Descriptions (System Control Offset) ...................................................... 263
Flash Register Descriptions (Flash Control Offset) ......................................................... 264
Flash Register Descriptions (System Control Offset) ...................................................... 272
8
Micro Direct Memory Access (μDMA) ................................................................ 287
8.1
8.2
8.2.1
8.2.2
8.2.3
8.2.4
8.2.5
8.2.6
8.2.7
8.2.8
8.2.9
8.2.10
8.3
8.3.1
Block Diagram ............................................................................................................ 288
Functional Description ................................................................................................. 288
Channel Assigments .................................................................................................... 289
Priority ........................................................................................................................ 289
Arbitration Size ............................................................................................................ 289
Request Types ............................................................................................................ 290
Channel Configuration ................................................................................................. 290
Transfer Modes ........................................................................................................... 292
Transfer Size and Increment ........................................................................................ 300
Peripheral Interface ..................................................................................................... 300
Software Request ........................................................................................................ 300
Interrupts and Errors .................................................................................................... 301
Initialization and Configuration ..................................................................................... 301
Module Initialization ..................................................................................................... 301
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8.3.2
8.3.3
8.3.4
8.4
8.5
8.6
Configuring a Memory-to-Memory Transfer ...................................................................
Configuring a Peripheral for Simple Transmit ................................................................
Configuring a Peripheral for Ping-Pong Receive ............................................................
Register Map ..............................................................................................................
μDMA Channel Control Structure .................................................................................
μDMA Register Descriptions ........................................................................................
301
303
304
307
308
314
9
General-Purpose Input/Outputs (GPIOs) ........................................................... 348
9.1
9.2
9.2.1
9.2.2
9.2.3
9.2.4
9.2.5
9.2.6
9.3
9.4
9.5
Signal Description ....................................................................................................... 348
Functional Description ................................................................................................. 352
Data Control ............................................................................................................... 354
Interrupt Control .......................................................................................................... 355
Mode Control .............................................................................................................. 356
Commit Control ........................................................................................................... 356
Pad Control ................................................................................................................. 356
Identification ............................................................................................................... 357
Initialization and Configuration ..................................................................................... 357
Register Map .............................................................................................................. 358
Register Descriptions .................................................................................................. 360
10
General-Purpose Timers ...................................................................................... 400
10.1
10.2
10.3
10.3.1
10.3.2
10.3.3
10.4
10.4.1
10.4.2
10.4.3
10.4.4
10.4.5
10.4.6
10.5
10.6
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
GPTM Reset Conditions ..............................................................................................
32-Bit Timer Operating Modes ......................................................................................
16-Bit Timer Operating Modes ......................................................................................
Initialization and Configuration .....................................................................................
32-Bit One-Shot/Periodic Timer Mode ...........................................................................
32-Bit Real-Time Clock (RTC) Mode .............................................................................
16-Bit One-Shot/Periodic Timer Mode ...........................................................................
16-Bit Input Edge Count Mode .....................................................................................
16-Bit Input Edge Timing Mode ....................................................................................
16-Bit PWM Mode .......................................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
401
401
402
402
402
403
407
407
408
408
409
409
410
410
411
11
Watchdog Timer ................................................................................................... 434
11.1
11.2
11.3
11.4
11.5
Block Diagram ............................................................................................................
Functional Description .................................................................................................
Initialization and Configuration .....................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
435
435
436
436
437
12
Analog-to-Digital Converter (ADC) ..................................................................... 458
12.1
12.2
12.3
12.3.1
12.3.2
12.3.3
Block Diagram ............................................................................................................ 458
Signal Description ....................................................................................................... 459
Functional Description ................................................................................................. 460
Sample Sequencers .................................................................................................... 460
Module Control ............................................................................................................ 460
Hardware Sample Averaging Circuit ............................................................................. 461
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12.3.4
12.3.5
12.3.6
12.4
12.4.1
12.4.2
12.5
12.6
Analog-to-Digital Converter ..........................................................................................
Differential Sampling ...................................................................................................
Internal Temperature Sensor ........................................................................................
Initialization and Configuration .....................................................................................
Module Initialization .....................................................................................................
Sample Sequencer Configuration .................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
461
462
464
465
465
465
466
467
13
Universal Asynchronous Receivers/Transmitters (UARTs) ............................. 493
13.1
13.2
13.3
13.3.1
13.3.2
13.3.3
13.3.4
13.3.5
13.3.6
13.3.7
13.3.8
13.3.9
13.4
13.5
13.6
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
Transmit/Receive Logic ...............................................................................................
Baud-Rate Generation .................................................................................................
Data Transmission ......................................................................................................
Serial IR (SIR) .............................................................................................................
FIFO Operation ...........................................................................................................
Interrupts ....................................................................................................................
Loopback Operation ....................................................................................................
DMA Operation ...........................................................................................................
IrDA SIR block ............................................................................................................
Initialization and Configuration .....................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
494
494
495
495
495
496
496
497
498
499
499
499
499
500
501
14
Synchronous Serial Interface (SSI) .................................................................... 536
14.1
14.2
14.3
14.3.1
14.3.2
14.3.3
14.3.4
14.3.5
14.4
14.5
14.6
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
Bit Rate Generation .....................................................................................................
FIFO Operation ...........................................................................................................
Interrupts ....................................................................................................................
Frame Formats ...........................................................................................................
DMA Operation ...........................................................................................................
Initialization and Configuration .....................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
15
Inter-Integrated Circuit (I2C) Interface ................................................................ 576
15.1
15.2
15.3
15.3.1
15.3.2
15.3.3
15.3.4
15.3.5
15.4
15.5
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
I2C Bus Functional Overview ........................................................................................
Available Speed Modes ...............................................................................................
Interrupts ....................................................................................................................
Loopback Operation ....................................................................................................
Command Sequence Flow Charts ................................................................................
Initialization and Configuration .....................................................................................
Register Map ..............................................................................................................
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537
538
538
538
539
539
547
547
548
549
577
577
577
578
580
581
581
582
589
590
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15.6
15.7
Register Descriptions (I2C Master) ............................................................................... 591
Register Descriptions (I2C Slave) ................................................................................. 604
16
Controller Area Network (CAN) Module ............................................................. 613
16.1
Block Diagram ............................................................................................................ 614
16.2
Signal Description ....................................................................................................... 614
16.3
Functional Description ................................................................................................. 615
16.3.1 Initialization ................................................................................................................. 616
16.3.2 Operation ................................................................................................................... 616
16.3.3 Transmitting Message Objects ..................................................................................... 617
16.3.4 Configuring a Transmit Message Object ........................................................................ 617
16.3.5 Updating a Transmit Message Object ........................................................................... 619
16.3.6 Accepting Received Message Objects .......................................................................... 619
16.3.7 Receiving a Data Frame .............................................................................................. 619
16.3.8 Receiving a Remote Frame .......................................................................................... 620
16.3.9 Receive/Transmit Priority ............................................................................................. 620
16.3.10 Configuring a Receive Message Object ........................................................................ 620
16.3.11 Handling of Received Message Objects ........................................................................ 621
16.3.12 Handling of Interrupts .................................................................................................. 624
16.3.13 Test Mode ................................................................................................................... 624
16.3.14 Bit Timing Configuration Error Considerations ............................................................... 626
16.3.15 Bit Time and Bit Rate ................................................................................................... 626
16.3.16 Calculating the Bit Timing Parameters .......................................................................... 628
16.4
Register Map .............................................................................................................. 631
16.5
CAN Register Descriptions .......................................................................................... 633
17
Universal Serial Bus (USB) Controller ............................................................... 659
17.1
17.2
17.3
17.3.1
17.3.2
17.3.3
17.4
17.4.1
17.4.2
17.5
17.6
Block Diagram ............................................................................................................
Signal Description .......................................................................................................
Functional Description .................................................................................................
Operation as a Device .................................................................................................
Operation as a Host ....................................................................................................
DMA Operation ...........................................................................................................
Initialization and Configuration .....................................................................................
Pin Configuration .........................................................................................................
Endpoint Configuration ................................................................................................
Register Map ..............................................................................................................
Register Descriptions ..................................................................................................
18
Pin Diagram .......................................................................................................... 753
660
660
660
661
666
670
671
671
671
672
675
19
Signal Tables ........................................................................................................ 754
19.1
Connections for Unused Signals ................................................................................... 766
20
Operating Characteristics ................................................................................... 767
21
Electrical Characteristics .................................................................................... 768
21.1
21.1.1
21.1.2
21.1.3
21.1.4
21.1.5
DC Characteristics ...................................................................................................... 768
Maximum Ratings ....................................................................................................... 768
Recommended DC Operating Conditions ...................................................................... 768
On-Chip Low Drop-Out (LDO) Regulator Characteristics ................................................ 769
GPIO Module Characteristics ....................................................................................... 769
Power Specifications ................................................................................................... 769
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21.1.6 Flash Memory Characteristics ...................................................................................... 771
21.1.7 Hibernation ................................................................................................................. 771
21.1.8 USB ........................................................................................................................... 771
21.2
AC Characteristics ....................................................................................................... 772
21.2.1 Load Conditions .......................................................................................................... 772
21.2.2 Clocks ........................................................................................................................ 772
21.2.3 JTAG and Boundary Scan ............................................................................................ 774
21.2.4 Reset ......................................................................................................................... 775
21.2.5 Sleep Modes ............................................................................................................... 777
21.2.6 Hibernation Module ..................................................................................................... 777
21.2.7 General-Purpose I/O (GPIO) ........................................................................................ 778
21.2.8 Analog-to-Digital Converter .......................................................................................... 778
21.2.9 Synchronous Serial Interface (SSI) ............................................................................... 779
21.2.10 Inter-Integrated Circuit (I2C) Interface ........................................................................... 781
21.2.11 Universal Serial Bus (USB) Controller ........................................................................... 782
A
Boot Loader .......................................................................................................... 783
A.1
A.2
A.2.1
A.2.2
A.2.3
A.3
A.3.1
A.3.2
A.3.3
A.4
A.4.1
A.4.2
A.4.3
A.4.4
A.4.5
A.4.6
Boot Loader ................................................................................................................
Interfaces ...................................................................................................................
UART .........................................................................................................................
SSI .............................................................................................................................
I2C .............................................................................................................................
Packet Handling ..........................................................................................................
Packet Format ............................................................................................................
Sending Packets .........................................................................................................
Receiving Packets .......................................................................................................
Commands .................................................................................................................
COMMAND_PING (0X20) ............................................................................................
COMMAND_DOWNLOAD (0x21) .................................................................................
COMMAND_RUN (0x22) .............................................................................................
COMMAND_GET_STATUS (0x23) ...............................................................................
COMMAND_SEND_DATA (0x24) .................................................................................
COMMAND_RESET (0x25) .........................................................................................
783
783
783
784
784
784
784
784
785
785
785
785
786
786
786
787
B
ROM DriverLib Functions .................................................................................... 788
B.1
DriverLib Functions Included in the Integrated ROM ...................................................... 788
C
Register Quick Reference ................................................................................... 799
D
Ordering and Contact Information ..................................................................... 827
D.1
D.2
D.3
D.4
Ordering Information .................................................................................................... 827
Part Markings .............................................................................................................. 827
Kits ............................................................................................................................. 828
Support Information ..................................................................................................... 828
E
Package Information ............................................................................................ 829
E.1
E.1.1
E.1.2
E.1.3
100-Pin LQFP Package ...............................................................................................
Package Dimensions ...................................................................................................
Tray Dimensions .........................................................................................................
Tape and Reel Dimensions ..........................................................................................
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829
831
831
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List of Figures
Figure 1-1.
Figure 2-1.
Figure 2-2.
Figure 2-3.
Figure 2-4.
Figure 2-5.
Figure 2-6.
Figure 2-7.
Figure 3-1.
Figure 4-1.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5.
Figure 5-1.
Figure 5-2.
Figure 5-3.
Figure 5-4.
Figure 6-1.
Figure 6-2.
Figure 6-3.
Figure 7-1.
Figure 8-1.
Figure 8-2.
Figure 8-3.
Figure 8-4.
Figure 8-5.
Figure 8-6.
Figure 9-1.
Figure 9-2.
Figure 9-3.
Figure 9-4.
Figure 10-1.
Figure 10-2.
Figure 10-3.
Figure 10-4.
Figure 11-1.
Figure 12-1.
Figure 12-2.
Figure 12-3.
Figure 12-4.
Figure 12-5.
Figure 13-1.
Figure 13-2.
Figure 13-3.
Figure 14-1.
Stellaris LM3S5737 Microcontroller High-Level Block Diagram .............................. 44
CPU Block Diagram ............................................................................................. 53
TPIU Block Diagram ............................................................................................ 54
Cortex-M3 Register Set ........................................................................................ 56
Bit-Band Mapping ................................................................................................ 76
Data Storage ....................................................................................................... 77
Vector Table ........................................................................................................ 83
Exception Stack Frame ........................................................................................ 85
SRD Use Example ............................................................................................... 99
JTAG Module Block Diagram .............................................................................. 158
Test Access Port State Machine ......................................................................... 161
IDCODE Register Format ................................................................................... 167
BYPASS Register Format ................................................................................... 167
Boundary Scan Register Format ......................................................................... 168
Basic RST Configuration .................................................................................... 171
External Circuitry to Extend Power-On Reset ....................................................... 171
Reset Circuit Controlled by Switch ...................................................................... 172
Main Clock Tree ................................................................................................ 176
Hibernation Module Block Diagram ..................................................................... 237
Clock Source Using Crystal ................................................................................ 239
Clock Source Using Dedicated Oscillator ............................................................. 239
Flash Block Diagram .......................................................................................... 258
μDMA Block Diagram ......................................................................................... 288
Example of Ping-Pong DMA Transaction ............................................................. 293
Memory Scatter-Gather, Setup and Configuration ................................................ 295
Memory Scatter-Gather, μDMA Copy Sequence .................................................. 296
Peripheral Scatter-Gather, Setup and Configuration ............................................. 298
Peripheral Scatter-Gather, μDMA Copy Sequence ............................................... 299
Digital I/O Pads ................................................................................................. 353
Analog/Digital I/O Pads ...................................................................................... 354
GPIODATA Write Example ................................................................................. 355
GPIODATA Read Example ................................................................................. 355
GPTM Module Block Diagram ............................................................................ 401
16-Bit Input Edge Count Mode Example .............................................................. 405
16-Bit Input Edge Time Mode Example ............................................................... 406
16-Bit PWM Mode Example ................................................................................ 407
WDT Module Block Diagram .............................................................................. 435
ADC Module Block Diagram ............................................................................... 459
Differential Sampling Range, VIN_ODD = 1.5 V ...................................................... 463
Differential Sampling Range, VIN_ODD = 0.75 V .................................................... 463
Differential Sampling Range, VIN_ODD = 2.25 V .................................................... 464
Internal Temperature Sensor Characteristic ......................................................... 465
UART Module Block Diagram ............................................................................. 494
UART Character Frame ..................................................................................... 495
IrDA Data Modulation ......................................................................................... 497
SSI Module Block Diagram ................................................................................. 537
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Stellaris® LM3S5737 Microcontroller
Figure 14-2.
Figure 14-3.
Figure 14-4.
Figure 14-5.
Figure 14-6.
Figure 14-7.
Figure 14-8.
Figure 14-9.
Figure 14-10.
Figure 14-11.
Figure 14-12.
Figure 15-1.
Figure 15-2.
Figure 15-3.
Figure 15-4.
Figure 15-5.
Figure 15-6.
Figure 15-7.
Figure 15-8.
Figure 15-9.
Figure 15-10.
Figure 15-11.
Figure 15-12.
Figure 15-13.
Figure 16-1.
Figure 16-2.
Figure 16-3.
Figure 16-4.
Figure 17-1.
Figure 18-1.
Figure 21-1.
Figure 21-2.
Figure 21-3.
Figure 21-4.
Figure 21-5.
Figure 21-6.
Figure 21-7.
Figure 21-8.
Figure 21-9.
Figure 21-10.
Figure 21-11.
TI Synchronous Serial Frame Format (Single Transfer) ........................................ 540
TI Synchronous Serial Frame Format (Continuous Transfer) ................................ 541
Freescale SPI Format (Single Transfer) with SPO=0 and SPH=0 .......................... 541
Freescale SPI Format (Continuous Transfer) with SPO=0 and SPH=0 .................. 542
Freescale SPI Frame Format with SPO=0 and SPH=1 ......................................... 543
Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0 ............... 543
Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0 ........ 544
Freescale SPI Frame Format with SPO=1 and SPH=1 ......................................... 545
MICROWIRE Frame Format (Single Frame) ........................................................ 545
MICROWIRE Frame Format (Continuous Transfer) ............................................. 546
MICROWIRE Frame Format, SSIFss Input Setup and Hold Requirements ............ 547
I2C Block Diagram ............................................................................................. 577
I2C Bus Configuration ........................................................................................ 578
START and STOP Conditions ............................................................................. 578
Complete Data Transfer with a 7-Bit Address ....................................................... 579
R/S Bit in First Byte ............................................................................................ 579
Data Validity During Bit Transfer on the I2C Bus ................................................... 579
Master Single SEND .......................................................................................... 583
Master Single RECEIVE ..................................................................................... 584
Master Burst SEND ........................................................................................... 585
Master Burst RECEIVE ...................................................................................... 586
Master Burst RECEIVE after Burst SEND ............................................................ 587
Master Burst SEND after Burst RECEIVE ............................................................ 588
Slave Command Sequence ................................................................................ 589
CAN Controller Block Diagram ............................................................................ 614
CAN Data/Remote Frame .................................................................................. 615
Message Objects in a FIFO Buffer ...................................................................... 623
CAN Bit Time .................................................................................................... 627
USB Module Block Diagram ............................................................................... 660
100-Pin LQFP Package Pin Diagram .................................................................. 753
Load Conditions ................................................................................................ 772
JTAG Test Clock Input Timing ............................................................................. 775
JTAG Test Access Port (TAP) Timing .................................................................. 775
External Reset Timing (RST) .............................................................................. 776
Power-On Reset Timing ..................................................................................... 776
Brown-Out Reset Timing .................................................................................... 776
Software Reset Timing ....................................................................................... 776
Watchdog Reset Timing ..................................................................................... 777
Hibernation Module Timing ................................................................................. 778
ADC Input Equivalency Diagram ......................................................................... 779
SSI Timing for TI Frame Format (FRF=01), Single Transfer Timing
Measurement .................................................................................................... 780
Figure 21-12. SSI Timing for MICROWIRE Frame Format (FRF=10), Single Transfer ................. 780
Figure 21-13. SSI Timing for SPI Frame Format (FRF=00), with SPH=1 ..................................... 781
Figure 21-14. I2C Timing ......................................................................................................... 782
Figure E-1.
Stellaris LM3S5737 100-Pin LQFP Package Dimensions ..................................... 829
Figure E-2.
100-Pin LQFP Tray Dimensions .......................................................................... 831
Figure E-3.
100-Pin LQFP Tape and Reel Dimensions ........................................................... 832
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Table of Contents
List of Tables
Table 1.
Table 2.
Table 2-1.
Table 2-2.
Table 2-3.
Table 2-4.
Table 2-5.
Table 2-6.
Table 2-7.
Table 2-8.
Table 2-9.
Table 2-10.
Table 2-11.
Table 2-12.
Table 2-13.
Table 3-1.
Table 3-2.
Table 3-3.
Table 3-4.
Table 3-5.
Table 3-6.
Table 3-7.
Table 3-8.
Table 3-9.
Table 4-1.
Table 4-2.
Table 4-3.
Table 5-1.
Table 5-2.
Table 5-3.
Table 5-4.
Table 5-5.
Table 5-6.
Table 5-7.
Table 6-1.
Table 6-2.
Table 7-1.
Table 7-2.
Table 7-3.
Table 8-1.
Table 8-2.
Table 8-3.
Table 8-4.
Table 8-5.
Table 8-6.
Table 8-7.
Revision History .................................................................................................. 25
Documentation Conventions ................................................................................ 32
Summary of Processor Mode, Privilege Level, and Stack Use ................................ 56
Processor Register Map ....................................................................................... 57
PSR Register Combinations ................................................................................. 62
Memory Map ....................................................................................................... 70
Memory Access Behavior ..................................................................................... 73
SRAM Memory Bit-Banding Regions .................................................................... 75
Peripheral Memory Bit-Banding Regions ............................................................... 75
Exception Types .................................................................................................. 80
Interrupts ............................................................................................................ 81
Exception Return Behavior ................................................................................... 86
Faults ................................................................................................................. 87
Fault Status and Fault Address Registers .............................................................. 88
Cortex-M3 Instruction Summary ........................................................................... 90
Core Peripheral Register Regions ......................................................................... 93
Memory Attributes Summary ................................................................................ 96
TEX, S, C, and B Bit Field Encoding ..................................................................... 99
Cache Policy for Memory Attribute Encoding ....................................................... 100
AP Bit Field Encoding ........................................................................................ 100
Memory Region Attributes for Stellaris Microcontrollers ........................................ 100
Peripherals Register Map ................................................................................... 101
Interrupt Priority Levels ...................................................................................... 126
Example SIZE Field Values ................................................................................ 154
JTAG_SWD_SWO Signals (100LQFP) ................................................................ 158
JTAG Port Pins Reset State ............................................................................... 159
JTAG Instruction Register Commands ................................................................. 165
System Control & Clocks Signals (100LQFP) ...................................................... 169
Reset Sources ................................................................................................... 170
Clock Source Options ........................................................................................ 175
Possible System Clock Frequencies Using the SYSDIV Field ............................... 177
Examples of Possible System Clock Frequencies Using the SYSDIV2 Field .......... 177
System Control Register Map ............................................................................. 181
RCC2 Fields that Override RCC fields ................................................................. 199
Hibernate Signals (100LQFP) ............................................................................. 237
Hibernation Module Register Map ....................................................................... 243
Flash Protection Policy Combinations ................................................................. 260
User-Programmable Flash Memory Resident Registers ....................................... 262
Flash Register Map ............................................................................................ 262
DMA Channel Assignments ............................................................................... 289
Request Type Support ....................................................................................... 290
Control Structure Memory Map ........................................................................... 291
Channel Control Structure .................................................................................. 291
μDMA Read Example: 8-Bit Peripheral ................................................................ 300
μDMA Interrupt Assignments .............................................................................. 301
Channel Control Structure Offsets for Channel 30 ................................................ 302
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Stellaris® LM3S5737 Microcontroller
Table 8-8.
Table 8-9.
Table 8-10.
Table 8-11.
Table 8-12.
Table 8-13.
Table 9-1.
Table 9-2.
Table 9-3.
Table 9-4.
Table 9-5.
Table 9-6.
Table 10-1.
Table 10-2.
Table 10-3.
Table 10-4.
Table 11-1.
Table 12-1.
Table 12-2.
Table 12-3.
Table 12-4.
Table 13-1.
Table 13-2.
Table 14-1.
Table 14-2.
Table 15-1.
Table 15-2.
Table 15-3.
Table 15-4.
Table 16-1.
Table 16-2.
Table 16-3.
Table 16-4.
Table 17-1.
Table 17-2.
Table 17-3.
Table 17-4.
Table 17-5.
Table 19-1.
Table 19-2.
Table 19-3.
Table 19-4.
Table 19-5.
Table 20-1.
Table 20-2.
Table 20-3.
Table 21-1.
Channel Control Word Configuration for Memory Transfer Example ...................... 302
Channel Control Structure Offsets for Channel 7 .................................................. 303
Channel Control Word Configuration for Peripheral Transmit Example .................. 304
Primary and Alternate Channel Control Structure Offsets for Channel 8 ................. 305
Channel Control Word Configuration for Peripheral Ping-Pong Receive
Example ............................................................................................................ 306
μDMA Register Map .......................................................................................... 307
GPIO Pins With Non-Zero Reset Values .............................................................. 349
GPIO Pins and Alternate Functions (100LQFP) ................................................... 349
GPIO Signals (100LQFP) ................................................................................... 350
GPIO Pad Configuration Examples ..................................................................... 357
GPIO Interrupt Configuration Example ................................................................ 358
GPIO Register Map ........................................................................................... 359
Available CCP Pins ............................................................................................ 401
General-Purpose Timers Signals (100LQFP) ....................................................... 402
16-Bit Timer With Prescaler Configurations ......................................................... 404
Timers Register Map .......................................................................................... 411
Watchdog Timer Register Map ............................................................................ 436
ADC Signals (100LQFP) .................................................................................... 459
Samples and FIFO Depth of Sequencers ............................................................ 460
Differential Sampling Pairs ................................................................................. 462
ADC Register Map ............................................................................................. 466
UART Signals (100LQFP) .................................................................................. 494
UART Register Map ........................................................................................... 501
SSI Signals (100LQFP) ...................................................................................... 538
SSI Register Map .............................................................................................. 549
I2C Signals (100LQFP) ...................................................................................... 577
Examples of I2C Master Timer Period versus Speed Mode ................................... 580
Inter-Integrated Circuit (I2C) Interface Register Map ............................................. 590
Write Field Decoding for I2CMCS[3:0] Field (Sheet 1 of 3) .................................... 595
Controller Area Network Signals (100LQFP) ........................................................ 614
CAN Protocol Ranges ........................................................................................ 627
CANBIT Register Values .................................................................................... 627
CAN Register Map ............................................................................................. 631
USB Signals (100LQFP) .................................................................................... 660
Remainder (MAXLOAD/4) .................................................................................. 670
Actual Bytes Read ............................................................................................. 670
Packet Sizes That Clear RXRDY ........................................................................ 670
Universal Serial Bus (USB) Controller Register Map ............................................ 672
Signals by Pin Number ....................................................................................... 754
Signals by Signal Name ..................................................................................... 758
Signals by Function, Except for GPIO ................................................................. 762
GPIO Pins and Alternate Functions ..................................................................... 764
Connections for Unused Signals (100-pin LQFP) ................................................. 766
Temperature Characteristics ............................................................................... 767
Thermal Characteristics ..................................................................................... 767
ESD Absolute Maximum Ratings ........................................................................ 767
Maximum Ratings .............................................................................................. 768
November 17, 2011
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Table of Contents
Table 21-2.
Table 21-3.
Table 21-4.
Table 21-5.
Table 21-6.
Table 21-7.
Table 21-8.
Table 21-9.
Table 21-10.
Table 21-11.
Table 21-12.
Table 21-13.
Table 21-14.
Table 21-15.
Table 21-16.
Table 21-17.
Table 21-18.
Table 21-19.
Table 21-20.
Table 21-21.
Table 21-22.
Table 21-23.
Table D-1.
Recommended DC Operating Conditions ............................................................ 768
LDO Regulator Characteristics ........................................................................... 769
GPIO Module DC Characteristics ........................................................................ 769
Detailed Power Specifications ............................................................................ 770
Flash Memory Characteristics ............................................................................ 771
Hibernation Module DC Characteristics ............................................................... 771
USB Controller DC Characteristics ...................................................................... 771
Phase Locked Loop (PLL) Characteristics ........................................................... 772
Actual PLL Frequency ........................................................................................ 772
Clock Characteristics ......................................................................................... 773
Crystal Characteristics ....................................................................................... 773
System Clock Characteristics with ADC Operation ............................................... 774
System Clock Characteristics with USB Operation ............................................... 774
JTAG Characteristics ......................................................................................... 774
Reset Characteristics ......................................................................................... 775
Sleep Modes AC Characteristics ......................................................................... 777
Hibernation Module AC Characteristics ............................................................... 777
GPIO Characteristics ......................................................................................... 778
ADC Characteristics ........................................................................................... 778
ADC Module Internal Reference Characteristics .................................................. 779
SSI Characteristics ............................................................................................ 779
I2C Characteristics ............................................................................................. 781
Part Ordering Information ................................................................................... 827
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Stellaris® LM3S5737 Microcontroller
List of Registers
The Cortex-M3 Processor ............................................................................................................. 51
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Cortex General-Purpose Register 0 (R0) ........................................................................... 58
Cortex General-Purpose Register 1 (R1) ........................................................................... 58
Cortex General-Purpose Register 2 (R2) ........................................................................... 58
Cortex General-Purpose Register 3 (R3) ........................................................................... 58
Cortex General-Purpose Register 4 (R4) ........................................................................... 58
Cortex General-Purpose Register 5 (R5) ........................................................................... 58
Cortex General-Purpose Register 6 (R6) ........................................................................... 58
Cortex General-Purpose Register 7 (R7) ........................................................................... 58
Cortex General-Purpose Register 8 (R8) ........................................................................... 58
Cortex General-Purpose Register 9 (R9) ........................................................................... 58
Cortex General-Purpose Register 10 (R10) ....................................................................... 58
Cortex General-Purpose Register 11 (R11) ........................................................................ 58
Cortex General-Purpose Register 12 (R12) ....................................................................... 58
Stack Pointer (SP) ........................................................................................................... 59
Link Register (LR) ............................................................................................................ 60
Program Counter (PC) ..................................................................................................... 61
Program Status Register (PSR) ........................................................................................ 62
Priority Mask Register (PRIMASK) .................................................................................... 66
Fault Mask Register (FAULTMASK) .................................................................................. 67
Base Priority Mask Register (BASEPRI) ............................................................................ 68
Control Register (CONTROL) ........................................................................................... 69
Cortex-M3 Peripherals ................................................................................................................... 93
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
SysTick Control and Status Register (STCTRL), offset 0x010 ........................................... 104
SysTick Reload Value Register (STRELOAD), offset 0x014 .............................................. 106
SysTick Current Value Register (STCURRENT), offset 0x018 ........................................... 107
Interrupt 0-31 Set Enable (EN0), offset 0x100 .................................................................. 108
Interrupt 32-47 Set Enable (EN1), offset 0x104 ................................................................ 109
Interrupt 0-31 Clear Enable (DIS0), offset 0x180 .............................................................. 110
Interrupt 32-47 Clear Enable (DIS1), offset 0x184 ............................................................ 111
Interrupt 0-31 Set Pending (PEND0), offset 0x200 ........................................................... 112
Interrupt 32-47 Set Pending (PEND1), offset 0x204 ......................................................... 113
Interrupt 0-31 Clear Pending (UNPEND0), offset 0x280 ................................................... 114
Interrupt 32-47 Clear Pending (UNPEND1), offset 0x284 .................................................. 115
Interrupt 0-31 Active Bit (ACTIVE0), offset 0x300 ............................................................. 116
Interrupt 32-47 Active Bit (ACTIVE1), offset 0x304 ........................................................... 117
Interrupt 0-3 Priority (PRI0), offset 0x400 ......................................................................... 118
Interrupt 4-7 Priority (PRI1), offset 0x404 ......................................................................... 118
Interrupt 8-11 Priority (PRI2), offset 0x408 ....................................................................... 118
Interrupt 12-15 Priority (PRI3), offset 0x40C .................................................................... 118
Interrupt 16-19 Priority (PRI4), offset 0x410 ..................................................................... 118
Interrupt 20-23 Priority (PRI5), offset 0x414 ..................................................................... 118
Interrupt 24-27 Priority (PRI6), offset 0x418 ..................................................................... 118
Interrupt 28-31 Priority (PRI7), offset 0x41C .................................................................... 118
Interrupt 32-35 Priority (PRI8), offset 0x420 ..................................................................... 118
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Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
Register 30:
Register 31:
Register 32:
Register 33:
Register 34:
Register 35:
Register 36:
Register 37:
Register 38:
Register 39:
Register 40:
Register 41:
Register 42:
Register 43:
Register 44:
Register 45:
Register 46:
Register 47:
Register 48:
Register 49:
Register 50:
Register 51:
Interrupt 36-39 Priority (PRI9), offset 0x424 ..................................................................... 118
Interrupt 40-43 Priority (PRI10), offset 0x428 ................................................................... 118
Interrupt 44-47 Priority (PRI11), offset 0x42C ................................................................... 118
Software Trigger Interrupt (SWTRIG), offset 0xF00 .......................................................... 120
CPU ID Base (CPUID), offset 0xD00 ............................................................................... 121
Interrupt Control and State (INTCTRL), offset 0xD04 ........................................................ 122
Vector Table Offset (VTABLE), offset 0xD08 .................................................................... 125
Application Interrupt and Reset Control (APINT), offset 0xD0C ......................................... 126
System Control (SYSCTRL), offset 0xD10 ....................................................................... 128
Configuration and Control (CFGCTRL), offset 0xD14 ....................................................... 130
System Handler Priority 1 (SYSPRI1), offset 0xD18 ......................................................... 132
System Handler Priority 2 (SYSPRI2), offset 0xD1C ........................................................ 133
System Handler Priority 3 (SYSPRI3), offset 0xD20 ......................................................... 134
System Handler Control and State (SYSHNDCTRL), offset 0xD24 .................................... 135
Configurable Fault Status (FAULTSTAT), offset 0xD28 ..................................................... 139
Hard Fault Status (HFAULTSTAT), offset 0xD2C .............................................................. 145
Memory Management Fault Address (MMADDR), offset 0xD34 ........................................ 146
Bus Fault Address (FAULTADDR), offset 0xD38 .............................................................. 147
MPU Type (MPUTYPE), offset 0xD90 ............................................................................. 148
MPU Control (MPUCTRL), offset 0xD94 .......................................................................... 149
MPU Region Number (MPUNUMBER), offset 0xD98 ....................................................... 151
MPU Region Base Address (MPUBASE), offset 0xD9C ................................................... 152
MPU Region Base Address Alias 1 (MPUBASE1), offset 0xDA4 ....................................... 152
MPU Region Base Address Alias 2 (MPUBASE2), offset 0xDAC ...................................... 152
MPU Region Base Address Alias 3 (MPUBASE3), offset 0xDB4 ....................................... 152
MPU Region Attribute and Size (MPUATTR), offset 0xDA0 ............................................... 154
MPU Region Attribute and Size Alias 1 (MPUATTR1), offset 0xDA8 .................................. 154
MPU Region Attribute and Size Alias 2 (MPUATTR2), offset 0xDB0 .................................. 154
MPU Region Attribute and Size Alias 3 (MPUATTR3), offset 0xDB8 .................................. 154
System Control ............................................................................................................................ 169
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Device Identification 0 (DID0), offset 0x000 ..................................................................... 184
Brown-Out Reset Control (PBORCTL), offset 0x030 ........................................................ 186
LDO Power Control (LDOPCTL), offset 0x034 ................................................................. 187
Raw Interrupt Status (RIS), offset 0x050 .......................................................................... 188
Interrupt Mask Control (IMC), offset 0x054 ...................................................................... 189
Masked Interrupt Status and Clear (MISC), offset 0x058 .................................................. 190
Reset Cause (RESC), offset 0x05C ................................................................................ 191
Run-Mode Clock Configuration (RCC), offset 0x060 ......................................................... 192
XTAL to PLL Translation (PLLCFG), offset 0x064 ............................................................. 196
GPIO High-Performance Bus Control (GPIOHBCTL), offset 0x06C ................................... 197
Run-Mode Clock Configuration 2 (RCC2), offset 0x070 .................................................... 199
Main Oscillator Control (MOSCCTL), offset 0x07C ........................................................... 201
Deep Sleep Clock Configuration (DSLPCLKCFG), offset 0x144 ........................................ 202
Device Identification 1 (DID1), offset 0x004 ..................................................................... 203
Device Capabilities 0 (DC0), offset 0x008 ........................................................................ 205
Device Capabilities 1 (DC1), offset 0x010 ........................................................................ 206
Device Capabilities 2 (DC2), offset 0x014 ........................................................................ 208
Device Capabilities 3 (DC3), offset 0x018 ........................................................................ 209
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Stellaris® LM3S5737 Microcontroller
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
Register 30:
Register 31:
Register 32:
Register 33:
Register 34:
Device Capabilities 4 (DC4), offset 0x01C ....................................................................... 210
Device Capabilities 5 (DC5), offset 0x020 ........................................................................ 211
Device Capabilities 6 (DC6), offset 0x024 ........................................................................ 212
Device Capabilities 7 (DC7), offset 0x028 ........................................................................ 213
Run Mode Clock Gating Control Register 0 (RCGC0), offset 0x100 ................................... 215
Sleep Mode Clock Gating Control Register 0 (SCGC0), offset 0x110 ................................. 217
Deep Sleep Mode Clock Gating Control Register 0 (DCGC0), offset 0x120 ....................... 219
Run Mode Clock Gating Control Register 1 (RCGC1), offset 0x104 ................................... 221
Sleep Mode Clock Gating Control Register 1 (SCGC1), offset 0x114 ................................. 223
Deep Sleep Mode Clock Gating Control Register 1 (DCGC1), offset 0x124 ....................... 225
Run Mode Clock Gating Control Register 2 (RCGC2), offset 0x108 ................................... 227
Sleep Mode Clock Gating Control Register 2 (SCGC2), offset 0x118 ................................. 229
Deep Sleep Mode Clock Gating Control Register 2 (DCGC2), offset 0x128 ....................... 231
Software Reset Control 0 (SRCR0), offset 0x040 ............................................................. 233
Software Reset Control 1 (SRCR1), offset 0x044 ............................................................. 234
Software Reset Control 2 (SRCR2), offset 0x048 ............................................................. 235
Hibernation Module ..................................................................................................................... 236
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Hibernation RTC Counter (HIBRTCC), offset 0x000 .........................................................
Hibernation RTC Match 0 (HIBRTCM0), offset 0x004 .......................................................
Hibernation RTC Match 1 (HIBRTCM1), offset 0x008 .......................................................
Hibernation RTC Load (HIBRTCLD), offset 0x00C ...........................................................
Hibernation Control (HIBCTL), offset 0x010 .....................................................................
Hibernation Interrupt Mask (HIBIM), offset 0x014 .............................................................
Hibernation Raw Interrupt Status (HIBRIS), offset 0x018 ..................................................
Hibernation Masked Interrupt Status (HIBMIS), offset 0x01C ............................................
Hibernation Interrupt Clear (HIBIC), offset 0x020 .............................................................
Hibernation RTC Trim (HIBRTCT), offset 0x024 ...............................................................
Hibernation Data (HIBDATA), offset 0x030-0x12C ............................................................
245
246
247
248
249
252
253
254
255
256
257
Internal Memory ........................................................................................................................... 258
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
ROM Control (RMCTL), offset 0x0F0 .............................................................................. 264
Flash Memory Address (FMA), offset 0x000 .................................................................... 265
Flash Memory Data (FMD), offset 0x004 ......................................................................... 266
Flash Memory Control (FMC), offset 0x008 ..................................................................... 267
Flash Controller Raw Interrupt Status (FCRIS), offset 0x00C ............................................ 269
Flash Controller Interrupt Mask (FCIM), offset 0x010 ........................................................ 270
Flash Controller Masked Interrupt Status and Clear (FCMISC), offset 0x014 ..................... 271
USec Reload (USECRL), offset 0x140 ............................................................................ 273
Flash Memory Protection Read Enable 0 (FMPRE0), offset 0x130 and 0x200 ................... 274
Flash Memory Protection Program Enable 0 (FMPPE0), offset 0x134 and 0x400 ............... 275
User Debug (USER_DBG), offset 0x1D0 ......................................................................... 276
User Register 0 (USER_REG0), offset 0x1E0 .................................................................. 277
User Register 1 (USER_REG1), offset 0x1E4 .................................................................. 278
User Register 2 (USER_REG2), offset 0x1E8 .................................................................. 279
User Register 3 (USER_REG3), offset 0x1EC ................................................................. 280
Flash Memory Protection Read Enable 1 (FMPRE1), offset 0x204 .................................... 281
Flash Memory Protection Read Enable 2 (FMPRE2), offset 0x208 .................................... 282
Flash Memory Protection Read Enable 3 (FMPRE3), offset 0x20C ................................... 283
Flash Memory Protection Program Enable 1 (FMPPE1), offset 0x404 ............................... 284
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Register 20:
Register 21:
Flash Memory Protection Program Enable 2 (FMPPE2), offset 0x408 ............................... 285
Flash Memory Protection Program Enable 3 (FMPPE3), offset 0x40C ............................... 286
Micro Direct Memory Access (μDMA) ........................................................................................ 287
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
DMA Channel Source Address End Pointer (DMASRCENDP), offset 0x000 ...................... 309
DMA Channel Destination Address End Pointer (DMADSTENDP), offset 0x004 ................ 310
DMA Channel Control Word (DMACHCTL), offset 0x008 .................................................. 311
DMA Status (DMASTAT), offset 0x000 ............................................................................ 315
DMA Configuration (DMACFG), offset 0x004 ................................................................... 317
DMA Channel Control Base Pointer (DMACTLBASE), offset 0x008 .................................. 318
DMA Alternate Channel Control Base Pointer (DMAALTBASE), offset 0x00C .................... 319
DMA Channel Wait on Request Status (DMAWAITSTAT), offset 0x010 ............................. 320
DMA Channel Software Request (DMASWREQ), offset 0x014 ......................................... 321
DMA Channel Useburst Set (DMAUSEBURSTSET), offset 0x018 .................................... 322
DMA Channel Useburst Clear (DMAUSEBURSTCLR), offset 0x01C ................................. 324
DMA Channel Request Mask Set (DMAREQMASKSET), offset 0x020 .............................. 325
DMA Channel Request Mask Clear (DMAREQMASKCLR), offset 0x024 ........................... 327
DMA Channel Enable Set (DMAENASET), offset 0x028 ................................................... 328
DMA Channel Enable Clear (DMAENACLR), offset 0x02C ............................................... 330
DMA Channel Primary Alternate Set (DMAALTSET), offset 0x030 .................................... 331
DMA Channel Primary Alternate Clear (DMAALTCLR), offset 0x034 ................................. 333
DMA Channel Priority Set (DMAPRIOSET), offset 0x038 ................................................. 334
DMA Channel Priority Clear (DMAPRIOCLR), offset 0x03C .............................................. 336
DMA Bus Error Clear (DMAERRCLR), offset 0x04C ........................................................ 337
DMA Peripheral Identification 0 (DMAPeriphID0), offset 0xFE0 ......................................... 339
DMA Peripheral Identification 1 (DMAPeriphID1), offset 0xFE4 ......................................... 340
DMA Peripheral Identification 2 (DMAPeriphID2), offset 0xFE8 ......................................... 341
DMA Peripheral Identification 3 (DMAPeriphID3), offset 0xFEC ........................................ 342
DMA Peripheral Identification 4 (DMAPeriphID4), offset 0xFD0 ......................................... 343
DMA PrimeCell Identification 0 (DMAPCellID0), offset 0xFF0 ........................................... 344
DMA PrimeCell Identification 1 (DMAPCellID1), offset 0xFF4 ........................................... 345
DMA PrimeCell Identification 2 (DMAPCellID2), offset 0xFF8 ........................................... 346
DMA PrimeCell Identification 3 (DMAPCellID3), offset 0xFFC ........................................... 347
General-Purpose Input/Outputs (GPIOs) ................................................................................... 348
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
GPIO Data (GPIODATA), offset 0x000 ............................................................................ 361
GPIO Direction (GPIODIR), offset 0x400 ......................................................................... 362
GPIO Interrupt Sense (GPIOIS), offset 0x404 .................................................................. 363
GPIO Interrupt Both Edges (GPIOIBE), offset 0x408 ........................................................ 364
GPIO Interrupt Event (GPIOIEV), offset 0x40C ................................................................ 365
GPIO Interrupt Mask (GPIOIM), offset 0x410 ................................................................... 366
GPIO Raw Interrupt Status (GPIORIS), offset 0x414 ........................................................ 367
GPIO Masked Interrupt Status (GPIOMIS), offset 0x418 ................................................... 368
GPIO Interrupt Clear (GPIOICR), offset 0x41C ................................................................ 370
GPIO Alternate Function Select (GPIOAFSEL), offset 0x420 ............................................ 371
GPIO 2-mA Drive Select (GPIODR2R), offset 0x500 ........................................................ 373
GPIO 4-mA Drive Select (GPIODR4R), offset 0x504 ........................................................ 374
GPIO 8-mA Drive Select (GPIODR8R), offset 0x508 ........................................................ 375
GPIO Open Drain Select (GPIOODR), offset 0x50C ......................................................... 376
GPIO Pull-Up Select (GPIOPUR), offset 0x510 ................................................................ 377
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Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
Register 30:
Register 31:
Register 32:
Register 33:
GPIO Pull-Down Select (GPIOPDR), offset 0x514 ........................................................... 379
GPIO Slew Rate Control Select (GPIOSLR), offset 0x518 ................................................ 380
GPIO Digital Enable (GPIODEN), offset 0x51C ................................................................ 381
GPIO Lock (GPIOLOCK), offset 0x520 ............................................................................ 383
GPIO Commit (GPIOCR), offset 0x524 ............................................................................ 384
GPIO Analog Mode Select (GPIOAMSEL), offset 0x528 ................................................... 386
GPIO Peripheral Identification 4 (GPIOPeriphID4), offset 0xFD0 ....................................... 388
GPIO Peripheral Identification 5 (GPIOPeriphID5), offset 0xFD4 ....................................... 389
GPIO Peripheral Identification 6 (GPIOPeriphID6), offset 0xFD8 ....................................... 390
GPIO Peripheral Identification 7 (GPIOPeriphID7), offset 0xFDC ...................................... 391
GPIO Peripheral Identification 0 (GPIOPeriphID0), offset 0xFE0 ....................................... 392
GPIO Peripheral Identification 1 (GPIOPeriphID1), offset 0xFE4 ....................................... 393
GPIO Peripheral Identification 2 (GPIOPeriphID2), offset 0xFE8 ....................................... 394
GPIO Peripheral Identification 3 (GPIOPeriphID3), offset 0xFEC ...................................... 395
GPIO PrimeCell Identification 0 (GPIOPCellID0), offset 0xFF0 .......................................... 396
GPIO PrimeCell Identification 1 (GPIOPCellID1), offset 0xFF4 .......................................... 397
GPIO PrimeCell Identification 2 (GPIOPCellID2), offset 0xFF8 .......................................... 398
GPIO PrimeCell Identification 3 (GPIOPCellID3), offset 0xFFC ......................................... 399
General-Purpose Timers ............................................................................................................. 400
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
GPTM Configuration (GPTMCFG), offset 0x000 .............................................................. 412
GPTM TimerA Mode (GPTMTAMR), offset 0x004 ............................................................ 413
GPTM TimerB Mode (GPTMTBMR), offset 0x008 ............................................................ 415
GPTM Control (GPTMCTL), offset 0x00C ........................................................................ 417
GPTM Interrupt Mask (GPTMIMR), offset 0x018 .............................................................. 420
GPTM Raw Interrupt Status (GPTMRIS), offset 0x01C ..................................................... 422
GPTM Masked Interrupt Status (GPTMMIS), offset 0x020 ................................................ 423
GPTM Interrupt Clear (GPTMICR), offset 0x024 .............................................................. 424
GPTM TimerA Interval Load (GPTMTAILR), offset 0x028 ................................................. 426
GPTM TimerB Interval Load (GPTMTBILR), offset 0x02C ................................................ 427
GPTM TimerA Match (GPTMTAMATCHR), offset 0x030 ................................................... 428
GPTM TimerB Match (GPTMTBMATCHR), offset 0x034 .................................................. 429
GPTM TimerA Prescale (GPTMTAPR), offset 0x038 ........................................................ 430
GPTM TimerB Prescale (GPTMTBPR), offset 0x03C ....................................................... 431
GPTM TimerA (GPTMTAR), offset 0x048 ........................................................................ 432
GPTM TimerB (GPTMTBR), offset 0x04C ....................................................................... 433
Watchdog Timer ........................................................................................................................... 434
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Watchdog Load (WDTLOAD), offset 0x000 ...................................................................... 438
Watchdog Value (WDTVALUE), offset 0x004 ................................................................... 439
Watchdog Control (WDTCTL), offset 0x008 ..................................................................... 440
Watchdog Interrupt Clear (WDTICR), offset 0x00C .......................................................... 441
Watchdog Raw Interrupt Status (WDTRIS), offset 0x010 .................................................. 442
Watchdog Masked Interrupt Status (WDTMIS), offset 0x014 ............................................. 443
Watchdog Test (WDTTEST), offset 0x418 ....................................................................... 444
Watchdog Lock (WDTLOCK), offset 0xC00 ..................................................................... 445
Watchdog Peripheral Identification 4 (WDTPeriphID4), offset 0xFD0 ................................. 446
Watchdog Peripheral Identification 5 (WDTPeriphID5), offset 0xFD4 ................................. 447
Watchdog Peripheral Identification 6 (WDTPeriphID6), offset 0xFD8 ................................. 448
Watchdog Peripheral Identification 7 (WDTPeriphID7), offset 0xFDC ................................ 449
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Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Watchdog Peripheral Identification 0 (WDTPeriphID0), offset 0xFE0 .................................
Watchdog Peripheral Identification 1 (WDTPeriphID1), offset 0xFE4 .................................
Watchdog Peripheral Identification 2 (WDTPeriphID2), offset 0xFE8 .................................
Watchdog Peripheral Identification 3 (WDTPeriphID3), offset 0xFEC .................................
Watchdog PrimeCell Identification 0 (WDTPCellID0), offset 0xFF0 ....................................
Watchdog PrimeCell Identification 1 (WDTPCellID1), offset 0xFF4 ....................................
Watchdog PrimeCell Identification 2 (WDTPCellID2), offset 0xFF8 ....................................
Watchdog PrimeCell Identification 3 (WDTPCellID3 ), offset 0xFFC ..................................
450
451
452
453
454
455
456
457
Analog-to-Digital Converter (ADC) ............................................................................................. 458
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
ADC Active Sample Sequencer (ADCACTSS), offset 0x000 ............................................. 468
ADC Raw Interrupt Status (ADCRIS), offset 0x004 ........................................................... 469
ADC Interrupt Mask (ADCIM), offset 0x008 ..................................................................... 470
ADC Interrupt Status and Clear (ADCISC), offset 0x00C .................................................. 471
ADC Overflow Status (ADCOSTAT), offset 0x010 ............................................................ 472
ADC Event Multiplexer Select (ADCEMUX), offset 0x014 ................................................. 473
ADC Underflow Status (ADCUSTAT), offset 0x018 ........................................................... 476
ADC Sample Sequencer Priority (ADCSSPRI), offset 0x020 ............................................. 477
ADC Processor Sample Sequence Initiate (ADCPSSI), offset 0x028 ................................. 479
ADC Sample Averaging Control (ADCSAC), offset 0x030 ................................................. 480
ADC Sample Sequence Input Multiplexer Select 0 (ADCSSMUX0), offset 0x040 ............... 481
ADC Sample Sequence Control 0 (ADCSSCTL0), offset 0x044 ........................................ 483
ADC Sample Sequence Result FIFO 0 (ADCSSFIFO0), offset 0x048 ................................ 486
ADC Sample Sequence Result FIFO 1 (ADCSSFIFO1), offset 0x068 ................................ 486
ADC Sample Sequence Result FIFO 2 (ADCSSFIFO2), offset 0x088 ................................ 486
ADC Sample Sequence Result FIFO 3 (ADCSSFIFO3), offset 0x0A8 ............................... 486
ADC Sample Sequence FIFO 0 Status (ADCSSFSTAT0), offset 0x04C ............................. 487
ADC Sample Sequence FIFO 1 Status (ADCSSFSTAT1), offset 0x06C ............................. 487
ADC Sample Sequence FIFO 2 Status (ADCSSFSTAT2), offset 0x08C ............................ 487
ADC Sample Sequence FIFO 3 Status (ADCSSFSTAT3), offset 0x0AC ............................ 487
ADC Sample Sequence Input Multiplexer Select 1 (ADCSSMUX1), offset 0x060 ............... 488
ADC Sample Sequence Input Multiplexer Select 2 (ADCSSMUX2), offset 0x080 ............... 488
ADC Sample Sequence Control 1 (ADCSSCTL1), offset 0x064 ........................................ 489
ADC Sample Sequence Control 2 (ADCSSCTL2), offset 0x084 ........................................ 489
ADC Sample Sequence Input Multiplexer Select 3 (ADCSSMUX3), offset 0x0A0 ............... 491
ADC Sample Sequence Control 3 (ADCSSCTL3), offset 0x0A4 ........................................ 492
Universal Asynchronous Receivers/Transmitters (UARTs) ..................................................... 493
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
UART Data (UARTDR), offset 0x000 ............................................................................... 502
UART Receive Status/Error Clear (UARTRSR/UARTECR), offset 0x004 ........................... 504
UART Flag (UARTFR), offset 0x018 ................................................................................ 506
UART IrDA Low-Power Register (UARTILPR), offset 0x020 ............................................. 508
UART Integer Baud-Rate Divisor (UARTIBRD), offset 0x024 ............................................ 509
UART Fractional Baud-Rate Divisor (UARTFBRD), offset 0x028 ....................................... 510
UART Line Control (UARTLCRH), offset 0x02C ............................................................... 511
UART Control (UARTCTL), offset 0x030 ......................................................................... 513
UART Interrupt FIFO Level Select (UARTIFLS), offset 0x034 ........................................... 515
UART Interrupt Mask (UARTIM), offset 0x038 ................................................................. 517
UART Raw Interrupt Status (UARTRIS), offset 0x03C ...................................................... 519
UART Masked Interrupt Status (UARTMIS), offset 0x040 ................................................. 520
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Stellaris® LM3S5737 Microcontroller
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
UART Interrupt Clear (UARTICR), offset 0x044 ............................................................... 521
UART DMA Control (UARTDMACTL), offset 0x048 .......................................................... 523
UART Peripheral Identification 4 (UARTPeriphID4), offset 0xFD0 ..................................... 524
UART Peripheral Identification 5 (UARTPeriphID5), offset 0xFD4 ..................................... 525
UART Peripheral Identification 6 (UARTPeriphID6), offset 0xFD8 ..................................... 526
UART Peripheral Identification 7 (UARTPeriphID7), offset 0xFDC ..................................... 527
UART Peripheral Identification 0 (UARTPeriphID0), offset 0xFE0 ...................................... 528
UART Peripheral Identification 1 (UARTPeriphID1), offset 0xFE4 ...................................... 529
UART Peripheral Identification 2 (UARTPeriphID2), offset 0xFE8 ...................................... 530
UART Peripheral Identification 3 (UARTPeriphID3), offset 0xFEC ..................................... 531
UART PrimeCell Identification 0 (UARTPCellID0), offset 0xFF0 ........................................ 532
UART PrimeCell Identification 1 (UARTPCellID1), offset 0xFF4 ........................................ 533
UART PrimeCell Identification 2 (UARTPCellID2), offset 0xFF8 ........................................ 534
UART PrimeCell Identification 3 (UARTPCellID3), offset 0xFFC ........................................ 535
Synchronous Serial Interface (SSI) ............................................................................................ 536
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
SSI Control 0 (SSICR0), offset 0x000 .............................................................................. 550
SSI Control 1 (SSICR1), offset 0x004 .............................................................................. 552
SSI Data (SSIDR), offset 0x008 ...................................................................................... 554
SSI Status (SSISR), offset 0x00C ................................................................................... 555
SSI Clock Prescale (SSICPSR), offset 0x010 .................................................................. 557
SSI Interrupt Mask (SSIIM), offset 0x014 ......................................................................... 558
SSI Raw Interrupt Status (SSIRIS), offset 0x018 .............................................................. 560
SSI Masked Interrupt Status (SSIMIS), offset 0x01C ........................................................ 561
SSI Interrupt Clear (SSIICR), offset 0x020 ....................................................................... 562
SSI DMA Control (SSIDMACTL), offset 0x024 ................................................................. 563
SSI Peripheral Identification 4 (SSIPeriphID4), offset 0xFD0 ............................................. 564
SSI Peripheral Identification 5 (SSIPeriphID5), offset 0xFD4 ............................................. 565
SSI Peripheral Identification 6 (SSIPeriphID6), offset 0xFD8 ............................................. 566
SSI Peripheral Identification 7 (SSIPeriphID7), offset 0xFDC ............................................ 567
SSI Peripheral Identification 0 (SSIPeriphID0), offset 0xFE0 ............................................. 568
SSI Peripheral Identification 1 (SSIPeriphID1), offset 0xFE4 ............................................. 569
SSI Peripheral Identification 2 (SSIPeriphID2), offset 0xFE8 ............................................. 570
SSI Peripheral Identification 3 (SSIPeriphID3), offset 0xFEC ............................................ 571
SSI PrimeCell Identification 0 (SSIPCellID0), offset 0xFF0 ............................................... 572
SSI PrimeCell Identification 1 (SSIPCellID1), offset 0xFF4 ............................................... 573
SSI PrimeCell Identification 2 (SSIPCellID2), offset 0xFF8 ............................................... 574
SSI PrimeCell Identification 3 (SSIPCellID3), offset 0xFFC ............................................... 575
Inter-Integrated Circuit (I2C) Interface ........................................................................................ 576
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
I2C Master Slave Address (I2CMSA), offset 0x000 ........................................................... 592
I2C Master Control/Status (I2CMCS), offset 0x004 ........................................................... 593
I2C Master Data (I2CMDR), offset 0x008 ......................................................................... 597
I2C Master Timer Period (I2CMTPR), offset 0x00C ........................................................... 598
I2C Master Interrupt Mask (I2CMIMR), offset 0x010 ......................................................... 599
I2C Master Raw Interrupt Status (I2CMRIS), offset 0x014 ................................................. 600
I2C Master Masked Interrupt Status (I2CMMIS), offset 0x018 ........................................... 601
I2C Master Interrupt Clear (I2CMICR), offset 0x01C ......................................................... 602
I2C Master Configuration (I2CMCR), offset 0x020 ............................................................ 603
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Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
I2C Slave Own Address (I2CSOAR), offset 0x800 ............................................................
I2C Slave Control/Status (I2CSCSR), offset 0x804 ...........................................................
I2C Slave Data (I2CSDR), offset 0x808 ...........................................................................
I2C Slave Interrupt Mask (I2CSIMR), offset 0x80C ...........................................................
I2C Slave Raw Interrupt Status (I2CSRIS), offset 0x810 ...................................................
I2C Slave Masked Interrupt Status (I2CSMIS), offset 0x814 ..............................................
I2C Slave Interrupt Clear (I2CSICR), offset 0x818 ............................................................
605
606
608
609
610
611
612
Controller Area Network (CAN) Module ..................................................................................... 613
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
Register 30:
Register 31:
Register 32:
Register 33:
Register 34:
Register 35:
Register 36:
Register 37:
CAN Control (CANCTL), offset 0x000 ............................................................................. 634
CAN Status (CANSTS), offset 0x004 ............................................................................... 636
CAN Error Counter (CANERR), offset 0x008 ................................................................... 638
CAN Bit Timing (CANBIT), offset 0x00C .......................................................................... 639
CAN Interrupt (CANINT), offset 0x010 ............................................................................. 640
CAN Test (CANTST), offset 0x014 .................................................................................. 641
CAN Baud Rate Prescaler Extension (CANBRPE), offset 0x018 ....................................... 643
CAN IF1 Command Request (CANIF1CRQ), offset 0x020 ................................................ 644
CAN IF2 Command Request (CANIF2CRQ), offset 0x080 ................................................ 644
CAN IF1 Command Mask (CANIF1CMSK), offset 0x024 .................................................. 645
CAN IF2 Command Mask (CANIF2CMSK), offset 0x084 .................................................. 645
CAN IF1 Mask 1 (CANIF1MSK1), offset 0x028 ................................................................ 647
CAN IF2 Mask 1 (CANIF2MSK1), offset 0x088 ................................................................ 647
CAN IF1 Mask 2 (CANIF1MSK2), offset 0x02C ................................................................ 648
CAN IF2 Mask 2 (CANIF2MSK2), offset 0x08C ................................................................ 648
CAN IF1 Arbitration 1 (CANIF1ARB1), offset 0x030 ......................................................... 649
CAN IF2 Arbitration 1 (CANIF2ARB1), offset 0x090 ......................................................... 649
CAN IF1 Arbitration 2 (CANIF1ARB2), offset 0x034 ......................................................... 650
CAN IF2 Arbitration 2 (CANIF2ARB2), offset 0x094 ......................................................... 650
CAN IF1 Message Control (CANIF1MCTL), offset 0x038 .................................................. 652
CAN IF2 Message Control (CANIF2MCTL), offset 0x098 .................................................. 652
CAN IF1 Data A1 (CANIF1DA1), offset 0x03C ................................................................. 654
CAN IF1 Data A2 (CANIF1DA2), offset 0x040 ................................................................. 654
CAN IF1 Data B1 (CANIF1DB1), offset 0x044 ................................................................. 654
CAN IF1 Data B2 (CANIF1DB2), offset 0x048 ................................................................. 654
CAN IF2 Data A1 (CANIF2DA1), offset 0x09C ................................................................. 654
CAN IF2 Data A2 (CANIF2DA2), offset 0x0A0 ................................................................. 654
CAN IF2 Data B1 (CANIF2DB1), offset 0x0A4 ................................................................. 654
CAN IF2 Data B2 (CANIF2DB2), offset 0x0A8 ................................................................. 654
CAN Transmission Request 1 (CANTXRQ1), offset 0x100 ................................................ 655
CAN Transmission Request 2 (CANTXRQ2), offset 0x104 ................................................ 655
CAN New Data 1 (CANNWDA1), offset 0x120 ................................................................. 656
CAN New Data 2 (CANNWDA2), offset 0x124 ................................................................. 656
CAN Message 1 Interrupt Pending (CANMSG1INT), offset 0x140 ..................................... 657
CAN Message 2 Interrupt Pending (CANMSG2INT), offset 0x144 ..................................... 657
CAN Message 1 Valid (CANMSG1VAL), offset 0x160 ....................................................... 658
CAN Message 2 Valid (CANMSG2VAL), offset 0x164 ....................................................... 658
Universal Serial Bus (USB) Controller ....................................................................................... 659
Register 1:
Register 2:
USB Device Functional Address (USBFADDR), offset 0x000 ............................................ 676
USB Power (USBPOWER), offset 0x001 ......................................................................... 677
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Stellaris® LM3S5737 Microcontroller
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Register 10:
Register 11:
Register 12:
Register 13:
Register 14:
Register 15:
Register 16:
Register 17:
Register 18:
Register 19:
Register 20:
Register 21:
Register 22:
Register 23:
Register 24:
Register 25:
Register 26:
Register 27:
Register 28:
Register 29:
Register 30:
Register 31:
Register 32:
Register 33:
Register 34:
Register 35:
Register 36:
Register 37:
Register 38:
Register 39:
Register 40:
Register 41:
Register 42:
Register 43:
Register 44:
Register 45:
Register 46:
Register 47:
Register 48:
Register 49:
Register 50:
USB Transmit Interrupt Status (USBTXIS), offset 0x002 ................................................... 680
USB Receive Interrupt Status (USBRXIS), offset 0x004 ................................................... 681
USB Transmit Interrupt Enable (USBTXIE), offset 0x006 .................................................. 682
USB Receive Interrupt Enable (USBRXIE), offset 0x008 .................................................. 683
USB General Interrupt Status (USBIS), offset 0x00A ........................................................ 684
USB Interrupt Enable (USBIE), offset 0x00B .................................................................... 687
USB Frame Value (USBFRAME), offset 0x00C ................................................................ 690
USB Endpoint Index (USBEPIDX), offset 0x00E .............................................................. 691
USB Test Mode (USBTEST), offset 0x00F ....................................................................... 692
USB FIFO Endpoint 0 (USBFIFO0), offset 0x020 ............................................................. 694
USB FIFO Endpoint 1 (USBFIFO1), offset 0x024 ............................................................. 694
USB FIFO Endpoint 2 (USBFIFO2), offset 0x028 ............................................................. 694
USB FIFO Endpoint 3 (USBFIFO3), offset 0x02C ............................................................ 694
USB Device Control (USBDEVCTL), offset 0x060 ............................................................ 695
USB Transmit Dynamic FIFO Sizing (USBTXFIFOSZ), offset 0x062 ................................. 696
USB Receive Dynamic FIFO Sizing (USBRXFIFOSZ), offset 0x063 .................................. 696
USB Transmit FIFO Start Address (USBTXFIFOADD), offset 0x064 ................................. 697
USB Receive FIFO Start Address (USBRXFIFOADD), offset 0x066 .................................. 697
USB Connect Timing (USBCONTIM), offset 0x07A .......................................................... 698
USB Full-Speed Last Transaction to End of Frame Timing (USBFSEOF), offset 0x07D ...... 699
USB Low-Speed Last Transaction to End of Frame Timing (USBLSEOF), offset 0x07E ...... 700
USB Transmit Functional Address Endpoint 0 (USBTXFUNCADDR0), offset 0x080 ........... 701
USB Transmit Functional Address Endpoint 1 (USBTXFUNCADDR1), offset 0x088 ........... 701
USB Transmit Functional Address Endpoint 2 (USBTXFUNCADDR2), offset 0x090 ........... 701
USB Transmit Functional Address Endpoint 3 (USBTXFUNCADDR3), offset 0x098 ........... 701
USB Transmit Hub Address Endpoint 0 (USBTXHUBADDR0), offset 0x082 ...................... 702
USB Transmit Hub Address Endpoint 1 (USBTXHUBADDR1), offset 0x08A ...................... 702
USB Transmit Hub Address Endpoint 2 (USBTXHUBADDR2), offset 0x092 ...................... 702
USB Transmit Hub Address Endpoint 3 (USBTXHUBADDR3), offset 0x09A ...................... 702
USB Transmit Hub Port Endpoint 0 (USBTXHUBPORT0), offset 0x083 ............................. 703
USB Transmit Hub Port Endpoint 1 (USBTXHUBPORT1), offset 0x08B ............................ 703
USB Transmit Hub Port Endpoint 2 (USBTXHUBPORT2), offset 0x093 ............................. 703
USB Transmit Hub Port Endpoint 3 (USBTXHUBPORT3), offset 0x09B ............................ 703
USB Receive Functional Address Endpoint 1 (USBRXFUNCADDR1), offset 0x08C ........... 704
USB Receive Functional Address Endpoint 2 (USBRXFUNCADDR2), offset 0x094 ........... 704
USB Receive Functional Address Endpoint 3 (USBRXFUNCADDR3), offset 0x09C ........... 704
USB Receive Hub Address Endpoint 1 (USBRXHUBADDR1), offset 0x08E ...................... 705
USB Receive Hub Address Endpoint 2 (USBRXHUBADDR2), offset 0x096 ....................... 705
USB Receive Hub Address Endpoint 3 (USBRXHUBADDR3), offset 0x09E ...................... 705
USB Receive Hub Port Endpoint 1 (USBRXHUBPORT1), offset 0x08F ............................. 706
USB Receive Hub Port Endpoint 2 (USBRXHUBPORT2), offset 0x097 ............................. 706
USB Receive Hub Port Endpoint 3 (USBRXHUBPORT3), offset 0x09F ............................. 706
USB Maximum Transmit Data Endpoint 1 (USBTXMAXP1), offset 0x110 .......................... 707
USB Maximum Transmit Data Endpoint 2 (USBTXMAXP2), offset 0x120 .......................... 707
USB Maximum Transmit Data Endpoint 3 (USBTXMAXP3), offset 0x130 .......................... 707
USB Control and Status Endpoint 0 Low (USBCSRL0), offset 0x102 ................................. 708
USB Control and Status Endpoint 0 High (USBCSRH0), offset 0x103 ............................... 712
USB Receive Byte Count Endpoint 0 (USBCOUNT0), offset 0x108 ................................... 714
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Register 51:
Register 52:
Register 53:
Register 54:
Register 55:
Register 56:
Register 57:
Register 58:
Register 59:
Register 60:
Register 61:
Register 62:
Register 63:
Register 64:
Register 65:
Register 66:
Register 67:
Register 68:
Register 69:
Register 70:
Register 71:
Register 72:
Register 73:
Register 74:
Register 75:
Register 76:
Register 77:
Register 78:
Register 79:
Register 80:
Register 81:
Register 82:
Register 83:
Register 84:
Register 85:
Register 86:
Register 87:
Register 88:
Register 89:
Register 90:
Register 91:
Register 92:
Register 93:
Register 94:
Register 95:
USB Type Endpoint 0 (USBTYPE0), offset 0x10A ............................................................ 715
USB NAK Limit (USBNAKLMT), offset 0x10B .................................................................. 716
USB Transmit Control and Status Endpoint 1 Low (USBTXCSRL1), offset 0x112 ............... 717
USB Transmit Control and Status Endpoint 2 Low (USBTXCSRL2), offset 0x122 ............... 717
USB Transmit Control and Status Endpoint 3 Low (USBTXCSRL3), offset 0x132 ............... 717
USB Transmit Control and Status Endpoint 1 High (USBTXCSRH1), offset 0x113 .............. 721
USB Transmit Control and Status Endpoint 2 High (USBTXCSRH2), offset 0x123 ............. 721
USB Transmit Control and Status Endpoint 3 High (USBTXCSRH3), offset 0x133 ............. 721
USB Maximum Receive Data Endpoint 1 (USBRXMAXP1), offset 0x114 ........................... 725
USB Maximum Receive Data Endpoint 2 (USBRXMAXP2), offset 0x124 ........................... 725
USB Maximum Receive Data Endpoint 3 (USBRXMAXP3), offset 0x134 ........................... 725
USB Receive Control and Status Endpoint 1 Low (USBRXCSRL1), offset 0x116 ............... 726
USB Receive Control and Status Endpoint 2 Low (USBRXCSRL2), offset 0x126 ............... 726
USB Receive Control and Status Endpoint 3 Low (USBRXCSRL3), offset 0x136 ............... 726
USB Receive Control and Status Endpoint 1 High (USBRXCSRH1), offset 0x117 .............. 731
USB Receive Control and Status Endpoint 2 High (USBRXCSRH2), offset 0x127 .............. 731
USB Receive Control and Status Endpoint 3 High (USBRXCSRH3), offset 0x137 .............. 731
USB Receive Byte Count Endpoint 1 (USBRXCOUNT1), offset 0x118 .............................. 735
USB Receive Byte Count Endpoint 2 (USBRXCOUNT2), offset 0x128 .............................. 735
USB Receive Byte Count Endpoint 3 (USBRXCOUNT3), offset 0x138 .............................. 735
USB Host Transmit Configure Type Endpoint 1 (USBTXTYPE1), offset 0x11A ................... 736
USB Host Transmit Configure Type Endpoint 2 (USBTXTYPE2), offset 0x12A ................... 736
USB Host Transmit Configure Type Endpoint 3 (USBTXTYPE3), offset 0x13A ................... 736
USB Host Transmit Interval Endpoint 1 (USBTXINTERVAL1), offset 0x11B ....................... 737
USB Host Transmit Interval Endpoint 2 (USBTXINTERVAL2), offset 0x12B ....................... 737
USB Host Transmit Interval Endpoint 3 (USBTXINTERVAL3), offset 0x13B ....................... 737
USB Host Configure Receive Type Endpoint 1 (USBRXTYPE1), offset 0x11C ................... 738
USB Host Configure Receive Type Endpoint 2 (USBRXTYPE2), offset 0x12C ................... 738
USB Host Configure Receive Type Endpoint 3 (USBRXTYPE3), offset 0x13C ................... 738
USB Host Receive Polling Interval Endpoint 1 (USBRXINTERVAL1), offset 0x11D ............. 739
USB Host Receive Polling Interval Endpoint 2 (USBRXINTERVAL2), offset 0x12D ............ 739
USB Host Receive Polling Interval Endpoint 3 (USBRXINTERVAL3), offset 0x13D ............ 739
USB Request Packet Count in Block Transfer Endpoint 1 (USBRQPKTCOUNT1), offset
0x304 ........................................................................................................................... 740
USB Request Packet Count in Block Transfer Endpoint 2 (USBRQPKTCOUNT2), offset
0x308 ........................................................................................................................... 740
USB Request Packet Count in Block Transfer Endpoint 3 (USBRQPKTCOUNT3), offset
0x30C ........................................................................................................................... 740
USB Receive Double Packet Buffer Disable (USBRXDPKTBUFDIS), offset 0x340 ............. 741
USB Transmit Double Packet Buffer Disable (USBTXDPKTBUFDIS), offset 0x342 ............ 742
USB External Power Control (USBEPC), offset 0x400 ...................................................... 743
USB External Power Control Raw Interrupt Status (USBEPCRIS), offset 0x404 ................. 746
USB External Power Control Interrupt Mask (USBEPCIM), offset 0x408 ............................ 747
USB External Power Control Interrupt Status and Clear (USBEPCISC), offset 0x40C ......... 748
USB Device RESUME Raw Interrupt Status (USBDRRIS), offset 0x410 ............................ 749
USB Device RESUME Interrupt Mask (USBDRIM), offset 0x414 ....................................... 750
USB Device RESUME Interrupt Status and Clear (USBDRISC), offset 0x418 .................... 751
USB General-Purpose Control and Status (USBGPCS), offset 0x41C ............................... 752
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Revision History
The revision history table notes changes made between the indicated revisions of the LM3S5737
data sheet.
Table 1. Revision History
Date
Revision
November 2011
11107
Description
■
Clarified that when the USB module is in operation, MOSC must be provided with a clock source,
and the system clock must be at least 30 MHz.
■
Added module-specific pin tables to each chapter in the new Signal Description sections.
■
In Hibernation chapter:
–
Changed terminology from non-volatile memory to battery-backed memory.
–
Clarified Hibernation module register reset conditions.
■
In Internal Memory chapter, corrected note in USER_DBG and USER_REG0/1/2/3 registers, that
once committed, the value of the register can never be restored to the factory default value.
■
In Timer chapter, clarified that in 16-Bit Input Edge Time Mode, the timer is capable of capturing
three types of events: rising edge, falling edge, or both.
■
In UART chapter, clarified interrupt behavior.
■
In SSI chapter, corrected SSIClk in the figure "Synchronous Serial Frame Format (Single Transfer)".
■
In USB chapter:
■
–
Removed MULTTRAN bit from USB Transmit Hub Address Endpoint n (USBTXHUBADDRn)
and USB Receive Hub Address Endpoint n (USBRXHUBADDRn) registers.
–
Removed DISCON bit from Device Mode table for USB General Interrupt Status (USBIS)
register.
–
Added WTID bit to USB Connect Timing (USBCONTIM) register.
In Signal Tables chapter:
–
■
■
Corrected pin numbers in table "Connections for Unused Signals" (other pin tables were correct).
In Electrical Characteristics chapter:
–
Corrected values in "Detailed Power Specifications" table.
–
Added "System Clock Characteristics with USB Operation" table.
–
Corrected Nom values for parameters "TCK clock Low time" and "TCK clock High time" in "JTAG
Characteristics" table.
–
Corrected missing values for "Conversion time" and "Conversion rate" parameters in "ADC
Characteristics" table.
Additional minor data sheet clarifications and corrections.
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Revision History
Table 1. Revision History (continued)
Date
Revision
January 2011
9102
Description
■
In Application Interrupt and Reset Control (APINT) register, changed bit name from SYSRESETREQ
to SYSRESREQ.
■
Added DEBUG (Debug Priority) bit field to System Handler Priority 3 (SYSPRI3) register.
■
Added "Reset Sources" table to System Control chapter.
■
Corrected GPIOAMSEL bit field in GPIO Analog Mode Select (GPIOAMSEL) register to be four-bits
wide, bits[7:4].
■
Removed mention of false-start bit detection in the UART chapter. This feature is not supported.
■
Added note that specific module clocks must be enabled before that module's registers can be
programmed. There must be a delay of 3 system clocks after the module clock is enabled before
any of that module's registers are accessed.
■
Changed I2C slave register base addresses and offsets to be relative to the I2C module base address
of 0x4002.0000 and 0x4002.1000, so register bases and offsets were changed for all I2C slave
®
registers. Note that the hw_i2c.h file in the StellarisWare Driver Library uses a base address of
2
0x4002.0800 and 0x4002.1800 for the I C slave registers. Be aware when using registers with
offsets between 0x800 and 0x818 that StellarisWare uses the old slave base address for these
offsets.
■
Corrected nonlinearity and offset error parameters (EL, ED and EO) in ADC Characteristics table.
■
Added specification for maximum input voltage on a non-power pin when the microcontroller is
unpowered (VNON parameter in Maximum Ratings table).
■
Additional minor data sheet clarifications and corrections.
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Table 1. Revision History (continued)
Date
Revision
September 2010
7783
June 2010
April 2010
7403
7021
Description
■
Reorganized ARM Cortex-M3 Processor Core, Memory Map and Interrupts chapters, creating two
new chapters, The Cortex-M3 Processor and Cortex-M3 Peripherals. Much additional content was
added, including all the Cortex-M3 registers.
■
Changed register names to be consistent with StellarisWare names: the Cortex-M3 Interrupt Control
and Status (ICSR) register to the Interrupt Control and State (INTCTRL) register, and the
Cortex-M3 Interrupt Set Enable (SETNA) register to the Interrupt 0-31 Set Enable (EN0) register.
■
In the Internal Memory chapter:
– Added clarification of instruction execution during Flash operations.
– Deleted ROM Version (RMVER) register as it is not used.
■
In the GPIO chapter:
– Renamed the GPIO High-Speed Control (GPIOHSCTL) register to the GPIO High-Performance
Bus Control (GPIOHBCTL) register.
– Added clarification about the operation of the Advanced High-Performance Bus (AHB) and the
legacy Advanced Peripheral Bus (APB).
– Modified Figure 9-1 on page 353 and Figure 9-2 on page 354 to clarify operation of the GPIO
inputs when used as an alternate function.
– Corrected GPIOAMSEL bit field in GPIO Analog Mode Select (GPIOAMSEL) register to be
eight-bits wide, bits[7:0].
■
In General-Purpose Timers chapter, clarified operation of the 32-bit RTC mode.
■
Numerous improvements and clarifications to the USB chapter. Also corrected definitions for bits
2 and 5 in the USBIE register.
■
In Electrical Characteristics chapter:
– Added "Input voltage for a GPIO configured as an analog input" value to Table 21-1 on page 768.
– Added ILKG parameter (GPIO input leakage current) to Table 21-4 on page 769.
– Corrected values for tCLKRF parameter (SSIClk rise/fall time) in Table 21-22 on page 779.
■
Added dimensions for Tray and Tape and Reel shipping mediums.
■
Corrected base address for SRAM in architectural overview chapter.
■
Clarified system clock operation, adding content to “Clock Control” on page 174.
■
Clarified CAN bit timing examples.
■
In Signal Tables chapter, added table "Connections for Unused Signals."
■
In "Reset Characteristics" table, corrected value for supply voltage (VDD) rise time.
■
Additional minor data sheet clarifications and corrections.
■
Added caution note to the I2C Master Timer Period (I2CMTPR) register description and changed
field width to 7 bits.
■
Added note about RST signal routing.
■
Clarified the function of the TnSTALL bit in the GPTMCTL register.
■
Additional minor data sheet clarifications and corrections.
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Revision History
Table 1. Revision History (continued)
Date
Revision
January 2010
6707
Description
■
In "System Control" section, clarified Debug Access Port operation after Sleep modes.
■
Clarified wording on Flash memory access errors.
■
Added section on Flash interrupts.
■
Changed the reset value of the ADC Sample Sequence Result FIFO n (ADCSSFIFOn) registers
to be indeterminate.
■
Clarified operation of SSI transmit FIFO.
■
Made these changes to the Operating Characteristics chapter:
■
October 2009
6449
–
Added storage temperature ratings to "Temperature Characteristics" table
–
Added "ESD Absolute Maximum Ratings" table
Made these changes to the Electrical Characteristics chapter:
–
In "Flash Memory Characteristics" table, corrected Mass erase time
–
Added sleep and deep-sleep wake-up times ("Sleep Modes AC Characteristics" table)
–
In "Reset Characteristics" table, corrected units for supply voltage (VDD) rise time
■
Removed the MAXADCSPD bit field from the DCGC0 register as it has no function in deep-sleep
mode.
■
Deleted reset value for 16-bit mode from GPTMTAILR, GPTMTAMATCHR, and GPTMTAR registers
because the module resets in 32-bit mode.
■
Clarified CAN bit timing and corrected examples.
■
Corrected description for ADDR bit field in USBTXFIFOSZ and USBRXFIFOSZ registers.
■
Clarified PWM source for ADC triggering
■
Made these changes to the Electrical Characteristics chapter:
■
–
Removed VSIH and VSIL parameters from Operating Conditions table.
–
Changed SSI set up and hold times to be expressed in system clocks, not ns.
–
Revised ADC electrical specifications to clarify, including reorganizing and adding new data.
–
Changed the name of the tHIB_REG_WRITE parameter to tHIB_REG_ACCESS.
–
Table added showing actual PLL frequency depending on input crystal.
Additional minor data sheet clarifications and corrections.
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Table 1. Revision History (continued)
Date
Revision
July 2009
5920
April 2009
January 2009
November 2008
5368
4724
4283
Description
■
Clarified Power-on reset and RST pin operation; added new diagrams.
■
Corrected the reset value of the Hibernation Data (HIBDATA) and Hibernation Control (HIBCTL)
registers.
■
Clarified explanation of nonvolatile register programming in Internal Memory chapter.
■
Added explanation of reset value to FMPRE0/1/2/3, FMPPE0/1/2/3, USER_DBG, and USER_REG0/1
registers.
■
Special bulk handling and packet splitting has never been supported as the µDMA module can
support the same function. As a result, all references to these topics has been removed. Bit 7 in
the USBTXCSRLn register only functions as NAKTO in Host mode and is reserved in Device mode.
In addition, bit 0 in the USBRXCSRHn register is reserved.
■
The DISCON and CONN bits in the USBIS and USBIE registers are not available in Device mode.
When the USB controller is acting as a self-powered Device, a GPIO input or analog comparator
input must be connected to VBUS and configured to generate an interrupt when the VBUS level
drops. This interrupt is used to disable the pullup resistor on the USB0DP signal.
■
Changed buffer type for WAKE pin to TTL.
■
In ADC characteristics table, changed Max value for GAIN parameter from ±1 to ±3 and added
EIR(Internal voltage reference error) parameter.
■
Changed ordering numbers.
■
Additional minor data sheet clarifications and corrections.
■
Added JTAG/SWD clarification (see “Communication with JTAG/SWD” on page 163).
■
Added clarification that the PLL operates at 400 MHz, but is divided by two prior to the application
of the output divisor.
■
Corrected bits 2:1 in I2CSIMR, I2CSRIS, I2CSMIS, and I2CSICR registers to be reserved bits
(cannot interrupt on start and stop conditions).
■
Corrected bits 15:11 in USBTXMAXP0/1/2 and USBRXMAXP0/1/2 registers to be reserved bits
(cannot define multiplier).
■
Additional minor data sheet clarifications and corrections.
■
Corrected bit type for RELOAD bit field in SysTick Reload Value register; changed to R/W.
■
Added clarification as to what happens when the SSI in slave mode is required to transmit but there
is no data in the TX FIFO.
■
Added section called "Setting the Device Address" for special considerations when writing the
USBFADDR register.
■
Corrected USBEPIDX to be an 8-bit register.
■
Added comparator operating mode tables.
■
Corrected pin types of signals RST to "in" and USB0RBIAS to "out".
■
Additional minor data sheet clarifications and corrections.
■
Revised High-Level Block Diagram.
■
Additional minor data sheet clarifications and corrections were made.
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Revision History
Table 1. Revision History (continued)
Date
Revision
October 2008
4149
Description
■
Added note on clearing interrupts to the Interrupts chapter:
Note:
■
It may take several processor cycles after a write to clear an interrupt source in order for
NVIC to see the interrupt source de-assert. This means if the interrupt clear is done as
the last action in an interrupt handler, it is possible for the interrupt handler to complete
while NVIC sees the interrupt as still asserted, causing the interrupt handler to be
re-entered errantly. This can be avoided by either clearing the interrupt source at the
beginning of the interrupt handler or by performing a read or write after the write to clear
the interrupt source (and flush the write buffer)
Added clarification on JTAG reset to the JTAG chapter:
In order to reset the JTAG module after the device has been powered on, the TMS input must be
held HIGH for five TCK clock cycles, resetting the TAP controller and all associated JTAG chains.
■
The binary value was incorrect in the JTAG 16-bit switch sequence in the JTAG-to-SWD Switching
section in the JTAG chapter. Sentence changed to:
The 16-bit switch sequence for switching to JTAG mode is defined as b1110011100111100,
transmitted LSB first.
■
The FMA value for the FMPRE3 register was incorrect in the Flash Resident Registers table in the
Internal Memory chapter. The correct value is 0x0000.0006.
■
Step 1 of the Initialization and Configuration procedure in the ADC chapter states the wrong register
to use to enable the ADC clock. Sentence changed to:
1. Enable the ADC clock by writing a value of 0x0001.0000 to the RCGC0 register.
June 2008
2972
■
In the CAN chapter, major improvements were made including a rewrite of the conceptual information
and the addition of new figures to clarify how to use the Controller Area Network (CAN) module.
■
In the USB chapter, clarified endpoint terminology and added a new section on DMA Operation.
■
Additional minor data sheet clarifications and corrections were made.
Started tracking revision history.
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About This Document
This data sheet provides reference information for the LM3S5737 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 related documents are available on the Stellaris web site at www.ti.com/stellaris:
■ Stellaris® Errata
■ ARM® Cortex™-M3 Errata
■ Cortex™-M3/M4 Instruction Set Technical User's Manual
■ Stellaris® Boot Loader User's Guide
■ Stellaris® Graphics Library User's Guide
■ Stellaris® Peripheral Driver Library User's Guide
■ Stellaris® ROM User’s Guide
■ Stellaris® USB Library User's Guide
The following related documents are also referenced:
■ ARM® Debug Interface V5 Architecture Specification
■ ARM® Embedded Trace Macrocell Architecture Specification
■ IEEE Standard 1149.1-Test Access Port and Boundary-Scan Architecture
This documentation list was current as of publication date. Please check the web site for additional
documentation, including application notes and white papers.
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About This Document
Documentation Conventions
This document uses the conventions shown in Table 2 on page 32.
Table 2. Documentation Conventions
Notation
Meaning
General Register Notation
REGISTER
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.
bit
A single bit in a register.
bit field
Two or more consecutive and related bits.
offset 0xnnn
A hexadecimal increment to a register's address, relative to that module's base address as specified
in Table 2-4 on page 70.
Register N
Registers are numbered consecutively throughout the document to aid in referencing them. The
register number has no meaning to software.
reserved
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.
yy:xx
The range of register bits inclusive from xx to yy. For example, 31:15 means bits 15 through 31 in
that register.
Register Bit/Field
Types
This value in the register bit diagram indicates whether software running on the controller can
change the value of the bit field.
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.
R/WC
Software can read or write this field. Writing to it with any value clears the register.
R/W1C
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/W1S
Software can read or write a 1 to this field. A write of a 0 to a R/W1S bit does not affect the bit
value in the register.
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.
WO
Only a write by software is valid; a read of the register returns no meaningful data.
Register Bit/Field
Reset Value
This value in the register bit diagram shows the bit/field value after any reset, unless noted.
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.
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Table 2. Documentation Conventions (continued)
Notation
Meaning
assert a signal
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).
deassert a signal
Change the value of the signal from the logically True state to the logically False state.
SIGNAL
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.
Numbers
X
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.
0x
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.
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Architectural Overview
1
Architectural Overview
®
The 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 LM3S5000 series combines USB 2.0 Full-Speed On-The-Go/Host/Device
combinations with Bosch CAN networking technology.
The LM3S5737 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 LM3S5737 microcontroller features
a battery-backed Hibernation module to efficiently power down the LM3S5737 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 LM3S5737 microcontroller perfectly for
battery applications.
In addition, the LM3S5737 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 LM3S5737 microcontroller is code-compatible
to all members of the extensive Stellaris family; providing flexibility to fit our customers' precise
needs.
Texas Instruments 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. See “Ordering and Contact
Information” on page 827 for ordering information for Stellaris family devices.
1.1
Product Features
The LM3S5737 microcontroller includes the following product features:
■ 32-Bit RISC Performance
– 32-bit ARM® Cortex™-M3 v7M architecture optimized for small-footprint embedded
applications
– 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
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– Integrated Nested Vectored Interrupt Controller (NVIC) providing deterministic interrupt
handling
– 31 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
■ ARM® Cortex™-M3 Processor Core
– 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.
– Deterministic, fast interrupt processing: always 12 cycles, or just 6 cycles with tail-chaining
– External non-maskable interrupt signal (NMI) available for immediate execution of NMI handler
for safety critical applications.
– 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
•
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
– Optimized for single-cycle flash usage
– Three sleep modes with clock gating for low power
– Single-cycle multiply instruction and hardware divide
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Architectural Overview
– Atomic operations
– ARM Thumb2 mixed 16-/32-bit instruction set
– 1.25 DMIPS/MHz
■ JTAG
– IEEE 1149.1-1990 compatible Test Access Port (TAP) controller
– Four-bit Instruction Register (IR) chain for storing JTAG instructions
– IEEE standard instructions: BYPASS, IDCODE, SAMPLE/PRELOAD, EXTEST and INTEST
– ARM additional instructions: APACC, DPACC and ABORT
– Integrated ARM Serial Wire Debug (SWD)
■ Hibernation
– System power control using discrete external regulator
– Dedicated pin for waking from an external signal
– Low-battery detection, signaling, and interrupt generation
– 32-bit real-time clock (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
■ Internal Memory
– 128 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
– Pre-programmed ROM
•
Stellaris family peripheral driver library (DriverLib)
•
Stellaris boot loader
■ DMA Controller
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– ARM PrimeCell® 32-channel configurable µDMA controller
– Support for multiple transfer modes
•
Basic, for simple transfer scenarios
•
Ping-pong, for continuous data flow to/from peripherals
•
Scatter-gather, from a programmable list of arbitrary transfers initiated from a single request
– Dedicated channels for supported peripherals
– One channel each for receive and transmit path for bidirectional peripherals
– Dedicated channel for software-initiated transfers
– Independently configured and operated channels
– Per-channel configurable bus arbitration scheme
– Two levels of priority
– Design optimizations for improved bus access performance between µDMA controller and
the processor core
•
µDMA controller access is subordinate to core access
•
RAM striping
•
Peripheral bus segmentation
– Data sizes of 8, 16, and 32 bits
– Source and destination address increment size of byte, half-word, word, or no increment
– Maskable device requests
– Optional software initiated requests for any channel
– Interrupt on transfer completion, with a separate interrupt per channel
■ GPIOs
– 27-61 GPIOs, depending on configuration
– 5-V-tolerant in input configuration
– Two means of port access: either Advanced High-Performance Bus (AHB) with better
back-to-back access performance, or the legacy Advanced Peripheral Bus (APB) for
backwards-compatibility with existing code
– Fast toggle capable of a change every clock cycle for ports on AHB, every two clock cycles
for ports on APB
– Programmable control for GPIO interrupts
•
Interrupt generation masking
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•
Edge-triggered on rising, falling, or both
•
Level-sensitive on High or Low values
– Bit masking in both read and write operations through address lines
– Can initiate an ADC sample sequence
– Pins configured as digital inputs are Schmitt-triggered.
– Programmable control for GPIO pad configuration
•
Weak pull-up or pull-down resistors
•
2-mA, 4-mA, and 8-mA pad drive for digital communication; up to four pads can be
configured with an 18-mA pad drive for high-current applications
•
Slew rate control for the 8-mA drive
•
Open drain enables
•
Digital input enables
■ General-Purpose Timers
– Three General-Purpose Timer Modules (GPTM), each of which provides two 16-bit
timers/counters. 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
•
User-enabled stalling when the controller asserts CPU Halt flag during debug
•
ADC event trigger
– 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
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•
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
■ ADC
– Eight analog input channels
– Single-ended and differential-input configurations
– On-chip internal temperature sensor
– 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
– Flexible trigger control
•
Controller (software)
•
Timers
•
GPIO
– Hardware averaging of up to 64 samples for improved accuracy
– Converter uses an internal 3-V reference
– Power and ground for the analog circuitry is separate from the digital power and ground
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■ UART
– Fully programmable 16C550-type UART with IrDA support
– Separate 16x8 transmit (TX) and receive (RX) FIFOs to reduce CPU interrupt service loading
– Programmable baud-rate generator allowing speeds up to 3.125 Mbps
– 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
– 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
– Dedicated Direct Memory Access (DMA) transmit and receive channels
■ Synchronous Serial Interface (SSI)
– Two SSI modules, each with the following features:
– Master or slave operation
– Support for Direct Memory Access (DMA)
– 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
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■ I2C
– Two I2C modules, each with the following features:
– Devices on the I2C bus can be designated as either a master or a slave
•
Supports both sending and receiving data as either a master or a slave
•
Supports simultaneous master and slave operation
– Four I2C modes
•
Master transmit
•
Master receive
•
Slave transmit
•
Slave receive
– Two transmission speeds: Standard (100 Kbps) and Fast (400 Kbps)
– Master and slave interrupt generation
•
Master generates interrupts when a transmit or receive operation completes (or aborts
due to an error)
•
Slave generates interrupts when data has been sent or requested by a master
– Master with arbitration and clock synchronization, multimaster support, and 7-bit addressing
mode
■ Controller Area Network (CAN)
– CAN protocol version 2.0 part A/B
– Bit rates up to 1 Mbps
– 32 message objects with individual identifier masks
– Maskable interrupt
– Disable Automatic Retransmission mode for Time-Triggered CAN (TTCAN) applications
– Programmable Loopback mode for self-test operation
– Programmable FIFO mode enables storage of multiple message objects
– Gluelessly attaches to an external CAN interface through the CANnTX and CANnRX signals
■ USB
– Standards-based
– USB 2.0 full-speed (12 Mbps) and low-speed (1.5 Mbps) operation
– USB Device or Host mode
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– Integrated PHY
– 4 transfer types: Control, Interrupt, Bulk, and Isochronous
– 8 endpoints
•
1 dedicated control IN endpoint and 1 dedicated control OUT endpoint
•
3 configurable IN endpoints and 3 configurable OUT endpoints
– 2 KB dedicated endpoint memory
•
Direct memory access (DMA)
•
One endpoint may be defined for double-buffered 1023-byte isochronous packet size
■ 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
– 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
■ Industrial temperature 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
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■ Factory automation
■ HVAC and building control
■ Gaming equipment
■ Motion control
■ Medical instrumentation
■ Fire and security
■ Power and energy
■ Transportation
1.3
High-Level Block Diagram
Figure 1-1 on page 44 depicts the features on the Stellaris LM3S5737 microcontroller.
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Figure 1-1. Stellaris LM3S5737 Microcontroller High-Level Block Diagram
JTAG/SWD
ARM®
Cortex™-M3
ROM
Boot Loader
DriverLib
(50MHz)
System
Control and
Clocks
(w/ Precis. Osc.)
Flash
(128KB)
DCode bus
NVIC
MPU
ICode bus
System Bus
LM3S5737
Bus Matrix
SRAM
(64KB)
SYSTEM PERIPHERALS
GeneralPurpose
Timer (3)
Hibernation
Module
USB Host
(FS PHY)
SSI
(2)
Advanced Peripheral Bus (APB)
Watchdog
Timer
(1)
Advanced High-Performance Bus (AHB)
DMA
GPIOs
(27-61)
SERIAL PERIPHERALS
UART
(1)
I2C
(2)
CAN
Controller
(1)
ANALOG PERIPHERALS
10- Bit ADC
Channels
(8)
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1.4
Functional Overview
The following sections provide an overview of the features of the LM3S5737 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 827.
1.4.1
ARM Cortex™-M3
1.4.1.1
Processor Core (see page 51)
All members of the Stellaris product family, including the LM3S5737 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.
1.4.1.2
Memory Map (see page 70)
A memory map lists the location of instructions and data in memory. The memory map for the
LM3S5737 controller can be found in Table 2-4 on page 70. Register addresses are given as a
hexadecimal increment, relative to the module's base address as shown in the memory map.
1.4.1.3
System Timer (SysTick) (see page 93)
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.
1.4.1.4
Nested Vectored Interrupt Controller (NVIC) (see page 94)
The LM3S5737 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 31 interrupts.
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1.4.1.5
System Control Block (SCB) (see page 96)
The SCB provides system implementation information and system control, including configuration,
control, and reporting of system exceptions.
1.4.1.6
Memory Protection Unit (MPU) (see page 96)
The MPU 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.
1.4.1.7
Direct Memory Access (see page 287)
The LM3S5737 microcontroller includes a Direct Memory Access (DMA) controller, known as
micro-DMA (μDMA). The μDMA controller provides a way to offload data transfer tasks from the
Cortex-M3 processor, allowing for more efficient use of the processor and the expanded available
bus bandwidth. The μDMA controller can perform transfers between memory and peripherals. It
has dedicated channels for each supported peripheral and can be programmed to automatically
perform transfers between peripherals and memory as the peripheral is ready to transfer more data.
The μDMA controller also supports sophisticated transfer modes such as ping-pong and
scatter-gather, which allows the processor to set up a list of transfer tasks for the controller.
1.4.2
Motor Control Peripherals
To enhance motor control, the LM3S5737 controller features Pulse Width Modulation (PWM) outputs.
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
wave is modulated to encode an analog signal. Typical applications include switching power supplies
and motor control.
On the LM3S5737, PWM motion control functionality can be achieved through:
■ The motion control features of the general-purpose timers using the CCP pins
CCP Pins (see page 406)
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.
1.4.3
Analog Peripherals
To handle analog signals, the LM3S5737 microcontroller offers an Analog-to-Digital Converter
(ADC).
1.4.3.1
ADC (see page 458)
An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a
discrete digital number.
The LM3S5737 ADC module features 10-bit conversion resolution and supports eight 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.
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1.4.4
Serial Communications Peripherals
The LM3S5737 controller supports both asynchronous and synchronous serial communications
with:
■ One fully programmable 16C550-type UART
■ Two SSI modules
■ Two I2C modules
■ One USB 2.0 full-speed controller
■ One CAN unit
1.4.4.1
UART (see page 493)
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 LM3S5737 controller includes one fully programmable 16C550-type UARTthat supports data
transfer speeds up to 3.125 Mbps. (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 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 536)
Synchronous Serial Interface (SSI) is a four-wire bi-directional full and low-speed communications
interface.
The LM3S5737 controller includes two SSI modules that provide 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.
Each 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.
Each 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.
Each 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 576)
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).
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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 LM3S5737 controller includes two I2C modules that provide 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. Each 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
USB (see page 659)
Universal Serial Bus (USB) is a serial bus standard designed to allow peripherals to be connected
and disconnected using a standardized interface without rebooting the system.
The LM3S5737 controller supports the USB 2.0 full-speed configuration with Device or USB Host
mode. The specified throughput for a USB 2.0 full-speed controller is 12 Mbps.
1.4.4.5
Controller Area Network (see page 613)
Controller Area Network (CAN) is a multicast shared serial-bus standard for connecting electronic
control units (ECUs). CAN was specifically designed to be robust in electromagnetically noisy
environments and can utilize a differential balanced line like RS-485 or a more robust twisted-pair
wire. Originally created for automotive purposes, now it is used in many embedded control
applications (for example, industrial or medical). Bit rates up to 1Mb/s are possible at network lengths
below 40 meters. Decreased bit rates allow longer network distances (for example, 125 Kb/s at
500m).
A transmitter sends a message to all CAN nodes (broadcasting). Each node decides on the basis
of the identifier received whether it should process the message. The identifier also determines the
priority that the message enjoys in competition for bus access. Each CAN message can transmit
from 0 to 8 bytes of user information. The LM3S5737 includes one CAN unit.
1.4.5
System Peripherals
1.4.5.1
Programmable GPIOs (see page 348)
General-purpose input/output (GPIO) pins offer flexibility for a variety of connections.
The Stellaris GPIO module is comprised of eight 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 27-61 programmable input/output pins.
The number of GPIOs available depends on the peripherals being used (see “Signal
Tables” on page 754 for the signals available to each GPIO pin).
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. Pins configured as digital inputs are
Schmitt-triggered.
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1.4.5.2
Three Programmable Timers (see page 400)
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 434)
A watchdog timer can generate an interrupt 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 LM3S5737 controller offers both single-cycle SRAM and single-cycle Flash memory.
1.4.6.1
SRAM (see page 258)
The LM3S5737 static random access memory (SRAM) controller supports 64 KB SRAM. The internal
SRAM of the Stellaris devices starts at base 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 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 259)
The LM3S5737 Flash controller supports 128 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.
1.4.6.3
ROM (see page 788)
The LM3S5737 microcontroller ships with the Stellaris family Peripheral Driver Library conveniently
preprogrammed in read-only memory (ROM). The Stellaris Peripheral Driver Library is a royalty-free
software library for controlling on-chip peripherals, and includes a boot-loader capability. The library
performs both peripheral initialization and peripheral control functions, with a choice of polled or
interrupt-driven peripheral support, and takes full advantage of the stellar interrupt performance of
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the ARM® Cortex™-M3 core. No special pragmas or custom assembly code prologue/epilogue
functions are required. For applications that require in-field programmability, the royalty-free Stellaris
boot loader included in the Stellaris Peripheral Driver Library can act as an application loader and
support in-field firmware updates.
1.4.7
Additional Features
1.4.7.1
JTAG TAP Controller (see page 157)
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 composed of the standard four pins: 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 Stellaris 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 Stellaris JTAG instructions select the Stellaris TDO
outputs. The multiplexer is controlled by the Stellaris JTAG controller, which has comprehensive
programming for the ARM, Stellaris, and unimplemented JTAG instructions.
1.4.7.2
System Control and Clocks (see page 169)
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.
1.4.7.3
Hibernation Module (see page 236)
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 753
■ “Signal Tables” on page 754
■ “Operating Characteristics” on page 767
■ “Electrical Characteristics” on page 768
■ “Package Information” on page 829
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2
The Cortex-M3 Processor
The ARM® Cortex™-M3 processor provides a high-performance, low-cost platform that meets the
system requirements 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.
■ Deterministic, fast interrupt processing: always 12 cycles, or just 6 cycles with tail-chaining
■ External non-maskable interrupt signal (NMI) available for immediate execution of NMI handler
for safety critical applications.
■ 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
– 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
■ Optimized for single-cycle flash usage
■ Three sleep modes with clock gating for low power
■ Single-cycle multiply instruction and hardware divide
■ Atomic operations
■ ARM Thumb2 mixed 16-/32-bit instruction set
■ 1.25 DMIPS/MHz
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The Cortex-M3 Processor
®
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 motor control.
This chapter provides information on the Stellaris implementation of the Cortex-M3 processor,
including the programming model, the memory model, the exception model, fault handling, and
power management.
For technical details on the instruction set, see the Cortex™-M3/M4 Instruction Set Technical User's
Manual.
2.1
Block Diagram
The Cortex-M3 processor is built on a high-performance processor core, with a 3-stage pipeline
Harvard architecture, making it ideal for demanding embedded applications. The processor delivers
exceptional power efficiency through an efficient instruction set and extensively optimized design,
providing high-end processing hardware including a range of single-cycle and SIMD multiplication
and multiply-with-accumulate capabilities, saturating arithmetic and dedicated hardware division.
To facilitate the design of cost-sensitive devices, the Cortex-M3 processor implements tightly coupled
system components that reduce processor area while significantly improving interrupt handling and
system debug capabilities. The Cortex-M3 processor implements a version of the Thumb® instruction
set based on Thumb-2 technology, ensuring high code density and reduced program memory
requirements. The Cortex-M3 instruction set provides the exceptional performance expected of a
modern 32-bit architecture, with the high code density of 8-bit and 16-bit microcontrollers.
The Cortex-M3 processor closely integrates a nested interrupt controller (NVIC), to deliver
industry-leading interrupt performance. The Stellaris NVIC includes a non-maskable interrupt (NMI)
and provides eight interrupt priority levels. The tight integration of the processor core and NVIC
provides fast execution of interrupt service routines (ISRs), dramatically reducing interrupt latency.
The hardware stacking of registers and the ability to suspend load-multiple and store-multiple
operations further reduce interrupt latency. Interrupt handlers do not require any assembler stubs
which removes code overhead from the ISRs. Tail-chaining optimization also significantly reduces
the overhead when switching from one ISR to another. To optimize low-power designs, the NVIC
integrates with the sleep modes, including Deep-sleep mode, which enables the entire device to be
rapidly powered down.
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Figure 2-1. CPU Block Diagram
Nested
Vectored
Interrupt
Controller
Interrupts
Sleep
ARM
Cortex-M3
CM3 Core
Debug
Instructions
Data
Trace
Port
Interface
Unit
Memory
Protection
Unit
Flash
Patch and
Breakpoint
Instrumentation
Data
Watchpoint Trace Macrocell
and Trace
ROM
Table
Private Peripheral
Bus
(internal)
Adv. Peripheral
Bus
Bus
Matrix
Serial Wire JTAG
Debug Port
Debug
Access Port
2.2
Overview
2.2.1
System-Level Interface
Serial
Wire
Output
Trace
Port
(SWO)
I-code bus
D-code bus
System bus
The Cortex-M3 processor provides multiple interfaces using AMBA® technology to provide
high-speed, low-latency memory accesses. The core supports unaligned data accesses and
implements atomic bit manipulation that enables faster peripheral controls, system spinlocks, and
thread-safe Boolean data handling.
The Cortex-M3 processor has a memory protection unit (MPU) that provides fine-grain memory
control, enabling applications to implement security privilege levels and separate code, data and
stack on a task-by-task basis.
2.2.2
Integrated Configurable Debug
The Cortex-M3 processor implements a complete hardware debug solution, providing high system
visibility of the processor and memory through either a traditional JTAG port or a 2-pin Serial Wire
Debug (SWD) port that is ideal for microcontrollers and other small package devices. The Stellaris
implementation replaces the ARM SW-DP and JTAG-DP with the ARM CoreSight™-compliant
Serial Wire JTAG Debug Port (SWJ-DP) interface. The SWJ-DP interface combines the SWD and
JTAG debug ports into one module. See the ARM® Debug Interface V5 Architecture Specification
for details on SWJ-DP.
For system trace, the processor integrates an Instrumentation Trace Macrocell (ITM) alongside data
watchpoints and a profiling unit. To enable simple and cost-effective profiling of the system trace
events, a Serial Wire Viewer (SWV) can export a stream of software-generated messages, data
trace, and profiling information through a single pin.
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The Flash Patch and Breakpoint Unit (FPB) provides up to eight hardware breakpoint comparators
that debuggers can use. The comparators in the FPB also provide remap functions of up to eight
words in the program code in the CODE memory region. This enables applications stored in a
read-only area of Flash memory to be patched in another area of on-chip SRAM or Flash memory.
If a patch is required, the application programs the FPB to remap a number of addresses. When
those addresses are accessed, the accesses are redirected to a remap table specified in the FPB
configuration.
For more information on the Cortex-M3 debug capabilities, see theARM® Debug Interface V5
Architecture Specification.
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, as shown in Figure 2-2 on page 54.
Figure 2-2. TPIU Block Diagram
2.2.4
Debug
ATB
Slave
Port
ATB
Interface
APB
Slave
Port
APB
Interface
Asynchronous FIFO
Trace Out
(serializer)
Serial Wire
Trace Port
(SWO)
Cortex-M3 System Component Details
The Cortex-M3 includes the following system components:
■ SysTick
A 24-bit count-down timer that can be used as a Real-Time Operating System (RTOS) tick timer
or as a simple counter (see “System Timer (SysTick)” on page 93).
■ Nested Vectored Interrupt Controller (NVIC)
An embedded interrupt controller that supports low latency interrupt processing (see “Nested
Vectored Interrupt Controller (NVIC)” on page 94).
■ System Control Block (SCB)
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The programming model interface to the processor. The SCB provides system implementation
information and system control, including configuration, control, and reporting of system exceptions
(see “System Control Block (SCB)” on page 96).
■ Memory Protection Unit (MPU)
Improves system reliability by defining the memory attributes for different memory regions. The
MPU provides up to eight different regions and an optional predefined background region (see
“Memory Protection Unit (MPU)” on page 96).
2.3
Programming Model
This section describes the Cortex-M3 programming model. In addition to the individual core register
descriptions, information about the processor modes and privilege levels for software execution and
stacks is included.
2.3.1
Processor Mode and Privilege Levels for Software Execution
The Cortex-M3 has two modes of operation:
■ Thread mode
Used to execute application software. The processor enters Thread mode when it comes out of
reset.
■ Handler mode
Used to handle exceptions. When the processor has finished exception processing, it returns to
Thread mode.
In addition, the Cortex-M3 has two privilege levels:
■ Unprivileged
In this mode, software has the following restrictions:
– Limited access to the MSR and MRS instructions and no use of the CPS instruction
– No access to the system timer, NVIC, or system control block
– Possibly restricted access to memory or peripherals
■ Privileged
In this mode, software can use all the instructions and has access to all resources.
In Thread mode, the CONTROL register (see page 69) controls whether software execution is
privileged or unprivileged. In Handler mode, software execution is always privileged.
Only privileged software can write to the CONTROL register to change the privilege level for software
execution in Thread mode. Unprivileged software can use the SVC instruction to make a supervisor
call to transfer control to privileged software.
2.3.2
Stacks
The processor uses a full descending stack, meaning that the stack pointer indicates the last stacked
item on the memory. When the processor pushes a new item onto the stack, it decrements the stack
pointer and then writes the item to the new memory location. The processor implements two stacks:
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the main stack and the process stack, with a pointer for each held in independent registers (see the
SP register on page 59).
In Thread mode, the CONTROL register (see page 69) controls whether the processor uses the
main stack or the process stack. In Handler mode, the processor always uses the main stack. The
options for processor operations are shown in Table 2-1 on page 56.
Table 2-1. Summary of Processor Mode, Privilege Level, and Stack Use
Processor Mode
Use
Privilege Level
Thread
Applications
Privileged or unprivileged
Stack Used
Handler
Exception handlers
Always privileged
a
Main stack or process stack
a
Main stack
a. See CONTROL (page 69).
2.3.3
Register Map
Figure 2-3 on page 56 shows the Cortex-M3 register set. Table 2-2 on page 57 lists the Core
registers. The core registers are not memory mapped and are accessed by register name, so the
base address is n/a (not applicable) and there is no offset.
Figure 2-3. Cortex-M3 Register Set
R0
R1
R2
Low registers
R3
R4
R5
R6
General-purpose registers
R7
R8
R9
High registers
R10
R11
R12
Stack Pointer
SP (R13)
Link Register
LR (R14)
Program Counter
PC (R15)
PSR
PSP‡
MSP‡
‡
Banked version of SP
Program status register
PRIMASK
FAULTMASK
Exception mask registers
Special registers
BASEPRI
CONTROL
CONTROL register
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Table 2-2. Processor Register Map
Offset
Type
Reset
-
R0
R/W
-
Cortex General-Purpose Register 0
58
-
R1
R/W
-
Cortex General-Purpose Register 1
58
-
R2
R/W
-
Cortex General-Purpose Register 2
58
-
R3
R/W
-
Cortex General-Purpose Register 3
58
-
R4
R/W
-
Cortex General-Purpose Register 4
58
-
R5
R/W
-
Cortex General-Purpose Register 5
58
-
R6
R/W
-
Cortex General-Purpose Register 6
58
-
R7
R/W
-
Cortex General-Purpose Register 7
58
-
R8
R/W
-
Cortex General-Purpose Register 8
58
-
R9
R/W
-
Cortex General-Purpose Register 9
58
-
R10
R/W
-
Cortex General-Purpose Register 10
58
-
R11
R/W
-
Cortex General-Purpose Register 11
58
-
R12
R/W
-
Cortex General-Purpose Register 12
58
-
SP
R/W
-
Stack Pointer
59
-
LR
R/W
0xFFFF.FFFF
Link Register
60
-
PC
R/W
-
Program Counter
61
-
PSR
R/W
0x0100.0000
Program Status Register
62
-
PRIMASK
R/W
0x0000.0000
Priority Mask Register
66
-
FAULTMASK
R/W
0x0000.0000
Fault Mask Register
67
-
BASEPRI
R/W
0x0000.0000
Base Priority Mask Register
68
-
CONTROL
R/W
0x0000.0000
Control Register
69
2.3.4
Description
See
page
Name
Register Descriptions
This section lists and describes the Cortex-M3 registers, in the order shown in Figure 2-3 on page 56.
The core registers are not memory mapped and are accessed by register name rather than offset.
Note:
The register type shown in the register descriptions refers to type during program execution
in Thread mode and Handler mode. Debug access can differ.
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Register 1: Cortex General-Purpose Register 0 (R0)
Register 2: Cortex General-Purpose Register 1 (R1)
Register 3: Cortex General-Purpose Register 2 (R2)
Register 4: Cortex General-Purpose Register 3 (R3)
Register 5: Cortex General-Purpose Register 4 (R4)
Register 6: Cortex General-Purpose Register 5 (R5)
Register 7: Cortex General-Purpose Register 6 (R6)
Register 8: Cortex General-Purpose Register 7 (R7)
Register 9: Cortex General-Purpose Register 8 (R8)
Register 10: Cortex General-Purpose Register 9 (R9)
Register 11: Cortex General-Purpose Register 10 (R10)
Register 12: Cortex General-Purpose Register 11 (R11)
Register 13: Cortex General-Purpose Register 12 (R12)
The Rn registers are 32-bit general-purpose registers for data operations and can be accessed
from either privileged or unprivileged mode.
Cortex General-Purpose Register 0 (R0)
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
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
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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
-
DATA
Type
Reset
DATA
Type
Reset
Bit/Field
Name
Type
Reset
31:0
DATA
R/W
-
Description
Register data.
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Register 14: Stack Pointer (SP)
The Stack Pointer (SP) is register R13. In Thread mode, the function of this register changes
depending on the ASP bit in the Control Register (CONTROL) register. When the ASP bit is clear,
this register is the Main Stack Pointer (MSP). When the ASP bit is set, this register is the Process
Stack Pointer (PSP). On reset, the ASP bit is clear, and the processor loads the MSP with the value
from address 0x0000.0000. The MSP can only be accessed in privileged mode; the PSP can be
accessed in either privileged or unprivileged mode.
Stack Pointer (SP)
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
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
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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
-
SP
Type
Reset
SP
Type
Reset
Bit/Field
Name
Type
Reset
31:0
SP
R/W
-
Description
This field is the address of the stack pointer.
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Register 15: Link Register (LR)
The Link Register (LR) is register R14, and it stores the return information for subroutines, function
calls, and exceptions. LR can be accessed from either privileged or unprivileged mode.
EXC_RETURN is loaded into LR on exception entry. See Table 2-10 on page 86 for the values and
description.
Link Register (LR)
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
LINK
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
LINK
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
LINK
R/W
R/W
1
Reset
R/W
1
Description
0xFFFF.FFFF This field is the return address.
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Register 16: Program Counter (PC)
The Program Counter (PC) is register R15, and it contains the current program address. On reset,
the processor loads the PC with the value of the reset vector, which is at address 0x0000.0004. Bit
0 of the reset vector is loaded into the THUMB bit of the EPSR at reset and must be 1. The PC register
can be accessed in either privileged or unprivileged mode.
Program Counter (PC)
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
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
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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
-
PC
Type
Reset
PC
Type
Reset
Bit/Field
Name
Type
Reset
31:0
PC
R/W
-
Description
This field is the current program address.
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Register 17: Program Status Register (PSR)
Note:
This register is also referred to as xPSR.
The Program Status Register (PSR) has three functions, and the register bits are assigned to the
different functions:
■ Application Program Status Register (APSR), bits 31:27,
■ Execution Program Status Register (EPSR), bits 26:24, 15:10
■ Interrupt Program Status Register (IPSR), bits 6:0
The PSR, IPSR, and EPSR registers can only be accessed in privileged mode; the APSR register
can be accessed in either privileged or unprivileged mode.
APSR contains the current state of the condition flags from previous instruction executions.
EPSR contains the Thumb state bit and the execution state bits for the If-Then (IT) instruction or
the Interruptible-Continuable Instruction (ICI) field for an interrupted load multiple or store multiple
instruction. Attempts to read the EPSR directly through application software using the MSR instruction
always return zero. Attempts to write the EPSR using the MSR instruction in application software
are always ignored. Fault handlers can examine the EPSR value in the stacked PSR to determine
the operation that faulted (see “Exception Entry and Return” on page 84).
IPSR contains the exception type number of the current Interrupt Service Routine (ISR).
These registers can be accessed individually or as a combination of any two or all three registers,
using the register name as an argument to the MSR or MRS instructions. For example, all of the
registers can be read using PSR with the MRS instruction, or APSR only can be written to using
APSR with the MSR instruction. page 62 shows the possible register combinations for the PSR. See
the MRS and MSR instruction descriptions in the Cortex™-M3/M4 Instruction Set Technical User's
Manual for more information about how to access the program status registers.
Table 2-3. PSR Register Combinations
Register
Type
PSR
R/W
Combination
APSR, EPSR, and IPSR
IEPSR
RO
EPSR and IPSR
a, b
a
APSR and IPSR
b
APSR and EPSR
IAPSR
R/W
EAPSR
R/W
a. The processor ignores writes to the IPSR bits.
b. Reads of the EPSR bits return zero, and the processor ignores writes to these bits.
Program Status Register (PSR)
Type R/W, reset 0x0100.0000
Type
Reset
31
30
29
28
27
N
Z
C
V
Q
26
25
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
15
14
13
12
11
10
9
ICI / IT
ICI / IT
Type
Reset
RO
0
RO
0
RO
0
24
23
22
21
20
THUMB
RO
1
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
reserved
ISRNUM
RO
0
RO
0
62
RO
0
RO
0
RO
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Bit/Field
Name
Type
Reset
31
N
R/W
0
Description
APSR Negative or Less Flag
Value Description
1
The previous operation result was negative or less than.
0
The previous operation result was positive, zero, greater than,
or equal.
The value of this bit is only meaningful when accessing PSR or APSR.
30
Z
R/W
0
APSR Zero Flag
Value Description
1
The previous operation result was zero.
0
The previous operation result was non-zero.
The value of this bit is only meaningful when accessing PSR or APSR.
29
C
R/W
0
APSR Carry or Borrow Flag
Value Description
1
The previous add operation resulted in a carry bit or the previous
subtract operation did not result in a borrow bit.
0
The previous add operation did not result in a carry bit or the
previous subtract operation resulted in a borrow bit.
The value of this bit is only meaningful when accessing PSR or APSR.
28
V
R/W
0
APSR Overflow Flag
Value Description
1
The previous operation resulted in an overflow.
0
The previous operation did not result in an overflow.
The value of this bit is only meaningful when accessing PSR or APSR.
27
Q
R/W
0
APSR DSP Overflow and Saturation Flag
Value Description
1
DSP Overflow or saturation has occurred.
0
DSP overflow or saturation has not occurred since reset or since
the bit was last cleared.
The value of this bit is only meaningful when accessing PSR or APSR.
This bit is cleared by software using an MRS instruction.
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Bit/Field
Name
Type
Reset
26:25
ICI / IT
RO
0x0
Description
EPSR ICI / IT status
These bits, along with bits 15:10, contain the Interruptible-Continuable
Instruction (ICI) field for an interrupted load multiple or store multiple
instruction or the execution state bits of the IT instruction.
When EPSR holds the ICI execution state, bits 26:25 are zero.
The If-Then block contains up to four instructions following an IT
instruction. Each instruction in the block is conditional. The conditions
for the instructions are either all the same, or some can be the inverse
of others. See the Cortex™-M3/M4 Instruction Set Technical User's
Manual for more information.
The value of this field is only meaningful when accessing PSR or EPSR.
24
THUMB
RO
1
EPSR Thumb State
This bit indicates the Thumb state and should always be set.
The following can clear the THUMB bit:
■
The BLX, BX and POP{PC} instructions
■
Restoration from the stacked xPSR value on an exception return
■
Bit 0 of the vector value on an exception entry or reset
Attempting to execute instructions when this bit is clear results in a fault
or lockup. See “Lockup” on page 88 for more information.
The value of this bit is only meaningful when accessing PSR or EPSR.
23:16
reserved
RO
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.
15:10
ICI / IT
RO
0x0
EPSR ICI / IT status
These bits, along with bits 26:25, contain the Interruptible-Continuable
Instruction (ICI) field for an interrupted load multiple or store multiple
instruction or the execution state bits of the IT instruction.
When an interrupt occurs during the execution of an LDM, STM, PUSH
or POP instruction, the processor stops the load multiple or store multiple
instruction operation temporarily and stores the next register operand
in the multiple operation to bits 15:12. After servicing the interrupt, the
processor returns to the register pointed to by bits 15:12 and resumes
execution of the multiple load or store instruction. When EPSR holds
the ICI execution state, bits 11:10 are zero.
The If-Then block contains up to four instructions following a 16-bit IT
instruction. Each instruction in the block is conditional. The conditions
for the instructions are either all the same, or some can be the inverse
of others. See the Cortex™-M3/M4 Instruction Set Technical User's
Manual for more information.
The value of this field is only meaningful when accessing PSR or EPSR.
9:7
reserved
RO
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.
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Bit/Field
Name
Type
Reset
Description
6:0
ISRNUM
RO
0x00
IPSR ISR Number
This field contains the exception type number of the current Interrupt
Service Routine (ISR).
Value
Description
0x00
Thread mode
0x01
Reserved
0x02
NMI
0x03
Hard fault
0x04
Memory management fault
0x05
Bus fault
0x06
Usage fault
0x07-0x0A Reserved
0x0B
SVCall
0x0C
Reserved for Debug
0x0D
Reserved
0x0E
PendSV
0x0F
SysTick
0x10
Interrupt Vector 0
0x11
Interrupt Vector 1
...
...
0x3F
Interrupt Vector 47
0x40-0x7F Reserved
See “Exception Types” on page 79 for more information.
The value of this field is only meaningful when accessing PSR or IPSR.
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Register 18: Priority Mask Register (PRIMASK)
The PRIMASK register prevents activation of all exceptions with programmable priority. Reset,
non-maskable interrupt (NMI), and hard fault are the only exceptions with fixed priority. Exceptions
should be disabled when they might impact the timing of critical tasks. This register is only accessible
in privileged mode. The MSR and MRS instructions are used to access the PRIMASK register, and
the CPS instruction may be used to change the value of the PRIMASK register. See the
Cortex™-M3/M4 Instruction Set Technical User's Manual for more information on these instructions.
For more information on exception priority levels, see “Exception Types” on page 79.
Priority Mask Register (PRIMASK)
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:1
reserved
RO
0x0000.000
0
PRIMASK
R/W
0
RO
0
PRIMASK
R/W
0
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.
Priority Mask
Value Description
1
Prevents the activation of all exceptions with configurable
priority.
0
No effect.
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Register 19: Fault Mask Register (FAULTMASK)
The FAULTMASK register prevents activation of all exceptions except for the Non-Maskable Interrupt
(NMI). Exceptions should be disabled when they might impact the timing of critical tasks. This register
is only accessible in privileged mode. The MSR and MRS instructions are used to access the
FAULTMASK register, and the CPS instruction may be used to change the value of the FAULTMASK
register. See the Cortex™-M3/M4 Instruction Set Technical User's Manual for more information on
these instructions. For more information on exception priority levels, see “Exception
Types” on page 79.
Fault Mask Register (FAULTMASK)
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:1
reserved
RO
0x0000.000
0
FAULTMASK
R/W
0
RO
0
FAULTMASK
R/W
0
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.
Fault Mask
Value Description
1
Prevents the activation of all exceptions except for NMI.
0
No effect.
The processor clears the FAULTMASK bit on exit from any exception
handler except the NMI handler.
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Register 20: Base Priority Mask Register (BASEPRI)
The BASEPRI register defines the minimum priority for exception processing. When BASEPRI is
set to a nonzero value, it prevents the activation of all exceptions with the same or lower priority
level as the BASEPRI value. Exceptions should be disabled when they might impact the timing of
critical tasks. This register is only accessible in privileged mode. For more information on exception
priority levels, see “Exception Types” on page 79.
Base Priority Mask Register (BASEPRI)
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
BASEPRI
RO
0
Bit/Field
Name
Type
Reset
31:8
reserved
RO
0x0000.00
7:5
BASEPRI
R/W
0x0
R/W
0
reserved
RO
0
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.
Base Priority
Any exception that has a programmable priority level with the same or
lower priority as the value of this field is masked. The PRIMASK register
can be used to mask all exceptions with programmable priority levels.
Higher priority exceptions have lower priority levels.
Value Description
4:0
reserved
RO
0x0
0x0
All exceptions are unmasked.
0x1
All exceptions with priority level 1-7 are masked.
0x2
All exceptions with priority level 2-7 are masked.
0x3
All exceptions with priority level 3-7 are masked.
0x4
All exceptions with priority level 4-7 are masked.
0x5
All exceptions with priority level 5-7 are masked.
0x6
All exceptions with priority level 6-7 are masked.
0x7
All exceptions with priority level 7 are masked.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Register 21: Control Register (CONTROL)
The CONTROL register controls the stack used and the privilege level for software execution when
the processor is in Thread mode. This register is only accessible in privileged mode.
Handler mode always uses MSP, so the processor ignores explicit writes to the ASP bit of the
CONTROL register when in Handler mode. The exception entry and return mechanisms automatically
update the CONTROL register based on the EXC_RETURN value (see Table 2-10 on page 86).
In an OS environment, threads running in Thread mode should use the process stack and the kernel
and exception handlers should use the main stack. By default, Thread mode uses MSP. To switch
the stack pointer used in Thread mode to PSP, either use the MSR instruction to set the ASP bit, as
detailed in the Cortex™-M3/M4 Instruction Set Technical User's Manual, or perform an exception
return to Thread mode with the appropriate EXC_RETURN value, as shown in Table 2-10 on page 86.
Note:
When changing the stack pointer, software must use an ISB instruction immediately after
the MSR instruction, ensuring that instructions after the ISB execute use the new stack
pointer. See the Cortex™-M3/M4 Instruction Set Technical User's Manual.
Control Register (CONTROL)
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
ASP
TMPL
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0x0000.000
1
ASP
R/W
0
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.
Active Stack Pointer
Value Description
1
PSP is the current stack pointer.
0
MSP is the current stack pointer
In Handler mode, this bit reads as zero and ignores writes. The
Cortex-M3 updates this bit automatically on exception return.
0
TMPL
R/W
0
Thread Mode Privilege Level
Value Description
1
Unprivileged software can be executed in Thread mode.
0
Only privileged software can be executed in Thread mode.
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2.3.5
Exceptions and Interrupts
The Cortex-M3 processor supports interrupts and system exceptions. The processor and the Nested
Vectored Interrupt Controller (NVIC) prioritize and handle all exceptions. An exception changes the
normal flow of software control. The processor uses Handler mode to handle all exceptions except
for reset. See “Exception Entry and Return” on page 84 for more information.
The NVIC registers control interrupt handling. See “Nested Vectored Interrupt Controller
(NVIC)” on page 94 for more information.
2.3.6
Data Types
The Cortex-M3 supports 32-bit words, 16-bit halfwords, and 8-bit bytes. The processor also supports
64-bit data transfer instructions. All instruction and data memory accesses are little endian. See
“Memory Regions, Types and Attributes” on page 72 for more information.
2.4
Memory Model
This section describes the processor memory map, the behavior of memory accesses, and the
bit-banding features. The processor has a fixed memory map that provides up to 4 GB of addressable
memory.
The memory map for the LM3S5737 controller is provided in Table 2-4 on page 70. In this manual,
register addresses are given as a hexadecimal increment, relative to the module’s base address
as shown in the memory map.
The regions for SRAM and peripherals include bit-band regions. Bit-banding provides atomic
operations to bit data (see “Bit-Banding” on page 74).
The processor reserves regions of the Private peripheral bus (PPB) address range for core peripheral
registers (see “Cortex-M3 Peripherals” on page 93).
Note:
Within the memory map, all reserved space returns a bus fault when read or written.
Table 2-4. Memory Map
Start
End
Description
For details,
see page ...
0x0000.0000
0x0001.FFFF
On-chip Flash
259
0x0002.0000
0x00FF.FFFF
Reserved
-
0x0100.0000
0x1FFF.FFFF
Reserved for ROM
259
0x2000.0000
0x2000.FFFF
Bit-banded on-chip SRAM
258
0x2001.0000
0x21FF.FFFF
Reserved
-
0x2200.0000
0x221F.FFFF
Bit-band alias of bit-banded on-chip SRAM starting at
0x2000.0000
258
0x2220.0000
0x3FFF.FFFF
Reserved
-
0x4000.0000
0x4000.0FFF
Watchdog timer 0
437
0x4000.1000
0x4000.3FFF
Reserved
-
0x4000.4000
0x4000.4FFF
GPIO Port A
360
0x4000.5000
0x4000.5FFF
GPIO Port B
360
0x4000.6000
0x4000.6FFF
GPIO Port C
360
0x4000.7000
0x4000.7FFF
GPIO Port D
360
Memory
FiRM Peripherals
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Table 2-4. Memory Map (continued)
Start
End
Description
For details,
see page ...
0x4000.8000
0x4000.8FFF
SSI0
549
0x4000.9000
0x4000.9FFF
SSI1
549
0x4000.A000
0x4000.BFFF
Reserved
-
0x4000.C000
0x4000.CFFF
UART0
501
0x4000.D000
0x4001.FFFF
Reserved
-
0x4002.0000
0x4002.0FFF
I2C 0
591
0x4002.1000
0x4002.1FFF
I2C 1
591
0x4002.2000
0x4002.3FFF
Reserved
-
0x4002.4000
0x4002.4FFF
GPIO Port E
360
0x4002.5000
0x4002.5FFF
GPIO Port F
360
0x4002.6000
0x4002.6FFF
GPIO Port G
360
0x4002.7000
0x4002.7FFF
GPIO Port H
360
0x4002.8000
0x4002.FFFF
Reserved
-
0x4003.0000
0x4003.0FFF
Timer 0
411
0x4003.1000
0x4003.1FFF
Timer 1
411
0x4003.2000
0x4003.2FFF
Timer 2
411
0x4003.3000
0x4003.7FFF
Reserved
-
0x4003.8000
0x4003.8FFF
ADC0
467
0x4003.9000
0x4003.FFFF
Reserved
-
0x4004.0000
0x4004.0FFF
CAN0 Controller
633
0x4004.1000
0x4004.FFFF
Reserved
-
0x4005.0000
0x4005.0FFF
USB
675
0x4005.1000
0x4005.7FFF
Reserved
-
0x4005.8000
0x4005.8FFF
GPIO Port A (AHB aperture)
360
0x4005.9000
0x4005.9FFF
GPIO Port B (AHB aperture)
360
0x4005.A000
0x4005.AFFF
GPIO Port C (AHB aperture)
360
0x4005.B000
0x4005.BFFF
GPIO Port D (AHB aperture)
360
0x4005.C000
0x4005.CFFF
GPIO Port E (AHB aperture)
360
0x4005.D000
0x4005.DFFF
GPIO Port F (AHB aperture)
360
0x4005.E000
0x4005.EFFF
GPIO Port G (AHB aperture)
360
0x4005.F000
0x4005.FFFF
GPIO Port H (AHB aperture)
360
0x4006.0000
0x400F.BFFF
Reserved
-
0x400F.C000
0x400F.CFFF
Hibernation Module
244
0x400F.D000
0x400F.DFFF
Flash memory control
264
0x400F.E000
0x400F.EFFF
System control
183
0x400F.F000
0x400F.FFFF
µDMA
307
0x4010.0000
0x41FF.FFFF
Reserved
-
0x4200.0000
0x43FF.FFFF
Bit-banded alias of 0x4000.0000 through 0x400F.FFFF
-
0x4400.0000
0xDFFF.FFFF
Reserved
-
Peripherals
Private Peripheral Bus
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Table 2-4. Memory Map (continued)
Start
End
Description
For details,
see page ...
0xE000.0000
0xE000.0FFF
Instrumentation Trace Macrocell (ITM)
53
0xE000.1000
0xE000.1FFF
Data Watchpoint and Trace (DWT)
53
0xE000.2000
0xE000.2FFF
Flash Patch and Breakpoint (FPB)
53
0xE000.3000
0xE000.DFFF
Reserved
-
0xE000.E000
0xE000.EFFF
Cortex-M3 Peripherals (SysTick, NVIC, MPU and SCB)
101
0xE000.F000
0xE003.FFFF
Reserved
-
0xE004.0000
0xE004.0FFF
Trace Port Interface Unit (TPIU)
54
0xE004.1000
0xFFFF.FFFF
Reserved
-
2.4.1
Memory Regions, Types and Attributes
The memory map and the programming of the MPU split the memory map into regions. Each region
has a defined memory type, and some regions have additional memory attributes. The memory
type and attributes determine the behavior of accesses to the region.
The memory types are:
■ Normal: The processor can re-order transactions for efficiency and perform speculative reads.
■ Device: The processor preserves transaction order relative to other transactions to Device or
Strongly Ordered memory.
■ Strongly Ordered: The processor preserves transaction order relative to all other transactions.
The different ordering requirements for Device and Strongly Ordered memory mean that the memory
system can buffer a write to Device memory but must not buffer a write to Strongly Ordered memory.
An additional memory attribute is Execute Never (XN), which means the processor prevents
instruction accesses. A fault exception is generated only on execution of an instruction executed
from an XN region.
2.4.2
Memory System Ordering of Memory Accesses
For most memory accesses caused by explicit memory access instructions, the memory system
does not guarantee that the order in which the accesses complete matches the program order of
the instructions, providing the order does not affect the behavior of the instruction sequence. Normally,
if correct program execution depends on two memory accesses completing in program order,
software must insert a memory barrier instruction between the memory access instructions (see
“Software Ordering of Memory Accesses” on page 73).
However, the memory system does guarantee ordering of accesses to Device and Strongly Ordered
memory. For two memory access instructions A1 and A2, if both A1 and A2 are accesses to either
Device or Strongly Ordered memory, and if A1 occurs before A2 in program order, A1 is always
observed before A2.
2.4.3
Behavior of Memory Accesses
Table 2-5 on page 73 shows the behavior of accesses to each region in the memory map. See
“Memory Regions, Types and Attributes” on page 72 for more information on memory types and
the XN attribute. Stellaris devices may have reserved memory areas within the address ranges
shown below (refer to Table 2-4 on page 70 for more information).
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Table 2-5. Memory Access Behavior
Address Range
Memory Region
Memory Type
Execute
Never
(XN)
Description
0x0000.0000 - 0x1FFF.FFFF Code
Normal
-
This executable region is for program code.
Data can also be stored here.
0x2000.0000 - 0x3FFF.FFFF SRAM
Normal
-
This executable region is for data. Code
can also be stored here. This region
includes bit band and bit band alias areas
(see Table 2-6 on page 75).
0x4000.0000 - 0x5FFF.FFFF Peripheral
Device
XN
This region includes bit band and bit band
alias areas (see Table 2-7 on page 75).
0x6000.0000 - 0x9FFF.FFFF External RAM
Normal
-
This executable region is for data.
0xA000.0000 - 0xDFFF.FFFF External device
Device
XN
This region is for external device memory.
0xE000.0000- 0xE00F.FFFF Private peripheral
bus
Strongly
Ordered
XN
This region includes the NVIC, system
timer, and system control block.
0xE010.0000- 0xFFFF.FFFF Reserved
-
-
-
The Code, SRAM, and external RAM regions can hold programs. However, it is recommended that
programs always use the Code region because the Cortex-M3 has separate buses that can perform
instruction fetches and data accesses simultaneously.
The MPU can override the default memory access behavior described in this section. For more
information, see “Memory Protection Unit (MPU)” on page 96.
The Cortex-M3 prefetches instructions ahead of execution and speculatively prefetches from branch
target addresses.
2.4.4
Software Ordering of Memory Accesses
The order of instructions in the program flow does not always guarantee the order of the
corresponding memory transactions for the following reasons:
■ The processor can reorder some memory accesses to improve efficiency, providing this does
not affect the behavior of the instruction sequence.
■ The processor has multiple bus interfaces.
■ Memory or devices in the memory map have different wait states.
■ Some memory accesses are buffered or speculative.
“Memory System Ordering of Memory Accesses” on page 72 describes the cases where the memory
system guarantees the order of memory accesses. Otherwise, if the order of memory accesses is
critical, software must include memory barrier instructions to force that ordering. The Cortex-M3
has the following memory barrier instructions:
■ The Data Memory Barrier (DMB) instruction ensures that outstanding memory transactions
complete before subsequent memory transactions.
■ The Data Synchronization Barrier (DSB) instruction ensures that outstanding memory transactions
complete before subsequent instructions execute.
■ The Instruction Synchronization Barrier (ISB) instruction ensures that the effect of all completed
memory transactions is recognizable by subsequent instructions.
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Memory barrier instructions can be used in the following situations:
■ MPU programming
– If the MPU settings are changed and the change must be effective on the very next instruction,
use a DSB instruction to ensure the effect of the MPU takes place immediately at the end of
context switching.
– Use an ISB instruction to ensure the new MPU setting takes effect immediately after
programming the MPU region or regions, if the MPU configuration code was accessed using
a branch or call. If the MPU configuration code is entered using exception mechanisms, then
an ISB instruction is not required.
■ Vector table
If the program changes an entry in the vector table and then enables the corresponding exception,
use a DMB instruction between the operations. The DMB instruction ensures that if the exception
is taken immediately after being enabled, the processor uses the new exception vector.
■ Self-modifying code
If a program contains self-modifying code, use an ISB instruction immediately after the code
modification in the program. The ISB instruction ensures subsequent instruction execution uses
the updated program.
■ Memory map switching
If the system contains a memory map switching mechanism, use a DSB instruction after switching
the memory map in the program. The DSB instruction ensures subsequent instruction execution
uses the updated memory map.
■ Dynamic exception priority change
When an exception priority has to change when the exception is pending or active, use DSB
instructions after the change. The change then takes effect on completion of the DSB instruction.
Memory accesses to Strongly Ordered memory, such as the System Control Block, do not require
the use of DMB instructions.
For more information on the memory barrier instructions, see the Cortex™-M3/M4 Instruction Set
Technical User's Manual.
2.4.5
Bit-Banding
A bit-band region maps each word in a bit-band alias region to a single bit in the bit-band region.
The bit-band regions occupy the lowest 1 MB of the SRAM and peripheral memory regions. Accesses
to the 32-MB SRAM alias region map to the 1-MB SRAM bit-band region, as shown in Table
2-6 on page 75. Accesses to the 32-MB peripheral alias region map to the 1-MB peripheral bit-band
region, as shown in Table 2-7 on page 75. For the specific address range of the bit-band regions,
see Table 2-4 on page 70.
Note:
A word access to the SRAM or the peripheral bit-band alias region maps to a single bit in
the SRAM or peripheral bit-band region.
A word access to a bit band address results in a word access to the underlying memory,
and similarly for halfword and byte accesses. This allows bit band accesses to match the
access requirements of the underlying peripheral.
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Table 2-6. SRAM Memory Bit-Banding Regions
Address Range
Memory Region
Instruction and Data Accesses
0x2000.0000 - 0x200F.FFFF SRAM bit-band region
Direct accesses to this memory range behave as SRAM memory
accesses, but this region is also bit addressable through bit-band
alias.
0x2200.0000 - 0x23FF.FFFF SRAM bit-band alias
Data accesses to this region are remapped to bit band region.
A write operation is performed as read-modify-write. Instruction
accesses are not remapped.
Table 2-7. Peripheral Memory Bit-Banding Regions
Address Range
Memory Region
Instruction and Data Accesses
0x4000.0000 - 0x400F.FFFF Peripheral bit-band region
Direct accesses to this memory range behave as peripheral
memory accesses, but this region is also bit addressable through
bit-band alias.
0x4200.0000 - 0x43FF.FFFF Peripheral bit-band alias
Data accesses to this region are remapped to bit band region.
A write operation is performed as read-modify-write. Instruction
accesses are not permitted.
The following formula shows how the alias region maps onto the bit-band region:
bit_word_offset = (byte_offset x 32) + (bit_number x 4)
bit_word_addr = bit_band_base + bit_word_offset
where:
bit_word_offset
The position of the target bit in the bit-band memory region.
bit_word_addr
The address of the word in the alias memory region that maps to the targeted bit.
bit_band_base
The starting address of the alias region.
byte_offset
The number of the byte in the bit-band region that contains the targeted bit.
bit_number
The bit position, 0-7, of the targeted bit.
Figure 2-4 on page 76 shows examples of bit-band mapping between the SRAM bit-band alias
region and the SRAM bit-band region:
■ The alias word at 0x23FF.FFE0 maps to bit 0 of the bit-band byte at 0x200F.FFFF:
0x23FF.FFE0 = 0x2200.0000 + (0x000F.FFFF*32) + (0*4)
■ The alias word at 0x23FF.FFFC maps to bit 7 of the bit-band byte at 0x200F.FFFF:
0x23FF.FFFC = 0x2200.0000 + (0x000F.FFFF*32) + (7*4)
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■ The alias word at 0x2200.0000 maps to bit 0 of the bit-band byte at 0x2000.0000:
0x2200.0000 = 0x2200.0000 + (0*32) + (0*4)
■ The alias word at 0x2200.001C maps to bit 7 of the bit-band byte at 0x2000.0000:
0x2200.001C = 0x2200.0000+ (0*32) + (7*4)
Figure 2-4. Bit-Band Mapping
32-MB Alias Region
0x23FF.FFFC
0x23FF.FFF8
0x23FF.FFF4
0x23FF.FFF0
0x23FF.FFEC
0x23FF.FFE8
0x23FF.FFE4
0x23FF.FFE0
0x2200.001C
0x2200.0018
0x2200.0014
0x2200.0010
0x2200.000C
0x2200.0008
0x2200.0004
0x2200.0000
7
3
1-MB SRAM Bit-Band Region
7
6
5
4
3
2
1
0
7
6
0x200F.FFFF
7
6
5
4
3
2
0x2000.0003
2.4.5.1
5
4
3
2
1
0
7
6
0x200F.FFFE
1
0
7
6
5
4
3
2
5
4
3
2
1
0
6
0x200F.FFFD
1
0
0x2000.0002
7
6
5
4
3
2
0x2000.0001
5
4
2
1
0
1
0
0x200F.FFFC
1
0
7
6
5
4
3
2
0x2000.0000
Directly Accessing an Alias Region
Writing to a word in the alias region updates a single bit in the bit-band region.
Bit 0 of the value written to a word in the alias region determines the value written to the targeted
bit in the bit-band region. Writing a value with bit 0 set writes a 1 to the bit-band bit, and writing a
value with bit 0 clear writes a 0 to the bit-band bit.
Bits 31:1 of the alias word have no effect on the bit-band bit. Writing 0x01 has the same effect as
writing 0xFF. Writing 0x00 has the same effect as writing 0x0E.
When reading a word in the alias region, 0x0000.0000 indicates that the targeted bit in the bit-band
region is clear and 0x0000.0001 indicates that the targeted bit in the bit-band region is set.
2.4.5.2
Directly Accessing a Bit-Band Region
“Behavior of Memory Accesses” on page 72 describes the behavior of direct byte, halfword, or word
accesses to the bit-band regions.
2.4.6
Data Storage
The processor views memory as a linear collection of bytes numbered in ascending order from zero.
For example, bytes 0-3 hold the first stored word, and bytes 4-7 hold the second stored word. Data
is stored in little-endian format, with the least-significant byte (lsbyte) of a word stored at the
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lowest-numbered byte, and the most-significant byte (msbyte) stored at the highest-numbered byte.
Figure 2-5 on page 77 illustrates how data is stored.
Figure 2-5. Data Storage
Memory
7
Register
0
31
2.4.7
Address A
B0
A+1
B1
A+2
B2
A+3
B3
lsbyte
24 23
B3
16 15
B2
8 7
B1
0
B0
msbyte
Synchronization Primitives
The Cortex-M3 instruction set includes pairs of synchronization primitives which provide a
non-blocking mechanism that a thread or process can use to obtain exclusive access to a memory
location. Software can use these primitives to perform a guaranteed read-modify-write memory
update sequence or for a semaphore mechanism.
A pair of synchronization primitives consists of:
■ A Load-Exclusive instruction, which is used to read the value of a memory location and requests
exclusive access to that location.
■ A Store-Exclusive instruction, which is used to attempt to write to the same memory location and
returns a status bit to a register. If this status bit is clear, it indicates that the thread or process
gained exclusive access to the memory and the write succeeds; if this status bit is set, it indicates
that the thread or process did not gain exclusive access to the memory and no write was
performed.
The pairs of Load-Exclusive and Store-Exclusive instructions are:
■ The word instructions LDREX and STREX
■ The halfword instructions LDREXH and STREXH
■ The byte instructions LDREXB and STREXB
Software must use a Load-Exclusive instruction with the corresponding Store-Exclusive instruction.
To perform an exclusive read-modify-write of a memory location, software must:
1. Use a Load-Exclusive instruction to read the value of the location.
2. Modify the value, as required.
3. Use a Store-Exclusive instruction to attempt to write the new value back to the memory location.
4. Test the returned status bit.
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If the status bit is clear, the read-modify-write completed successfully. If the status bit is set, no
write was performed, which indicates that the value returned at step 1 might be out of date. The
software must retry the entire read-modify-write sequence.
Software can use the synchronization primitives to implement a semaphore as follows:
1. Use a Load-Exclusive instruction to read from the semaphore address to check whether the
semaphore is free.
2. If the semaphore is free, use a Store-Exclusive to write the claim value to the semaphore
address.
3. If the returned status bit from step 2 indicates that the Store-Exclusive succeeded, then the
software has claimed the semaphore. However, if the Store-Exclusive failed, another process
might have claimed the semaphore after the software performed step 1.
The Cortex-M3 includes an exclusive access monitor that tags the fact that the processor has
executed a Load-Exclusive instruction. The processor removes its exclusive access tag if:
■ It executes a CLREX instruction.
■ It executes a Store-Exclusive instruction, regardless of whether the write succeeds.
■ An exception occurs, which means the processor can resolve semaphore conflicts between
different threads.
For more information about the synchronization primitive instructions, see the Cortex™-M3/M4
Instruction Set Technical User's Manual.
2.5
Exception Model
The ARM Cortex-M3 processor and the Nested Vectored Interrupt Controller (NVIC) prioritize and
handle all exceptions 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, enabling 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 2-8 on page 80 lists all exception types. Software can set eight priority levels on seven of
these exceptions (system handlers) as well as on 31 interrupts (listed in Table 2-9 on page 81).
Priorities on the system handlers are set with the NVIC System Handler Priority n (SYSPRIn)
registers. Interrupts are enabled through the NVIC Interrupt Set Enable n (ENn) register and
prioritized with the NVIC Interrupt Priority n (PRIn) registers. Priorities can be grouped by splitting
priority levels into preemption priorities and subpriorities. All the interrupt registers are described in
“Nested Vectored Interrupt Controller (NVIC)” on page 94.
Internally, the highest user-programmable priority (0) is treated as fourth priority, after a Reset,
Non-Maskable Interrupt (NMI), and a Hard Fault, in that order. Note that 0 is the default priority for
all the programmable priorities.
Important: After a write to clear an interrupt source, it may take several processor cycles for the
NVIC to see the interrupt source de-assert. Thus if the interrupt clear is done as the
last action in an interrupt handler, it is possible for the interrupt handler to complete
while the NVIC sees the interrupt as still asserted, causing the interrupt handler to be
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re-entered errantly. This situation can be avoided by either clearing the interrupt source
at the beginning of the interrupt handler or by performing a read or write after the write
to clear the interrupt source (and flush the write buffer).
See “Nested Vectored Interrupt Controller (NVIC)” on page 94 for more information on exceptions
and interrupts.
2.5.1
Exception States
Each exception is in one of the following states:
■ Inactive. The exception is not active and not pending.
■ Pending. The exception is waiting to be serviced by the processor. An interrupt request from a
peripheral or from software can change the state of the corresponding interrupt to pending.
■ Active. An exception that is being serviced by the processor but has not completed.
Note:
An exception handler can interrupt the execution of another exception handler. In this
case, both exceptions are in the active state.
■ Active and Pending. The exception is being serviced by the processor, and there is a pending
exception from the same source.
2.5.2
Exception Types
The exception types are:
■ Reset. Reset is invoked on power up or a warm reset. The exception model treats reset as a
special form of exception. When reset is asserted, the operation of the processor stops, potentially
at any point in an instruction. When reset is deasserted, execution restarts from the address
provided by the reset entry in the vector table. Execution restarts as privileged execution in
Thread mode.
■ NMI. A non-maskable Interrupt (NMI) can be signaled using the NMI signal or triggered by
software using the Interrupt Control and State (INTCTRL) register. This exception has the
highest priority other than reset. NMI is permanently enabled and has a fixed priority of -2. NMIs
cannot be masked or prevented from activation by any other exception or preempted by any
exception other than reset.
■ Hard Fault. A hard fault is an exception that occurs because of an error during exception
processing, or because an exception cannot be managed by any other exception mechanism.
Hard faults have a fixed priority of -1, meaning they have higher priority than any exception with
configurable priority.
■ Memory Management Fault. A memory management fault is an exception that occurs because
of a memory protection related fault, including access violation and no match. The MPU or the
fixed memory protection constraints determine this fault, for both instruction and data memory
transactions. This fault is used to abort instruction accesses to Execute Never (XN) memory
regions, even if the MPU is disabled.
■ Bus Fault. A bus fault is an exception that occurs because of a memory-related fault for an
instruction or data memory transaction such as a prefetch fault or a memory access fault. This
fault can be enabled or disabled.
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■ Usage Fault. A usage fault is an exception that occurs because of a fault related to instruction
execution, such as:
– An undefined instruction
– An illegal unaligned access
– Invalid state on instruction execution
– An error on exception return
An unaligned address on a word or halfword memory access or division by zero can cause a
usage fault when the core is properly configured.
■ SVCall. A supervisor call (SVC) is an exception that is triggered by the SVC instruction. In an
OS environment, applications can use SVC instructions to access OS kernel functions and device
drivers.
■ Debug Monitor. This exception is caused by the debug monitor (when not halting). This exception
is only active when enabled. This exception does not activate if it is a lower priority than the
current activation.
■ PendSV. PendSV is a pendable, interrupt-driven request for system-level service. In an OS
environment, use PendSV for context switching when no other exception is active. PendSV is
triggered using the Interrupt Control and State (INTCTRL) register.
■ SysTick. A SysTick exception is an exception that the system timer generates when it reaches
zero when it is enabled to generate an interrupt. Software can also generate a SysTick exception
using the Interrupt Control and State (INTCTRL) register. In an OS environment, the processor
can use this exception as system tick.
■ Interrupt (IRQ). An interrupt, or IRQ, is an exception signaled by a peripheral or generated by
a software request and fed through the NVIC (prioritized). All interrupts are asynchronous to
instruction execution. In the system, peripherals use interrupts to communicate with the processor.
Table 2-9 on page 81 lists the interrupts on the LM3S5737 controller.
For an asynchronous exception, other than reset, the processor can execute another instruction
between when the exception is triggered and when the processor enters the exception handler.
Privileged software can disable the exceptions that Table 2-8 on page 80 shows as having
configurable priority (see the SYSHNDCTRL register on page 135 and the DIS0 register on page 110).
For more information about hard faults, memory management faults, bus faults, and usage faults,
see “Fault Handling” on page 86.
Table 2-8. Exception Types
Exception Type
a
Vector
Number
Priority
Vector Address or
b
Offset
-
0
-
0x0000.0000
Stack top is loaded from the first
entry of the vector table on reset.
Reset
1
-3 (highest)
0x0000.0004
Asynchronous
Non-Maskable Interrupt
(NMI)
2
-2
0x0000.0008
Asynchronous
Hard Fault
3
-1
0x0000.000C
-
0x0000.0010
Synchronous
Memory Management
4
c
programmable
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Table 2-8. Exception Types (continued)
Exception Type
a
Vector
Number
Priority
Bus Fault
5
programmable
Usage Fault
6
7-10
-
Vector Address or
b
Offset
Activation
c
0x0000.0014
Synchronous when precise and
asynchronous when imprecise
programmable
c
0x0000.0018
Synchronous
-
c
c
Reserved
SVCall
11
programmable
0x0000.002C
Synchronous
Debug Monitor
12
programmable
0x0000.0030
Synchronous
-
13
-
0x0000.0038
Asynchronous
c
0x0000.003C
Asynchronous
PendSV
14
programmable
SysTick
15
programmable
Interrupts
16 and above
Reserved
c
d
programmable
0x0000.0040 and above Asynchronous
a. 0 is the default priority for all the programmable priorities.
b. See “Vector Table” on page 82.
c. See SYSPRI1 on page 132.
d. See PRIn registers on page 118.
Table 2-9. Interrupts
Vector Number
Interrupt Number (Bit
in Interrupt Registers)
Vector Address or
Offset
Description
0-15
-
0x0000.0000 0x0000.003C
16
0
0x0000.0040
GPIO Port A
17
1
0x0000.0044
GPIO Port B
18
2
0x0000.0048
GPIO Port C
19
3
0x0000.004C
GPIO Port D
20
4
0x0000.0050
GPIO Port E
21
5
0x0000.0054
UART0
22
6
-
23
7
0x0000.005C
SSI0
24
8
0x0000.0060
I2C0
25-29
9-13
-
30
14
0x0000.0078
ADC0 Sequence 0
31
15
0x0000.007C
ADC0 Sequence 1
32
16
0x0000.0080
ADC0 Sequence 2
33
17
0x0000.0084
ADC0 Sequence 3
34
18
0x0000.0088
Watchdog Timer 0
35
19
0x0000.008C
Timer 0A
36
20
0x0000.0090
Timer 0B
37
21
0x0000.0094
Timer 1A
38
22
0x0000.0098
Timer 1B
39
23
0x0000.009C
Timer 2A
40
24
0x0000.00A0
Timer 2B
41-43
25-27
-
Reserved
Processor exceptions
Reserved
Reserved
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Table 2-9. Interrupts (continued)
2.5.3
Vector Number
Interrupt Number (Bit
in Interrupt Registers)
Vector Address or
Offset
44
28
0x0000.00B0
System Control
45
29
0x0000.00B4
Flash Memory Control
46
30
0x0000.00B8
GPIO Port F
47
31
0x0000.00BC
GPIO Port G
48
32
0x0000.00C0
GPIO Port H
49
33
-
50
34
0x0000.00C8
51-52
35-36
-
53
37
0x0000.00D4
54
38
-
Description
Reserved
SSI1
Reserved
I2C1
Reserved
55
39
0x0000.00DC
56-58
40-42
-
CAN0
59
43
0x0000.00EC
Hibernation Module
60
44
0x0000.00F0
USB
61
45
-
Reserved
Reserved
62
46
0x0000.00F8
µDMA Software
63
47
0x0000.00FC
µDMA Error
Exception Handlers
The processor handles exceptions using:
■ Interrupt Service Routines (ISRs). Interrupts (IRQx) are the exceptions handled by ISRs.
■ Fault Handlers. Hard fault, memory management fault, usage fault, and bus fault are fault
exceptions handled by the fault handlers.
■ System Handlers. NMI, PendSV, SVCall, SysTick, and the fault exceptions are all system
exceptions that are handled by system handlers.
2.5.4
Vector Table
The vector table contains the reset value of the stack pointer and the start addresses, also called
exception vectors, for all exception handlers. The vector table is constructed using the vector address
or offset shown in Table 2-8 on page 80. Figure 2-6 on page 83 shows the order of the exception
vectors in the vector table. The least-significant bit of each vector must be 1, indicating that the
exception handler is Thumb code
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Figure 2-6. Vector Table
Exception number IRQ number
63
47
.
.
.
18
2
17
1
16
0
15
-1
14
-2
13
Offset
0x00FC
.
.
.
0x004C
0x0048
0x0044
0x0040
0x003C
0x0038
12
11
Vector
IRQ47
.
.
.
IRQ2
IRQ1
IRQ0
Systick
PendSV
Reserved
Reserved for Debug
-5
10
0x002C
9
SVCall
Reserved
8
7
6
-10
5
-11
4
-12
3
-13
2
-14
1
0x0018
0x0014
0x0010
0x000C
0x0008
0x0004
0x0000
Usage fault
Bus fault
Memory management fault
Hard fault
NMI
Reset
Initial SP value
On system reset, the vector table is fixed at address 0x0000.0000. Privileged software can write to
the Vector Table Offset (VTABLE) register to relocate the vector table start address to a different
memory location, in the range 0x0000.0100 to 0x3FFF.FF00 (see “Vector Table” on page 82). Note
that when configuring the VTABLE register, the offset must be aligned on a 256-byte boundary.
2.5.5
Exception Priorities
As Table 2-8 on page 80 shows, all exceptions have an associated priority, with a lower priority
value indicating a higher priority and configurable priorities for all exceptions except Reset, Hard
fault, and NMI. If software does not configure any priorities, then all exceptions with a configurable
priority have a priority of 0. For information about configuring exception priorities, see page 132 and
page 118.
Note:
Configurable priority values for the Stellaris implementation are in the range 0-7. This means
that the Reset, Hard fault, and NMI exceptions, with fixed negative priority values, always
have higher priority than any other exception.
For example, assigning a higher priority value to IRQ[0] and a lower priority value to IRQ[1] means
that IRQ[1] has higher priority than IRQ[0]. If both IRQ[1] and IRQ[0] are asserted, IRQ[1] is processed
before IRQ[0].
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If multiple pending exceptions have the same priority, the pending exception with the lowest exception
number takes precedence. For example, if both IRQ[0] and IRQ[1] are pending and have the same
priority, then IRQ[0] is processed before IRQ[1].
When the processor is executing an exception handler, the exception handler is preempted if a
higher priority exception occurs. If an exception occurs with the same priority as the exception being
handled, the handler is not preempted, irrespective of the exception number. However, the status
of the new interrupt changes to pending.
2.5.6
Interrupt Priority Grouping
To increase priority control in systems with interrupts, the NVIC supports priority grouping. This
grouping divides each interrupt priority register entry into two fields:
■ An upper field that defines the group priority
■ A lower field that defines a subpriority within the group
Only the group priority determines preemption of interrupt exceptions. When the processor is
executing an interrupt exception handler, another interrupt with the same group priority as the
interrupt being handled does not preempt the handler.
If multiple pending interrupts have the same group priority, the subpriority field determines the order
in which they are processed. If multiple pending interrupts have the same group priority and
subpriority, the interrupt with the lowest IRQ number is processed first.
For information about splitting the interrupt priority fields into group priority and subpriority, see
page 126.
2.5.7
Exception Entry and Return
Descriptions of exception handling use the following terms:
■ Preemption. When the processor is executing an exception handler, an exception can preempt
the exception handler if its priority is higher than the priority of the exception being handled. See
“Interrupt Priority Grouping” on page 84 for more information about preemption by an interrupt.
When one exception preempts another, the exceptions are called nested exceptions. See
“Exception Entry” on page 85 more information.
■ Return. Return occurs when the exception handler is completed, and there is no pending
exception with sufficient priority to be serviced and the completed exception handler was not
handling a late-arriving exception. The processor pops the stack and restores the processor
state to the state it had before the interrupt occurred. See “Exception Return” on page 86 for
more information.
■ Tail-Chaining. This mechanism speeds up exception servicing. On completion of an exception
handler, if there is a pending exception that meets the requirements for exception entry, the
stack pop is skipped and control transfers to the new exception handler.
■ Late-Arriving. This mechanism speeds up preemption. If a higher priority exception occurs
during state saving for a previous exception, the processor switches to handle the higher priority
exception and initiates the vector fetch for that exception. State saving is not affected by late
arrival because the state saved is the same for both exceptions. Therefore, the state saving
continues uninterrupted. The processor can accept a late arriving exception until the first instruction
of the exception handler of the original exception enters the execute stage of the processor. On
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return from the exception handler of the late-arriving exception, the normal tail-chaining rules
apply.
2.5.7.1
Exception Entry
Exception entry occurs when there is a pending exception with sufficient priority and either the
processor is in Thread mode or the new exception is of higher priority than the exception being
handled, in which case the new exception preempts the original exception.
When one exception preempts another, the exceptions are nested.
Sufficient priority means the exception has more priority than any limits set by the mask registers
(see PRIMASK on page 66, FAULTMASK on page 67, and BASEPRI on page 68). An exception
with less priority than this is pending but is not handled by the processor.
When the processor takes an exception, unless the exception is a tail-chained or a late-arriving
exception, the processor pushes information onto the current stack. This operation is referred to as
stacking and the structure of eight data words is referred to as stack frame.
Figure 2-7. Exception Stack Frame
...
{aligner}
xPSR
PC
LR
R12
R3
R2
R1
R0
Pre-IRQ top of stack
IRQ top of stack
Immediately after stacking, the stack pointer indicates the lowest address in the stack frame. Unless
stack alignment is disabled, the stack frame is aligned to a double-word address. If the STKALIGN
bit of the Configuration Control (CCR) register is set, stack align adjustment is performed during
stacking.
The stack frame includes the return address, which is the address of the next instruction in the
interrupted program. This value is restored to the PC at exception return so that the interrupted
program resumes.
In parallel to the stacking operation, the processor performs a vector fetch that reads the exception
handler start address from the vector table. When stacking is complete, the processor starts executing
the exception handler. At the same time, the processor writes an EXC_RETURN value to the LR,
indicating which stack pointer corresponds to the stack frame and what operation mode the processor
was in before the entry occurred.
If no higher-priority exception occurs during exception entry, the processor starts executing the
exception handler and automatically changes the status of the corresponding pending interrupt to
active.
If another higher-priority exception occurs during exception entry, known as late arrival, the processor
starts executing the exception handler for this exception and does not change the pending status
of the earlier exception.
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2.5.7.2
Exception Return
Exception return occurs when the processor is in Handler mode and executes one of the following
instructions to load the EXC_RETURN value into the PC:
■ An LDM or POP instruction that loads the PC
■ A BX instruction using any register
■ An LDR instruction with the PC as the destination
EXC_RETURN is the value loaded into the LR on exception entry. The exception mechanism relies
on this value to detect when the processor has completed an exception handler. The lowest four
bits of this value provide information on the return stack and processor mode. Table 2-10 on page 86
shows the EXC_RETURN values with a description of the exception return behavior.
EXC_RETURN bits 31:4 are all set. When this value is loaded into the PC, it indicates to the processor
that the exception is complete, and the processor initiates the appropriate exception return sequence.
Table 2-10. Exception Return Behavior
EXC_RETURN[31:0]
Description
0xFFFF.FFF0
Reserved
0xFFFF.FFF1
Return to Handler mode.
Exception return uses state from MSP.
Execution uses MSP after return.
0xFFFF.FFF2 - 0xFFFF.FFF8
Reserved
0xFFFF.FFF9
Return to Thread mode.
Exception return uses state from MSP.
Execution uses MSP after return.
0xFFFF.FFFA - 0xFFFF.FFFC
Reserved
0xFFFF.FFFD
Return to Thread mode.
Exception return uses state from PSP.
Execution uses PSP after return.
0xFFFF.FFFE - 0xFFFF.FFFF
2.6
Reserved
Fault Handling
Faults are a subset of the exceptions (see “Exception Model” on page 78). The following conditions
generate a fault:
■ A bus error on an instruction fetch or vector table load or a data access.
■ An internally detected error such as an undefined instruction or an attempt to change state with
a BX instruction.
■ Attempting to execute an instruction from a memory region marked as Non-Executable (XN).
■ An MPU fault because of a privilege violation or an attempt to access an unmanaged region.
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2.6.1
Fault Types
Table 2-11 on page 87 shows the types of fault, the handler used for the fault, the corresponding
fault status register, and the register bit that indicates the fault has occurred. See page 139 for more
information about the fault status registers.
Table 2-11. Faults
Fault
Handler
Fault Status Register
Bit Name
Bus error on a vector read
Hard fault
Hard Fault Status (HFAULTSTAT)
VECT
Fault escalated to a hard fault
Hard fault
Hard Fault Status (HFAULTSTAT)
FORCED
MPU or default memory mismatch on Memory management
instruction access
fault
Memory Management Fault Status
(MFAULTSTAT)
IERR
MPU or default memory mismatch on Memory management
data access
fault
Memory Management Fault Status
(MFAULTSTAT)
DERR
MPU or default memory mismatch on Memory management
exception stacking
fault
Memory Management Fault Status
(MFAULTSTAT)
MSTKE
MPU or default memory mismatch on Memory management
exception unstacking
fault
Memory Management Fault Status
(MFAULTSTAT)
MUSTKE
Bus error during exception stacking
Bus fault
Bus Fault Status (BFAULTSTAT)
BSTKE
Bus error during exception unstacking Bus fault
Bus Fault Status (BFAULTSTAT)
BUSTKE
Bus error during instruction prefetch
Bus fault
Bus Fault Status (BFAULTSTAT)
IBUS
Precise data bus error
Bus fault
Bus Fault Status (BFAULTSTAT)
PRECISE
Imprecise data bus error
Bus fault
Bus Fault Status (BFAULTSTAT)
IMPRE
Attempt to access a coprocessor
Usage fault
Usage Fault Status (UFAULTSTAT)
NOCP
Undefined instruction
Usage fault
Usage Fault Status (UFAULTSTAT)
UNDEF
Attempt to enter an invalid instruction Usage fault
b
set state
Usage Fault Status (UFAULTSTAT)
INVSTAT
a
Invalid EXC_RETURN value
Usage fault
Usage Fault Status (UFAULTSTAT)
INVPC
Illegal unaligned load or store
Usage fault
Usage Fault Status (UFAULTSTAT)
UNALIGN
Divide by 0
Usage fault
Usage Fault Status (UFAULTSTAT)
DIV0
a. Occurs on an access to an XN region even if the MPU is disabled.
b. Attempting to use an instruction set other than the Thumb instruction set, or returning to a non load-store-multiple instruction
with ICI continuation.
2.6.2
Fault Escalation and Hard Faults
All fault exceptions except for hard fault have configurable exception priority (see SYSPRI1 on
page 132). Software can disable execution of the handlers for these faults (see SYSHNDCTRL on
page 135).
Usually, the exception priority, together with the values of the exception mask registers, determines
whether the processor enters the fault handler, and whether a fault handler can preempt another
fault handler as described in “Exception Model” on page 78.
In some situations, a fault with configurable priority is treated as a hard fault. This process is called
priority escalation, and the fault is described as escalated to hard fault. Escalation to hard fault
occurs when:
■ A fault handler causes the same kind of fault as the one it is servicing. This escalation to hard
fault occurs because a fault handler cannot preempt itself because it must have the same priority
as the current priority level.
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■ A fault handler causes a fault with the same or lower priority as the fault it is servicing. This
situation happens because the handler for the new fault cannot preempt the currently executing
fault handler.
■ An exception handler causes a fault for which the priority is the same as or lower than the currently
executing exception.
■ A fault occurs and the handler for that fault is not enabled.
If a bus fault occurs during a stack push when entering a bus fault handler, the bus fault does not
escalate to a hard fault. Thus if a corrupted stack causes a fault, the fault handler executes even
though the stack push for the handler failed. The fault handler operates but the stack contents are
corrupted.
Note:
2.6.3
Only Reset and NMI can preempt the fixed priority hard fault. A hard fault can preempt any
exception other than Reset, NMI, or another hard fault.
Fault Status Registers and Fault Address Registers
The fault status registers indicate the cause of a fault. For bus faults and memory management
faults, the fault address register indicates the address accessed by the operation that caused the
fault, as shown in Table 2-12 on page 88.
Table 2-12. Fault Status and Fault Address Registers
2.6.4
Handler
Status Register Name
Address Register Name
Register Description
Hard fault
Hard Fault Status (HFAULTSTAT)
-
page 145
Memory management Memory Management Fault Status
fault
(MFAULTSTAT)
Memory Management Fault
Address (MMADDR)
page 139
Bus fault
Bus Fault Status (BFAULTSTAT)
Bus Fault Address
(FAULTADDR)
page 139
Usage fault
Usage Fault Status (UFAULTSTAT)
-
page 139
page 146
page 147
Lockup
The processor enters a lockup state if a hard fault occurs when executing the NMI or hard fault
handlers. When the processor is in the lockup state, it does not execute any instructions. The
processor remains in lockup state until it is reset, an NMI occurs, or it is halted by a debugger.
Note:
2.7
If the lockup state occurs from the NMI handler, a subsequent NMI does not cause the
processor to leave the lockup state.
Power Management
The Cortex-M3 processor sleep modes reduce power consumption:
■ Sleep mode stops the processor clock.
■ Deep-sleep mode stops the system clock and switches off the PLL and Flash memory.
The SLEEPDEEP bit of the System Control (SYSCTRL) register selects which sleep mode is used
(see page 128). For more information about the behavior of the sleep modes, see “System
Control” on page 180.
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This section describes the mechanisms for entering sleep mode and the conditions for waking up
from sleep mode, both of which apply to Sleep mode and Deep-sleep mode.
2.7.1
Entering Sleep Modes
This section describes the mechanisms software can use to put the processor into one of the sleep
modes.
The system can generate spurious wake-up events, for example a debug operation wakes up the
processor. Therefore, software must be able to put the processor back into sleep mode after such
an event. A program might have an idle loop to put the processor back to sleep mode.
2.7.1.1
Wait for Interrupt
The wait for interrupt instruction, WFI, causes immediate entry to sleep mode unless the wake-up
condition is true (see “Wake Up from WFI or Sleep-on-Exit” on page 89). When the processor
executes a WFI instruction, it stops executing instructions and enters sleep mode. See the
Cortex™-M3/M4 Instruction Set Technical User's Manual for more information.
2.7.1.2
Wait for Event
The wait for event instruction, WFE, causes entry to sleep mode conditional on the value of a one-bit
event register. When the processor executes a WFE instruction, it checks the event register. If the
register is 0, the processor stops executing instructions and enters sleep mode. If the register is 1,
the processor clears the register and continues executing instructions without entering sleep mode.
If the event register is 1, the processor must not enter sleep mode on execution of a WFE instruction.
Typically, this situation occurs if an SEV instruction has been executed. Software cannot access
this register directly.
See the Cortex™-M3/M4 Instruction Set Technical User's Manual for more information.
2.7.1.3
Sleep-on-Exit
If the SLEEPEXIT bit of the SYSCTRL register is set, when the processor completes the execution
of all exception handlers, it returns to Thread mode and immediately enters sleep mode. This
mechanism can be used in applications that only require the processor to run when an exception
occurs.
2.7.2
Wake Up from Sleep Mode
The conditions for the processor to wake up depend on the mechanism that cause it to enter sleep
mode.
2.7.2.1
Wake Up from WFI or Sleep-on-Exit
Normally, the processor wakes up only when the NVIC detects an exception with sufficient priority
to cause exception entry. Some embedded systems might have to execute system restore tasks
after the processor wakes up and before executing an interrupt handler. Entry to the interrupt handler
can be delayed by setting the PRIMASK bit and clearing the FAULTMASK bit. If an interrupt arrives
that is enabled and has a higher priority than current exception priority, the processor wakes up but
does not execute the interrupt handler until the processor clears PRIMASK. For more information
about PRIMASK and FAULTMASK, see page 66 and page 67.
2.7.2.2
Wake Up from WFE
The processor wakes up if it detects an exception with sufficient priority to cause exception entry.
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In addition, if the SEVONPEND bit in the SYSCTRL register is set, any new pending interrupt triggers
an event and wakes up the processor, even if the interrupt is disabled or has insufficient priority to
cause exception entry. For more information about SYSCTRL, see page 128.
2.8
Instruction Set Summary
The processor implements a version of the Thumb instruction set. Table 2-13 on page 90 lists the
supported instructions.
Note:
In Table 2-13 on page 90:
■
■
■
■
■
Angle brackets, <>, enclose alternative forms of the operand
Braces, {}, enclose optional operands
The Operands column is not exhaustive
Op2 is a flexible second operand that can be either a register or a constant
Most instructions can use an optional condition code suffix
For more information on the instructions and operands, see the instruction descriptions in
the Cortex™-M3/M4 Instruction Set Technical User's Manual.
Table 2-13. Cortex-M3 Instruction Summary
Mnemonic
Operands
Brief Description
Flags
ADC, ADCS
{Rd,} Rn, Op2
Add with carry
N,Z,C,V
ADD, ADDS
{Rd,} Rn, Op2
Add
N,Z,C,V
ADD, ADDW
{Rd,} Rn , #imm12
Add
N,Z,C,V
ADR
Rd, label
Load PC-relative address
-
AND, ANDS
{Rd,} Rn, Op2
Logical AND
N,Z,C
ASR, ASRS
Rd, Rm, <Rs|#n>
Arithmetic shift right
N,Z,C
B
label
Branch
-
BFC
Rd, #lsb, #width
Bit field clear
-
BFI
Rd, Rn, #lsb, #width
Bit field insert
-
BIC, BICS
{Rd,} Rn, Op2
Bit clear
N,Z,C
BKPT
#imm
Breakpoint
-
BL
label
Branch with link
-
BLX
Rm
Branch indirect with link
-
BX
Rm
Branch indirect
-
CBNZ
Rn, label
Compare and branch if non-zero
-
CBZ
Rn, label
Compare and branch if zero
-
CLREX
-
Clear exclusive
-
CLZ
Rd, Rm
Count leading zeros
-
CMN
Rn, Op2
Compare negative
N,Z,C,V
CMP
Rn, Op2
Compare
N,Z,C,V
CPSID
i
Change processor state, disable
interrupts
-
CPSIE
i
Change processor state, enable
interrupts
-
DMB
-
Data memory barrier
-
DSB
-
Data synchronization barrier
-
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Table 2-13. Cortex-M3 Instruction Summary (continued)
Mnemonic
Operands
Brief Description
Flags
EOR, EORS
{Rd,} Rn, Op2
Exclusive OR
N,Z,C
ISB
-
Instruction synchronization barrier
-
IT
-
If-Then condition block
-
LDM
Rn{!}, reglist
Load multiple registers, increment after -
LDMDB, LDMEA
Rn{!}, reglist
Load multiple registers, decrement
before
LDMFD, LDMIA
Rn{!}, reglist
Load multiple registers, increment after -
LDR
Rt, [Rn, #offset]
Load register with word
-
LDRB, LDRBT
Rt, [Rn, #offset]
Load register with byte
-
LDRD
Rt, Rt2, [Rn, #offset]
Load register with two bytes
-
LDREX
Rt, [Rn, #offset]
Load register exclusive
-
LDREXB
Rt, [Rn]
Load register exclusive with byte
-
LDREXH
Rt, [Rn]
Load register exclusive with halfword
-
LDRH, LDRHT
Rt, [Rn, #offset]
Load register with halfword
-
LDRSB, LDRSBT
Rt, [Rn, #offset]
Load register with signed byte
-
LDRSH, LDRSHT
Rt, [Rn, #offset]
Load register with signed halfword
-
LDRT
Rt, [Rn, #offset]
Load register with word
-
LSL, LSLS
Rd, Rm, <Rs|#n>
Logical shift left
N,Z,C
LSR, LSRS
Rd, Rm, <Rs|#n>
Logical shift right
N,Z,C
MLA
Rd, Rn, Rm, Ra
Multiply with accumulate, 32-bit result
-
MLS
Rd, Rn, Rm, Ra
Multiply and subtract, 32-bit result
-
MOV, MOVS
Rd, Op2
Move
N,Z,C
MOV, MOVW
Rd, #imm16
Move 16-bit constant
N,Z,C
MOVT
Rd, #imm16
Move top
-
MRS
Rd, spec_reg
Move from special register to general
register
-
MSR
spec_reg, Rm
Move from general register to special
register
N,Z,C,V
MUL, MULS
{Rd,} Rn, Rm
Multiply, 32-bit result
N,Z
MVN, MVNS
Rd, Op2
Move NOT
N,Z,C
NOP
-
No operation
-
ORN, ORNS
{Rd,} Rn, Op2
Logical OR NOT
N,Z,C
ORR, ORRS
{Rd,} Rn, Op2
Logical OR
N,Z,C
POP
reglist
Pop registers from stack
-
PUSH
reglist
Push registers onto stack
-
RBIT
Rd, Rn
Reverse bits
-
REV
Rd, Rn
Reverse byte order in a word
-
REV16
Rd, Rn
Reverse byte order in each halfword
-
REVSH
Rd, Rn
Reverse byte order in bottom halfword
and sign extend
-
ROR, RORS
Rd, Rm, <Rs|#n>
Rotate right
N,Z,C
RRX, RRXS
Rd, Rm
Rotate right with extend
N,Z,C
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Table 2-13. Cortex-M3 Instruction Summary (continued)
Mnemonic
Operands
Brief Description
Flags
RSB, RSBS
{Rd,} Rn, Op2
Reverse subtract
N,Z,C,V
SBC, SBCS
{Rd,} Rn, Op2
Subtract with carry
N,Z,C,V
SBFX
Rd, Rn, #lsb, #width
Signed bit field extract
-
SDIV
{Rd,} Rn, Rm
Signed divide
-
SEV
-
Send event
-
SMLAL
RdLo, RdHi, Rn, Rm
Signed multiply with accumulate
(32x32+64), 64-bit result
-
SMULL
RdLo, RdHi, Rn, Rm
Signed multiply (32x32), 64-bit result
-
SSAT
Rd, #n, Rm {,shift #s}
Signed saturate
Q
STM
Rn{!}, reglist
Store multiple registers, increment after -
STMDB, STMEA
Rn{!}, reglist
Store multiple registers, decrement
before
STMFD, STMIA
Rn{!}, reglist
Store multiple registers, increment after -
STR
Rt, [Rn {, #offset}]
Store register word
-
STRB, STRBT
Rt, [Rn {, #offset}]
Store register byte
-
STRD
Rt, Rt2, [Rn {, #offset}]
Store register two words
-
STREX
Rt, Rt, [Rn {, #offset}]
Store register exclusive
-
STREXB
Rd, Rt, [Rn]
Store register exclusive byte
-
STREXH
Rd, Rt, [Rn]
Store register exclusive halfword
-
STRH, STRHT
Rt, [Rn {, #offset}]
Store register halfword
-
STRSB, STRSBT
Rt, [Rn {, #offset}]
Store register signed byte
-
STRSH, STRSHT
Rt, [Rn {, #offset}]
Store register signed halfword
-
STRT
Rt, [Rn {, #offset}]
Store register word
-
SUB, SUBS
{Rd,} Rn, Op2
Subtract
N,Z,C,V
SUB, SUBW
{Rd,} Rn, #imm12
Subtract 12-bit constant
N,Z,C,V
SVC
#imm
Supervisor call
-
SXTB
{Rd,} Rm {,ROR #n}
Sign extend a byte
-
SXTH
{Rd,} Rm {,ROR #n}
Sign extend a halfword
-
TBB
[Rn, Rm]
Table branch byte
-
TBH
[Rn, Rm, LSL #1]
Table branch halfword
-
TEQ
Rn, Op2
Test equivalence
N,Z,C
TST
Rn, Op2
Test
N,Z,C
UBFX
Rd, Rn, #lsb, #width
Unsigned bit field extract
-
UDIV
{Rd,} Rn, Rm
Unsigned divide
-
UMLAL
RdLo, RdHi, Rn, Rm
Unsigned multiply with accumulate
(32x32+32+32), 64-bit result
-
UMULL
RdLo, RdHi, Rn, Rm
Unsigned multiply (32x 2), 64-bit result -
USAT
Rd, #n, Rm {,shift #s}
Unsigned Saturate
Q
UXTB
{Rd,} Rm, {,ROR #n}
Zero extend a Byte
-
UXTH
{Rd,} Rm, {,ROR #n}
Zero extend a Halfword
-
WFE
-
Wait for event
-
WFI
-
Wait for interrupt
-
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3
Cortex-M3 Peripherals
®
This chapter provides information on the Stellaris implementation of the Cortex-M3 processor
peripherals, including:
■ SysTick (see page 93)
Provides a simple, 24-bit clear-on-write, decrementing, wrap-on-zero counter with a flexible
control mechanism.
■ Nested Vectored Interrupt Controller (NVIC) (see page 94)
– Facilitates low-latency exception and interrupt handling
– Controls power management
– Implements system control registers
■ System Control Block (SCB) (see page 96)
Provides system implementation information and system control, including configuration, control,
and reporting of system exceptions.
■ Memory Protection Unit (MPU) (see page 96)
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.
Table 3-1 on page 93 shows the address map of the Private Peripheral Bus (PPB). Some peripheral
register regions are split into two address regions, as indicated by two addresses listed.
Table 3-1. Core Peripheral Register Regions
Address
Core Peripheral
Description (see page ...)
0xE000.E010-0xE000.E01F
System Timer
93
0xE000.E100-0xE000.E4EF
Nested Vectored Interrupt Controller
94
0xE000.ED00-0xE000.ED3F
System Control Block
96
0xE000.ED90-0xE000.EDB8
Memory Protection Unit
96
0xE000.EF00-0xE000.EF03
3.1
Functional Description
This chapter provides information on the Stellaris implementation of the Cortex-M3 processor
peripherals: SysTick, NVIC, SCB and MPU.
3.1.1
System Timer (SysTick)
Cortex-M3 includes an integrated system timer, SysTick, which 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 as:
■ An RTOS tick timer that fires at a programmable rate (for example, 100 Hz) and invokes a SysTick
routine.
■ A high-speed alarm timer using the system clock.
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■ 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 used to measure time to completion and time used.
■ An internal clock source control based on missing/meeting durations. The COUNT bit in the
STCTRL 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.
The timer consists of three registers:
■ SysTick Control and Status (STCTRL): A control and status counter to configure its clock,
enable the counter, enable the SysTick interrupt, and determine counter status.
■ SysTick Reload Value (STRELOAD): The reload value for the counter, used to provide the
counter's wrap value.
■ SysTick Current Value (STCURRENT): The current value of the counter.
When enabled, the timer counts down on each clock from the reload value to zero, reloads (wraps)
to the value in the STRELOAD register on the next clock edge, then decrements on subsequent
clocks. Clearing the STRELOAD register disables the counter on the next wrap. When the counter
reaches zero, the COUNT status bit is set. The COUNT bit clears on reads.
Writing to the STCURRENT register clears the register and the COUNT 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.
The SysTick counter runs on the system clock. If this clock signal is stopped for low power mode,
the SysTick counter stops. Ensure software uses aligned word accesses to access the SysTick
registers.
Note:
3.1.2
When the processor is halted for debugging, the counter does not decrement.
Nested Vectored Interrupt Controller (NVIC)
This section describes the Nested Vectored Interrupt Controller (NVIC) and the registers it uses.
The NVIC supports:
■ 31 interrupts.
■ A programmable priority level of 0-7 for each interrupt. A higher level corresponds to a lower
priority, so level 0 is the highest interrupt priority.
■ Low-latency exception and interrupt handling.
■ Level and pulse detection of interrupt signals.
■ Dynamic reprioritization of interrupts.
■ Grouping of priority values into group priority and subpriority fields.
■ Interrupt tail-chaining.
■ An external Non-maskable interrupt (NMI).
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The processor automatically stacks its state on exception entry and unstacks this state on exception
exit, with no instruction overhead, providing low latency exception handling.
3.1.2.1
Level-Sensitive and Pulse Interrupts
The processor supports both level-sensitive and pulse interrupts. Pulse interrupts are also described
as edge-triggered interrupts.
A level-sensitive interrupt is held asserted until the peripheral deasserts the interrupt signal. Typically
this happens because the ISR accesses the peripheral, causing it to clear the interrupt request. A
pulse interrupt is an interrupt signal sampled synchronously on the rising edge of the processor
clock. To ensure the NVIC detects the interrupt, the peripheral must assert the interrupt signal for
at least one clock cycle, during which the NVIC detects the pulse and latches the interrupt.
When the processor enters the ISR, it automatically removes the pending state from the interrupt
(see “Hardware and Software Control of Interrupts” on page 95 for more information). For a
level-sensitive interrupt, if the signal is not deasserted before the processor returns from the ISR,
the interrupt becomes pending again, and the processor must execute its ISR again. As a result,
the peripheral can hold the interrupt signal asserted until it no longer needs servicing.
3.1.2.2
Hardware and Software Control of Interrupts
The Cortex-M3 latches all interrupts. A peripheral interrupt becomes pending for one of the following
reasons:
■ The NVIC detects that the interrupt signal is High and the interrupt is not active.
■ The NVIC detects a rising edge on the interrupt signal.
■ Software writes to the corresponding interrupt set-pending register bit, or to the Software Trigger
Interrupt (SWTRIG) register to make a Software-Generated Interrupt pending. See the INT bit
in the PEND0 register on page 112 or SWTRIG on page 120.
A pending interrupt remains pending until one of the following:
■ The processor enters the ISR for the interrupt, changing the state of the interrupt from pending
to active. Then:
– For a level-sensitive interrupt, when the processor returns from the ISR, the NVIC samples
the interrupt signal. If the signal is asserted, the state of the interrupt changes to pending,
which might cause the processor to immediately re-enter the ISR. Otherwise, the state of the
interrupt changes to inactive.
– For a pulse interrupt, the NVIC continues to monitor the interrupt signal, and if this is pulsed
the state of the interrupt changes to pending and active. In this case, when the processor
returns from the ISR the state of the interrupt changes to pending, which might cause the
processor to immediately re-enter the ISR.
If the interrupt signal is not pulsed while the processor is in the ISR, when the processor
returns from the ISR the state of the interrupt changes to inactive.
■ Software writes to the corresponding interrupt clear-pending register bit
– For a level-sensitive interrupt, if the interrupt signal is still asserted, the state of the interrupt
does not change. Otherwise, the state of the interrupt changes to inactive.
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– For a pulse interrupt, the state of the interrupt changes to inactive, if the state was pending
or to active, if the state was active and pending.
3.1.3
System Control Block (SCB)
The System Control Block (SCB) provides system implementation information and system control,
including configuration, control, and reporting of the system exceptions.
3.1.4
Memory Protection Unit (MPU)
This section describes the Memory protection unit (MPU). The MPU divides the memory map into
a number of regions and defines the location, size, access permissions, and memory attributes of
each region. The MPU supports independent attribute settings for each region, overlapping regions,
and export of memory attributes to the system.
The memory attributes affect the behavior of memory accesses to the region. The Cortex-M3 MPU
defines eight separate memory regions, 0-7, and a background region.
When memory regions overlap, a memory access is affected by the attributes of the region with the
highest number. For example, the attributes for region 7 take precedence over the attributes of any
region that overlaps region 7.
The background region has the same memory access attributes as the default memory map, but is
accessible from privileged software only.
The Cortex-M3 MPU memory map is unified, meaning that instruction accesses and data accesses
have the same region settings.
If a program accesses a memory location that is prohibited by the MPU, the processor generates
a memory management fault, causing a fault exception and possibly causing termination of the
process in an OS environment. In an OS environment, the kernel can update the MPU region setting
dynamically based on the process to be executed. Typically, an embedded OS uses the MPU for
memory protection.
Configuration of MPU regions is based on memory types (see “Memory Regions, Types and
Attributes” on page 72 for more information).
Table 3-2 on page 96 shows the possible MPU region attributes. See the section called “MPU
Configuration for a Stellaris Microcontroller” on page 100 for guidelines for programming a
microcontroller implementation.
Table 3-2. Memory Attributes Summary
Memory Type
Description
Strongly Ordered
All accesses to Strongly Ordered memory occur in program order.
Device
Memory-mapped peripherals
Normal
Normal memory
To avoid unexpected behavior, disable the interrupts before updating the attributes of a region that
the interrupt handlers might access.
Ensure software uses aligned accesses of the correct size to access MPU registers:
■ Except for the MPU Region Attribute and Size (MPUATTR) register, all MPU registers must
be accessed with aligned word accesses.
■ The MPUATTR register can be accessed with byte or aligned halfword or word accesses.
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The processor does not support unaligned accesses to MPU registers.
When setting up the MPU, and if the MPU has previously been programmed, disable unused regions
to prevent any previous region settings from affecting the new MPU setup.
3.1.4.1
Updating an MPU Region
To update the attributes for an MPU region, the MPU Region Number (MPUNUMBER), MPU
Region Base Address (MPUBASE) and MPUATTR registers must be updated. Each register can
be programmed separately or with a multiple-word write to program all of these registers. You can
use the MPUBASEx and MPUATTRx aliases to program up to four regions simultaneously using
an STM instruction.
Updating an MPU Region Using Separate Words
This example simple code configures one region:
; R1 = region number
; R2 = size/enable
; R3 = attributes
; R4 = address
LDR R0,=MPUNUMBER
STR R1, [R0, #0x0]
STR R4, [R0, #0x4]
STRH R2, [R0, #0x8]
STRH R3, [R0, #0xA]
;
;
;
;
;
0xE000ED98, MPU region number register
Region Number
Region Base Address
Region Size and Enable
Region Attribute
Disable a region before writing new region settings to the MPU if you have previously enabled the
region being changed. For example:
; R1 = region number
; R2 = size/enable
; R3 = attributes
; R4 = address
LDR R0,=MPUNUMBER
STR R1, [R0, #0x0]
BIC R2, R2, #1
STRH R2, [R0, #0x8]
STR R4, [R0, #0x4]
STRH R3, [R0, #0xA]
ORR R2, #1
STRH R2, [R0, #0x8]
;
;
;
;
;
;
;
;
0xE000ED98, MPU region number register
Region Number
Disable
Region Size and Enable
Region Base Address
Region Attribute
Enable
Region Size and Enable
Software must use memory barrier instructions:
■ Before MPU setup, if there might be outstanding memory transfers, such as buffered writes, that
might be affected by the change in MPU settings.
■ After MPU setup, if it includes memory transfers that must use the new MPU settings.
However, memory barrier instructions are not required if the MPU setup process starts by entering
an exception handler, or is followed by an exception return, because the exception entry and
exception return mechanism cause memory barrier behavior.
Software does not need any memory barrier instructions during MPU setup, because it accesses
the MPU through the Private Peripheral Bus (PPB), which is a Strongly Ordered memory region.
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For example, if all of the memory access behavior is intended to take effect immediately after the
programming sequence, then a DSB instruction and an ISB instruction should be used. A DSB is
required after changing MPU settings, such as at the end of context switch. An ISB is required if
the code that programs the MPU region or regions is entered using a branch or call. If the
programming sequence is entered using a return from exception, or by taking an exception, then
an ISB is not required.
Updating an MPU Region Using Multi-Word Writes
The MPU can be programmed directly using multi-word writes, depending how the information is
divided. Consider the following reprogramming:
; R1 = region number
; R2 = address
; R3 = size, attributes in one
LDR R0, =MPUNUMBER ; 0xE000ED98, MPU region number register
STR R1, [R0, #0x0] ; Region Number
STR R2, [R0, #0x4] ; Region Base Address
STR R3, [R0, #0x8] ; Region Attribute, Size and Enable
An STM instruction can be used to optimize this:
; R1 = region number
; R2 = address
; R3 = size, attributes in one
LDR R0, =MPUNUMBER ; 0xE000ED98, MPU region number register
STM R0, {R1-R3}
; Region number, address, attribute, size and enable
This operation can be done in two words for pre-packed information, meaning that the MPU Region
Base Address (MPUBASE) register (see page 152) contains the required region number and has
the VALID bit set. This method can be used when the data is statically packed, for example in a
boot loader:
; R1 = address and region number in one
; R2 = size and attributes in one
LDR R0, =MPUBASE
; 0xE000ED9C, MPU Region Base register
STR R1, [R0, #0x0] ; Region base address and region number combined
; with VALID (bit 4) set
STR R2, [R0, #0x4] ; Region Attribute, Size and Enable
Subregions
Regions of 256 bytes or more are divided into eight equal-sized subregions. Set the corresponding
bit in the SRD field of the MPU Region Attribute and Size (MPUATTR) register (see page 154) to
disable a subregion. The least-significant bit of the SRD field controls the first subregion, and the
most-significant bit controls the last subregion. Disabling a subregion means another region
overlapping the disabled range matches instead. If no other enabled region overlaps the disabled
subregion, the MPU issues a fault.
Regions of 32, 64, and 128 bytes do not support subregions. With regions of these sizes, the SRD
field must be configured to 0x00, otherwise the MPU behavior is unpredictable.
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Example of SRD Use
Two regions with the same base address overlap. Region one is 128 KB, and region two is 512 KB.
To ensure the attributes from region one apply to the first 128 KB region, configure the SRD field for
region two to 0x03 to disable the first two subregions, as Figure 3-1 on page 99 shows.
Figure 3-1. SRD Use Example
Region 2, with
subregions
Region 1
Base address of both regions
3.1.4.2
Offset from
base address
512KB
448KB
384KB
320KB
256KB
192KB
128KB
Disabled subregion
64KB
Disabled subregion
0
MPU Access Permission Attributes
The access permission bits, TEX, S, C, B, AP, and XN of the MPUATTR register, control access to
the corresponding memory region. If an access is made to an area of memory without the required
permissions, then the MPU generates a permission fault.
Table 3-3 on page 99 shows the encodings for the TEX, C, B, and S access permission bits. All
encodings are shown for completeness, however the current implementation of the Cortex-M3 does
not support the concept of cacheability or shareability. Refer to the section called “MPU Configuration
for a Stellaris Microcontroller” on page 100 for information on programming the MPU for Stellaris
implementations.
Table 3-3. TEX, S, C, and B Bit Field Encoding
TEX
S
000b
x
C
B
Memory Type
Shareability
Other Attributes
a
0
0
Strongly Ordered
Shareable
-
a
-
000
x
0
1
Device
Shareable
000
0
1
0
Normal
Not shareable
000
1
1
0
Normal
Shareable
000
0
1
1
Normal
Not shareable
000
1
1
1
Normal
Shareable
001
0
0
0
Normal
Not shareable
001
1
0
0
Normal
Shareable
Outer and inner
noncacheable.
001
x
a
0
1
Reserved encoding
-
-
a
Outer and inner
write-through. No write
allocate.
001
x
1
0
Reserved encoding
-
-
001
0
1
1
Normal
Not shareable
001
1
1
1
Normal
Shareable
Outer and inner
write-back. Write and
read allocate.
010
x
a
0
0
Device
Not shareable
Nonshared Device.
a
0
1
Reserved encoding
-
-
a
1
x
Reserved encoding
-
-
010
x
010
x
a
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Table 3-3. TEX, S, C, and B Bit Field Encoding (continued)
TEX
S
C
B
Memory Type
Shareability
Other Attributes
1BB
0
A
A
Normal
Not shareable
1BB
1
A
A
Normal
Shareable
Cached memory (BB =
outer policy, AA = inner
policy).
See Table 3-4 for the
encoding of the AA and
BB bits.
a. The MPU ignores the value of this bit.
Table 3-4 on page 100 shows the cache policy for memory attribute encodings with a TEX value in
the range of 0x4-0x7.
Table 3-4. Cache Policy for Memory Attribute Encoding
Encoding, AA or BB
Corresponding Cache Policy
00
Non-cacheable
01
Write back, write and read allocate
10
Write through, no write allocate
11
Write back, no write allocate
Table 3-5 on page 100 shows the AP encodings in the MPUATTR register that define the access
permissions for privileged and unprivileged software.
Table 3-5. AP Bit Field Encoding
AP Bit Field
Privileged
Permissions
Unprivileged
Permissions
Description
000
No access
No access
All accesses generate a permission fault.
001
R/W
No access
Access from privileged software only.
010
R/W
RO
Writes by unprivileged software generate a
permission fault.
011
R/W
R/W
Full access.
100
Unpredictable
Unpredictable
Reserved.
101
RO
No access
Reads by privileged software only.
110
RO
RO
Read-only, by privileged or unprivileged software.
111
RO
RO
Read-only, by privileged or unprivileged software.
MPU Configuration for a Stellaris Microcontroller
Stellaris microcontrollers have only a single processor and no caches. As a result, the MPU should
be programmed as shown in Table 3-6 on page 100.
Table 3-6. Memory Region Attributes for Stellaris Microcontrollers
Memory Region
TEX
S
C
B
Memory Type and Attributes
Flash memory
000b
0
1
0
Normal memory, non-shareable, write-through
Internal SRAM
000b
1
1
0
Normal memory, shareable, write-through
External SRAM
000b
1
1
1
Normal memory, shareable, write-back,
write-allocate
Peripherals
000b
1
0
1
Device memory, shareable
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In current Stellaris microcontroller implementations, the shareability and cache policy attributes do
not affect the system behavior. However, using these settings for the MPU regions can make the
application code more portable. The values given are for typical situations.
3.1.4.3
MPU Mismatch
When an access violates the MPU permissions, the processor generates a memory management
fault (see “Exceptions and Interrupts” on page 70 for more information). The MFAULTSTAT register
indicates the cause of the fault. See page 139 for more information.
3.2
Register Map
Table 3-7 on page 101 lists the Cortex-M3 Peripheral SysTick, NVIC, MPU and SCB registers. The
offset listed is a hexadecimal increment to the register's address, relative to the Core Peripherals
base address of 0xE000.E000.
Note:
Register spaces that are not used are reserved for future or internal use. Software should
not modify any reserved memory address.
Table 3-7. Peripherals Register Map
Offset
Name
Type
Reset
Description
See
page
System Timer (SysTick) Registers
0x010
STCTRL
R/W
0x0000.0000
SysTick Control and Status Register
104
0x014
STRELOAD
R/W
0x0000.0000
SysTick Reload Value Register
106
0x018
STCURRENT
R/WC
0x0000.0000
SysTick Current Value Register
107
Nested Vectored Interrupt Controller (NVIC) Registers
0x100
EN0
R/W
0x0000.0000
Interrupt 0-31 Set Enable
108
0x104
EN1
R/W
0x0000.0000
Interrupt 32-47 Set Enable
109
0x180
DIS0
R/W
0x0000.0000
Interrupt 0-31 Clear Enable
110
0x184
DIS1
R/W
0x0000.0000
Interrupt 32-47 Clear Enable
111
0x200
PEND0
R/W
0x0000.0000
Interrupt 0-31 Set Pending
112
0x204
PEND1
R/W
0x0000.0000
Interrupt 32-47 Set Pending
113
0x280
UNPEND0
R/W
0x0000.0000
Interrupt 0-31 Clear Pending
114
0x284
UNPEND1
R/W
0x0000.0000
Interrupt 32-47 Clear Pending
115
0x300
ACTIVE0
RO
0x0000.0000
Interrupt 0-31 Active Bit
116
0x304
ACTIVE1
RO
0x0000.0000
Interrupt 32-47 Active Bit
117
0x400
PRI0
R/W
0x0000.0000
Interrupt 0-3 Priority
118
0x404
PRI1
R/W
0x0000.0000
Interrupt 4-7 Priority
118
0x408
PRI2
R/W
0x0000.0000
Interrupt 8-11 Priority
118
0x40C
PRI3
R/W
0x0000.0000
Interrupt 12-15 Priority
118
0x410
PRI4
R/W
0x0000.0000
Interrupt 16-19 Priority
118
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Table 3-7. Peripherals Register Map (continued)
Description
See
page
Offset
Name
Type
Reset
0x414
PRI5
R/W
0x0000.0000
Interrupt 20-23 Priority
118
0x418
PRI6
R/W
0x0000.0000
Interrupt 24-27 Priority
118
0x41C
PRI7
R/W
0x0000.0000
Interrupt 28-31 Priority
118
0x420
PRI8
R/W
0x0000.0000
Interrupt 32-35 Priority
118
0x424
PRI9
R/W
0x0000.0000
Interrupt 36-39 Priority
118
0x428
PRI10
R/W
0x0000.0000
Interrupt 40-43 Priority
118
0x42C
PRI11
R/W
0x0000.0000
Interrupt 44-47 Priority
118
0xF00
SWTRIG
WO
0x0000.0000
Software Trigger Interrupt
120
System Control Block (SCB) Registers
0xD00
CPUID
RO
0x411F.C231
CPU ID Base
121
0xD04
INTCTRL
R/W
0x0000.0000
Interrupt Control and State
122
0xD08
VTABLE
R/W
0x0000.0000
Vector Table Offset
125
0xD0C
APINT
R/W
0xFA05.0000
Application Interrupt and Reset Control
126
0xD10
SYSCTRL
R/W
0x0000.0000
System Control
128
0xD14
CFGCTRL
R/W
0x0000.0000
Configuration and Control
130
0xD18
SYSPRI1
R/W
0x0000.0000
System Handler Priority 1
132
0xD1C
SYSPRI2
R/W
0x0000.0000
System Handler Priority 2
133
0xD20
SYSPRI3
R/W
0x0000.0000
System Handler Priority 3
134
0xD24
SYSHNDCTRL
R/W
0x0000.0000
System Handler Control and State
135
0xD28
FAULTSTAT
R/W1C
0x0000.0000
Configurable Fault Status
139
0xD2C
HFAULTSTAT
R/W1C
0x0000.0000
Hard Fault Status
145
0xD34
MMADDR
R/W
-
Memory Management Fault Address
146
0xD38
FAULTADDR
R/W
-
Bus Fault Address
147
Memory Protection Unit (MPU) Registers
0xD90
MPUTYPE
RO
0x0000.0800
MPU Type
148
0xD94
MPUCTRL
R/W
0x0000.0000
MPU Control
149
0xD98
MPUNUMBER
R/W
0x0000.0000
MPU Region Number
151
0xD9C
MPUBASE
R/W
0x0000.0000
MPU Region Base Address
152
0xDA0
MPUATTR
R/W
0x0000.0000
MPU Region Attribute and Size
154
0xDA4
MPUBASE1
R/W
0x0000.0000
MPU Region Base Address Alias 1
152
0xDA8
MPUATTR1
R/W
0x0000.0000
MPU Region Attribute and Size Alias 1
154
0xDAC
MPUBASE2
R/W
0x0000.0000
MPU Region Base Address Alias 2
152
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Table 3-7. Peripherals Register Map (continued)
Name
Type
Reset
0xDB0
MPUATTR2
R/W
0x0000.0000
MPU Region Attribute and Size Alias 2
154
0xDB4
MPUBASE3
R/W
0x0000.0000
MPU Region Base Address Alias 3
152
0xDB8
MPUATTR3
R/W
0x0000.0000
MPU Region Attribute and Size Alias 3
154
3.3
Description
See
page
Offset
System Timer (SysTick) Register Descriptions
This section lists and describes the System Timer registers, in numerical order by address offset.
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Register 1: SysTick Control and Status Register (STCTRL), offset 0x010
Note:
This register can only be accessed from privileged mode.
The SysTick STCTRL register enables the SysTick features.
SysTick Control and Status Register (STCTRL)
Base 0xE000.E000
Offset 0x010
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
9
8
7
6
5
4
3
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
16
COUNT
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
2
1
0
CLK_SRC
INTEN
ENABLE
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:17
reserved
RO
0x000
Software should not rely on the value of 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
COUNT
RO
0
Count Flag
Value
Description
0
The SysTick timer has not counted to 0 since the last time
this bit was read.
1
The SysTick timer has counted to 0 since the last time
this bit was read.
This bit is cleared by a read of the register or if the STCURRENT register
is written with any value.
If read by the debugger using the DAP, this bit is cleared only if the
MasterType bit in the AHB-AP Control Register is clear. Otherwise,
the COUNT bit is not changed by the debugger read. See the ARM®
Debug Interface V5 Architecture Specification for more information on
MasterType.
15:3
reserved
RO
0x000
2
CLK_SRC
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.
Clock Source
Value Description
0
External reference clock. (Not implemented for most Stellaris
microcontrollers.)
1
System clock
Because an external reference clock is not implemented, this bit must
be set in order for SysTick to operate.
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Bit/Field
Name
Type
Reset
1
INTEN
R/W
0
0
ENABLE
R/W
0
Description
Interrupt Enable
Value
Description
0
Interrupt generation is disabled. Software can use the
COUNT bit to determine if the counter has ever reached 0.
1
An interrupt is generated to the NVIC when SysTick counts
to 0.
Enable
Value
Description
0
The counter is disabled.
1
Enables SysTick to operate in a multi-shot way. That is, the
counter loads the RELOAD value and begins counting down.
On reaching 0, the COUNT bit is set and an interrupt is
generated if enabled by INTEN. The counter then loads the
RELOAD value again and begins counting.
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Register 2: SysTick Reload Value Register (STRELOAD), offset 0x014
Note:
This register can only be accessed from privileged mode.
The STRELOAD register specifies the start value to load into the SysTick Current Value
(STCURRENT) register when the counter reaches 0. The start value can be between 0x1 and
0x00FF.FFFF. A start value of 0 is possible but has no effect because the SysTick interrupt and the
COUNT bit are activated when counting from 1 to 0.
SysTick can be configured as a multi-shot timer, repeated over and over, firing every N+1 clock
pulses, where N is any value from 1 to 0x00FF.FFFF. For example, if a tick interrupt is required
every 100 clock pulses, 99 must be written into the RELOAD field.
SysTick Reload Value Register (STRELOAD)
Base 0xE000.E000
Offset 0x014
Type R/W, reset 0x0000.0000
31
30
29
28
RO
0
RO
0
RO
0
RO
0
15
14
13
R/W
0
R/W
0
R/W
0
27
26
25
24
23
22
21
20
18
17
16
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
19
RELOAD
RELOAD
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:24
reserved
RO
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.
23:0
RELOAD
R/W
0x00.0000
Reload Value
Value to load into the SysTick Current Value (STCURRENT) register
when the counter reaches 0.
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Register 3: SysTick Current Value Register (STCURRENT), offset 0x018
Note:
This register can only be accessed from privileged mode.
The STCURRENT register contains the current value of the SysTick counter.
SysTick Current Value Register (STCURRENT)
Base 0xE000.E000
Offset 0x018
Type R/WC, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
reserved
Type
Reset
20
19
18
17
16
CURRENT
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
CURRENT
Type
Reset
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
R/WC
0
Bit/Field
Name
Type
Reset
Description
31:24
reserved
RO
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.
23:0
CURRENT
R/WC
0x00.0000
Current Value
This field contains the 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.
Clearing this register also clears the COUNT bit of the STCTRL register.
3.4
NVIC Register Descriptions
This section lists and describes the NVIC registers, in numerical order by address offset.
The NVIC registers can only be fully accessed from privileged mode, but interrupts can be pended
while in unprivileged mode by enabling the Configuration and Control (CFGCTRL) register. Any
other unprivileged mode access causes a bus fault.
Ensure software uses correctly aligned register accesses. The processor does not support unaligned
accesses to NVIC registers.
An interrupt can enter the pending state even if it is disabled.
Before programming the VTABLE register to relocate the vector table, ensure the vector table
entries of the new vector table are set up for fault handlers, NMI, and all enabled exceptions such
as interrupts. For more information, see page 125.
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Register 4: Interrupt 0-31 Set Enable (EN0), offset 0x100
Note:
This register can only be accessed from privileged mode.
The EN0 register enables interrupts and shows which interrupts are enabled. Bit 0 corresponds to
Interrupt 0; bit 31 corresponds to Interrupt 31.
See Table 2-9 on page 81 for interrupt assignments.
If a pending interrupt is enabled, the NVIC activates the interrupt based on its priority. If an interrupt
is not enabled, asserting its interrupt signal changes the interrupt state to pending, but the NVIC
never activates the interrupt, regardless of its priority.
Interrupt 0-31 Set Enable (EN0)
Base 0xE000.E000
Offset 0x100
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
INT
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
INT
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
31:0
INT
R/W
R/W
0
Reset
R/W
0
Description
0x0000.0000 Interrupt Enable
Value
Description
0
On a read, indicates the interrupt is disabled.
On a write, no effect.
1
On a read, indicates the interrupt is enabled.
On a write, enables the interrupt.
A bit can only be cleared by setting the corresponding INT[n] bit in
the DISn register.
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Register 5: Interrupt 32-47 Set Enable (EN1), offset 0x104
Note:
This register can only be accessed from privileged mode.
The EN1 register enables interrupts and shows which interrupts are enabled. Bit 0 corresponds to
Interrupt 32; bit 15 corresponds to Interrupt 47. See Table 2-9 on page 81 for interrupt assignments.
If a pending interrupt is enabled, the NVIC activates the interrupt based on its priority. If an interrupt
is not enabled, asserting its interrupt signal changes the interrupt state to pending, but the NVIC
never activates the interrupt, regardless of its priority.
Interrupt 32-47 Set Enable (EN1)
Base 0xE000.E000
Offset 0x104
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
INT
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
INT
R/W
0x0.0000
Interrupt Enable
Value
Description
0
On a read, indicates the interrupt is disabled.
On a write, no effect.
1
On a read, indicates the interrupt is enabled.
On a write, enables the interrupt.
A bit can only be cleared by setting the corresponding INT[n] bit in
the DIS1 register.
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Register 6: Interrupt 0-31 Clear Enable (DIS0), offset 0x180
Note:
This register can only be accessed from privileged mode.
The DIS0 register disables interrupts. Bit 0 corresponds to Interrupt 0; bit 31 corresponds to Interrupt
31.
See Table 2-9 on page 81 for interrupt assignments.
Interrupt 0-31 Clear Enable (DIS0)
Base 0xE000.E000
Offset 0x180
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
INT
Type
Reset
INT
Type
Reset
Bit/Field
Name
Type
31:0
INT
R/W
Reset
Description
0x0000.0000 Interrupt Disable
Value Description
0
On a read, indicates the interrupt is disabled.
On a write, no effect.
1
On a read, indicates the interrupt is enabled.
On a write, clears the corresponding INT[n] bit in the EN0
register, disabling interrupt [n].
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Register 7: Interrupt 32-47 Clear Enable (DIS1), offset 0x184
Note:
This register can only be accessed from privileged mode.
The DIS1 register disables interrupts. Bit 0 corresponds to Interrupt 32; bit 15 corresponds to Interrupt
47. See Table 2-9 on page 81 for interrupt assignments.
Interrupt 32-47 Clear Enable (DIS1)
Base 0xE000.E000
Offset 0x184
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
INT
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
INT
R/W
0x0.0000
Interrupt Disable
Value Description
0
On a read, indicates the interrupt is disabled.
On a write, no effect.
1
On a read, indicates the interrupt is enabled.
On a write, clears the corresponding INT[n] bit in the EN1
register, disabling interrupt [n].
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Register 8: Interrupt 0-31 Set Pending (PEND0), offset 0x200
Note:
This register can only be accessed from privileged mode.
The PEND0 register forces interrupts into the pending state and shows which interrupts are pending.
Bit 0 corresponds to Interrupt 0; bit 31 corresponds to Interrupt 31.
See Table 2-9 on page 81 for interrupt assignments.
Interrupt 0-31 Set Pending (PEND0)
Base 0xE000.E000
Offset 0x200
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
INT
Type
Reset
INT
Type
Reset
Bit/Field
Name
Type
31:0
INT
R/W
Reset
Description
0x0000.0000 Interrupt Set Pending
Value
Description
0
On a read, indicates that the interrupt is not pending.
On a write, no effect.
1
On a read, indicates that the interrupt is pending.
On a write, the corresponding interrupt is set to pending
even if it is disabled.
If the corresponding interrupt is already pending, setting a bit has no
effect.
A bit can only be cleared by setting the corresponding INT[n] bit in
the UNPEND0 register.
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Register 9: Interrupt 32-47 Set Pending (PEND1), offset 0x204
Note:
This register can only be accessed from privileged mode.
The PEND1 register forces interrupts into the pending state and shows which interrupts are pending.
Bit 0 corresponds to Interrupt 32; bit 15 corresponds to Interrupt 47. See Table 2-9 on page 81 for
interrupt assignments.
Interrupt 32-47 Set Pending (PEND1)
Base 0xE000.E000
Offset 0x204
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
INT
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
INT
R/W
0x0.0000
Interrupt Set Pending
Value
Description
0
On a read, indicates that the interrupt is not pending.
On a write, no effect.
1
On a read, indicates that the interrupt is pending.
On a write, the corresponding interrupt is set to pending
even if it is disabled.
If the corresponding interrupt is already pending, setting a bit has no
effect.
A bit can only be cleared by setting the corresponding INT[n] bit in
the UNPEND1 register.
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Register 10: Interrupt 0-31 Clear Pending (UNPEND0), offset 0x280
Note:
This register can only be accessed from privileged mode.
The UNPEND0 register shows which interrupts are pending and removes the pending state from
interrupts. Bit 0 corresponds to Interrupt 0; bit 31 corresponds to Interrupt 31.
See Table 2-9 on page 81 for interrupt assignments.
Interrupt 0-31 Clear Pending (UNPEND0)
Base 0xE000.E000
Offset 0x280
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
INT
Type
Reset
INT
Type
Reset
Bit/Field
Name
Type
31:0
INT
R/W
Reset
Description
0x0000.0000 Interrupt Clear Pending
Value Description
0
On a read, indicates that the interrupt is not pending.
On a write, no effect.
1
On a read, indicates that the interrupt is pending.
On a write, clears the corresponding INT[n] bit in the PEND0
register, so that interrupt [n] is no longer pending.
Setting a bit does not affect the active state of the corresponding
interrupt.
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Register 11: Interrupt 32-47 Clear Pending (UNPEND1), offset 0x284
Note:
This register can only be accessed from privileged mode.
The UNPEND1 register shows which interrupts are pending and removes the pending state from
interrupts. Bit 0 corresponds to Interrupt 32; bit 15 corresponds to Interrupt 47. See Table
2-9 on page 81 for interrupt assignments.
Interrupt 32-47 Clear Pending (UNPEND1)
Base 0xE000.E000
Offset 0x284
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
INT
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
INT
R/W
0x0.0000
Interrupt Clear Pending
Value Description
0
On a read, indicates that the interrupt is not pending.
On a write, no effect.
1
On a read, indicates that the interrupt is pending.
On a write, clears the corresponding INT[n] bit in the PEND1
register, so that interrupt [n] is no longer pending.
Setting a bit does not affect the active state of the corresponding
interrupt.
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Register 12: Interrupt 0-31 Active Bit (ACTIVE0), offset 0x300
Note:
This register can only be accessed from privileged mode.
The ACTIVE0 register indicates which interrupts are active. Bit 0 corresponds to Interrupt 0; bit 31
corresponds to Interrupt 31.
See Table 2-9 on page 81 for interrupt assignments.
Caution – Do not manually set or clear the bits in this register.
Interrupt 0-31 Active Bit (ACTIVE0)
Base 0xE000.E000
Offset 0x300
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
INT
Type
Reset
INT
Type
Reset
Bit/Field
Name
Type
31:0
INT
RO
Reset
Description
0x0000.0000 Interrupt Active
Value Description
0
The corresponding interrupt is not active.
1
The corresponding interrupt is active, or active and pending.
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Register 13: Interrupt 32-47 Active Bit (ACTIVE1), offset 0x304
Note:
This register can only be accessed from privileged mode.
The ACTIVE1 register indicates which interrupts are active. Bit 0 corresponds to Interrupt 32; bit
15 corresponds to Interrupt 47. See Table 2-9 on page 81 for interrupt assignments.
Caution – Do not manually set or clear the bits in this register.
Interrupt 32-47 Active Bit (ACTIVE1)
Base 0xE000.E000
Offset 0x304
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
INT
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
INT
RO
0x0.0000
Interrupt Active
Value Description
0
The corresponding interrupt is not active.
1
The corresponding interrupt is active, or active and pending.
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Register 14: Interrupt 0-3 Priority (PRI0), offset 0x400
Register 15: Interrupt 4-7 Priority (PRI1), offset 0x404
Register 16: Interrupt 8-11 Priority (PRI2), offset 0x408
Register 17: Interrupt 12-15 Priority (PRI3), offset 0x40C
Register 18: Interrupt 16-19 Priority (PRI4), offset 0x410
Register 19: Interrupt 20-23 Priority (PRI5), offset 0x414
Register 20: Interrupt 24-27 Priority (PRI6), offset 0x418
Register 21: Interrupt 28-31 Priority (PRI7), offset 0x41C
Register 22: Interrupt 32-35 Priority (PRI8), offset 0x420
Register 23: Interrupt 36-39 Priority (PRI9), offset 0x424
Register 24: Interrupt 40-43 Priority (PRI10), offset 0x428
Register 25: Interrupt 44-47 Priority (PRI11), offset 0x42C
Note:
This register can only be accessed from privileged mode.
The PRIn registers provide 3-bit priority fields for each interrupt. These registers are byte accessible.
Each register holds four priority fields that are assigned to interrupts as follows:
PRIn Register Bit Field
Interrupt
Bits 31:29
Interrupt [4n+3]
Bits 23:21
Interrupt [4n+2]
Bits 15:13
Interrupt [4n+1]
Bits 7:5
Interrupt [4n]
See Table 2-9 on page 81 for interrupt assignments.
Each priority level can be split into separate group priority and subpriority fields. The PRIGROUP
field in the Application Interrupt and Reset Control (APINT) register (see page 126) indicates the
position of the binary point that splits the priority and subpriority fields.
These registers can only be accessed from privileged mode.
Interrupt 0-3 Priority (PRI0)
Base 0xE000.E000
Offset 0x400
Type R/W, reset 0x0000.0000
31
30
29
28
27
INTD
Type
Reset
R/W
0
15
R/W
0
R/W
0
RO
0
RO
0
14
13
12
11
INTB
Type
Reset
R/W
0
R/W
0
26
25
24
23
reserved
RO
0
RO
0
RO
0
R/W
0
10
9
8
7
reserved
R/W
0
RO
0
RO
0
RO
0
22
21
20
19
INTC
R/W
0
R/W
0
RO
0
RO
0
6
5
4
3
INTA
RO
0
RO
0
R/W
0
R/W
0
18
17
16
RO
0
RO
0
RO
0
2
1
0
RO
0
RO
0
reserved
reserved
R/W
0
118
RO
0
RO
0
RO
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Bit/Field
Name
Type
Reset
31:29
INTD
R/W
0x0
Description
Interrupt Priority for Interrupt [4n+3]
This field holds a priority value, 0-7, for the interrupt with the number
[4n+3], where n is the number of the Interrupt Priority register (n=0 for
PRI0, and so on). The lower the value, the greater the priority of the
corresponding interrupt.
28:24
reserved
RO
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.
23:21
INTC
R/W
0x0
Interrupt Priority for Interrupt [4n+2]
This field holds a priority value, 0-7, for the interrupt with the number
[4n+2], where n is the number of the Interrupt Priority register (n=0 for
PRI0, and so on). The lower the value, the greater the priority of the
corresponding interrupt.
20:16
reserved
RO
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.
15:13
INTB
R/W
0x0
Interrupt Priority for Interrupt [4n+1]
This field holds a priority value, 0-7, for the interrupt with the number
[4n+1], where n is the number of the Interrupt Priority register (n=0 for
PRI0, and so on). The lower the value, the greater the priority of the
corresponding interrupt.
12:8
reserved
RO
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.
7:5
INTA
R/W
0x0
Interrupt Priority for Interrupt [4n]
This field holds a priority value, 0-7, for the interrupt with the number
[4n], where n is the number of the Interrupt Priority register (n=0 for
PRI0, and so on). The lower the value, the greater the priority of the
corresponding interrupt.
4:0
reserved
RO
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.
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Register 26: Software Trigger Interrupt (SWTRIG), offset 0xF00
Note:
Only privileged software can enable unprivileged access to the SWTRIG register.
Writing an interrupt number to the SWTRIG register generates a Software Generated Interrupt (SGI).
See Table 2-9 on page 81 for interrupt assignments.
When the MAINPEND bit in the Configuration and Control (CFGCTRL) register (see page 130) is
set, unprivileged software can access the SWTRIG register.
Software Trigger Interrupt (SWTRIG)
Base 0xE000.E000
Offset 0xF00
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
INTID
Bit/Field
Name
Type
Reset
31:6
reserved
RO
0x0000.00
5:0
INTID
WO
0x00
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.
Interrupt ID
This field holds the interrupt ID of the required SGI. For example, a value
of 0x3 generates an interrupt on IRQ3.
3.5
System Control Block (SCB) Register Descriptions
This section lists and describes the System Control Block (SCB) registers, in numerical order by
address offset. The SCB registers can only be accessed from privileged mode.
All registers must be accessed with aligned word accesses except for the FAULTSTAT and
SYSPRI1-SYSPRI3 registers, which can be accessed with byte or aligned halfword or word accesses.
The processor does not support unaligned accesses to system control block registers.
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Register 27: CPU ID Base (CPUID), offset 0xD00
Note:
This register can only be accessed from privileged mode.
The CPUID register contains the ARM® Cortex™-M3 processor part number, version, and
implementation information.
CPU ID Base (CPUID)
Base 0xE000.E000
Offset 0xD00
Type RO, reset 0x411F.C231
31
30
29
28
27
26
25
24
23
22
IMP
Type
Reset
21
20
19
18
VAR
R0
0
R0
1
R0
0
R0
0
R0
0
R0
0
R0
0
R0
1
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
PARTNO
Type
Reset
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
RO
1
17
16
RO
1
RO
1
1
0
RO
0
RO
1
CON
REV
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:24
IMP
R0
0x41
Implementer Code
RO
1
RO
1
RO
0
RO
0
Value Description
0x41 ARM
23:20
VAR
RO
0x1
Variant Number
Value Description
0x1
19:16
CON
RO
0xF
The rn value in the rnpn product revision identifier, for example,
the 1 in r1p1.
Constant
Value Description
0xF
15:4
PARTNO
RO
0xC23
Always reads as 0xF.
Part Number
Value Description
0xC23 Cortex-M3 processor.
3:0
REV
RO
0x1
Revision Number
Value Description
0x1
The pn value in the rnpn product revision identifier, for example,
the 1 in r1p1.
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Register 28: Interrupt Control and State (INTCTRL), offset 0xD04
Note:
This register can only be accessed from privileged mode.
The INCTRL register provides a set-pending bit for the NMI exception, and set-pending and
clear-pending bits for the PendSV and SysTick exceptions. In addition, bits in this register indicate
the exception number of the exception being processed, whether there are preempted active
exceptions, the exception number of the highest priority pending exception, and whether any interrupts
are pending.
When writing to INCTRL, the effect is unpredictable when writing a 1 to both the PENDSV and
UNPENDSV bits, or writing a 1 to both the PENDSTSET and PENDSTCLR bits.
Interrupt Control and State (INTCTRL)
Base 0xE000.E000
Offset 0xD04
Type R/W, reset 0x0000.0000
31
NMISET
Type
Reset
30
29
reserved
28
26
25
24
PENDSV UNPENDSV PENDSTSET PENDSTCLR reserved
23
22
21
ISRPRE ISRPEND
20
19
18
reserved
17
16
VECPEND
R/W
0
RO
0
RO
0
R/W
0
WO
0
R/W
0
WO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
VECPEND
Type
Reset
27
RO
0
RETBASE
RO
0
reserved
RO
0
Bit/Field
Name
Type
Reset
31
NMISET
R/W
0
VECACT
RO
0
Description
NMI Set Pending
Value Description
0
On a read, indicates an NMI exception is not pending.
On a write, no effect.
1
On a read, indicates an NMI exception is pending.
On a write, changes the NMI exception state to pending.
Because NMI is the highest-priority exception, normally the processor
enters the NMI exception handler as soon as it registers the setting of
this bit, and clears this bit on entering the interrupt handler. A read of
this bit by the NMI exception handler returns 1 only if the NMI signal is
reasserted while the processor is executing that handler.
30:29
reserved
RO
0x0
28
PENDSV
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.
PendSV Set Pending
Value Description
0
On a read, indicates a PendSV exception is not pending.
On a write, no effect.
1
On a read, indicates a PendSV exception is pending.
On a write, changes the PendSV exception state to pending.
Setting this bit is the only way to set the PendSV exception state to
pending. This bit is cleared by writing a 1 to the UNPENDSV bit.
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Bit/Field
Name
Type
Reset
27
UNPENDSV
WO
0
Description
PendSV Clear Pending
Value Description
0
On a write, no effect.
1
On a write, removes the pending state from the PendSV
exception.
This bit is write only; on a register read, its value is unknown.
26
PENDSTSET
R/W
0
SysTick Set Pending
Value Description
0
On a read, indicates a SysTick exception is not pending.
On a write, no effect.
1
On a read, indicates a SysTick exception is pending.
On a write, changes the SysTick exception state to pending.
This bit is cleared by writing a 1 to the PENDSTCLR bit.
25
PENDSTCLR
WO
0
SysTick Clear Pending
Value Description
0
On a write, no effect.
1
On a write, removes the pending state from the SysTick
exception.
This bit is write only; on a register read, its value is unknown.
24
reserved
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.
23
ISRPRE
RO
0
Debug Interrupt Handling
Value Description
0
The release from halt does not take an interrupt.
1
The release from halt takes an interrupt.
This bit is only meaningful in Debug mode and reads as zero when the
processor is not in Debug mode.
22
ISRPEND
RO
0
Interrupt Pending
Value Description
0
No interrupt is pending.
1
An interrupt is pending.
This bit provides status for all interrupts excluding NMI and Faults.
21:19
reserved
RO
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.
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Bit/Field
Name
Type
Reset
Description
18:12
VECPEND
RO
0x00
Interrupt Pending Vector Number
This field contains the exception number of the highest priority pending
enabled exception. The value indicated by this field includes the effect
of the BASEPRI and FAULTMASK registers, but not any effect of the
PRIMASK register.
Value
Description
0x00
No exceptions are pending
0x01
Reserved
0x02
NMI
0x03
Hard fault
0x04
Memory management fault
0x05
Bus fault
0x06
Usage fault
0x07-0x0A Reserved
0x0B
SVCall
0x0C
Reserved for Debug
0x0D
Reserved
0x0E
PendSV
0x0F
SysTick
0x10
Interrupt Vector 0
0x11
Interrupt Vector 1
...
...
0x3F
Interrupt Vector 47
0x40-0x7F Reserved
11
RETBASE
RO
0
Return to Base
Value Description
0
There are preempted active exceptions to execute.
1
There are no active exceptions, or the currently executing
exception is the only active exception.
This bit provides status for all interrupts excluding NMI and Faults. This
bit only has meaning if the processor is currently executing an ISR (the
Interrupt Program Status (IPSR) register is non-zero).
10:7
reserved
RO
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.
6:0
VECACT
RO
0x00
Interrupt Pending Vector Number
This field contains the active exception number. The exception numbers
can be found in the description for the VECPEND field. If this field is clear,
the processor is in Thread mode. This field contains the same value as
the ISRNUM field in the IPSR register.
Subtract 16 from this value to obtain the IRQ number required to index
into the Interrupt Set Enable (ENn), Interrupt Clear Enable (DISn),
Interrupt Set Pending (PENDn), Interrupt Clear Pending (UNPENDn),
and Interrupt Priority (PRIn) registers (see page 62).
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Register 29: Vector Table Offset (VTABLE), offset 0xD08
Note:
This register can only be accessed from privileged mode.
The VTABLE register indicates the offset of the vector table base address from memory address
0x0000.0000.
Vector Table Offset (VTABLE)
Base 0xE000.E000
Offset 0xD08
Type R/W, reset 0x0000.0000
31
30
reserved
Type
Reset
29
28
27
26
25
24
23
BASE
22
21
20
19
18
17
16
OFFSET
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
OFFSET
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
reserved
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
31:30
reserved
RO
0x0
29
BASE
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
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.
Vector Table Base
Value Description
28:8
OFFSET
R/W
0x000.00
0
The vector table is in the code memory region.
1
The vector table is in the SRAM memory region.
Vector Table Offset
When configuring the OFFSET field, the offset must be aligned to the
number of exception entries in the vector table. Because there are 47
interrupts, the offset must be aligned on a 256-byte boundary.
7:0
reserved
RO
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.
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Register 30: Application Interrupt and Reset Control (APINT), offset 0xD0C
Note:
This register can only be accessed from privileged mode.
The APINT register provides priority grouping control for the exception model, endian status for
data accesses, and reset control of the system. To write to this register, 0x05FA must be written to
the VECTKEY field, otherwise the write is ignored.
The PRIGROUP field indicates the position of the binary point that splits the INTx fields in the
Interrupt Priority (PRIx) registers into separate group priority and subpriority fields. Table
3-8 on page 126 shows how the PRIGROUP value controls this split. The bit numbers in the Group
Priority Field and Subpriority Field columns in the table refer to the bits in the INTA field. For the
INTB field, the corresponding bits are 15:13; for INTC, 23:21; and for INTD, 31:29.
Note:
Determining preemption of an exception uses only the group priority field.
Table 3-8. Interrupt Priority Levels
a
PRIGROUP Bit Field
Binary Point
Group Priority Field Subpriority Field
Group
Priorities
Subpriorities
0x0 - 0x4
bxxx.
[7:5]
None
8
1
0x5
bxx.y
[7:6]
[5]
4
2
0x6
bx.yy
[7]
[6:5]
2
4
0x7
b.yyy
None
[7:5]
1
8
a. INTx field showing the binary point. An x denotes a group priority field bit, and a y denotes a subpriority field bit.
Application Interrupt and Reset Control (APINT)
Base 0xE000.E000
Offset 0xD0C
Type R/W, reset 0xFA05.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
1
R/W
0
R/W
1
5
4
3
2
1
0
VECTKEY
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
15
14
13
12
11
10
reserved
ENDIANESS
Type
Reset
RO
0
RO
0
RO
0
RO
0
R/W
1
R/W
0
R/W
0
R/W
0
9
8
7
6
PRIGROUP
RO
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
31:16
VECTKEY
R/W
0xFA05
reserved
R/W
0
RO
0
RO
0
RO
0
SYSRESREQ VECTCLRACT VECTRESET
RO
0
RO
0
WO
0
WO
0
WO
0
Description
Register Key
This field is used to guard against accidental writes to this register.
0x05FA must be written to this field in order to change the bits in this
register. On a read, 0xFA05 is returned.
15
ENDIANESS
RO
0
Data Endianess
The Stellaris implementation uses only little-endian mode so this is
cleared to 0.
14:11
reserved
RO
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.
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Bit/Field
Name
Type
Reset
10:8
PRIGROUP
R/W
0x0
Description
Interrupt Priority Grouping
This field determines the split of group priority from subpriority (see
Table 3-8 on page 126 for more information).
7:3
reserved
RO
0x0
2
SYSRESREQ
WO
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.
System Reset Request
Value Description
0
No effect.
1
Resets the core and all on-chip peripherals except the Debug
interface.
This bit is automatically cleared during the reset of the core and reads
as 0.
1
VECTCLRACT
WO
0
Clear Active NMI / Fault
This bit is reserved for Debug use and reads as 0. This bit must be
written as a 0, otherwise behavior is unpredictable.
0
VECTRESET
WO
0
System Reset
This bit is reserved for Debug use and reads as 0. This bit must be
written as a 0, otherwise behavior is unpredictable.
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Register 31: System Control (SYSCTRL), offset 0xD10
Note:
This register can only be accessed from privileged mode.
The SYSCTRL register controls features of entry to and exit from low-power state.
System Control (SYSCTRL)
Base 0xE000.E000
Offset 0xD10
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
2
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
10
9
8
7
6
5
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:5
reserved
RO
0x0000.00
4
SEVONPEND
R/W
0
RO
0
RO
0
RO
0
RO
0
4
3
SEVONPEND
reserved
R/W
0
RO
0
SLEEPDEEP SLEEPEXIT
R/W
0
R/W
0
0
reserved
RO
0
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.
Wake Up on Pending
Value Description
0
Only enabled interrupts or events can wake up the processor;
disabled interrupts are excluded.
1
Enabled events and all interrupts, including disabled interrupts,
can wake up the processor.
When an event or interrupt enters the pending state, the event signal
wakes up the processor from WFE. If the processor is not waiting for an
event, the event is registered and affects the next WFE.
The processor also wakes up on execution of a SEV instruction or an
external event.
3
reserved
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
SLEEPDEEP
R/W
0
Deep Sleep Enable
Value Description
0
Use Sleep mode as the low power mode.
1
Use Deep-sleep mode as the low power mode.
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Bit/Field
Name
Type
Reset
1
SLEEPEXIT
R/W
0
Description
Sleep on ISR Exit
Value Description
0
When returning from Handler mode to Thread mode, do not
sleep when returning to Thread mode.
1
When returning from Handler mode to Thread mode, enter sleep
or deep sleep on return from an ISR.
Setting this bit enables an interrupt-driven application to avoid returning
to an empty main application.
0
reserved
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.
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Register 32: Configuration and Control (CFGCTRL), offset 0xD14
Note:
This register can only be accessed from privileged mode.
The CFGCTRL register controls entry to Thread mode and enables: the handlers for NMI, hard fault
and faults escalated by the FAULTMASK register to ignore bus faults; trapping of divide by zero
and unaligned accesses; and access to the SWTRIG register by unprivileged software (see page 120).
Configuration and Control (CFGCTRL)
Base 0xE000.E000
Offset 0xD14
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
6
5
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
9
8
7
reserved
STKALIGN BFHFNMIGN
RO
0
RO
0
R/W
0
Bit/Field
Name
Type
Reset
31:10
reserved
RO
0x0000.00
9
STKALIGN
R/W
0
R/W
0
RO
0
RO
0
RO
0
4
3
2
1
0
DIV0
UNALIGNED
reserved
MAINPEND
BASETHR
R/W
0
R/W
0
RO
0
R/W
0
R/W
0
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.
Stack Alignment on Exception Entry
Value Description
0
The stack is 4-byte aligned.
1
The stack is 8-byte aligned.
On exception entry, the processor uses bit 9 of the stacked PSR to
indicate the stack alignment. On return from the exception, it uses this
stacked bit to restore the correct stack alignment.
8
BFHFNMIGN
R/W
0
Ignore Bus Fault in NMI and Fault
This bit enables handlers with priority -1 or -2 to ignore data bus faults
caused by load and store instructions. The setting of this bit applies to
the hard fault, NMI, and FAULTMASK escalated handlers.
Value Description
0
Data bus faults caused by load and store instructions cause a
lock-up.
1
Handlers running at priority -1 and -2 ignore data bus faults
caused by load and store instructions.
Set this bit only when the handler and its data are in absolutely safe
memory. The normal use of this bit is to probe system devices and
bridges to detect control path problems and fix them.
7:5
reserved
RO
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.
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Bit/Field
Name
Type
Reset
4
DIV0
R/W
0
Description
Trap on Divide by 0
This bit enables faulting or halting when the processor executes an
SDIV or UDIV instruction with a divisor of 0.
Value Description
3
UNALIGNED
R/W
0
0
Do not trap on divide by 0. A divide by zero returns a quotient
of 0.
1
Trap on divide by 0.
Trap on Unaligned Access
Value Description
0
Do not trap on unaligned halfword and word accesses.
1
Trap on unaligned halfword and word accesses. An unaligned
access generates a usage fault.
Unaligned LDM, STM, LDRD, and STRD instructions always fault
regardless of whether UNALIGNED is set.
2
reserved
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.
1
MAINPEND
R/W
0
Allow Main Interrupt Trigger
Value Description
0
BASETHR
R/W
0
0
Disables unprivileged software access to the SWTRIG register.
1
Enables unprivileged software access to the SWTRIG register
(see page 120).
Thread State Control
Value Description
0
The processor can enter Thread mode only when no exception
is active.
1
The processor can enter Thread mode from any level under the
control of an EXC_RETURN value (see “Exception
Return” on page 86 for more information).
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Register 33: System Handler Priority 1 (SYSPRI1), offset 0xD18
Note:
This register can only be accessed from privileged mode.
The SYSPRI1 register configures the priority level, 0 to 7 of the usage fault, bus fault, and memory
management fault exception handlers. This register is byte-accessible.
System Handler Priority 1 (SYSPRI1)
Base 0xE000.E000
Offset 0xD18
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
reserved
Type
Reset
RO
0
15
RO
0
RO
0
RO
0
RO
0
14
13
12
11
BUS
Type
Reset
R/W
0
R/W
0
RO
0
RO
0
RO
0
R/W
0
10
9
8
7
reserved
R/W
0
RO
0
22
21
20
19
USAGE
RO
0
RO
0
R/W
0
R/W
0
RO
0
RO
0
6
5
4
3
MEM
RO
0
RO
0
R/W
0
R/W
0
18
17
16
RO
0
RO
0
RO
0
2
1
0
RO
0
RO
0
reserved
reserved
R/W
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:24
reserved
RO
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.
23:21
USAGE
R/W
0x0
Usage Fault Priority
This field configures the priority level of the usage fault. Configurable
priority values are in the range 0-7, with lower values having higher
priority.
20:16
reserved
RO
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.
15:13
BUS
R/W
0x0
Bus Fault Priority
This field configures the priority level of the bus fault. Configurable priority
values are in the range 0-7, with lower values having higher priority.
12:8
reserved
RO
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.
7:5
MEM
R/W
0x0
Memory Management Fault Priority
This field configures the priority level of the memory management fault.
Configurable priority values are in the range 0-7, with lower values
having higher priority.
4:0
reserved
RO
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.
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 34: System Handler Priority 2 (SYSPRI2), offset 0xD1C
Note:
This register can only be accessed from privileged mode.
The SYSPRI2 register configures the priority level, 0 to 7 of the SVCall handler. This register is
byte-accessible.
System Handler Priority 2 (SYSPRI2)
Base 0xE000.E000
Offset 0xD1C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
SVC
Type
Reset
22
21
20
19
18
17
16
reserved
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:29
SVC
R/W
0x0
RO
0
Description
SVCall Priority
This field configures the priority level of SVCall. Configurable priority
values are in the range 0-7, with lower values having higher priority.
28:0
reserved
RO
0x000.0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Register 35: System Handler Priority 3 (SYSPRI3), offset 0xD20
Note:
This register can only be accessed from privileged mode.
The SYSPRI3 register configures the priority level, 0 to 7 of the SysTick exception and PendSV
handlers. This register is byte-accessible.
System Handler Priority 3 (SYSPRI3)
Base 0xE000.E000
Offset 0xD20
Type R/W, reset 0x0000.0000
31
30
29
28
27
TICK
Type
Reset
26
25
24
23
reserved
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
15
14
13
12
11
10
9
8
7
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
22
21
20
19
PENDSV
R/W
0
R/W
0
RO
0
RO
0
6
5
4
3
DEBUG
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:29
TICK
R/W
0x0
RO
0
R/W
0
R/W
0
18
17
16
RO
0
RO
0
RO
0
2
1
0
RO
0
RO
0
reserved
reserved
R/W
0
RO
0
RO
0
RO
0
Description
SysTick Exception Priority
This field configures the priority level of the SysTick exception.
Configurable priority values are in the range 0-7, with lower values
having higher priority.
28:24
reserved
RO
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.
23:21
PENDSV
R/W
0x0
PendSV Priority
This field configures the priority level of PendSV. Configurable priority
values are in the range 0-7, with lower values having higher priority.
20:8
reserved
RO
0x000
7:5
DEBUG
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.
Debug Priority
This field configures the priority level of Debug. Configurable priority
values are in the range 0-7, with lower values having higher priority.
4:0
reserved
RO
0x0.0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Register 36: System Handler Control and State (SYSHNDCTRL), offset 0xD24
Note:
This register can only be accessed from privileged mode.
The SYSHNDCTRL register enables the system handlers, and indicates the pending status of the
usage fault, bus fault, memory management fault, and SVC exceptions as well as the active status
of the system handlers.
If a system handler is disabled and the corresponding fault occurs, the processor treats the fault as
a hard fault.
This register can be modified to change the pending or active status of system exceptions. An OS
kernel can write to the active bits to perform a context switch that changes the current exception
type.
Caution – Software that changes the value of an active bit in this register without correct adjustment
to the stacked content can cause the processor to generate a fault exception. Ensure software that writes
to this register retains and subsequently restores the current active status.
If the value of a bit in this register must be modified after enabling the system handlers, a
read-modify-write procedure must be used to ensure that only the required bit is modified.
System Handler Control and State (SYSHNDCTRL)
Base 0xE000.E000
Offset 0xD24
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
SVC
BUSP
MEMP
USAGEP
R/W
0
R/W
0
R/W
0
R/W
0
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
USAGE
BUS
MEM
R/W
0
R/W
0
R/W
0
10
9
8
7
6
5
4
3
2
1
0
TICK
PNDSV
reserved
MON
SVCA
R/W
0
R/W
0
RO
0
R/W
0
R/W
0
USGA
reserved
BUSA
MEMA
R/W
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
Type
Reset
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:19
reserved
RO
0x000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
18
USAGE
R/W
0
Usage Fault Enable
Value Description
17
BUS
R/W
0
0
Disables the usage fault exception.
1
Enables the usage fault exception.
Bus Fault Enable
Value Description
0
Disables the bus fault exception.
1
Enables the bus fault exception.
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Bit/Field
Name
Type
Reset
16
MEM
R/W
0
Description
Memory Management Fault Enable
Value Description
15
SVC
R/W
0
0
Disables the memory management fault exception.
1
Enables the memory management fault exception.
SVC Call Pending
Value Description
0
An SVC call exception is not pending.
1
An SVC call exception is pending.
This bit can be modified to change the pending status of the SVC call
exception.
14
BUSP
R/W
0
Bus Fault Pending
Value Description
0
A bus fault exception is not pending.
1
A bus fault exception is pending.
This bit can be modified to change the pending status of the bus fault
exception.
13
MEMP
R/W
0
Memory Management Fault Pending
Value Description
0
A memory management fault exception is not pending.
1
A memory management fault exception is pending.
This bit can be modified to change the pending status of the memory
management fault exception.
12
USAGEP
R/W
0
Usage Fault Pending
Value Description
0
A usage fault exception is not pending.
1
A usage fault exception is pending.
This bit can be modified to change the pending status of the usage fault
exception.
11
TICK
R/W
0
SysTick Exception Active
Value Description
0
A SysTick exception is not active.
1
A SysTick exception is active.
This bit can be modified to change the active status of the SysTick
exception, however, see the Caution above before setting this bit.
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Bit/Field
Name
Type
Reset
10
PNDSV
R/W
0
Description
PendSV Exception Active
Value Description
0
A PendSV exception is not active.
1
A PendSV exception is active.
This bit can be modified to change the active status of the PendSV
exception, however, see the Caution above before setting this bit.
9
reserved
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.
8
MON
R/W
0
Debug Monitor Active
Value Description
7
SVCA
R/W
0
0
The Debug monitor is not active.
1
The Debug monitor is active.
SVC Call Active
Value Description
0
SVC call is not active.
1
SVC call is active.
This bit can be modified to change the active status of the SVC call
exception, however, see the Caution above before setting this bit.
6:4
reserved
RO
0x0
3
USGA
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.
Usage Fault Active
Value Description
0
Usage fault is not active.
1
Usage fault is active.
This bit can be modified to change the active status of the usage fault
exception, however, see the Caution above before setting this bit.
2
reserved
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.
1
BUSA
R/W
0
Bus Fault Active
Value Description
0
Bus fault is not active.
1
Bus fault is active.
This bit can be modified to change the active status of the bus fault
exception, however, see the Caution above before setting this bit.
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Bit/Field
Name
Type
Reset
0
MEMA
R/W
0
Description
Memory Management Fault Active
Value Description
0
Memory management fault is not active.
1
Memory management fault is active.
This bit can be modified to change the active status of the memory
management fault exception, however, see the Caution above before
setting this bit.
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Register 37: Configurable Fault Status (FAULTSTAT), offset 0xD28
Note:
This register can only be accessed from privileged mode.
The FAULTSTAT register indicates the cause of a memory management fault, bus fault, or usage
fault. Each of these functions is assigned to a subregister as follows:
■ Usage Fault Status (UFAULTSTAT), bits 31:16
■ Bus Fault Status (BFAULTSTAT), bits 15:8
■ Memory Management Fault Status (MFAULTSTAT), bits 7:0
FAULTSTAT is byte accessible. FAULTSTAT or its subregisters can be accessed as follows:
■
■
■
■
■
The complete FAULTSTAT register, with a word access to offset 0xD28
The MFAULTSTAT, with a byte access to offset 0xD28
The MFAULTSTAT and BFAULTSTAT, with a halfword access to offset 0xD28
The BFAULTSTAT, with a byte access to offset 0xD29
The UFAULTSTAT, with a halfword access to offset 0xD2A
Bits are cleared by writing a 1 to them.
In a fault handler, the true faulting address can be determined by:
1. Read and save the Memory Management Fault Address (MMADDR) or Bus Fault Address
(FAULTADDR) value.
2. Read the MMARV bit in MFAULTSTAT, or the BFARV bit in BFAULTSTAT to determine if the
MMADDR or FAULTADDR contents are valid.
Software must follow this sequence because another higher priority exception might change the
MMADDR or FAULTADDR value. For example, if a higher priority handler preempts the current
fault handler, the other fault might change the MMADDR or FAULTADDR value.
Configurable Fault Status (FAULTSTAT)
Base 0xE000.E000
Offset 0xD28
Type R/W1C, reset 0x0000.0000
31
30
29
28
27
26
reserved
Type
Reset
RO
0
RO
0
RO
0
15
14
13
BFARV
Type
Reset
R/W1C
0
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
25
24
DIV0
UNALIGN
R/W1C
0
R/W1C
0
23
22
21
20
reserved
RO
0
RO
0
RO
0
6
5
12
11
10
9
8
7
BSTKE
BUSTKE
IMPRE
PRECISE
IBUS
MMARV
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
reserved
RO
0
RO
0
RO
0
19
18
17
16
NOCP
INVPC
INVSTAT
UNDEF
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
4
3
2
1
0
MSTKE
MUSTKE
reserved
DERR
IERR
R/W1C
0
R/W1C
0
RO
0
R/W1C
0
R/W1C
0
Bit/Field
Name
Type
Reset
Description
31:26
reserved
RO
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.
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Bit/Field
Name
Type
Reset
25
DIV0
R/W1C
0
Description
Divide-by-Zero Usage Fault
Value Description
0
No divide-by-zero fault has occurred, or divide-by-zero trapping
is not enabled.
1
The processor has executed an SDIV or UDIV instruction with
a divisor of 0.
When this bit is set, the PC value stacked for the exception return points
to the instruction that performed the divide by zero.
Trapping on divide-by-zero is enabled by setting the DIV0 bit in the
Configuration and Control (CFGCTRL) register (see page 130).
This bit is cleared by writing a 1 to it.
24
UNALIGN
R/W1C
0
Unaligned Access Usage Fault
Value Description
0
No unaligned access fault has occurred, or unaligned access
trapping is not enabled.
1
The processor has made an unaligned memory access.
Unaligned LDM, STM, LDRD, and STRD instructions always fault
regardless of the configuration of this bit.
Trapping on unaligned access is enabled by setting the UNALIGNED bit
in the CFGCTRL register (see page 130).
This bit is cleared by writing a 1 to it.
23:20
reserved
RO
0x00
19
NOCP
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.
No Coprocessor Usage Fault
Value Description
0
A usage fault has not been caused by attempting to access a
coprocessor.
1
The processor has attempted to access a coprocessor.
This bit is cleared by writing a 1 to it.
18
INVPC
R/W1C
0
Invalid PC Load Usage Fault
Value Description
0
A usage fault has not been caused by attempting to load an
invalid PC value.
1
The processor has attempted an illegal load of EXC_RETURN
to the PC as a result of an invalid context or an invalid
EXC_RETURN value.
When this bit is set, the PC value stacked for the exception return points
to the instruction that tried to perform the illegal load of the PC.
This bit is cleared by writing a 1 to it.
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Bit/Field
Name
Type
Reset
17
INVSTAT
R/W1C
0
Description
Invalid State Usage Fault
Value Description
0
A usage fault has not been caused by an invalid state.
1
The processor has attempted to execute an instruction that
makes illegal use of the EPSR register.
When this bit is set, the PC value stacked for the exception return points
to the instruction that attempted the illegal use of the Execution
Program Status Register (EPSR) register.
This bit is not set if an undefined instruction uses the EPSR register.
This bit is cleared by writing a 1 to it.
16
UNDEF
R/W1C
0
Undefined Instruction Usage Fault
Value Description
0
A usage fault has not been caused by an undefined instruction.
1
The processor has attempted to execute an undefined
instruction.
When this bit is set, the PC value stacked for the exception return points
to the undefined instruction.
An undefined instruction is an instruction that the processor cannot
decode.
This bit is cleared by writing a 1 to it.
15
BFARV
R/W1C
0
Bus Fault Address Register Valid
Value Description
0
The value in the Bus Fault Address (FAULTADDR) register
is not a valid fault address.
1
The FAULTADDR register is holding a valid fault address.
This bit is set after a bus fault, where the address is known. Other faults
can clear this bit, such as a memory management fault occurring later.
If a bus fault occurs and is escalated to a hard fault because of priority,
the hard fault handler must clear this bit. This action prevents problems
if returning to a stacked active bus fault handler whose FAULTADDR
register value has been overwritten.
This bit is cleared by writing a 1 to it.
14:13
reserved
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.
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Bit/Field
Name
Type
Reset
12
BSTKE
R/W1C
0
Description
Stack Bus Fault
Value Description
0
No bus fault has occurred on stacking for exception entry.
1
Stacking for an exception entry has caused one or more bus
faults.
When this bit is set, the SP is still adjusted but the values in the context
area on the stack might be incorrect. A fault address is not written to
the FAULTADDR register.
This bit is cleared by writing a 1 to it.
11
BUSTKE
R/W1C
0
Unstack Bus Fault
Value Description
0
No bus fault has occurred on unstacking for a return from
exception.
1
Unstacking for a return from exception has caused one or more
bus faults.
This fault is chained to the handler. Thus, when this bit is set, the original
return stack is still present. The SP is not adjusted from the failing return,
a new save is not performed, and a fault address is not written to the
FAULTADDR register.
This bit is cleared by writing a 1 to it.
10
IMPRE
R/W1C
0
Imprecise Data Bus Error
Value Description
0
An imprecise data bus error has not occurred.
1
A data bus error has occurred, but the return address in the
stack frame is not related to the instruction that caused the error.
When this bit is set, a fault address is not written to the FAULTADDR
register.
This fault is asynchronous. Therefore, if the fault is detected when the
priority of the current process is higher than the bus fault priority, the
bus fault becomes pending and becomes active only when the processor
returns from all higher-priority processes. If a precise fault occurs before
the processor enters the handler for the imprecise bus fault, the handler
detects that both the IMPRE bit is set and one of the precise fault status
bits is set.
This bit is cleared by writing a 1 to it.
9
PRECISE
R/W1C
0
Precise Data Bus Error
Value Description
0
A precise data bus error has not occurred.
1
A data bus error has occurred, and the PC value stacked for
the exception return points to the instruction that caused the
fault.
When this bit is set, the fault address is written to the FAULTADDR
register.
This bit is cleared by writing a 1 to it.
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Bit/Field
Name
Type
Reset
8
IBUS
R/W1C
0
Description
Instruction Bus Error
Value Description
0
An instruction bus error has not occurred.
1
An instruction bus error has occurred.
The processor detects the instruction bus error on prefetching an
instruction, but sets this bit only if it attempts to issue the faulting
instruction.
When this bit is set, a fault address is not written to the FAULTADDR
register.
This bit is cleared by writing a 1 to it.
7
MMARV
R/W1C
0
Memory Management Fault Address Register Valid
Value Description
0
The value in the Memory Management Fault Address
(MMADDR) register is not a valid fault address.
1
The MMADDR register is holding a valid fault address.
If a memory management fault occurs and is escalated to a hard fault
because of priority, the hard fault handler must clear this bit. This action
prevents problems if returning to a stacked active memory management
fault handler whose MMADDR register value has been overwritten.
This bit is cleared by writing a 1 to it.
6:5
reserved
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.
4
MSTKE
R/W1C
0
Stack Access Violation
Value Description
0
No memory management fault has occurred on stacking for
exception entry.
1
Stacking for an exception entry has caused one or more access
violations.
When this bit is set, the SP is still adjusted but the values in the context
area on the stack might be incorrect. A fault address is not written to
the MMADDR register.
This bit is cleared by writing a 1 to it.
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Bit/Field
Name
Type
Reset
3
MUSTKE
R/W1C
0
Description
Unstack Access Violation
Value Description
0
No memory management fault has occurred on unstacking for
a return from exception.
1
Unstacking for a return from exception has caused one or more
access violations.
This fault is chained to the handler. Thus, when this bit is set, the original
return stack is still present. The SP is not adjusted from the failing return,
a new save is not performed, and a fault address is not written to the
MMADDR register.
This bit is cleared by writing a 1 to it.
2
reserved
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.
1
DERR
R/W1C
0
Data Access Violation
Value Description
0
A data access violation has not occurred.
1
The processor attempted a load or store at a location that does
not permit the operation.
When this bit is set, the PC value stacked for the exception return points
to the faulting instruction and the address of the attempted access is
written to the MMADDR register.
This bit is cleared by writing a 1 to it.
0
IERR
R/W1C
0
Instruction Access Violation
Value Description
0
An instruction access violation has not occurred.
1
The processor attempted an instruction fetch from a location
that does not permit execution.
This fault occurs on any access to an XN region, even when the MPU
is disabled or not present.
When this bit is set, the PC value stacked for the exception return points
to the faulting instruction and the address of the attempted access is
not written to the MMADDR register.
This bit is cleared by writing a 1 to it.
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Register 38: Hard Fault Status (HFAULTSTAT), offset 0xD2C
Note:
This register can only be accessed from privileged mode.
The HFAULTSTAT register gives information about events that activate the hard fault handler.
Bits are cleared by writing a 1 to them.
Hard Fault Status (HFAULTSTAT)
Base 0xE000.E000
Offset 0xD2C
Type R/W1C, reset 0x0000.0000
Type
Reset
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
DBG
FORCED
R/W1C
0
R/W1C
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
VECT
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
RO
0
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31
DBG
R/W1C
0
Description
Debug Event
This bit is reserved for Debug use. This bit must be written as a 0,
otherwise behavior is unpredictable.
30
FORCED
R/W1C
0
Forced Hard Fault
Value Description
0
No forced hard fault has occurred.
1
A forced hard fault has been generated by escalation of a fault
with configurable priority that cannot be handled, either because
of priority or because it is disabled.
When this bit is set, the hard fault handler must read the other fault
status registers to find the cause of the fault.
This bit is cleared by writing a 1 to it.
29:2
reserved
RO
0x00
1
VECT
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.
Vector Table Read Fault
Value Description
0
No bus fault has occurred on a vector table read.
1
A bus fault occurred on a vector table read.
This error is always handled by the hard fault handler.
When this bit is set, the PC value stacked for the exception return points
to the instruction that was preempted by the exception.
This bit is cleared by writing a 1 to it.
0
reserved
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.
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Register 39: Memory Management Fault Address (MMADDR), offset 0xD34
Note:
This register can only be accessed from privileged mode.
The MMADDR register contains the address of the location that generated a memory management
fault. When an unaligned access faults, the address in the MMADDR register is the actual address
that faulted. Because a single read or write instruction can be split into multiple aligned accesses,
the fault address can be any address in the range of the requested access size. Bits in the Memory
Management Fault Status (MFAULTSTAT) register indicate the cause of the fault and whether
the value in the MMADDR register is valid (see page 139).
Memory Management Fault Address (MMADDR)
Base 0xE000.E000
Offset 0xD34
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
8
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
31:0
ADDR
R/W
-
R/W
-
Description
Fault Address
When the MMARV bit of MFAULTSTAT is set, this field holds the address
of the location that generated the memory management fault.
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Register 40: Bus Fault Address (FAULTADDR), offset 0xD38
Note:
This register can only be accessed from privileged mode.
The FAULTADDR register contains the address of the location that generated a bus fault. When
an unaligned access faults, the address in the FAULTADDR register is the one requested by the
instruction, even if it is not the address of the fault. Bits in the Bus Fault Status (BFAULTSTAT)
register indicate the cause of the fault and whether the value in the FAULTADDR register is valid
(see page 139).
Bus Fault Address (FAULTADDR)
Base 0xE000.E000
Offset 0xD38
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
8
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
31:0
ADDR
R/W
-
R/W
-
Description
Fault Address
When the FAULTADDRV bit of BFAULTSTAT is set, this field holds the
address of the location that generated the bus fault.
3.6
Memory Protection Unit (MPU) Register Descriptions
This section lists and describes the Memory Protection Unit (MPU) registers, in numerical order by
address offset.
The MPU registers can only be accessed from privileged mode.
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Register 41: MPU Type (MPUTYPE), offset 0xD90
Note:
This register can only be accessed from privileged mode.
The MPUTYPE register indicates whether the MPU is present, and if so, how many regions it
supports.
MPU Type (MPUTYPE)
Base 0xE000.E000
Offset 0xD90
Type RO, reset 0x0000.0800
31
30
29
28
27
26
25
24
23
22
21
20
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
DREGION
Type
Reset
RO
0
RO
0
RO
0
RO
0
19
18
17
16
RO
0
IREGION
RO
0
RO
0
RO
0
RO
0
4
3
2
1
reserved
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
0
SEPARATE
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:24
reserved
RO
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.
23:16
IREGION
RO
0x00
Number of I Regions
This field indicates the number of supported MPU instruction regions.
This field always contains 0x00. The MPU memory map is unified and
is described by the DREGION field.
15:8
DREGION
RO
0x08
Number of D Regions
Value Description
0x08 Indicates there are eight supported MPU data regions.
7:1
reserved
RO
0x00
0
SEPARATE
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.
Separate or Unified MPU
Value Description
0
Indicates the MPU is unified.
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Register 42: MPU Control (MPUCTRL), offset 0xD94
Note:
This register can only be accessed from privileged mode.
The MPUCTRL register enables the MPU, enables the default memory map background region,
and enables use of the MPU when in the hard fault, Non-maskable Interrupt (NMI), and Fault Mask
Register (FAULTMASK) escalated handlers.
When the ENABLE and PRIVDEFEN bits are both set:
■ For privileged accesses, the default memory map is as described in “Memory Model” on page 70.
Any access by privileged software that does not address an enabled memory region behaves
as defined by the default memory map.
■ Any access by unprivileged software that does not address an enabled memory region causes
a memory management fault.
Execute Never (XN) and Strongly Ordered rules always apply to the System Control Space regardless
of the value of the ENABLE bit.
When the ENABLE bit is set, at least one region of the memory map must be enabled for the system
to function unless the PRIVDEFEN bit is set. If the PRIVDEFEN bit is set and no regions are enabled,
then only privileged software can operate.
When the ENABLE bit is clear, the system uses the default memory map, which has the same
memory attributes as if the MPU is not implemented (see Table 2-5 on page 73 for more information).
The default memory map applies to accesses from both privileged and unprivileged software.
When the MPU is enabled, accesses to the System Control Space and vector table are always
permitted. Other areas are accessible based on regions and whether PRIVDEFEN is set.
Unless HFNMIENA is set, the MPU is not enabled when the processor is executing the handler for
an exception with priority –1 or –2. These priorities are only possible when handling a hard fault or
NMI exception or when FAULTMASK is enabled. Setting the HFNMIENA bit enables the MPU when
operating with these two priorities.
MPU Control (MPUCTRL)
Base 0xE000.E000
Offset 0xD94
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
Bit/Field
Name
Type
Reset
31:3
reserved
RO
0x0000.000
PRIVDEFEN HFNMIENA
R/W
0
R/W
0
ENABLE
R/W
0
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.
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Bit/Field
Name
Type
Reset
2
PRIVDEFEN
R/W
0
Description
MPU Default Region
This bit enables privileged software access to the default memory map.
Value Description
0
If the MPU is enabled, this bit disables use of the default memory
map. Any memory access to a location not covered by any
enabled region causes a fault.
1
If the MPU is enabled, this bit enables use of the default memory
map as a background region for privileged software accesses.
When this bit is set, the background region acts as if it is region number
-1. Any region that is defined and enabled has priority over this default
map.
If the MPU is disabled, the processor ignores this bit.
1
HFNMIENA
R/W
0
MPU Enabled During Faults
This bit controls the operation of the MPU during hard fault, NMI, and
FAULTMASK handlers.
Value Description
0
The MPU is disabled during hard fault, NMI, and FAULTMASK
handlers, regardless of the value of the ENABLE bit.
1
The MPU is enabled during hard fault, NMI, and FAULTMASK
handlers.
When the MPU is disabled and this bit is set, the resulting behavior is
unpredictable.
0
ENABLE
R/W
0
MPU Enable
Value Description
0
The MPU is disabled.
1
The MPU is enabled.
When the MPU is disabled and the HFNMIENA bit is set, the resulting
behavior is unpredictable.
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Register 43: MPU Region Number (MPUNUMBER), offset 0xD98
Note:
This register can only be accessed from privileged mode.
The MPUNUMBER register selects which memory region is referenced by the MPU Region Base
Address (MPUBASE) and MPU Region Attribute and Size (MPUATTR) registers. Normally, the
required region number should be written to this register before accessing the MPUBASE or the
MPUATTR register. However, the region number can be changed by writing to the MPUBASE
register with the VALID bit set (see page 152). This write updates the value of the REGION field.
MPU Region Number (MPUNUMBER)
Base 0xE000.E000
Offset 0xD98
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
1
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
9
8
7
6
5
4
3
2
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:3
reserved
RO
0x0000.000
2:0
NUMBER
R/W
0x0
NUMBER
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
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.
MPU Region to Access
This field indicates the MPU region referenced by the MPUBASE and
MPUATTR registers. The MPU supports eight memory regions.
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Register 44: MPU Region Base Address (MPUBASE), offset 0xD9C
Register 45: MPU Region Base Address Alias 1 (MPUBASE1), offset 0xDA4
Register 46: MPU Region Base Address Alias 2 (MPUBASE2), offset 0xDAC
Register 47: MPU Region Base Address Alias 3 (MPUBASE3), offset 0xDB4
Note:
This register can only be accessed from privileged mode.
The MPUBASE register defines the base address of the MPU region selected by the MPU Region
Number (MPUNUMBER) register and can update the value of the MPUNUMBER register. To
change the current region number and update the MPUNUMBER register, write the MPUBASE
register with the VALID bit set.
The ADDR field is bits 31:N of the MPUBASE register. Bits (N-1):5 are reserved. The region size,
as specified by the SIZE field in the MPU Region Attribute and Size (MPUATTR) register, defines
the value of N where:
N = Log2(Region size in bytes)
If the region size is configured to 4 GB in the MPUATTR register, there is no valid ADDR field. In
this case, the region occupies the complete memory map, and the base address is 0x0000.0000.
The base address is aligned to the size of the region. For example, a 64-KB region must be aligned
on a multiple of 64 KB, for example, at 0x0001.0000 or 0x0002.0000.
MPU Region Base Address (MPUBASE)
Base 0xE000.E000
Offset 0xD9C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
VALID
reserved
WO
0
RO
0
ADDR
Type
Reset
ADDR
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
31:5
ADDR
R/W
0x0000.000
R/W
0
R/W
0
R/W
0
R/W
0
REGION
R/W
0
R/W
0
R/W
0
Description
Base Address Mask
Bits 31:N in this field contain the region base address. The value of N
depends on the region size, as shown above. The remaining bits (N-1):5
are reserved.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Bit/Field
Name
Type
Reset
4
VALID
WO
0
Description
Region Number Valid
Value Description
0
The MPUNUMBER register is not changed and the processor
updates the base address for the region specified in the
MPUNUMBER register and ignores the value of the REGION
field.
1
The MPUNUMBER register is updated with the value of the
REGION field and the base address is updated for the region
specified in the REGION field.
This bit is always read as 0.
3
reserved
RO
0
2:0
REGION
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.
Region Number
On a write, contains the value to be written to the MPUNUMBER register.
On a read, returns the current region number in the MPUNUMBER
register.
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Register 48: MPU Region Attribute and Size (MPUATTR), offset 0xDA0
Register 49: MPU Region Attribute and Size Alias 1 (MPUATTR1), offset 0xDA8
Register 50: MPU Region Attribute and Size Alias 2 (MPUATTR2), offset 0xDB0
Register 51: MPU Region Attribute and Size Alias 3 (MPUATTR3), offset 0xDB8
Note:
This register can only be accessed from privileged mode.
The MPUATTR register defines the region size and memory attributes of the MPU region specified
by the MPU Region Number (MPUNUMBER) register and enables that region and any subregions.
The MPUATTR register is accessible using word or halfword accesses with the most-significant
halfword holding the region attributes and the least-significant halfword holds the region size and
the region and subregion enable bits.
The MPU access permission attribute bits, XN, AP, TEX, S, C, and B, control access to the
corresponding memory region. If an access is made to an area of memory without the required
permissions, then the MPU generates a permission fault.
The SIZE field defines the size of the MPU memory region specified by the MPUNUMBER register
as follows:
(Region size in bytes) = 2(SIZE+1)
The smallest permitted region size is 32 bytes, corresponding to a SIZE value of 4. Table
3-9 on page 154 gives example SIZE values with the corresponding region size and value of N in
the MPU Region Base Address (MPUBASE) register.
Table 3-9. Example SIZE Field Values
a
SIZE Encoding
Region Size
Value of N
Note
00100b (0x4)
32 B
5
Minimum permitted size
01001b (0x9)
1 KB
10
-
10011b (0x13)
1 MB
20
-
11101b (0x1D)
1 GB
30
-
11111b (0x1F)
4 GB
No valid ADDR field in MPUBASE; the Maximum possible size
region occupies the complete
memory map.
a. Refers to the N parameter in the MPUBASE register (see page 152).
MPU Region Attribute and Size (MPUATTR)
Base 0xE000.E000
Offset 0xDA0
Type R/W, reset 0x0000.0000
31
30
29
28
27
reserved
Type
Reset
26
25
24
23
AP
21
reserved
20
19
18
TEX
17
16
XN
reserved
S
C
B
RO
0
RO
0
RO
0
R/W
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
SRD
Type
Reset
22
reserved
SIZE
154
R/W
0
ENABLE
R/W
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Bit/Field
Name
Type
Reset
Description
31:29
reserved
RO
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.
28
XN
R/W
0
Instruction Access Disable
Value Description
0
Instruction fetches are enabled.
1
Instruction fetches are disabled.
27
reserved
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.
26:24
AP
R/W
0
Access Privilege
For information on using this bit field, see Table 3-5 on page 100.
23:22
reserved
RO
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.
21:19
TEX
R/W
0x0
Type Extension Mask
For information on using this bit field, see Table 3-3 on page 99.
18
S
R/W
0
Shareable
For information on using this bit, see Table 3-3 on page 99.
17
C
R/W
0
Cacheable
For information on using this bit, see Table 3-3 on page 99.
16
B
R/W
0
Bufferable
For information on using this bit, see Table 3-3 on page 99.
15:8
SRD
R/W
0x00
Subregion Disable Bits
Value Description
0
The corresponding subregion is enabled.
1
The corresponding subregion is disabled.
Region sizes of 128 bytes and less do not support subregions. When
writing the attributes for such a region, configure the SRD field as 0x00.
See the section called “Subregions” on page 98 for more information.
7:6
reserved
RO
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.
5:1
SIZE
R/W
0x0
Region Size Mask
The SIZE field defines the size of the MPU memory region specified by
the MPUNUMBER register. Refer to Table 3-9 on page 154 for more
information.
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Bit/Field
Name
Type
Reset
0
ENABLE
R/W
0
Description
Region Enable
Value Description
0
The region is disabled.
1
The region is enabled.
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4
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 four pins: 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 Stellaris 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 Stellaris JTAG instructions select the Stellaris TDO
outputs. The multiplexer is controlled by the Stellaris JTAG controller, which has comprehensive
programming for the ARM, Stellaris, and unimplemented JTAG instructions.
The Stellaris 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, IDCODE, SAMPLE/PRELOAD, EXTEST and INTEST
■ ARM additional instructions: APACC, DPACC and ABORT
■ Integrated ARM Serial Wire Debug (SWD)
See the ARM® Debug Interface V5 Architecture Specification for more information on the ARM
JTAG controller.
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4.1
Block Diagram
Figure 4-1. JTAG Module Block Diagram
TCK
TMS
TAP Controller
TDI
Instruction Register (IR)
BYPASS Data Register
TDO
Boundary Scan Data Register
IDCODE Data Register
ABORT Data Register
DPACC Data Register
APACC Data Register
Cortex-M3
Debug
Port
4.2
Signal Description
Table 4-1 on page 158 lists the external signals of the JTAG/SWD controller and describes the
function of each. The JTAG/SWD controller signals are alternate functions for some GPIO signals,
however note that the reset state of the pins is for the JTAG/SWD function. The JTAG/SWD controller
signals are under commit protection and require a special process to be configured as GPIOs, see
“Commit Control” on page 356. The column in the table below titled "Pin Assignment" lists the GPIO
pin placement for the JTAG/SWD controller signals. The AFSEL bit in the GPIO Alternate Function
Select (GPIOAFSEL) register (page 371) is set to choose the JTAG/SWD function. For more
information on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 348.
Table 4-1. JTAG_SWD_SWO Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
SWCLK
80
I
TTL
Description
JTAG/SWD CLK.
SWDIO
79
I/O
TTL
JTAG TMS and SWDIO.
SWO
77
O
TTL
JTAG TDO and SWO.
TCK
80
I
TTL
JTAG/SWD CLK.
TDI
78
I
TTL
JTAG TDI.
TDO
77
O
TTL
JTAG TDO and SWO.
TMS
79
I/O
TTL
JTAG TMS and SWDIO.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
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4.3
Functional Description
A high-level conceptual drawing of the JTAG module is shown in Figure 4-1 on page 158. 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 TCK and TMS inputs.
The current state of the TAP controller depends on 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 4-3 on page 165 for a list of implemented instructions).
See “JTAG and Boundary Scan” on page 774 for JTAG timing diagrams.
4.3.1
JTAG Interface Pins
The JTAG interface consists of four standard pins: TCK, TMS, TDI, and TDO. These pins and their
associated reset state are given in Table 4-2 on page 159. Detailed information on each pin follows.
Table 4-2. JTAG Port Pins Reset State
4.3.1.1
Pin Name
Data Direction
Internal Pull-Up
Internal Pull-Down
Drive Strength
Drive Value
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
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.
4.3.1.2
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.
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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
module and associated registers are reset to their default values. This procedure should be performed
to initialize the JTAG controller. The JTAG Test Access Port state machine can be seen in its entirety
in Figure 4-2 on page 161.
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.
4.3.1.3
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.
4.3.1.4
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.
4.3.2
JTAG TAP Controller
The JTAG TAP controller state machine is shown in Figure 4-2 on page 161. The TAP controller
state machine is reset to the Test-Logic-Reset state on the assertion of a Power-On-Reset (POR).
In order to reset the JTAG module after the device has been powered on, the TMS input must be
held HIGH for five TCK clock cycles, resetting the TAP controller and all associated JTAG chains.
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.
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Figure 4-2. Test Access Port State Machine
Test Logic Reset
1
0
Run Test Idle
0
Select DR Scan
1
Select IR Scan
1
0
1
Capture DR
1
Capture IR
0
0
Shift DR
Shift IR
0
1
Exit 1 DR
Exit 1 IR
1
Pause IR
0
1
Exit 2 DR
0
1
0
Exit 2 IR
1
1
Update DR
4.3.3
1
0
Pause DR
1
0
1
0
0
1
0
0
Update IR
1
0
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 164.
4.3.4
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.
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4.3.4.1
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 PC[3:0] JTAG/SWD pins.
It is possible for software to configure these pins as GPIOs after reset by writing 0s to 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 four more GPIOs for use in the design.
Caution – 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 GPIO commit control registers provide a layer of protection against accidental programming of
critical hardware peripherals. Protection is currently provided for the NMI pin (PB7) and the four
JTAG/SWD pins (PC[3:0]). Writes to protected bits of the GPIO Alternate Function Select
(GPIOAFSEL) register (see page 371), GPIO Pull-Up Select (GPIOPUR) register (see page 377),
and GPIO Digital Enable (GPIODEN) register (see page 381) are not committed to storage unless
the GPIO Lock (GPIOLOCK) register (see page 383) has been unlocked and the appropriate bits
of the GPIO Commit (GPIOCR) register (see page 384) have been set to 1.
Recovering a "Locked" Device
Note:
Performing the sequence below causes the nonvolatile registers discussed in “Nonvolatile
Register Programming” on page 261 to be restored to their factory default values. The mass
erase of the flash memory caused by the below sequence occurs prior to the nonvolatile
registers being restored.
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.
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10. Perform the JTAG-to-SWD switch sequence.
11. Perform the SWD-to-JTAG switch sequence.
12. Release the RST signal.
13. Wait 400 ms.
14. Power-cycle the device.
The JTAG-to-SWD and SWD-to-JTAG switch sequences are described in “ARM Serial Wire Debug
(SWD)” on page 163. When performing switch sequences for the purpose of recovering the debug
capabilities of the device, only steps 1 and 2 of the switch sequence in the section called
“JTAG-to-SWD Switching” on page 163 must be performed.
4.3.4.2
Communication with JTAG/SWD
Because the debug clock and the system clock can be running at different frequencies, care must
be taken to maintain reliable communication with the JTAG/SWD interface. In the Capture-DR state,
the result of the previous transaction, if any, is returned, together with a 3-bit ACK response. Software
should check the ACK response to see if the previous operation has completed before initiating a
new transaction. Alternatively, if the system clock is at least 8 times faster than the debug clock
(TCK or SWCLK), the previous operation has enough time to complete and the ACK bits do not have
to be checked.
4.3.4.3
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 switching 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®
Debug Interface V5 Architecture Specification.
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 the switching preamble 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:
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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 b1110011100111100, 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.
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.
4.4
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 four JTAG
pins (PC[3:0]) for their alternate function using the GPIOAFSEL register. In addition to enabling
the alternate functions, any other changes to the GPIO pad configurations on the four JTAG pins
(PC[3:0]) should be reverted to their default settings.
4.5
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.
4.5.1
Instruction Register (IR)
The JTAG TAP Instruction Register (IR) is a four-bit serial scan chain connected between the JTAG
TDI and TDO pins with a parallel load register. 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 4-3 on page 165. A detailed explanation of each instruction, along
with its associated Data Register, follows.
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Table 4-3. JTAG Instruction Register Commands
4.5.1.1
IR[3:0]
Instruction
Description
0000
EXTEST
Drives the values preloaded into the Boundary Scan Chain by the
SAMPLE/PRELOAD instruction onto the pads.
0001
INTEST
Drives the values preloaded into the Boundary Scan Chain by the
SAMPLE/PRELOAD instruction into the controller.
0010
SAMPLE / PRELOAD
Captures the current I/O values and shifts the sampled values out of the
Boundary Scan Chain while new preload data is shifted in.
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.
1110
IDCODE
Loads manufacturing information defined by the IEEE Standard 1149.1
into the IDCODE chain and shifts it out.
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.
EXTEST Instruction
The EXTEST instruction is not associated with its own 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
tests to be developed that drive known values out of the controller, which can be used to verify
connectivity. While the EXTEST instruction is present in the Instruction Register, the Boundary Scan
Data Register can be accessed to sample and shift out the current data and load new data into the
Boundary Scan Data Register.
4.5.1.2
INTEST Instruction
The INTEST instruction is not associated with its own 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.While the
INTEXT instruction is present in the Instruction Register, the Boundary Scan Data Register can be
accessed to sample and shift out the current data and load new data into the Boundary Scan Data
Register.
4.5.1.3
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.
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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 167 for more information.
4.5.1.4
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 168 for more
information.
4.5.1.5
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 168 for more information.
4.5.1.6
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 168 for more information.
4.5.1.7
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, or the Test-Logic-Reset
state is entered. Please see “IDCODE Data Register” on page 167 for more information.
4.5.1.8
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 167 for
more information.
4.5.2
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.
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4.5.2.1
IDCODE Data Register
The format for the 32-bit IDCODE Data Register defined by the IEEE Standard 1149.1 is shown in
Figure 4-3 on page 167. 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 0x3BA0.0477. This allows the debuggers to automatically configure
themselves to work correctly with the Cortex-M3 during debug.
Figure 4-3. IDCODE Register Format
31
TDI
4.5.2.2
28 27
12 11
Version
Part Number
1 0
Manufacturer ID
1
TDO
BYPASS Data Register
The format for the 1-bit BYPASS Data Register defined by the IEEE Standard 1149.1 is shown in
Figure 4-4 on page 167. 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.
Figure 4-4. BYPASS Register Format
0
TDI
4.5.2.3
0
TDO
Boundary Scan Data Register
The format of the Boundary Scan Data Register is shown in Figure 4-5 on page 168. Each GPIO
pin, starting with a GPIO pin next to 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.
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.
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Figure 4-5. Boundary Scan Register Format
TDI
I
N
O
U
T
O
E
...
GPIO PB6
4.5.2.4
I
N
O
U
T
GPIO m
O
E
I
N
O
U
T
O
E
GPIO m +1
...
I
N
O
U
T
O
E
TDO
GPIO n
APACC Data Register
The format for the 35-bit APACC Data Register defined by ARM is described in the ARM® Debug
Interface V5 Architecture Specification.
4.5.2.5
DPACC Data Register
The format for the 35-bit DPACC Data Register defined by ARM is described in the ARM® Debug
Interface V5 Architecture Specification.
4.5.2.6
ABORT Data Register
The format for the 35-bit ABORT Data Register defined by ARM is described in the ARM® Debug
Interface V5 Architecture Specification.
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5
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.
5.1
Signal Description
Table 5-1 on page 169 lists the external signals of the System Control module and describes the
function of each. The NMI signal is the alternate function for and functions as a GPIO after reset.
under commit protection and require a special process to be configured as any alternate function
or to subsequently return to the GPIO function, see “Commit Control” on page 356. The column in
the table below titled "Pin Assignment" lists the GPIO pin placement for the NMI signal. The AFSEL
bit in the GPIO Alternate Function Select (GPIOAFSEL) register (page 371) should be set to choose
the NMI function. For more information on configuring GPIOs, see “General-Purpose Input/Outputs
(GPIOs)” on page 348. The remaining signals (with the word "fixed" in the Pin Assignment column)
have a fixed pin assignment and function.
Table 5-1. System Control & Clocks Signals (100LQFP)
Pin Name
Pin Number
Pin Type
a
Buffer Type
Description
NMI
89
I
TTL
OSC0
48
I
Analog
Non-maskable interrupt.
Main oscillator crystal input or an external clock reference
input.
OSC1
49
O
Analog
Main oscillator crystal output. Leave unconnected when using
a single-ended clock source.
RST
64
I
TTL
System reset input.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
5.2
Functional Description
The System Control module provides the following capabilities:
■ Device identification (see “Device Identification” on page 169)
■ Local control, such as reset (see “Reset Control” on page 169), power (see “Power
Control” on page 174) and clock control (see “Clock Control” on page 174)
■ System control (Run, Sleep, and Deep-Sleep modes); see “System Control” on page 180
5.2.1
Device Identification
Several 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-DC7 registers.
5.2.2
Reset Control
This section discusses aspects of hardware functions during reset as well as system software
requirements following the reset sequence.
5.2.2.1
Reset Sources
The controller has six sources of reset:
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1. External reset input pin (RST) assertion; see “External RST Pin” on page 171.
2. Power-on reset (POR); see “Power-On Reset (POR)” on page 170.
3. Internal brown-out (BOR) detector; see “Brown-Out Reset (BOR)” on page 172.
4. Software-initiated reset (with the software reset registers); see “Software Reset” on page 172.
5. A watchdog timer reset condition violation; see “Watchdog Timer Reset” on page 173.
6. MOSC failure; see “Main Oscillator Verification Failure” on page 173.
Table 5-2 provides a summary of results of the various reset operations.
Table 5-2. Reset Sources
Reset Source
Core Reset?
JTAG Reset?
On-Chip Peripherals Reset?
Power-On Reset
Yes
Yes
Yes
RST
Yes
Pin Config Only
Yes
Brown-Out Reset
Yes
No
Yes
Software System Request
a
Reset
Yes
No
Yes
Software Peripheral Reset
No
No
Yes
Watchdog Reset
Yes
No
Yes
MOSC Failure Reset
Yes
No
Yes
b
a. By using the SYSRESREQ bit in the ARM Cortex-M3 Application Interrupt and Reset Control (APINT) register
b. Programmable on a module-by-module basis using the Software Reset Control Registers.
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.
5.2.2.2
Power-On Reset (POR)
Note:
The power-on reset also resets the JTAG controller. An external reset does not.
The internal Power-On Reset (POR) circuit monitors the power supply voltage (VDD) and generates
a reset signal to all of the internal logic including JTAG when the power supply ramp reaches a
threshold value (VTH). The microcontroller must be operating within the specified operating parameters
when the on-chip power-on reset pulse is complete. The 3.3-V power supply to the microcontroller
must reach 3.0 V within 10 msec of VDD crossing 2.0 V to guarantee proper operation. For applications
that require the use of an external reset signal to hold the microcontroller in reset longer than the
internal POR, the RST input may be used as discussed in “External RST Pin” on page 171.
The Power-On Reset sequence is as follows:
1. The microcontroller waits for 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, and the first instruction designated by the program counter, and then begins
execution.
The internal POR is only active on the initial power-up of the microcontroller. The Power-On Reset
timing is shown in Figure 21-5 on page 776.
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5.2.2.3
External RST Pin
Note:
It is recommended that the trace for the RST signal must be kept as short as possible. Be
sure to place any components connected to the RST signal as close to the microcontroller
as possible.
If the application only uses the internal POR circuit, the RST input must be connected to the power
supply (VDD) through an optional pull-up resistor (0 to 100K Ω) as shown in Figure 5-1 on page 171.
Figure 5-1. Basic RST Configuration
VDD
Stellaris®
RPU
RST
RPU = 0 to 100 kΩ
The external reset pin (RST) resets the microcontroller including the core and all the on-chip
peripherals except the JTAG TAP controller (see “JTAG Interface” on page 157). The external reset
sequence is as follows:
1. The external reset pin (RST) is asserted for the duration specified by TMIN and then de-asserted
(see “Reset” on page 775).
2. The internal reset is released and the core loads from memory the initial stack pointer, the initial
program counter, and the first instruction designated by the program counter, and then begins
execution.
To improve noise immunity and/or to delay reset at power up, the RST input may be connected to
an RC network as shown in Figure 5-2 on page 171.
Figure 5-2. External Circuitry to Extend Power-On Reset
VDD
Stellaris®
RPU
RST
C1
RPU = 1 kΩ to 100 kΩ
C1 = 1 nF to 10 µF
If the application requires the use of an external reset switch, Figure 5-3 on page 172 shows the
proper circuitry to use.
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Figure 5-3. Reset Circuit Controlled by Switch
VDD
Stellaris®
RPU
RST
C1
RS
Typical RPU = 10 kΩ
Typical RS = 470 Ω
C1 = 10 nF
The RPU and C1 components define the power-on delay.
The external reset timing is shown in Figure 21-4 on page 776.
5.2.2.4
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.
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 equivalent 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 21-6 on page 776.
5.2.2.5
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 180). 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:
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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 21-7 on page 776.
5.2.2.6
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.
The watchdog reset timing is shown in Figure 21-8 on page 777.
5.2.3
Non-Maskable Interrupt
The controller has two sources of non-maskable interrupt (NMI):
■ The assertion of the NMI signal.
■ A main oscillator verification error.
If both sources of NMI are enabled, software must check that the main oscillator verification is the
cause of the interrupt in order to distinguish between the two sources.
5.2.3.1
NMI Pin
The alternate function to GPIO port pin B7 is an NMI signal. The alternate function must be enabled
in the GPIO for the signal to be used as an interrupt, as described in “General-Purpose Input/Outputs
(GPIOs)” on page 348. Note that enabling the NMI alternate function requires the use of the GPIO
lock and commit function just like the GPIO port pins associated with JTAG/SWD functionality. The
active sense of the NMI signal is High; asserting the enabled NMI signal above VIH initiates the NMI
interrupt sequence.
5.2.3.2
Main Oscillator Verification Failure
The main oscillator verification circuit may generate a reset event, at which time a Power-on Reset
is generated and control is transferred to the NMI handler. The NMI handler is used to address the
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main oscillator verification failure because the necessary code can be removed from the general
reset handler, speeding up reset processing. The detection circuit is enabled using the CVAL bit in
the Main Oscillator Control (MOSCCTL) register. The main oscillator verification error is indicated
in the main oscillator fail status bit (MOSCFAIL) bit in the Reset Cause (RESC) register. The main
oscillator verification circuit action is described in more detail in “Clock Control” on page 174.
5.2.4
Power Control
®
The Stellaris microcontroller provides an integrated LDO regulator that is used to provide power
to the majority of the controller's internal logic. For power reduction, 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:
On the printed circuit board, use the LDO output as the source of VDD25 input. Do not use
an external regulator to supply the voltage to VDD25. In addition, the LDO requires decoupling
capacitors. See “On-Chip Low Drop-Out (LDO) Regulator Characteristics” on page 769.
VDDA must be supplied with 3.3 V, or the microcontroller does not function properly. VDDA
is the supply for all of the analog circuitry on the device, including the clock circuitry.
5.2.5
Clock Control
System control determines the control of clocks in this part.
5.2.5.1
Fundamental Clock Sources
There are multiple 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 (MOSC). 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. If the PLL is being
used, the crystal value must be one of the supported frequencies between 3.579545 MHz through
16.384 MHz (inclusive). If the PLL is not being used, the crystal may be any one of the supported
frequencies between 1 MHz and 16.384 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 field
in the RCC register (see page 192). Note that the MOSC must have a clock source for the USB
PLL.
■ 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 ± 50%. 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 (see “Hibernation Module” on page 236) and
may also provide an accurate source of Deep-Sleep or Hibernate mode power savings.
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The internal system clock (SysClk), is derived from any of the above sources plus two others: the
output of the main 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 16.384 MHz
(inclusive). Table 5-3 on page 175 shows how the various clock sources can be used in a system.
Table 5-3. Clock Source Options
5.2.5.2
Clock Source
Drive PLL?
Used as SysClk?
Internal Oscillator (12 MHz)
No
BYPASS = 1
Yes
BYPASS = 1, OSCSRC = 0x1
Internal Oscillator divide by 4 (3
MHz)
No
BYPASS = 1
Yes
BYPASS = 1, OSCSRC = 0x2
Main Oscillator
Yes
BYPASS = 0, OSCSRC = Yes
0x0
BYPASS = 1, OSCSRC = 0x0
Internal 30-kHz Oscillator
No
BYPASS = 1
Yes
BYPASS = 1, OSCSRC = 0x3
External Real-Time Oscillator
No
BYPASS = 1
Yes
BYPASS = 1, OSCSRC2 = 0x7
Clock Configuration
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. These registers control the following clock
functionality:
■ Source of clocks in sleep and deep-sleep modes
■ System clock derived from PLL or other clock source
■ Enabling/disabling of oscillators and PLL
■ Clock divisors
■ Crystal input selection
Figure 5-4 on page 176 shows the logic for the main clock tree. The peripheral blocks are driven by
the system clock signal and can be individually enabled/disabled. The ADC clock signal is
automatically divided down to 16 MHz for proper ADC operation.
Note:
When the ADC module is in operation, the system clock must be at least 16 MHz. When
the USB module is in operation, MOSC must be provided with a clock source, and the
system clock must be at least 30 MHz.
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Figure 5-4. Main Clock Tree
XTALa
USBPWRDN c
USB PLL
(240 MHz)
USB Clock
÷4
USEPWMDIV a
PWMDW a
PWM Clock
XTALa
PWRDN b
MOSCDIS a
PLL
(400 MHz)
Main OSC
USESYSDIV a,d
÷2
IOSCDIS a
System Clock
Internal
OSC
(12 MHz)
SYSDIV b,d
÷4
BYPASS
Internal
OSC
(30 kHz)
Hibernation
Module
(32.768 kHz)
b,d
OSCSRC b,d
PWRDN
ADC Clock
÷ 25
a. Control provided by RCC register bit/field.
b. Control provided by RCC register bit/field or RCC2 register bit/field, if overridden with RCC2 register bit USERCC2.
c. Control provided by RCC2 register bit/field.
d. Also may be controlled by DSLPCLKCFG when in deep sleep mode.
Note:
The figure above shows all features available on all Stellaris® DustDevil-class devices. Not all peripherals may
be available on this device.
In the RCC register, the SYSDIV field specifies which divisor is used to generate the system clock
from either the PLL output or the oscillator source (depending on how the BYPASS bit in this register
is configured). When using the PLL, the VCO frequency of 400 MHz is predivided by 2 before the
divisor is applied. Table 5-4 shows how the SYSDIV encoding affects the system clock frequency,
depending on whether the PLL is used (BYPASS=0) or another clock source is used (BYPASS=1).
The divisor is equivalent to the SYSDIV encoding plus 1. For a list of possible clock sources, see
Table 5-3 on page 175.
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Table 5-4. Possible System Clock Frequencies Using the SYSDIV Field
SYSDIV
Divisor
a
Frequency
(BYPASS=0)
Frequency (BYPASS=1)
StellarisWare Parameter
b
0x0
/1
reserved
Clock source frequency/2
SYSCTL_SYSDIV_1
0x1
/2
reserved
Clock source frequency/2
SYSCTL_SYSDIV_2
0x2
/3
reserved
Clock source frequency/3
SYSCTL_SYSDIV_3
0x3
/4
50 MHz
Clock source frequency/4
SYSCTL_SYSDIV_4
0x4
/5
40 MHz
Clock source frequency/5
SYSCTL_SYSDIV_5
0x5
/6
33.33 MHz
Clock source frequency/6
SYSCTL_SYSDIV_6
0x6
/7
28.57 MHz
Clock source frequency/7
SYSCTL_SYSDIV_7
0x7
/8
25 MHz
Clock source frequency/8
SYSCTL_SYSDIV_8
0x8
/9
22.22 MHz
Clock source frequency/9
SYSCTL_SYSDIV_9
0x9
/10
20 MHz
Clock source frequency/10
SYSCTL_SYSDIV_10
0xA
/11
18.18 MHz
Clock source frequency/11
SYSCTL_SYSDIV_11
0xB
/12
16.67 MHz
Clock source frequency/12
SYSCTL_SYSDIV_12
0xC
/13
15.38 MHz
Clock source frequency/13
SYSCTL_SYSDIV_13
0xD
/14
14.29 MHz
Clock source frequency/14
SYSCTL_SYSDIV_14
0xE
/15
13.33 MHz
Clock source frequency/15
SYSCTL_SYSDIV_15
0xF
/16
12.5 MHz (default)
Clock source frequency/16
SYSCTL_SYSDIV_16
a. This parameter is used in functions such as SysCtlClockSet() in the Stellaris Peripheral Driver Library.
b. SYSCTL_SYSDIV_1 does not set the USESYSDIV bit. As a result, using this parameter without enabling the PLL results
in the system clock having the same frequency as the clock source.
The SYSDIV2 field in the RCC2 register is 2 bits wider than the SYSDIV field in the RCC register
so that additional larger divisors up to /64 are possible, allowing a lower system clock frequency for
improved Deep Sleep power consumption. When using the PLL, the VCO frequency of 400 MHz is
predivided by 2 before the divisor is applied. The divisor is equivalent to the SYSDIV2 encoding
plus 1. Table 5-5 shows how the SYSDIV2 encoding affects the system clock frequency, depending
on whether the PLL is used (BYPASS2=0) or another clock source is used (BYPASS2=1). For a list
of possible clock sources, see Table 5-3 on page 175.
Table 5-5. Examples of Possible System Clock Frequencies Using the SYSDIV2 Field
SYSDIV2
Divisor
a
Frequency
(BYPASS2=0)
Frequency (BYPASS2=1)
StellarisWare Parameter
b
0x00
/1
reserved
Clock source frequency/2
SYSCTL_SYSDIV_1
0x01
/2
reserved
Clock source frequency/2
SYSCTL_SYSDIV_2
0x02
/3
reserved
Clock source frequency/3
SYSCTL_SYSDIV_3
0x03
/4
50 MHz
Clock source frequency/4
SYSCTL_SYSDIV_4
0x04
/5
40 MHz
Clock source frequency/5
SYSCTL_SYSDIV_5
0x05
/6
33.33 MHz
Clock source frequency/6
SYSCTL_SYSDIV_6
0x06
/7
28.57 MHz
Clock source frequency/7
SYSCTL_SYSDIV_7
0x07
/8
25 MHz
Clock source frequency/8
SYSCTL_SYSDIV_8
0x08
/9
22.22 MHz
Clock source frequency/9
SYSCTL_SYSDIV_9
0x09
/10
20 MHz
Clock source frequency/10
SYSCTL_SYSDIV_10
...
...
...
...
...
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Table 5-5. Examples of Possible System Clock Frequencies Using the SYSDIV2 Field
(continued)
SYSDIV2
0x3F
Divisor
/64
a
Frequency
(BYPASS2=0)
Frequency (BYPASS2=1)
StellarisWare Parameter
3.125 MHz
Clock source frequency/64
SYSCTL_SYSDIV_64
a. This parameter is used in functions such as SysCtlClockSet() in the Stellaris Peripheral Driver Library.
b. SYSCTL_SYSDIV_1 does not set the USESYSDIV bit. As a result, using this parameter without enabling the PLL results
in the system clock having the same frequency as the clock source.
5.2.5.3
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 16.384 MHz, otherwise,
the range of supported crystals is 1 to 16.384 MHz.
The XTAL bit in the RCC register (see page 192) 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.
5.2.5.4
Main PLL Frequency Configuration
The main PLL is disabled by default during power-on reset and is enabled later by software if
required. Software specifies the output divisor to set the system clock frequency, and enables the
main PLL to drive the output. The PLL operates at 400 MHz, but is divided by two prior to the
application of the output divisor.
If the main oscillator provides the clock reference to the main 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 196). The internal translation provides a translation within ± 1% of the
targeted PLL VCO frequency. Table 21-10 on page 772 shows the actual PLL frequency and error
for a given crystal choice.
The Crystal Value field (XTAL) in the Run-Mode Clock Configuration (RCC) register (see page 192)
describes the available crystal choices and default programming of the PLLCFG register. Any time
the XTAL field changes, the new settings are translated and the internal PLL settings are updated.
To configure the external 32-kHz real-time oscillator as the PLL input reference, program the OSCRC2
field in the Run-Mode Clock Configuration 2 (RCC2) register to be 0x7.
5.2.5.5
USB PLL Frequency Configuration
The USB PLL is disabled by default during power-on reset and is enabled later by software. The
USB PLL must be enabled and running for proper USB function. The main oscillator is the only clock
reference for the USB PLL. The USB PLL is enabled by clearing the USBPWRDN bit of the RCC2
register. The XTAL bit field (Crystal Value) of the RCC register describes the available crystal choices.
The main oscillator must be connected to one of the following crystal values in order to correctly
generate the USB clock: 4, 5, 6, 8, 10, 12, or 16 MHz. Only these crystals provide the necessary
USB PLL VCO frequency to conform with the USB timing specifications.
5.2.5.6
PLL Modes
Both PLLs have two modes of operation: Normal and Power-Down
■ Normal: The PLL multiplies the input clock reference and drives the output.
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■ 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 192 and page 199).
5.2.5.7
PLL Operation
If a 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
21-9 on page 772). During the relock time, the affected PLL is not usable as a clock reference.
Either 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
to 0x1200 (that is, ~600 μs at an 8.192 MHz external oscillator clock). When the XTAL value is
greater than 0x0f, the down counter is set to 0x2400 to maintain the required lock time on higher
frequency crystal inputs. 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.
If the main PLL is enabled and the system clock is switched to use the PLL in one step, the system
control hardware continues to clock the controller from the oscillator selected by the RCC/RCC2
register until the main PLL is stable (TREADY time met), after which it changes to the PLL. Software
can use many methods to ensure that the system is clocked from the main PLL, including periodically
polling the PLLLRIS bit in the Raw Interrupt Status (RIS) register, and enabling the PLL Lock
interrupt.
The USB PLL is not protected during the lock time (TREADY) and software should ensure that the
USB PLL has locked before using the interface. Software can use many methods to ensure the
TREADY period has passed, including periodically polling the USBPLLLRIS bit in the Raw Interrupt
Status (RIS) register, and enabling the USB PLL Lock interrupt.
5.2.5.8
Main Oscillator Verification Circuit
A circuit is added to ensure that the main oscillator is running at the appropriate frequency. The
circuit monitors the main oscillator frequency and signals if the frequency is outside of the allowable
band of attached crystals.
The detection circuit is enabled using the CVAL bit in the Main Oscillator Control (MOSCCTL)
register. If this circuit is enabled and detects an error, the following sequence is performed by the
hardware:
1. The MOSCFAIL bit in the Reset Cause (RESC) register is set.
2. If the internal oscillator (IOSC) is disabled, it is enabled.
3. The system clock is switched from the main oscillator to the IOSC.
4. An internal power-on reset is initiated that lasts for 32 IOSC periods.
5. Reset is de-asserted and the processor is directed to the NMI handler during the reset sequence.
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5.2.6
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.
There are four levels of operation for the device defined as:
■ Run Mode. In Run mode, the controller actively executes code. 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. In Sleep mode, the clock frequency of the active peripherals is unchanged, but the
processor and the memory subsystem are not clocked and therefore no longer execute code.
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 “Power Management” on page 88 for more details.
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. 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. 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 “Power Management” on page 88 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 determined by the DSDIVORIDE setting in the DSLPCLKCFG register,
up to /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
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.
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Caution – If the Cortex-M3 Debug Access Port (DAP) has been enabled, and the device wakes from a
low power sleep or deep-sleep mode, the core may start executing code before all clocks to peripherals
have been restored to their run mode configuration. The DAP is usually enabled by software tools
accessing the JTAG or SWD interface when debugging or flash programming. If this condition occurs,
a Hard Fault is triggered when software accesses a peripheral with an invalid clock.
A software delay loop can be used at the beginning of the interrupt routine that is used to wake up a
system from a WFI (Wait For Interrupt) instruction. This stalls the execution of any code that accesses
a peripheral register that might cause a fault. This loop can be removed for production software as the
DAP is most likely not enabled during normal execution.
Because the DAP is disabled by default (power on reset), the user can also power-cycle the device. The
DAP is not enabled unless it is enabled through the JTAG or SWD interface.
5.3
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 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.
5.4
Register Map
Table 5-6 on page 181 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. Software should not modify any reserved memory address.
Note:
Additional Flash and ROM registers defined in the System Control register space are
described in the “Internal Memory” on page 258.
Table 5-6. System Control Register Map
Description
See
page
Offset
Name
Type
Reset
0x000
DID0
RO
-
Device Identification 0
184
0x004
DID1
RO
-
Device Identification 1
203
0x008
DC0
RO
0x00FF.003F
Device Capabilities 0
205
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System Control
Table 5-6. System Control Register Map (continued)
Offset
Name
0x010
See
page
Type
Reset
Description
DC1
RO
0x0101.32FF
Device Capabilities 1
206
0x014
DC2
RO
0x0007.5031
Device Capabilities 2
208
0x018
DC3
RO
0x87FF.0000
Device Capabilities 3
209
0x01C
DC4
RO
0x0000.30FF
Device Capabilities 4
210
0x020
DC5
RO
0x0000.0000
Device Capabilities 5
211
0x024
DC6
RO
0x0000.0002
Device Capabilities 6
212
0x028
DC7
RO
0x4300.0F3F
Device Capabilities 7
213
0x030
PBORCTL
R/W
0x0000.7FFD
Brown-Out Reset Control
186
0x034
LDOPCTL
R/W
0x0000.0000
LDO Power Control
187
0x040
SRCR0
R/W
0x00000000
Software Reset Control 0
233
0x044
SRCR1
R/W
0x00000000
Software Reset Control 1
234
0x048
SRCR2
R/W
0x00000000
Software Reset Control 2
235
0x050
RIS
RO
0x0000.0000
Raw Interrupt Status
188
0x054
IMC
R/W
0x0000.0000
Interrupt Mask Control
189
0x058
MISC
R/W1C
0x0000.0000
Masked Interrupt Status and Clear
190
0x05C
RESC
R/W
-
Reset Cause
191
0x060
RCC
R/W
0x0780.3AD1
Run-Mode Clock Configuration
192
0x064
PLLCFG
RO
-
XTAL to PLL Translation
196
0x06C
GPIOHBCTL
R/W
0x0000.0000
GPIO High-Performance Bus Control
197
0x070
RCC2
R/W
0x0780.6810
Run-Mode Clock Configuration 2
199
0x07C
MOSCCTL
R/W
0x0000.0000
Main Oscillator Control
201
0x100
RCGC0
R/W
0x00000040
Run Mode Clock Gating Control Register 0
215
0x104
RCGC1
R/W
0x00000000
Run Mode Clock Gating Control Register 1
221
0x108
RCGC2
R/W
0x00000000
Run Mode Clock Gating Control Register 2
227
0x110
SCGC0
R/W
0x00000040
Sleep Mode Clock Gating Control Register 0
217
0x114
SCGC1
R/W
0x00000000
Sleep Mode Clock Gating Control Register 1
223
0x118
SCGC2
R/W
0x00000000
Sleep Mode Clock Gating Control Register 2
229
0x120
DCGC0
R/W
0x00000040
Deep Sleep Mode Clock Gating Control Register 0
219
0x124
DCGC1
R/W
0x00000000
Deep Sleep Mode Clock Gating Control Register 1
225
0x128
DCGC2
R/W
0x00000000
Deep Sleep Mode Clock Gating Control Register 2
231
0x144
DSLPCLKCFG
R/W
0x0780.0000
Deep Sleep Clock Configuration
202
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5.5
Register Descriptions
All addresses given are relative to the System Control base address of 0x400F.E000.
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System Control
Register 1: Device Identification 0 (DID0), offset 0x000
This register identifies the version of the microcontroller. Each microcontroller is uniquely identified
by the combined values of the CLASS field in the DID0 register and the PARTNO field in the DID1
register.
Device Identification 0 (DID0)
Base 0x400F.E000
Offset 0x000
Type RO, reset 31
30
28
27
26
VER
reserved
Type
Reset
29
25
24
23
22
21
20
reserved
18
17
16
CLASS
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
MAJOR
Type
Reset
19
MINOR
Bit/Field
Name
Type
Reset
31
reserved
RO
0
30:28
VER
RO
0x1
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.
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
0x1
Second version of the DID0 register format.
27:24
reserved
RO
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.
23:16
CLASS
RO
0x3
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
0x3
Stellaris® DustDevil-class devices
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Bit/Field
Name
Type
Reset
15:8
MAJOR
RO
-
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.
7:0
MINOR
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
BORIOR
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0x0
1
BORIOR
R/W
0
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.
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.
0
reserved
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
VADJ
Bit/Field
Name
Type
Reset
31:6
reserved
RO
0
5:0
VADJ
R/W
0x0
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.
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
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
BORRIS
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
MOSCPUPRIS USBPLLLRIS
RO
0
RO
0
PLLLRIS
RO
0
reserved
Bit/Field
Name
Type
Reset
Description
31:9
reserved
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.
8
MOSCPUPRIS
RO
0
MOSC Power Up Raw Interrupt Status
This bit is set when the PLL TMOSCPUP Timer asserts.
7
USBPLLLRIS
RO
0
USB PLL Lock Raw Interrupt Status
This bit is set when the USB PLL TUSBREADY Timer asserts.
6
PLLLRIS
RO
0
PLL Lock Raw Interrupt Status
This bit is set when the PLL TREADY Timer asserts.
5:2
reserved
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.
1
BORRIS
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.
0
reserved
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
BORIM
reserved
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
MOSCPUPIM USBPLLLIM
R/W
0
R/W
0
PLLLIM
R/W
0
reserved
Bit/Field
Name
Type
Reset
Description
31:9
reserved
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.
8
MOSCPUPIM
R/W
0
MOSC Power Up Interrupt Mask
This bit specifies whether a MOSC power up intterupt is promoted to a
controller interrupt. If set, an interrupt is generated if MOSCPUPRIS in
RIS is set; otherwise, an interrupt is not generated.
7
USBPLLLIM
R/W
0
USB PLL Lock Interrupt Mask
This bit specifies whether a USB PLL Lock interrupt is promoted to a
controller interrupt. If set, an interrupt is generated if USBPLLLRIS in
RIS is set; otherwise, an interrupt is not generated.
6
PLLLIM
R/W
0
PLL Lock Interrupt Mask
This bit specifies whether a PLL Lock interrupt is promoted to a controller
interrupt. If set, an interrupt is generated if PLLLRIS in RIS is set;
otherwise, an interrupt is not generated.
5:2
reserved
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.
1
BORIM
R/W
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.
0
reserved
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.
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System Control
Register 6: Masked Interrupt Status and Clear (MISC), offset 0x058
On a read, this register gives the current masked status value of the corresponding interrupt. All of
the bits are R/W1C and this action also clears the corresponding raw interrupt bit in the RIS register
(see page 188).
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
BORMIS
reserved
RO
0
RO
0
RO
0
RO
0
R/W1C
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
MOSCPUPMIS USBPLLLMIS
R/W1C
0
R/W1C
0
PLLLMIS
R/W1C
0
reserved
Bit/Field
Name
Type
Reset
Description
31:9
reserved
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.
8
MOSCPUPMIS
R/W1C
0
MOSC Power Up Masked Interrupt Status
This bit is set when the TMOSCPUP timer asserts. The interrupt is cleared
by writing a 1 to this bit.
7
USBPLLLMIS
R/W1C
0
USB PLL Lock Masked Interrupt Status
This bit is set when the USB PLL TUSBREADY timer asserts. The interrupt
is cleared by writing a 1 to this bit.
6
PLLLMIS
R/W1C
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.
5:2
reserved
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.
1
BORMIS
R/W1C
0
BOR Masked Interrupt Status
The BORMIS is simply the BORRIS ANDed with the mask value, BORIM.
0
reserved
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.
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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 power-on reset is the cause, in which
case, all bits other than POR 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
RO
0
RO
0
RO
0
24
23
22
21
20
19
18
17
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
-
9
8
7
6
5
4
3
2
1
0
SW
WDT
BOR
POR
EXT
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
reserved
Type
Reset
MOSCFAIL
reserved
Type
Reset
RO
0
16
Bit/Field
Name
Type
Reset
Description
31:17
reserved
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.
16
MOSCFAIL
R/W
-
MOSC Failure Reset
When set, indicates the MOSC circuit was enable for clock validation
and failed. This generated a reset event.
15:5
reserved
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.
4
SW
R/W
-
Software Reset
When set, indicates a software reset is the cause of the reset event.
3
WDT
R/W
-
Watchdog Timer Reset
When set, indicates a watchdog reset is the cause of the reset event.
2
BOR
R/W
-
Brown-Out Reset
When set, indicates a brown-out reset is the cause of the reset event.
1
POR
R/W
-
Power-On Reset
When set, indicates a power-on reset is the cause of the reset event.
0
EXT
R/W
-
External Reset
When set, indicates an external reset (RST assertion) is the cause of
the reset event.
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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 0x0780.3AD1
31
30
29
28
26
25
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
1
15
14
13
12
11
PWRDN
reserved
BYPASS
R/W
1
RO
1
R/W
1
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
27
24
23
R/W
1
R/W
1
R/W
1
10
9
8
R/W
0
R/W
1
ACG
21
20
19
R/W
0
RO
0
RO
0
RO
0
7
6
5
4
3
R/W
1
R/W
1
R/W
0
R/W
1
RO
0
SYSDIV
22
XTAL
Bit/Field
Name
Type
Reset
31:28
reserved
RO
0x0
27
ACG
R/W
0
17
16
RO
0
RO
0
RO
0
2
1
0
reserved
USESYSDIV
R/W
0
18
OSCSRC
reserved
RO
0
IOSCDIS MOSCDIS
R/W
0
R/W
1
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.
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.
26:23
SYSDIV
R/W
0xF
System Clock Divisor
Specifies which divisor is used to generate the system clock from either
the PLL output or the oscillator source (depending on how the BYPASS
bit in this register is configured). See Table 5-4 on page 177 for bit
encodings.
If the SYSDIV value is less than MINSYSDIV (see page 206), and the
PLL is being used, then the MINSYSDIV value is used as the divisor.
If the PLL is not being used, the SYSDIV value can be less than
MINSYSDIV.
22
USESYSDIV
R/W
0
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.
If the USERCC2 bit in the RCC2 register is set, then the SYSDIV2 field
in the RCC2 register is used as the system clock divider rather than the
SYSDIV field in this register.
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Bit/Field
Name
Type
Reset
Description
21:14
reserved
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.
13
PWRDN
R/W
1
PLL Power Down
This bit connects to the PLL PWRDN input. The reset value of 1 powers
down the PLL.
12
reserved
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.
11
BYPASS
R/W
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.
See Table 5-4 on page 177 for programming guidelines.
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.
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System Control
Bit/Field
Name
Type
Reset
10:6
XTAL
R/W
0xB
Description
Crystal Value
This field specifies the crystal value attached to the main oscillator. The
encoding for this field is provided below. Depending on the crystal used,
the PLL frequency may not be exactly 400 MHz (see Table
21-10 on page 772 for more information).
Frequencies that may be used with the USB interface are indicated in
the table. To function within the clocking requirements of the USB
specification, a crystal of 4, 5, 6, 8, 10, 12, or 16 MHz must be used.
Value Crystal Frequency (MHz) Not
Using the PLL
Crystal Frequency (MHz) Using
the PLL
0x00
1.000
reserved
0x01
1.8432
reserved
0x02
2.000
reserved
0x03
2.4576
0x04
reserved
3.579545 MHz
0x05
3.6864 MHz
0x06
4 MHz (USB)
0x07
4.096 MHz
0x08
4.9152 MHz
0x09
5 MHz (USB)
0x0A
5.12 MHz
0x0B
6 MHz (reset value)(USB)
0x0C
6.144 MHz
0x0D
7.3728 MHz
0x0E
8 MHz (USB)
0x0F
8.192 MHz
0x10
10.0 MHz (USB)
0x11
12.0 MHz (USB)
0x12
12.288 MHz
0x13
13.56 MHz
0x14
14.31818 MHz
0x15
16.0 MHz (USB)
0x16
16.384 MHz
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Bit/Field
Name
Type
Reset
5:4
OSCSRC
R/W
0x1
Description
Oscillator Source
Selects the input source for the OSC. The values are:
Value Input Source
0x0
MOSC
Main oscillator
0x1
IOSC
Internal oscillator (default)
0x2
IOSC/4
Internal oscillator / 4
0x3
30 kHz
30-KHz internal oscillator
For additional oscillator sources, see the RCC2 register.
3:2
reserved
RO
0x0
1
IOSCDIS
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.
Internal Oscillator Disable
0: Internal oscillator (IOSC) is enabled.
1: Internal oscillator is disabled.
0
MOSCDIS
R/W
1
Main Oscillator Disable
0: Main oscillator is enabled .
1: Main oscillator is disabled (default).
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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 192).
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
-
RO
-
RO
-
RO
-
RO
-
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
F
Bit/Field
Name
Type
Reset
31:14
reserved
RO
0x0
13:5
F
RO
-
R
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.
PLL F Value
This field specifies the value supplied to the PLL’s F input.
4:0
R
RO
-
PLL R Value
This field specifies the value supplied to the PLL’s R input.
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Register 10: GPIO High-Performance Bus Control (GPIOHBCTL), offset 0x06C
This register controls which internal bus is used to access each GPIO port. When a bit is clear, the
corresponding GPIO port is accessed across the legacy Advanced Peripheral Bus (APB) bus and
through the APB memory aperture. When a bit is set, the corresponding port is accessed across
the Advanced High-Performance Bus (AHB) bus and through the AHB memory aperture. Each
GPIO port can be individually configured to use AHB or APB, but may be accessed only through
one aperture. The AHB bus provides better back-to-back access performance than the APB bus.
The address aperture in the memory map changes for the ports that are enabled for AHB access
(see Table 9-6 on page 359).
GPIO High-Performance Bus Control (GPIOHBCTL)
Base 0x400F.E000
Offset 0x06C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
PORTH
PORTG
PORTF
PORTE
PORTD
PORTC
PORTB
PORTA
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
Bit/Field
Name
Type
Reset
31:8
reserved
RO
0x0000.0
7
PORTH
R/W
0
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.
Port H Advanced High-Performance Bus
This bit defines the memory aperture for Port H.
Value Description
6
PORTG
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port G Advanced High-Performance Bus
This bit defines the memory aperture for Port G.
Value Description
5
PORTF
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port F Advanced High-Performance Bus
This bit defines the memory aperture for Port F.
Value Description
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
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Bit/Field
Name
Type
Reset
4
PORTE
R/W
0
Description
Port E Advanced High-Performance Bus
This bit defines the memory aperture for Port E.
Value Description
3
PORTD
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port D Advanced High-Performance Bus
This bit defines the memory aperture for Port D.
Value Description
2
PORTC
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port C Advanced High-Performance Bus
This bit defines the memory aperture for Port C.
Value Description
1
PORTB
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port B Advanced High-Performance Bus
This bit defines the memory aperture for Port B.
Value Description
0
PORTA
R/W
0
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
Port A Advanced High-Performance Bus
This bit defines the memory aperture for Port A.
Value Description
1
Advanced High-Performance Bus (AHB)
0
Advanced Peripheral Bus (APB). This bus is the legacy bus.
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Stellaris® LM3S5737 Microcontroller
Register 11: Run-Mode Clock Configuration 2 (RCC2), offset 0x070
This register overrides the RCC equivalent register fields, as shown in Table 5-7, when the USERCC2
bit is set, allowing the extended capabilities of the RCC2 register to be used while also providing a
means to be backward-compatible to previous parts. Each RCC2 field that supersedes an RCC
field is located at the same LSB bit position; however, some RCC2 fields are larger than the
corresponding RCC field.
Table 5-7. RCC2 Fields that Override RCC fields
RCC2 Field...
Overrides RCC Field
SYSDIV2, bits[28:23]
SYSDIV, bits[26:23]
PWRDN2, bit[13]
PWRDN, bit[13]
BYPASS2, bit[11]
BYPASS, bit[11]
OSCSRC2, bits[6:4]
OSCSRC, bits[5:4]
Run-Mode Clock Configuration 2 (RCC2)
Base 0x400F.E000
Offset 0x070
Type R/W, reset 0x0780.6810
31
USERCC2
Type
Reset
Type
Reset
R/W
0
30
29
28
27
26
reserved
RO
0
25
24
23
22
21
20
SYSDIV2
RO
0
R/W
0
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
RO
0
10
9
8
7
6
15
14
13
12
11
reserved
USBPWRDN
PWRDN2
reserved
BYPASS2
RO
0
R/W
1
R/W
1
RO
0
R/W
1
reserved
RO
0
19
18
17
16
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
5
4
3
2
1
0
RO
0
RO
0
OSCSRC2
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31
USERCC2
R/W
0
Use RCC2
R/W
0
R/W
0
reserved
R/W
1
RO
0
RO
0
When set, overrides the RCC register fields.
30:29
reserved
RO
0x0
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.
System Clock Divisor
Specifies which divisor is used to generate the system clock from either
the PLL output or the oscillator source (depending on how the BYPASS2
bit is configured). SYSDIV2 is used for the divisor when both the
USESYSDIV bit in the RCC register and the USERCC2 bit in this register
are set. See Table 5-5 on page 177 for programming guidelines.
22:15
reserved
RO
0x0
14
USBPWRDN
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.
Power-Down USB PLL
When set, powers down the USB PLL.
13
PWRDN2
R/W
1
Power-Down PLL
When set, powers down the PLL.
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System Control
Bit/Field
Name
Type
Reset
Description
12
reserved
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
BYPASS2
R/W
1
Bypass PLL
When set, bypasses the PLL for the clock source.
See Table 5-5 on page 177 for programming guidelines.
10:7
reserved
RO
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.
6:4
OSCSRC2
R/W
0x1
Oscillator Source
Selects the input source for the OSC. The values are:
Value Description
0x0
MOSC
Main oscillator
0x1
IOSC
Internal oscillator
0x2
IOSC/4
Internal oscillator / 4
0x3
30 kHz
30-kHz internal oscillator
0x4
Reserved
0x5
Reserved
0x6
Reserved
0x7
32 kHz
32.768-kHz external oscillator
3:0
reserved
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.
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Stellaris® LM3S5737 Microcontroller
Register 12: Main Oscillator Control (MOSCCTL), offset 0x07C
This register provides control over the features of the main oscillator, including the ability to enable
the MOSC clock validation circuit. When enabled, this circuit monitors the energy on the MOSC
pins to provide a Clock Valid signal. If the clock goes invalid after being enabled, the part does a
hardware reset and reboots to the NMI handler.
Main Oscillator Control (MOSCCTL)
Base 0x400F.E000
Offset 0x07C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:1
reserved
RO
0x0
0
CVAL
R/W
0
RO
0
CVAL
R/W
0
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.
Clock Validation for MOSC
When set, the monitor circuit is enabled.
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System Control
Register 13: 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
reserved
Type
Reset
25
24
23
22
21
20
DSDIVORIDE
18
17
16
reserved
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
19
DSOSCSRC
RO
0
Bit/Field
Name
Type
Reset
31:29
reserved
RO
0x0
28:23
DSDIVORIDE
R/W
0x0F
R/W
0
reserved
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.
Divider Field Override
6-bit system divider field to override when Deep-Sleep occurs with PLL
running.
22:7
reserved
RO
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.
6:4
DSOSCSRC
R/W
0x0
Clock Source
Specifies the clock source during Deep-Sleep mode.
Value Description
0x0
MOSC
Use main oscillator as source.
0x1
IOSC
Use internal 12-MHz oscillator as source.
0x2
Reserved
0x3
30 kHz
Use 30-kHz internal oscillator as source.
0x4
Reserved
0x5
Reserved
0x6
Reserved
0x7
32 kHz
Use 32.768-kHz external oscillator as source.
3:0
reserved
RO
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.
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Stellaris® LM3S5737 Microcontroller
Register 14: Device Identification 1 (DID1), offset 0x004
This register identifies the device family, part number, temperature range, pin count, and package
type. Each microcontroller is uniquely identified by the combined values of the CLASS field in the
DID0 register and the PARTNO field in the DID1 register.
Device Identification 1 (DID1)
Base 0x400F.E000
Offset 0x004
Type RO, reset 31
30
29
28
27
26
RO
0
15
25
24
23
22
21
20
RO
0
RO
0
RO
1
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
1
14
13
12
11
10
9
8
7
6
5
4
RO
0
RO
0
RO
0
RO
0
RO
0
RO
-
RO
-
RO
-
VER
Type
Reset
FAM
PINCOUNT
Type
Reset
RO
0
RO
0
18
17
16
RO
0
RO
1
RO
1
RO
1
3
2
1
0
PARTNO
reserved
RO
1
19
TEMP
Bit/Field
Name
Type
Reset
31:28
VER
RO
0x1
RO
-
PKG
ROHS
RO
-
RO
1
QUAL
RO
-
RO
-
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
0x1
27:24
FAM
RO
0x0
Second version of the DID1 register format.
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
0x0
23:16
PARTNO
RO
0x97
Stellaris family of microcontollers, that is, all devices with
external part numbers starting with LM3S.
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
0x97 LM3S5737
15:13
PINCOUNT
RO
0x2
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
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Bit/Field
Name
Type
Reset
Description
12:8
reserved
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.
7:5
TEMP
RO
-
Temperature Range
This field specifies the temperature rating of the device. The value is
encoded as follows (all other encodings are reserved):
Value Description
4:3
PKG
RO
-
0x0
Commercial temperature range (0°C to 70°C)
0x1
Industrial temperature range (-40°C to 85°C)
0x2
Extended temperature range (-40°C to 105°C)
Package Type
This field specifies the package type. The value is encoded as follows
(all other encodings are reserved):
Value Description
2
ROHS
RO
1
0x0
SOIC package
0x1
LQFP package
0x2
BGA package
RoHS-Compliance
This bit specifies whether the device is RoHS-compliant. A 1 indicates
the part is RoHS-compliant.
1:0
QUAL
RO
-
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
204
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Stellaris® LM3S5737 Microcontroller
Register 15: 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.003F
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
SRAMSZ
Type
Reset
FLASHSZ
Type
Reset
RO
0
Bit/Field
Name
Type
Reset
Description
31:16
SRAMSZ
RO
0x00FF
SRAM Size
Indicates the size of the on-chip SRAM memory.
Value
Description
0x00FF 64 KB of SRAM
15:0
FLASHSZ
RO
0x003F
Flash Size
Indicates the size of the on-chip flash memory.
Value
Description
0x003F 128 KB of Flash
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System Control
Register 16: Device Capabilities 1 (DC1), offset 0x010
This register is predefined by the part and can be used to verify features. The PWM, SARADC0,
MAXADCSPD, WDT, SWO, SWD, and JTAG bits mask the RCGC0, SCGC0, and DCGC0 registers.
Other bits are passed as 0. MAXADCSPD is clipped to the maximum value specified in DC1.
Device Capabilities 1 (DC1)
Base 0x400F.E000
Offset 0x010
Type RO, reset 0x0101.32FF
31
30
29
RO
0
RO
0
RO
0
15
14
13
RO
0
RO
0
28
27
26
25
RO
0
RO
0
RO
0
RO
0
12
11
10
9
RO
1
RO
0
reserved
Type
Reset
MINSYSDIV
Type
Reset
RO
1
24
23
22
21
19
18
17
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
8
7
6
5
4
3
2
1
0
MPU
RO
1
HIB
TEMPSNS
PLL
WDT
SWO
SWD
JTAG
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
CAN0
reserved
RO
0
MAXADCSPD
RO
1
RO
0
20
reserved
16
ADC
Bit/Field
Name
Type
Reset
Description
31:25
reserved
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.
24
CAN0
RO
1
CAN Module 0 Present
When set, indicates that CAN unit 0 is present.
23:17
reserved
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.
16
ADC
RO
1
ADC Module Present. When set, indicates that the ADC module is
present.
15:12
MINSYSDIV
RO
0x3
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
11:10
reserved
RO
0
9:8
MAXADCSPD
RO
0x2
Specifies a 50-MHz CPU clock with a PLL divider of 4.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
Max ADC Speed. This field indicates the maximum rate at which the
ADC samples data.
Value Description
0x2
7
MPU
RO
1
500K samples/second
MPU Present. When set, indicates that the Cortex-M3 Memory Protection
Unit (MPU) module is present. See the "Cortex-M3 Peripherals" chapter
in the Stellaris Data Sheet for details on the MPU.
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
Description
6
HIB
RO
1
Hibernation Module Present. When set, indicates that the Hibernation
module is present.
5
TEMPSNS
RO
1
Temp Sensor Present. When set, indicates that the on-chip temperature
sensor is present.
4
PLL
RO
1
PLL Present. When set, indicates that the on-chip Phase Locked Loop
(PLL) is present.
3
WDT
RO
1
Watchdog Timer Present. When set, indicates that a watchdog timer is
present.
2
SWO
RO
1
SWO Trace Port Present. When set, indicates that the Serial Wire Output
(SWO) trace port is present.
1
SWD
RO
1
SWD Present. When set, indicates that the Serial Wire Debugger (SWD)
is present.
0
JTAG
RO
1
JTAG Present. When set, indicates that the JTAG debugger interface
is present.
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System Control
Register 17: Device Capabilities 2 (DC2), offset 0x014
This register is predefined by the part and can be used to verify features.
Device Capabilities 2 (DC2)
Base 0x400F.E000
Offset 0x014
Type RO, reset 0x0007.5031
31
30
29
28
27
26
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
reserved
I2C1
reserved
I2C0
RO
0
RO
1
RO
0
RO
1
RO
0
25
24
23
22
21
20
19
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
10
9
8
7
6
5
4
3
SSI1
SSI0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
reserved
Type
Reset
Type
Reset
reserved
18
17
16
TIMER2
TIMER1
TIMER0
RO
1
RO
1
RO
1
2
1
0
reserved
RO
0
RO
0
UART0
RO
0
RO
1
Bit/Field
Name
Type
Reset
Description
31:19
reserved
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.
18
TIMER2
RO
1
Timer 2 Present. When set, indicates that General-Purpose Timer
module 2 is present.
17
TIMER1
RO
1
Timer 1 Present. When set, indicates that General-Purpose Timer
module 1 is present.
16
TIMER0
RO
1
Timer 0 Present. When set, indicates that General-Purpose Timer
module 0 is present.
15
reserved
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
I2C1
RO
1
I2C Module 1 Present. When set, indicates that I2C module 1 is present.
13
reserved
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.
12
I2C0
RO
1
I2C Module 0 Present. When set, indicates that I2C module 0 is present.
11:6
reserved
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
SSI1
RO
1
SSI1 Present. When set, indicates that SSI module 1 is present.
4
SSI0
RO
1
SSI0 Present. When set, indicates that SSI module 0 is present.
3:1
reserved
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
UART0
RO
1
UART0 Present. When set, indicates that UART module 0 is present.
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Stellaris® LM3S5737 Microcontroller
Register 18: Device Capabilities 3 (DC3), offset 0x018
This register is predefined by the part and can be used to verify features.
Device Capabilities 3 (DC3)
Base 0x400F.E000
Offset 0x018
Type RO, reset 0x87FF.0000
31
30
29
RO
1
RO
0
RO
0
RO
0
RO
0
15
14
13
12
RO
0
RO
0
RO
0
RO
0
32KHZ
Type
Reset
28
27
26
25
24
23
22
21
20
19
18
17
16
CCP2
CCP1
CCP0
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
reserved
Type
Reset
Bit/Field
Name
Type
Reset
Description
31
32KHZ
RO
1
32KHz Input Clock Available. When set, indicates an even CCP pin is
present and can be used as a 32-KHz input clock.
30:27
reserved
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.
26
CCP2
RO
1
CCP2 Pin Present. When set, indicates that Capture/Compare/PWM
pin 2 is present.
25
CCP1
RO
1
CCP1 Pin Present. When set, indicates that Capture/Compare/PWM
pin 1 is present.
24
CCP0
RO
1
CCP0 Pin Present. When set, indicates that Capture/Compare/PWM
pin 0 is present.
23
ADC7
RO
1
ADC7 Pin Present. When set, indicates that ADC pin 7 is present.
22
ADC6
RO
1
ADC6 Pin Present. When set, indicates that ADC pin 6 is present.
21
ADC5
RO
1
ADC5 Pin Present. When set, indicates that ADC pin 5 is present.
20
ADC4
RO
1
ADC4 Pin Present. When set, indicates that ADC pin 4 is present.
19
ADC3
RO
1
ADC3 Pin Present. When set, indicates that ADC pin 3 is present.
18
ADC2
RO
1
ADC2 Pin Present. When set, indicates that ADC pin 2 is present.
17
ADC1
RO
1
ADC1 Pin Present. When set, indicates that ADC pin 1 is present.
16
ADC0
RO
1
ADC0 Pin Present. When set, indicates that ADC pin 0 is present.
15:0
reserved
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.
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System Control
Register 19: Device Capabilities 4 (DC4), offset 0x01C
This register is predefined by the part and can be used to verify features.
Device Capabilities 4 (DC4)
Base 0x400F.E000
Offset 0x01C
Type RO, reset 0x0000.30FF
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
UDMA
ROM
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
GPIOH
GPIOG
GPIOF
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
reserved
Bit/Field
Name
Type
Reset
Description
31:14
reserved
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.
13
UDMA
RO
1
Micro-DMA is present
12
ROM
RO
1
Internal Code ROM is present
11:8
reserved
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
GPIOH
RO
1
GPIO Port H Present. When set, indicates that GPIO Port H is present.
6
GPIOG
RO
1
GPIO Port G Present. When set, indicates that GPIO Port G is present.
5
GPIOF
RO
1
GPIO Port F Present. When set, indicates that GPIO Port F is present.
4
GPIOE
RO
1
GPIO Port E Present. When set, indicates that GPIO Port E is present.
3
GPIOD
RO
1
GPIO Port D Present. When set, indicates that GPIO Port D is present.
2
GPIOC
RO
1
GPIO Port C Present. When set, indicates that GPIO Port C is present.
1
GPIOB
RO
1
GPIO Port B Present. When set, indicates that GPIO Port B is present.
0
GPIOA
RO
1
GPIO Port A Present. When set, indicates that GPIO Port A is present.
210
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Stellaris® LM3S5737 Microcontroller
Register 20: Device Capabilities 5 (DC5), offset 0x020
This register is predefined by the part and can be used to verify features.
Device Capabilities 5 (DC5)
Base 0x400F.E000
Offset 0x020
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:0
reserved
RO
0
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.
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System Control
Register 21: Device Capabilities 6 (DC6), offset 0x024
This register is predefined by the part and can be used to verify features.
Device Capabilities 6 (DC6)
Base 0x400F.E000
Offset 0x024
Type RO, reset 0x0000.0002
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0
1:0
USB0
RO
0x2
USB0
RO
0
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.
This specifies that USB0 is present and its capability
Value Description
0x2
USB is Device or Host.
212
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Stellaris® LM3S5737 Microcontroller
Register 22: Device Capabilities 7 (DC7), offset 0x028
This register is predefined by the part and can be used to verify uDMA channel features.
Device Capabilities 7 (DC7)
Base 0x400F.E000
Offset 0x028
Type RO, reset 0x4300.0F3F
Type
Reset
31
30
29
28
reserved
SW
RO
0
RO
1
RO
0
RO
0
26
RO
0
RO
0
RO
1
15
14
13
12
11
10
9
RO
0
RO
0
reserved
reserved
Type
Reset
27
25
24
23
22
21
20
RO
1
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
SSI1_TX SSI1_RX
SSI0_TX SSI0_RX UART0_TX UART0_RX
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
reserved
reserved
RO
0
USB_EP3_TX USB_EP3_RX USB_EP2_TX USB_EP2_RX USB_EP1_TX USB_EP1_RX
RO
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
Bit/Field
Name
Type
Reset
Description
31
reserved
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.
30
SW
RO
1
Software transfer on uDMA Ch30. When set, indicates uDMA channel
30 is available for software.
29:26
reserved
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.
25
SSI1_TX
RO
1
SSI1 TX on uDMA Ch25. When set, indicates uDMA channel 25 is
available and connected to the transmit path of SSI module 1.
24
SSI1_RX
RO
1
SSI1 RX on uDMA Ch24. When set, indicates uDMA channel 24 is
available and connected to the receive path of SSI module 1.
23:12
reserved
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
SSI0_TX
RO
1
SSI0 TX on uDMA Ch11. When set, indicates uDMA channel 11 is
available and connected to the transmit path of SSI module 0.
10
SSI0_RX
RO
1
SSI0 RX on uDMA Ch10. When set, indicates uDMA channel 10 is
available and connected to the receive path of SSI module 0.
9
UART0_TX
RO
1
UART0 TX on uDMA Ch9. When set, indicates uDMA channel 9 is
available and connected to the transmit path of UART module 0.
8
UART0_RX
RO
1
UART0 RX on uDMA Ch8. When set, indicates uDMA channel 8 is
available and connected to the receive path of UART module 0.
7:6
reserved
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
USB_EP3_TX
RO
1
USB EP3 TX on uDMA Ch5. When set, indicates uDMA channel 5 is
available and connected to the transmit path of USB endpoint 3.
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Bit/Field
Name
Type
Reset
Description
4
USB_EP3_RX
RO
1
USB EP3 RX on uDMA Ch4. When set, indicates uDMA channel 4 is
available and connected to the receive path of USB endpoint 2.
3
USB_EP2_TX
RO
1
USB EP2 TX on uDMA Ch3. When set, indicates uDMA channel 3 is
available and connected to the transmit path of USB endpoint 2.
2
USB_EP2_RX
RO
1
USB EP2 RX on uDMA Ch2. When set, indicates uDMA channel 1 is
available and connected to the receive path of USB endpoint 2.
1
USB_EP1_TX
RO
1
USB EP1 TX on uDMA Ch1. When set, indicates uDMA channel 1 is
available and connected to the transmit path of USB endpoint 1.
0
USB_EP1_RX
RO
1
USB EP1 RX on uDMA Ch0. When set, indicates uDMA channel 0 is
available and connected to the receive path of USB endpoint 1.
214
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Stellaris® LM3S5737 Microcontroller
Register 23: 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
RO
0
RO
0
RO
0
15
14
13
RO
0
RO
0
RO
0
28
27
26
25
RO
0
RO
0
RO
0
RO
0
12
11
10
9
RO
0
RO
0
R/W
0
reserved
Type
Reset
RO
0
23
22
21
R/W
0
RO
0
RO
0
RO
0
8
7
6
5
CAN0
reserved
Type
Reset
24
MAXADCSPD
R/W
0
20
19
18
17
RO
0
RO
0
RO
0
RO
0
R/W
0
4
3
2
1
0
reserved
reserved
HIB
RO
0
R/W
1
reserved
RO
0
RO
0
16
ADC
WDT
R/W
0
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:25
reserved
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.
24
CAN0
R/W
0
CAN0 Clock Gating Control. This bit controls the clock gating for CAN
unit 0. If set, the unit receives a clock and functions. Otherwise, the unit
is unclocked and disabled.
23:17
reserved
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.
16
ADC
R/W
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.
15:10
reserved
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.
November 17, 2011
215
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
9:8
MAXADCSPD
R/W
0
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
7
reserved
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.
6
HIB
R/W
1
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.
5:4
reserved
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
WDT
R/W
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.
2:0
reserved
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.
216
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 24: 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
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
24
23
22
21
CAN0
RO
0
R/W
0
9
8
MAXADCSPD
RO
0
RO
0
R/W
0
R/W
0
20
19
18
17
reserved
RO
0
RO
0
RO
0
RO
0
5
4
7
6
reserved
HIB
RO
0
R/W
1
reserved
RO
0
RO
0
16
ADC
RO
0
RO
0
3
2
WDT
R/W
0
RO
0
R/W
0
1
0
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:25
reserved
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.
24
CAN0
R/W
0
CAN0 Clock Gating Control. This bit controls the clock gating for CAN
unit 0. If set, the unit receives a clock and functions. Otherwise, the unit
is unclocked and disabled.
23:17
reserved
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.
16
ADC
R/W
0
ADC0 Clock Gating Control. This bit controls the clock gating for general
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.
15:10
reserved
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.
November 17, 2011
217
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
9:8
MAXADCSPD
R/W
0
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
7
reserved
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.
6
HIB
R/W
1
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.
5:4
reserved
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
WDT
R/W
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.
2:0
reserved
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.
218
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 25: 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
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
15
14
13
12
24
23
RO
0
RO
0
RO
0
RO
0
21
RO
0
RO
0
RO
0
R/W
0
RO
0
11
10
9
8
7
RO
0
RO
0
RO
0
6
5
4
HIB
RO
0
RO
0
RO
0
RO
0
20
19
18
17
reserved
reserved
Type
Reset
22
CAN0
RO
0
R/W
1
reserved
RO
0
RO
0
16
ADC
RO
0
RO
0
3
2
WDT
R/W
0
RO
0
R/W
0
1
0
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:25
reserved
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.
24
CAN0
R/W
0
CAN0 Clock Gating Control. This bit controls the clock gating for CAN
unit 0. If set, the unit receives a clock and functions. Otherwise, the unit
is unclocked and disabled.
23:17
reserved
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.
16
ADC
R/W
0
ADC0 Clock Gating Control. This bit controls the clock gating for general
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.
15:7
reserved
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.
6
HIB
R/W
1
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.
5:4
reserved
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.
November 17, 2011
219
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
3
WDT
R/W
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.
2:0
reserved
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.
220
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 26: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
reserved
I2C1
reserved
I2C0
RO
0
R/W
0
RO
0
R/W
0
RO
0
25
24
23
22
21
20
19
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
10
9
8
7
6
5
4
3
SSI1
SSI0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
Type
Reset
reserved
18
17
16
TIMER2
TIMER1
TIMER0
R/W
0
R/W
0
R/W
0
2
1
0
reserved
RO
0
RO
0
UART0
RO
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:19
reserved
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.
18
TIMER2
R/W
0
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.
17
TIMER1
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.
16
TIMER0
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.
15
reserved
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
I2C1
R/W
0
I2C1 Clock Gating Control. This bit controls the clock gating for I2C
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.
November 17, 2011
221
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
13
reserved
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.
12
I2C0
R/W
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.
11:6
reserved
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
SSI1
R/W
0
SSI1 Clock Gating Control. This bit controls the clock gating for SSI
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.
4
SSI0
R/W
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.
3:1
reserved
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
UART0
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.
222
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 27: 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
reserved
Type
Reset
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
11
10
9
8
7
6
15
14
13
12
reserved
I2C1
reserved
I2C0
RO
0
R/W
0
RO
0
R/W
0
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
3
5
4
SSI1
SSI0
R/W
0
R/W
0
18
17
16
TIMER2
TIMER1
TIMER0
R/W
0
R/W
0
R/W
0
2
1
reserved
RO
0
RO
0
0
UART0
RO
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:19
reserved
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.
18
TIMER2
R/W
0
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.
17
TIMER1
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.
16
TIMER0
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.
15
reserved
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
I2C1
R/W
0
I2C1 Clock Gating Control. This bit controls the clock gating for I2C
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.
November 17, 2011
223
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
13
reserved
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.
12
I2C0
R/W
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.
11:6
reserved
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
SSI1
R/W
0
SSI1 Clock Gating Control. This bit controls the clock gating for SSI
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.
4
SSI0
R/W
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.
3:1
reserved
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
UART0
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.
224
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 28: 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
reserved
Type
Reset
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
11
10
9
8
7
6
15
14
13
12
reserved
I2C1
reserved
I2C0
RO
0
R/W
0
RO
0
R/W
0
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
3
5
4
SSI1
SSI0
R/W
0
R/W
0
18
17
16
TIMER2
TIMER1
TIMER0
R/W
0
R/W
0
R/W
0
2
1
reserved
RO
0
RO
0
0
UART0
RO
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:19
reserved
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.
18
TIMER2
R/W
0
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.
17
TIMER1
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.
16
TIMER0
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.
15
reserved
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
I2C1
R/W
0
I2C1 Clock Gating Control. This bit controls the clock gating for I2C
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.
November 17, 2011
225
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
13
reserved
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.
12
I2C0
R/W
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.
11:6
reserved
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
SSI1
R/W
0
SSI1 Clock Gating Control. This bit controls the clock gating for SSI
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.
4
SSI0
R/W
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.
3:1
reserved
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
UART0
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.
226
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 29: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
24
23
22
21
20
19
18
17
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
9
8
7
6
5
4
3
2
1
0
GPIOH
GPIOG
GPIOF
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
UDMA
RO
0
R/W
0
reserved
RO
0
16
USB0
Bit/Field
Name
Type
Reset
Description
31:17
reserved
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.
16
USB0
R/W
0
USB0 Clock Gating Control. This bit controls the clock gating for Port
H. 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.
15:14
reserved
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.
13
UDMA
R/W
0
UDMA Clock Gating Control. This bit controls the clock gating for Port
H. 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.
12:8
reserved
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
GPIOH
R/W
0
Port H Clock Gating Control. This bit controls the clock gating for Port
H. 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.
November 17, 2011
227
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
6
GPIOG
R/W
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.
5
GPIOF
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.
4
GPIOE
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.
3
GPIOD
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.
2
GPIOC
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.
1
GPIOB
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.
0
GPIOA
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.
228
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 30: 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
reserved
Type
Reset
RO
0
RO
0
15
14
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
13
12
11
UDMA
RO
0
R/W
0
RO
0
RO
0
RO
0
10
9
8
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
16
USB0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
7
6
5
4
3
2
1
0
GPIOH
GPIOG
GPIOF
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:17
reserved
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.
16
USB0
R/W
0
USB0 Clock Gating Control. This bit controls the clock gating for Port
H. 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.
15:14
reserved
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.
13
UDMA
R/W
0
UDMA Clock Gating Control. This bit controls the clock gating for Port
H. 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.
12:8
reserved
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
GPIOH
R/W
0
Port H Clock Gating Control. This bit controls the clock gating for Port
H. 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.
November 17, 2011
229
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
6
GPIOG
R/W
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.
5
GPIOF
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.
4
GPIOE
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.
3
GPIOD
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.
2
GPIOC
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.
1
GPIOB
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.
0
GPIOA
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.
230
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 31: 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
reserved
Type
Reset
RO
0
RO
0
15
14
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
13
12
11
UDMA
RO
0
R/W
0
RO
0
RO
0
RO
0
10
9
8
reserved
RO
0
RO
0
RO
0
RO
0
RO
0
16
USB0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
7
6
5
4
3
2
1
0
GPIOH
GPIOG
GPIOF
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:17
reserved
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.
16
USB0
R/W
0
USB0 Clock Gating Control. This bit controls the clock gating for Port
H. 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.
15:14
reserved
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.
13
UDMA
R/W
0
UDMA Clock Gating Control. This bit controls the clock gating for Port
H. 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.
12:8
reserved
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
GPIOH
R/W
0
Port H Clock Gating Control. This bit controls the clock gating for Port
H. 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.
November 17, 2011
231
Texas Instruments-Production Data
System Control
Bit/Field
Name
Type
Reset
Description
6
GPIOG
R/W
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.
5
GPIOF
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.
4
GPIOE
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.
3
GPIOD
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.
2
GPIOC
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.
1
GPIOB
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.
0
GPIOA
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.
232
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 32: 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
RO
0
RO
0
RO
0
15
14
RO
0
RO
0
23
22
21
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
13
12
11
10
9
8
7
6
5
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
reserved
Type
Reset
24
CAN0
HIB
RO
0
19
18
17
RO
0
RO
0
RO
0
RO
0
R/W
0
4
3
2
1
0
reserved
reserved
Type
Reset
20
reserved
RO
0
RO
0
16
ADC
WDT
R/W
0
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:25
reserved
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.
24
CAN0
R/W
0
CAN0 Reset Control. Reset control for CAN unit 0.
23:17
reserved
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.
16
ADC
R/W
0
ADC0 Reset Control. Reset control for SAR ADC module 0.
15:7
reserved
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.
6
HIB
R/W
0
HIB Reset Control. Reset control for the Hibernation module.
5:4
reserved
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
WDT
R/W
0
WDT Reset Control. Reset control for Watchdog unit.
2:0
reserved
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.
November 17, 2011
233
Texas Instruments-Production Data
System Control
Register 33: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
reserved
I2C1
reserved
I2C0
RO
0
R/W
0
RO
0
R/W
0
RO
0
25
24
23
22
21
20
19
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
10
9
8
7
6
5
4
3
SSI1
SSI0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
Type
Reset
reserved
18
17
16
TIMER2
TIMER1
TIMER0
R/W
0
R/W
0
R/W
0
2
1
0
reserved
RO
0
RO
0
UART0
RO
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:19
reserved
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.
18
TIMER2
R/W
0
Timer 2 Reset Control. Reset control for General-Purpose Timer module
2.
17
TIMER1
R/W
0
Timer 1 Reset Control. Reset control for General-Purpose Timer module
1.
16
TIMER0
R/W
0
Timer 0 Reset Control. Reset control for General-Purpose Timer module
0.
15
reserved
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
I2C1
R/W
0
I2C1 Reset Control. Reset control for I2C unit 1.
13
reserved
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.
12
I2C0
R/W
0
I2C0 Reset Control. Reset control for I2C unit 0.
11:6
reserved
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
SSI1
R/W
0
SSI1 Reset Control. Reset control for SSI unit 1.
4
SSI0
R/W
0
SSI0 Reset Control. Reset control for SSI unit 0.
3:1
reserved
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
UART0
R/W
0
UART0 Reset Control. Reset control for UART unit 0.
234
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 34: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
24
23
22
21
20
19
18
17
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
9
8
7
6
5
4
3
2
1
0
GPIOH
GPIOG
GPIOF
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
UDMA
RO
0
R/W
0
reserved
RO
0
16
USB0
Bit/Field
Name
Type
Reset
Description
31:17
reserved
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.
16
USB0
R/W
0
USB0 Reset Control. Reset control for USB unit 0.
15:14
reserved
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.
13
UDMA
R/W
0
UDMA Reset Control. Reset control for uDMA unit.
12:8
reserved
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
GPIOH
R/W
0
Port H Reset Control. Reset control for GPIO Port H.
6
GPIOG
R/W
0
Port G Reset Control. Reset control for GPIO Port G.
5
GPIOF
R/W
0
Port F Reset Control. Reset control for GPIO Port F.
4
GPIOE
R/W
0
Port E Reset Control. Reset control for GPIO Port E.
3
GPIOD
R/W
0
Port D Reset Control. Reset control for GPIO Port D.
2
GPIOC
R/W
0
Port C Reset Control. Reset control for GPIO Port C.
1
GPIOB
R/W
0
Port B Reset Control. Reset control for GPIO Port B.
0
GPIOA
R/W
0
Port A Reset Control. Reset control for GPIO Port A.
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6
Hibernation Module
The Hibernation Module manages removal and restoration of power 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:
■ System power control using discrete external regulator
■ Dedicated pin for waking from an external signal
■ Low-battery detection, signaling, and interrupt generation
■ 32-bit real-time clock (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
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6.1
Block Diagram
Figure 6-1. Hibernation Module Block Diagram
HIBCTL.CLK32EN
32.768 kHz
XOSC0
Pre-Divider
4.194304 MHz
XOSC1
Interrupts
HIBIM
HIBRIS
HIBMIS
HIBIC
HIBRTCT
/128
HIBCTL.CLKSEL
Non-Volatile
Memory
64 words
HIBDATA
RTC
HIBRTCC
HIBRTCLD
HIBRTCM0
HIBRTCM1
MATCH0/1
WAKE
LOWBAT
VDD
Low Battery
Detect
VBAT
HIBCTL.LOWBATEN
6.2
Interrupts
to CPU
Power
Sequence
Logic
HIB
HIBCTL.PWRCUT
HIBCTL.RTCWEN
HIBCTL.EXTWEN
HIBCTL.VABORT
Signal Description
Table 6-1 on page 237 lists the external signals of the Hibernation module and describes the function
of each. These signals have dedicated functions and are not alternate functions for any GPIO signals.
Table 6-1. Hibernate Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
HIB
51
O
OD
An output that indicates the processor is in Hibernate mode.
VBAT
55
-
Power
Power source for the Hibernation module. It is normally
connected to the positive terminal of a battery and serves as
the battery backup/Hibernation module power-source supply.
WAKE
50
I
TTL
An external input that brings the processor out of Hibernate
mode when asserted.
XOSC0
52
I
Analog
Hibernation module oscillator crystal input or an external clock
reference input. Note that this is either a crystal or a
32.768-kHz oscillator for the Hibernation module RTC.
XOSC1
53
O
Analog
Hibernation module oscillator crystal output. Leave
unconnected when using a single-ended clock source.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
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6.3
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 source 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.
When waking from hibernation, the HIB signal is deasserted. The return of VDD causes a POR to
be executed. The time from when the WAKE signal is asserted to when code begins execution is
equal to the wake-up time (tWAKE_TO_HIB) plus the power-on reset time (TIRPOR).
6.3.1
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
restriction on timing for back-to-back reads from the Hibernation module. Software may make use
of the WRC bit in the HIBCTL register to ensure that the required timing gap has elapsed. This bit is
cleared on a write operation and set once the write completes, indicating to software that another
write or read may be started safely. Software should poll HIBCTL for WRC=1 prior to accessing any
affected register. The following registers are subject to this timing restriction:
■ Hibernation RTC Counter (HIBRTCC)
■ Hibernation RTC Match 0 (HIBRTCM0)
■ Hibernation RTC Match 1 (HIBRTCM1)
■ Hibernation RTC Load (HIBRTCLD)
■ Hibernation RTC Trim (HIBRTCT)
■ Hibernation Data (HIBDATA)
6.3.2
Clock Source
The Hibernation module must be clocked by an external source, even if the RTC feature is not 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. For an alternate clock source, a 32.768-kHz oscillator can
be connected to the XOSC0 pin. See Figure 6-2 on page 239 and Figure 6-3 on page 239. Note that
these diagrams only show the connection to the Hibernation pins and not to the full system. See
“Hibernation Module” on page 777 for specific values.
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 4.194304-MHz input clock is divided by 128,
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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.
Figure 6-2. Clock Source Using Crystal
Stellaris Microcontroller
Regulator
or Switch
Input
Voltage
IN
OUT
VDD
EN
XOSC0
X1
RL
XOSC1
C1
C2
HIB
WAKE
RPU
Open drain
external wake
up circuit
Note:
VBAT
3V
Battery
GND
X1 = Crystal frequency is fXOSC_XTAL.
C1,2 = Capacitor value derived from crystal vendor load capacitance specifications.
RL = Load resistor is RXOSC_LOAD.
RPU = Pull-up resistor (1 M½).
See “Hibernation Module” on page 777 for specific parameter values.
Figure 6-3. Clock Source Using Dedicated Oscillator
Stellaris Microcontroller
Regulator
or Switch
Input
Voltage
IN
OUT
EN
VDD
Clock
Source
XOSC0
(fEXT_OSC)
N.C.
XOSC1
HIB
WAKE
RPU
Open drain
external wake
up circuit
Note:
VBAT
GND
3V
Battery
RPU = Pull-up resistor (1 M½).
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6.3.3
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 drops below
VLOWBAT. 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 drops below this threshold. Battery
voltage is not measured while in Hibernate mode.
Important: System level factors may affect the accuracy of the low battery detect circuit. The
designer should consider battery type, discharge characteristics, and a test load during
battery voltage measurements.
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 241).
6.3.4
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 238). 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, HIBRTCT. 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
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 241). As long as the RTC is enabled and a valid VBAT is present, the
RTC continues counting, regardless of whether VDD is present or if the part is in hibernation.
6.3.5
Battery-Backed 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 battery-backed memory can be accessed through the HIBDATA registers.
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6.3.6
Power Control
Important: The Hibernation Module requires special system implementation considerations when
using HIB to control power, as it is intended to power-down all other sections of its host
device. All system signals and power supplies that connect to the chip must be driven
to 0 VDC or powered down with the same regulator controlled by HIB. See “Hibernation
Module” on page 777 for more details.
The Hibernation module controls power to the microcontroller through the use of the HIB pin. This
pin 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 system. The Hibernation module remains
powered from the VBAT supply (which could be a battery or an auxiliary power source) until a Wake
event. Power to the device is restored by deasserting the HIB signal, which causes the external
regulator to turn power back on to the chip.
6.3.7
Initiating Hibernate
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. Software
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 241) and by looking for state data in the
battery-backed memory (see “Battery-Backed Memory” on page 240).
When the HIB signal deasserts, enabling the external regulator, the external regulator must reach
the operating voltage within tHIB_TO_VDD.
6.3.8
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.
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6.4
Initialization and Configuration
The Hibernation module can be set in several different configurations. 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 32.768 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 238). The registers that require a delay are listed in a note in “Register
Map” on page 243 as well as in each register description.
6.4.1
Initialization
The Hibernation module clock source must be enabled first, even if the RTC feature is not 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.
6.4.2
RTC Match Functionality (No Hibernation)
Use the following steps to implement 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.
6.4.3
RTC Match/Wake-Up from Hibernation
Use the following steps to implement 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.
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4. Set the RTC Match Wake-Up and start the hibernation sequence by writing 0x0000.004F to the
HIBCTL register at offset 0x010.
6.4.4
External Wake-Up from Hibernation
Use the following steps to implement 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.
6.4.5
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.
6.5
Register Map
Table 6-2 on page 243 lists the Hibernation registers. All addresses given are relative to the Hibernation
Module base address at 0x400F.C000. Note that the Hibernation module clock must be enabled
before the registers can be programmed (see page 215). There must be a delay of 3 system clocks
after the Hibernation module clock is enabled before any Hibernation module registers are accessed.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
Important: The Hibernation module registers are reset under two conditions:
1. A system reset when the RTCEN and the PINWEN bits in the HIBCTL register are
both cleared.
2. A cold POR, when both the VDD and VBAT supplies are removed.
Any other reset condition is ignored by the Hibernation module.
Table 6-2. Hibernation Module Register Map
Offset
Name
0x000
Description
See
page
Type
Reset
HIBRTCC
RO
0x0000.0000
Hibernation RTC Counter
245
0x004
HIBRTCM0
R/W
0xFFFF.FFFF
Hibernation RTC Match 0
246
0x008
HIBRTCM1
R/W
0xFFFF.FFFF
Hibernation RTC Match 1
247
0x00C
HIBRTCLD
R/W
0xFFFF.FFFF
Hibernation RTC Load
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Table 6-2. Hibernation Module Register Map (continued)
Name
Type
Reset
0x010
HIBCTL
R/W
0x8000.0000
Hibernation Control
249
0x014
HIBIM
R/W
0x0000.0000
Hibernation Interrupt Mask
252
0x018
HIBRIS
RO
0x0000.0000
Hibernation Raw Interrupt Status
253
0x01C
HIBMIS
RO
0x0000.0000
Hibernation Masked Interrupt Status
254
0x020
HIBIC
R/W1C
0x0000.0000
Hibernation Interrupt Clear
255
0x024
HIBRTCT
R/W
0x0000.7FFF
Hibernation RTC Trim
256
0x0300x12C
HIBDATA
R/W
-
Hibernation Data
257
6.6
Description
See
page
Offset
Register Descriptions
The remainder of this section lists and describes the Hibernation module registers, in numerical
order by address offset.
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Register 1: Hibernation RTC Counter (HIBRTCC), offset 0x000
This register is the current 32-bit value of the RTC counter.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RTCC
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RTCC
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
31:0
RTCC
RO
RO
0
Reset
RO
0
Description
0x0000.0000 RTC Counter
A read returns the 32-bit counter value. This register is read-only. To
change the value, use the HIBRTCLD register.
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Register 2: Hibernation RTC Match 0 (HIBRTCM0), offset 0x004
This register is the 32-bit match 0 register for the RTC counter.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
RTCM0
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
RTCM0
R/W
R/W
1
Reset
R/W
1
Description
0xFFFF.FFFF RTC Match 0
A write loads the value into the RTC match register.
A read returns the current match value.
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Register 3: Hibernation RTC Match 1 (HIBRTCM1), offset 0x008
This register is the 32-bit match 1 register for the RTC counter.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
RTCM1
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
RTCM1
R/W
R/W
1
Reset
R/W
1
Description
0xFFFF.FFFF RTC Match 1
A write loads the value into the RTC match register.
A read returns the current match value.
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Hibernation Module
Register 4: Hibernation RTC Load (HIBRTCLD), offset 0x00C
This register is the 32-bit value loaded into the RTC counter.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
RTCLD
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
RTCLD
R/W
R/W
1
Reset
R/W
1
Description
0xFFFF.FFFF RTC Load
A write loads the current value into the RTC counter (RTCC).
A read returns the 32-bit load value.
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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 0x8000.0000
31
30
29
28
27
26
25
24
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
WRC
Type
Reset
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
HIBREQ
RTCEN
R/W
0
R/W
0
reserved
reserved
Type
Reset
22
VABORT CLK32EN LOWBATEN PINWEN RTCWEN CLKSEL
RO
0
Bit/Field
Name
Type
Reset
31
WRC
RO
1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Description
Write Complete/Capable
This bit indicates whether the hibernation module can receive a write
operation.
Value Description
0
The interface is processing a prior write and is busy. Any write
operation that is attempted while WRC is 0 results in
undetermined behavior.
1
The interface is ready to accept a write.
Software must poll this bit between write requests and defer writes until
WRC=1 to ensure proper operation.
This difference may be exploited by software at reset time to detect
which method of programming is appropriate: 0 = software delay loops
required; 1 = WRC paced available.
The bit name WRC means "Write Complete," which is the normal use
of the bit (between write accesses). However, because the bit is set
out-of-reset, the name can also mean "Write Capable" which simply
indicates that the interface may be written to by software. This meaning
also has more meaning to the out-of-reset sense.
30:8
reserved
RO
0x00
7
VABORT
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.
Power Cut Abort Enable
Value
Description
0
Power cut occurs during a low-battery alert.
1
Power cut is aborted.
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Bit/Field
Name
Type
Reset
6
CLK32EN
R/W
0
Description
Clocking Enable
Value
Description
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.
5
LOWBATEN
R/W
0
Low Battery Monitoring Enable
Value
Description
0
Disabled
1
Enabled
When set, low battery voltage detection is enabled (VBAT < VLOWBAT).
4
PINWEN
R/W
0
External WAKE Pin Enable
Value
Description
0
Disabled
1
Enabled
When set, an external event on the WAKE pin will re-power the device.
3
RTCWEN
R/W
0
RTC Wake-up Enable
Value
Description
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.
2
CLKSEL
R/W
0
Hibernation Module Clock Select
Value
1
HIBREQ
R/W
0
Description
0
Use Divide by 128 output. Use this value for a
4.194304-MHz crystal.
1
Use raw output. Use this value for a 32.768-kHz
oscillator.
Hibernation Request
Value
Description
0
Disabled
1
Hibernation initiated
After a wake-up event, this bit is cleared by hardware.
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Bit/Field
Name
Type
Reset
0
RTCEN
R/W
0
Description
RTC Timer Enable
Value
Description
0
Disabled
1
Enabled
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
EXTW
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x000.0000
3
EXTW
R/W
0
LOWBAT
R/W
0
RTCALT1
R/W
0
RTCALT0
R/W
0
R/W
0
R/W
0
External Wake-Up Interrupt Mask
Description
0
Masked
1
Unmasked
Low Battery Voltage Interrupt Mask
Description
0
Masked
1
Unmasked
RTC Alert1 Interrupt Mask
Value
0
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.
Value
1
LOWBAT RTCALT1 RTCALT0
Description
Value
2
R/W
0
Description
0
Masked
1
Unmasked
RTC Alert0 Interrupt Mask
Value
Description
0
Masked
1
Unmasked
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
EXTW
RO
0
Bit/Field
Name
Type
Reset
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
LOWBAT RTCALT1 RTCALT0
RO
0
RO
0
RO
0
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
EXTW
RO
0
Bit/Field
Name
Type
Reset
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
LOWBAT RTCALT1 RTCALT0
RO
0
RO
0
RO
0
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.
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Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
reserved
Type
Reset
reserved
Type
Reset
EXTW
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x000.0000
3
EXTW
R/W1C
0
LOWBAT RTCALT1 RTCALT0
R/W1C
0
R/W1C
0
R/W1C
0
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.
External Wake-Up Masked Interrupt Clear
Reads return an indeterminate value.
2
LOWBAT
R/W1C
0
Low Battery Voltage Masked Interrupt Clear
Reads return an indeterminate value.
1
RTCALT1
R/W1C
0
RTC Alert1 Masked Interrupt Clear
Reads return an indeterminate value.
0
RTCALT0
R/W1C
0
RTC Alert0 Masked Interrupt Clear
Reads return an indeterminate value.
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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.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
TRIM
Type
Reset
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
TRIM
R/W
0x7FFF
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.
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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 state information and does not lose power during a power-cut
operation as long as a battery is present.
Note:
HIBRTCC, HIBRTCM0, HIBRTCM1, HIBRTCLD, HIBRTCT, and HIBDATA are on the
Hibernation module clock domain and and have special timing requirements. Software
should make use of the WRC bit in the HIBCTL register to ensure that the required timing
gap has elapsed. See “Register Access Timing” on page 238.
Hibernation Data (HIBDATA)
Base 0x400F.C000
Offset 0x030-0x12C
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
RTD
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
8
RTD
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
31:0
RTD
R/W
-
R/W
-
Description
Hibernation Module NV Registers[63:0]
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Internal Memory
7
Internal Memory
The LM3S5737 microcontroller comes with 64 KB of bit-banded SRAM and 128 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.
7.1
Block Diagram
Figure 7-1 on page 258 illustrates the Flash functions. The dashed boxes in the figure indicate
registers residing in the System Control module rather than the Flash Control module.
Figure 7-1. Flash Block Diagram
ROM Control
ROM Array
RMCTL
Icode Bus
Cortex-M3
System
Bus
Dcode Bus
Flash Control
FMA
FMD
FMC
FCRIS
FCIM
FCMISC
Flash Array
Flash Protection
Bridge
FMPREn
FMPPEn
Flash Timing
USECRL
User Registers
USER_DBG
USER_REG0
USER_REG1
USER_REG2
USER_REG3
SRAM Array
7.2
Functional Description
This section describes the functionality of the SRAM, ROM, and Flash memories.
7.2.1
SRAM Memory
Note:
The SRAM memory is implemented using two 32-bit wide SRAM banks (separate SRAM
arrays). The banks are partitioned so that one bank contains all even words (the even bank)
and the other contains all odd words (the odd bank). A write access that is followed
immediately by a read access to the same bank will incur a stall of a single clock cycle.
However, a write to one bank followed by a read of the other bank can occur in successive
clock cycles without incurring any delay.
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®
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:
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, see “Bit-Banding” on page 74.
7.2.2
ROM Memory
The ROM of the Stellaris device is located at address 0x0100.0000 of the device memory map and
contains the following components:
■ Stellaris Boot Loader and vector table (see “Boot Loader” on page 783)
■ Stellaris Peripheral Driver Library (DriverLib) release for product-specific peripherals and interfaces
(see “ROM DriverLib Functions” on page 788)
7.2.3
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.
7.2.3.1
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.
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Internal Memory
7.2.3.2
Flash Memory Protection
The user is provided two forms of flash protection per 2-KB flash blocks in two 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 a bit is set, the corresponding block may
be executed or read by software or debuggers. If a bit is cleared, the corresponding block may
only be executed, and contents of the memory block are prohibited from being read as data.
The policies may be combined as shown in Table 7-1 on page 260.
Table 7-1. Flash Protection Policy Combinations
FMPPEn
FMPREn
Protection
0
0
Execute-only protection. The block may only be executed and may not be written or erased.
This mode is used to protect code.
1
0
The block may be written, erased or executed, but not read. This combination is unlikely to
be used.
0
1
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.
1
1
No protection. The block may be written, erased, executed or read.
A Flash memory access that attempts to read a read-protected block (FMPREn bit is set) is prohibited
and generates a bus fault. A Flash memory access that attempts to program or erase a
program-protected block (FMPPEn bit is set) is prohibited and can optionally generate an interrupt
(by setting the AMASK bit in the Flash Controller Interrupt Mask (FCIM) register) 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. These settings create a policy of open access and programmability. The register bits may
be changed by clearing 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. The changes
are committed using the Flash Memory Control (FMC) register. Details on programming these bits
are discussed in “Nonvolatile Register Programming” on page 261.
7.2.3.3
Interrupts
The Flash memory controller can generate interrupts when the following conditions are observed:
■ Programming Interrupt - signals when a program or erase action is complete.
■ Access Interrupt - signals when a program or erase action has been attempted on a 2-kB block
of memory that is protected by its corresponding FMPPEn bit.
The interrupt events that can trigger a controller-level interrupt are defined in the Flash Controller
Masked Interrupt Status (FCMIS) register (see page 270) by setting the corresponding MASK bits.
If interrupts are not used, the raw interrupt status is always visible via the Flash Controller Raw
Interrupt Status (FCRIS) register (see page 269).
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Interrupts are always cleared (for both the FCMIS and FCRIS registers) by writing a 1 to the
corresponding bit in the Flash Controller Masked Interrupt Status and Clear (FCMISC) register
(see page 271).
7.3
Flash Memory Initialization and Configuration
7.3.1
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.
During a Flash memory operation (write, page erase, or mass erase) access to the Flash memory
is inhibited. As a result, instruction and literal fetches are held off until the Flash memory operation
is complete. If instruction execution is required during a Flash memory operation, the code that is
executing must be placed in SRAM and executed from there while the flash operation is in progress.
7.3.1.1
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.
7.3.1.2
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.
7.3.1.3
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.
7.3.2
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 memory array and are not affected
by an ERASE or MASS ERASE operation. The bits in these registers can be changed from 1 to 0
with a write operation. Prior to being committed, the register contents are unaffected by any reset
condition except power-on reset, which returns the register contents to the original value. By
committing the register values using the COMT bit in the FMC register, the register contents become
nonvolatile and are therefore retained following power cycling. Once the register contents are
committed, the only way to restore the factory default values is to perform the sequence described
in the section called “Recovering a "Locked" Device” on page 162.
With the exception of the USER_DBG register, the settings in these registers can be tested before
committing them to Flash memory. For the USER_DBG register, the data to be written is loaded
into the FMD register before it is committed. The FMD register is read only and does not allow the
USER_DBG operation to be tried before committing it to nonvolatile memory.
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Important: The Flash memory resident registers can only have bits changed from 1 to 0 by user
programming and can only be committed once. After being committed, these registers
can only be restored to their factory default values only by performing the sequence
described in the section called “Recovering a "Locked" Device” on page 162. The mass
erase of the main Flash memory array caused by the sequence is performed prior to
restoring these registers.
In addition, the USER_REG0, USER_REG1, USER_REG2, USER_REG3, and USER_DBG registers
each use bit 31 (NW) to indicate that they have not been committed and bits in the register may be
changed from 1 to 0. Table 7-2 on page 262 provides the FMA address required for commitment of
each of the registers and the source of the data to be written when 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 7-2. User-Programmable Flash Memory Resident Registers
Register to be Committed
7.4
FMA Value
Data Source
FMPRE0
0x0000.0000
FMPRE0
FMPRE1
0x0000.0002
FMPRE1
FMPPE0
0x0000.0001
FMPPE0
FMPPE1
0x0000.0003
FMPPE1
USER_REG0
0x8000.0000
USER_REG0
USER_REG1
0x8000.0001
USER_REG1
USER_REG2
0x8000.0002
USER_REG2
USER_REG3
0x8000.0003
USER_REG3
USER_DBG
0x7510.0000
FMD
Register Map
Table 7-3 on page 262 lists the ROM Controller register and 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 register offsets are relative to the Flash memory control base address of
0x400F.D000. The ROM and Flash memory protection register offsets are relative to the System
Control base address of 0x400F.E000.
Table 7-3. Flash Register Map
Offset
Name
Type
Reset
Description
See
page
-
ROM Control
264
ROM Registers (System Control Offset)
0x0F0
RMCTL
R/W1C
Flash Memory Control Registers (Flash Control Offset)
0x000
FMA
R/W
0x0000.0000
Flash Memory Address
265
0x004
FMD
R/W
0x0000.0000
Flash Memory Data
266
0x008
FMC
R/W
0x0000.0000
Flash Memory Control
267
0x00C
FCRIS
RO
0x0000.0000
Flash Controller Raw Interrupt Status
269
0x010
FCIM
R/W
0x0000.0000
Flash Controller Interrupt Mask
270
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Table 7-3. Flash Register Map (continued)
Offset
Name
0x014
FCMISC
Type
Reset
R/W1C
0x0000.0000
Description
See
page
Flash Controller Masked Interrupt Status and Clear
271
Flash Memory Protection Registers (System Control Offset)
0x130
FMPRE0
R/W
0xFFFF.FFFF
Flash Memory Protection Read Enable 0
274
0x200
FMPRE0
R/W
0xFFFF.FFFF
Flash Memory Protection Read Enable 0
274
0x134
FMPPE0
R/W
0xFFFF.FFFF
Flash Memory Protection Program Enable 0
275
0x400
FMPPE0
R/W
0xFFFF.FFFF
Flash Memory Protection Program Enable 0
275
0x140
USECRL
R/W
0x31
USec Reload
273
0x1D0
USER_DBG
R/W
0xFFFF.FFFE
User Debug
276
0x1E0
USER_REG0
R/W
0xFFFF.FFFF
User Register 0
277
0x1E4
USER_REG1
R/W
0xFFFF.FFFF
User Register 1
278
0x1E8
USER_REG2
R/W
0xFFFF.FFFF
User Register 2
279
0x1EC
USER_REG3
R/W
0xFFFF.FFFF
User Register 3
280
0x204
FMPRE1
R/W
0xFFFF.FFFF
Flash Memory Protection Read Enable 1
281
0x208
FMPRE2
R/W
0x0000.0000
Flash Memory Protection Read Enable 2
282
0x20C
FMPRE3
R/W
0x0000.0000
Flash Memory Protection Read Enable 3
283
0x404
FMPPE1
R/W
0xFFFF.FFFF
Flash Memory Protection Program Enable 1
284
0x408
FMPPE2
R/W
0x0000.0000
Flash Memory Protection Program Enable 2
285
0x40C
FMPPE3
R/W
0x0000.0000
Flash Memory Protection Program Enable 3
286
7.5
ROM Register Descriptions (System Control Offset)
This section lists and describes the ROM Controller registers, in numerical order by address offset.
Registers in this section are relative to the System Control base address of 0x400F.E000.
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Register 1: ROM Control (RMCTL), offset 0x0F0
This register provides control of the ROM controller state.
ROM Control (RMCTL)
Base 0x400F.E000
Offset 0x0F0
Type R/W1C, reset 31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
-
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:1
reserved
RO
0x0
0
BA
R/W1C
-
RO
0
BA
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.
Boot Alias
■
The device has ROM.
■
The first two words of the Flash memory contain 0xFFFF.FFFF.
This bit is cleared by writing a 1 to this bit position.
When the BA bit is set, the boot alias is in effect and the ROM appears
at address 0x0. When the BA bit is clear, the Flash appears at address
0x0.
7.6
Flash Register Descriptions (Flash Control Offset)
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.
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Register 2: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
24
23
22
21
20
19
18
17
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
16
OFFSET
OFFSET
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:17
reserved
RO
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.
16:0
OFFSET
R/W
0x0
Address Offset
Address offset in flash where operation is performed, except for
nonvolatile registers (see “Nonvolatile Register
Programming” on page 261 for details on values for this field).
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Register 3: 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
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
DATA
Type
Reset
DATA
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:0
DATA
R/W
0x0
Data Value
Data value for write operation.
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Register 4: 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 265). If the access is a write
access, the data contained in the Flash Memory Data (FMD) register (see page 266) 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
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
COMT
MERASE
ERASE
WRITE
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
WRKEY
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:16
WRKEY
WO
0x0
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.
15:4
reserved
RO
0x0
3
COMT
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.
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.
2
MERASE
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.
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Bit/Field
Name
Type
Reset
1
ERASE
R/W
0
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.
0
WRITE
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.
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Register 5: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
PRIS
ARIS
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0x0
1
PRIS
RO
0
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.
Programming Raw Interrupt Status
This bit provides status on programming cycles which are write or erase
actions generated through the FMC register bits (see page 267).
Value Description
1
The programming cycle has completed.
0
The programming cycle has not completed.
This status is sent to the interrupt controller when the PMASK bit in the
FCIM register is set.
This bit is cleared by writing a 1 to the PMISC bit in the FCMISC register.
0
ARIS
RO
0
Access Raw Interrupt Status
Value Description
1
A program or erase action was attempted on a block of Flash
memory that contradicts the protection policy for that block as
set in the FMPPEn registers.
0
No access has tried to improperly program or erase the Flash
memory.
This status is sent to the interrupt controller when the AMASK bit in the
FCIM register is set.
This bit is cleared by writing a 1 to the AMISC bit in the FCMISC register.
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Register 6: 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
PMASK
AMASK
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0x0
1
PMASK
R/W
0
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.
Programming Interrupt Mask
This bit controls the reporting of the programming raw interrupt status
to the interrupt controller.
Value Description
0
AMASK
R/W
0
1
An interrupt is sent to the interrupt controller when the PRIS bit
is set.
0
The PRIS interrupt is suppressed and not sent to the interrupt
controller.
Access Interrupt Mask
This bit controls the reporting of the access raw interrupt status to the
interrupt controller.
Value Description
1
An interrupt is sent to the interrupt controller when the ARIS bit
is set.
0
The ARIS interrupt is suppressed and not sent to the interrupt
controller.
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Register 7: 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
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:2
reserved
RO
0x0
1
PMISC
R/W1C
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
1
0
PMISC
AMISC
R/W1C
0
R/W1C
0
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.
Programming Masked Interrupt Status and Clear
Value Description
1
When read, a 1 indicates that an unmasked interrupt was
signaled because a programming cycle completed.
Writing a 1 to this bit clears PMISC and also the PRIS bit in the
FCRIS register (see page 269).
0
When read, a 0 indicates that a programming cycle complete
interrupt has not occurred.
A write of 0 has no effect on the state of this bit.
0
AMISC
R/W1C
0
Access Masked Interrupt Status and Clear
Value Description
1
When read, a 1 indicates that an unmasked interrupt was
signaled because a program or erase action was attempted on
a block of Flash memory that contradicts the protection policy
for that block as set in the FMPPEn registers.
Writing a 1 to this bit clears AMISC and also the ARIS bit in the
FCRIS register (see page 269).
0
When read, a 0 indicates that no improper accesses have
occurred.
A write of 0 has no effect on the state of this bit.
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7.7
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.
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Register 8: 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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
USEC
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
USEC
R/W
0x31
Microsecond Reload Value
MHz -1 of the controller clock when the flash is being erased or
programmed.
If the maximum system frequency is being used, USEC should be set to
0x31 (50 MHz) whenever the flash is being erased or programmed.
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Internal Memory
Register 9: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPREn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. For
additional information, see the "Flash Memory Protection" section.
Flash Memory Protection Read Enable 0 (FMPRE0)
Base 0x400F.E000
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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
READ_ENABLE
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
READ_ENABLE
R/W
R/W
1
Reset
R/W
1
R/W
1
Description
0xFFFFFFFF Flash Read Enable
Configures 2-KB flash blocks to be read only. The policies may be
combined as shown in the table “Flash Protection Policy Combinations”.
Value
Description
0xFFFFFFFF Bits [31:0] each enable protection on a 2-KB block of
Flash memory up to the total of 64 KB.
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Register 10: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPPEn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. For
additional information, see the "Flash Memory Protection" section.
Flash Memory Protection Program Enable 0 (FMPPE0)
Base 0x400F.E000
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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
PROG_ENABLE
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
PROG_ENABLE
R/W
R/W
1
Reset
R/W
1
R/W
1
Description
0xFFFFFFFF 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 Bits [31:0] each enable protection on a 2-KB block of
Flash memory up to the total of 64 KB.
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Internal Memory
Register 11: 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 NW bit (bit 31) indicates that the register has not yet been committed and
is controlled through hardware to ensure that the register is only committed once. Prior to being
committed, bits can only be changed from 1 to 0. The reset value shown only applies to power-on
reset; any other type of reset does not affect this register. Once commited, the value of this register
can never be restored to the factory default value.
User Debug (USER_DBG)
Base 0x400F.E000
Offset 0x1D0
Type R/W, reset 0xFFFF.FFFE
31
30
29
28
27
26
25
24
NW
Type
Reset
23
22
21
20
19
18
17
16
R/W
1
R/W
1
DATA
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
8
7
6
5
4
3
2
DATA
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
31
NW
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
1
0
DBG1
DBG0
R/W
1
R/W
0
Description
User Debug Not Written
When set, this bit indicates that this 32-bit register has not been
committed. When clear, this bit specifies that this register has been
committed and may not be committed again.
30:2
DATA
R/W
0x1FFFFFFF User Data
Contains the user data value. This field is initialized to all 1s and can
only be committed once.
1
DBG1
R/W
1
Debug Control 1
The DBG1 bit must be 1 and DBG0 must be 0 for debug to be available.
0
DBG0
R/W
0
Debug Control 0
The DBG1 bit must be 1 and DBG0 must be 0 for debug to be available.
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Register 12: 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. Once commited, the
value of this register can never be restored to the factory default value.
User Register 0 (USER_REG0)
Base 0x400F.E000
Offset 0x1E0
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
NW
Type
Reset
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
DATA
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
DATA
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31
NW
R/W
1
Not Written
When set, this bit indicates that this 32-bit register has not been
committed. When clear, this bit specifies that this register has been
committed and may not be committed again.
30:0
DATA
R/W
0x7FFFFFFF User Data
Contains the user data value. This field is initialized to all 1s and can
only be committed once.
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Internal Memory
Register 13: 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. Once commited, the
value of this register can never be restored to the factory default value.
User Register 1 (USER_REG1)
Base 0x400F.E000
Offset 0x1E4
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
NW
Type
Reset
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
DATA
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
DATA
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31
NW
R/W
1
Not Written
When set, this bit indicates that this 32-bit register has not been
committed. When clear, this bit specifies that this register has been
committed and may not be committed again.
30:0
DATA
R/W
0x7FFFFFFF User Data
Contains the user data value. This field is initialized to all 1s and can
only be committed once.
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Register 14: User Register 2 (USER_REG2), offset 0x1E8
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. Once commited, the
value of this register can never be restored to the factory default value.
User Register 2 (USER_REG2)
Base 0x400F.E000
Offset 0x1E8
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
NW
Type
Reset
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
DATA
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
DATA
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31
NW
R/W
1
Not Written
When set, this bit indicates that this 32-bit register has not been
committed. When clear, this bit specifies that this register has been
committed and may not be committed again.
30:0
DATA
R/W
0x7FFFFFFF User Data
Contains the user data value. This field is initialized to all 1s and can
only be committed once.
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Internal Memory
Register 15: User Register 3 (USER_REG3), offset 0x1EC
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. Once commited, the
value of this register can never be restored to the factory default value.
User Register 3 (USER_REG3)
Base 0x400F.E000
Offset 0x1EC
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
NW
Type
Reset
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
DATA
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
DATA
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
Reset
Description
31
NW
R/W
1
Not Written
When set, this bit indicates that this 32-bit register has not been
committed. When clear, this bit specifies that this register has been
committed and may not be committed again.
30:0
DATA
R/W
0x7FFFFFFF User Data
Contains the user data value. This field is initialized to all 1s and can
only be committed once.
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Register 16: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPREn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 64 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
READ_ENABLE
Type
Reset
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
Bit/Field
Name
Type
31:0
READ_ENABLE
R/W
R/W
1
Reset
R/W
1
R/W
1
Description
0xFFFFFFFF Flash Read Enable
Configures 2-KB flash blocks to be read only. The policies may be
combined as shown in the table “Flash Protection Policy Combinations”.
Value
Description
0xFFFFFFFF Bits [31:0] each enable protection on a 2-KB block of
Flash memory in memory range from 65 to 128 KB.
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Internal Memory
Register 17: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPREn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 128 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
READ_ENABLE
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
READ_ENABLE
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
31:0
READ_ENABLE
R/W
R/W
0
Reset
R/W
0
R/W
0
Description
0x00000000 Flash Read Enable
Configures 2-KB flash blocks to be read only. The policies may be
combined as shown in the table “Flash Protection Policy Combinations”.
Value
Description
0x00000000 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in the range from 129 to 192 KB.
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Register 18: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPREn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 192 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
READ_ENABLE
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
READ_ENABLE
Type
Reset
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
31:0
READ_ENABLE
R/W
R/W
0
Reset
R/W
0
R/W
0
Description
0x00000000 Flash Read Enable
Configures 2-KB flash blocks to be read only. The policies may be
combined as shown in the table “Flash Protection Policy Combinations”.
Value
Description
0x00000000 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in the range from 193 to 256 KB.
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Internal Memory
Register 19: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPPEn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 64 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
PROG_ENABLE
Type
Reset
PROG_ENABLE
Type
Reset
Bit/Field
Name
Type
31:0
PROG_ENABLE
R/W
Reset
R/W
1
R/W
1
Description
0xFFFFFFFF 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 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in memory range from 65 to 128 KB.
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Register 20: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPPEn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 128 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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 0x0000.0000
31
30
29
28
27
26
25
24
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
PROG_ENABLE
Type
Reset
PROG_ENABLE
Type
Reset
Bit/Field
Name
Type
31:0
PROG_ENABLE
R/W
Reset
R/W
0
R/W
0
Description
0x00000000 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
0x00000000 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in the range from 129 to 192 KB.
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Internal Memory
Register 21: 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). Flash memory up to a total of 64 KB is controlled by this register. Other FMPPEn
registers (if any) provide protection for other 64K blocks. 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. The reset value shown only applies to power-on reset; any other type of reset does
not affect this register. Once committed, the only way to restore the factory default value of this
register is to perform the "Recover Locked Device" sequence detailed in the JTAG chapter. If the
Flash memory size on the device is less than 192 KB, this register usually reads as zeroes, but
software should not rely on these bits to be zero. 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 0x0000.0000
31
30
29
28
27
26
25
24
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
PROG_ENABLE
Type
Reset
PROG_ENABLE
Type
Reset
Bit/Field
Name
Type
31:0
PROG_ENABLE
R/W
Reset
R/W
0
R/W
0
Description
0x00000000 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
0x00000000 Bits [31:0] each enable protection on a 2-KB block of
Flash memory in the range from 193 to 256 KB.
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8
Micro Direct Memory Access (μDMA)
The LM3S5737 microcontroller includes a Direct Memory Access (DMA) controller, known as
micro-DMA (μDMA). The μDMA controller provides a way to offload data transfer tasks from the
Cortex-M3 processor, allowing for more efficient use of the processor and the expanded available
bus bandwidth. The μDMA controller can perform transfers between memory and peripherals. It
has dedicated channels for each supported peripheral and can be programmed to automatically
perform transfers between peripherals and memory as the peripheral is ready to transfer more data.
The μDMA controller also supports sophisticated transfer modes such as ping-pong and
scatter-gather, which allows the processor to set up a list of transfer tasks for the controller.
The μDMA controller has the following features:
■ ARM PrimeCell® 32-channel configurable µDMA controller
■ Support for multiple transfer modes
– Basic, for simple transfer scenarios
– Ping-pong, for continuous data flow to/from peripherals
– Scatter-gather, from a programmable list of arbitrary transfers initiated from a single request
■ Dedicated channels for supported peripherals
■ One channel each for receive and transmit path for bidirectional peripherals
■ Dedicated channel for software-initiated transfers
■ Independently configured and operated channels
■ Per-channel configurable bus arbitration scheme
■ Two levels of priority
■ Design optimizations for improved bus access performance between µDMA controller and the
processor core
– µDMA controller access is subordinate to core access
– RAM striping
– Peripheral bus segmentation
■ Data sizes of 8, 16, and 32 bits
■ Source and destination address increment size of byte, half-word, word, or no increment
■ Maskable device requests
■ Optional software initiated requests for any channel
■ Interrupt on transfer completion, with a separate interrupt per channel
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8.1
Block Diagram
Figure 8-1. μDMA Block Diagram
μDMA
Controller
DMA error
System Memory
CH Control Table
request
Peripheral
done
DMA Channel 0
•
•
•
request
Peripheral
DMA Channel N-1 done
Nested
Vectored
Interrupt
Controller
(NVIC)
IRQ
General
Peripheral N
Registers
request
done
DMASTAT
DMACFG
DMACTLBASE
DMAALTBASE
DMAWAITSTAT
DMASWREQ
DMAUSEBURSTSET
DMAUSEBURSTCLR
DMAREQMASKSET
DMAREQMASKCLR
DMAENASET
DMAENACLR
DMAALTSET
DMAALTCLR
DMAPRIOSET
DMAPRIOCLR
DMAERRCLR
DMASRCENDP
DMADSTENDP
DMACHCTRL
•
•
•
DMASRCENDP
DMADSTENDP
DMACHCTRL
Transfer Buffers
Used by uDMA
ARM
Cortex-M3
8.2
Functional Description
The μDMA controller is a flexible and highly configurable DMA controller designed to work effeciently
with the microcontroller's Cortex-M3 processor core. It supports multiple data sizes and address
increment schemes, multiple levels of priority among DMA channels, and several transfer modes
to allow for sophisticated programmed data transfers. The DMA controller's usage of the bus is
always subordinate to the processor core, and so it will never hold up a bus transaction by the
processor. Because the μDMA controller is only using otherwise-idle bus cycles, the data transfer
bandwidth it provides is essentially free, with no impact on the rest of the system. The bus architecture
has been optimized to greatly reduce contention between the processor core and the μDMA controller,
thus improving performance. The optimizations include RAM striping and peripheral bus segmentation,
which in many cases allows both the processor core and the μDMA controller to access the bus
and perform simultaneous data transfers.
Each peripheral function that is supported has a dedicated channel on the μDMA controller that can
be configured independently.
The μDMA controller makes use of a unique configuration method by using channel control structures
that are maintained in system memory by the processor. While simple transfer modes are supported,
it is also possible to build up sophisticated "task" lists in memory that allow the controller to perform
arbitrary-sized transfers to and from arbitrary locations as part of a single transfer request. The
controller also supports the use of ping-pong buffering to accomodate constant streaming of data
to or from a peripheral.
Each channel also has a configurable arbitration size. The arbitration size is the number of items
that will be transferred in a burst before the controller rearbitrates for channel priority. Using the
arbitration size, it is possible to control exactly how many items are transferred to or from a peripheral
each time it makes a DMA service request.
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8.2.1
Channel Assigments
μDMA channels 0-31 are assigned to peripherals according to the following table.
Note:
Channels that are not listed in the table may be assigned to peripherals in the future.
However, they are currently available for software use.
Table 8-1. DMA Channel Assignments
8.2.2
DMA Channel
Peripheral Assigned
0
USB Endpoint 1 Receive
1
USB Endpoint 1 Transmit
2
USB Endpoint 2 Receive
3
USB Endpoint 2 Transmit
4
USB Endpoint 3 Receive
5
USB Endpoint 3 Transmit
8
UART0 Receive
9
UART0 Transmit
10
SSI0 Receive
11
SSI0 Transmit
24
SSI1 Receive
25
SSI1 Transmit
30
Dedicated for software use
Priority
The μDMA controller assigns priority to each channel based on the channel number and the priority
level bit for the channel. Channel number 0 has the highest priority and as the channel number
increases, the priority of a channel decreases. Each channel has a priority level bit to provide two
levels of priority: default priority and high priority. If the priority level bit is set, then that channel has
higher priority than all other channels at default priority. If multiple channels are set for high priority,
then the channel number is used to determine relative priority among all the high priority channels.
The priority bit for a channel can be set using the DMA Channel Priority Set (DMAPRIOSET)
register, and cleared with the DMA Channel Priority Clear (DMAPRIOCLR) register.
8.2.3
Arbitration Size
When a μDMA channel requests a transfer, the μDMA controller arbitrates between all the channels
making a request and services the DMA channel with the highest priority. Once a transfer begins,
it continues for a selectable number of transfers before rearbitrating among the requesting channels
again. The arbitration size can be configured for each channel, ranging from 1 to 1024 item transfers.
After the μDMA controller transfers the number of items specified by the arbitration size, it then
checks among all the channels making a request and services the channel with the highest priority.
If a lower priority DMA channel uses a large arbitration size, the latency for higher priority channels
will be increased because the μDMA controller will complete the lower priority burst before checking
for higher priority requests. Therefore, lower priority channels should not use a large arbitration size
for best response on high priority channels.
The arbitration size can also be thought of as a burst size. It is the maximum number of items that
will be transferred at any one time in a burst. Here, the term arbitration refers to determination of
DMA channel priority, not arbitration for the bus. When the μDMA controller arbitrates for the bus,
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the processor always takes priority. Furthermore, the μDMA controller will be held off whenever the
processor needs to perform a bus transaction on the same bus, even in the middle of a burst transfer.
8.2.4
Request Types
The μDMA controller responds to two types of requests from a peripheral: single or burst. Each
peripheral may support either or both types of requests. A single request means that the peripheral
is ready to transfer one item, while a burst request means that the peripheral is ready to transfer
multiple items.
The μDMA controller responds differently depending on whether the peripheral is making a single
request or a burst request. If both are asserted and the μDMA channel has been set up for a burst
transfer, then the burst request takes precedence. See Table 8-2 on page 290, which shows how
each peripheral supports the two request types.
Table 8-2. Request Type Support
8.2.4.1
Peripheral
Single Request Signal
Burst Request Signal
USB TX
None
FIFO TXRDY
USB RX
None
FIFO RXRDY
UART TX
TX FIFO Not Full
TX FIFO Level (configurable)
UART RX
RX FIFO Not Empty
RX FIFO Level (configurable)
SSI TX
TX FIFO Not Full
TX FIFO Level (fixed at 4)
SSI RX
RX FIFO Not Empty
RX FIFO Level (fixed at 4)
Single Request
When a single request is detected, and not a burst request, the μDMA controller will transfer one
item, and then stop and wait for another request.
8.2.4.2
Burst Request
When a burst request is detected, the μDMA controller will transfer the number of items that is the
lesser of the arbitration size or the number of items remaining in the transfer. Therefore, the arbitration
size should be the same as the number of data items that the peripheral can accomodate when
making a burst request. For example, the UART will generate a burst request based on the FIFO
trigger level. In this case, the arbitration size should be set to the amount of data that the FIFO can
transfer when the trigger level is reached.
It may be desirable to use only burst transfers and not allow single transfers. For example, perhaps
the nature of the data is such that it only makes sense when transferred together as a single unit
rather than one piece at a time. The single request can be disabled by using the DMA Channel
Useburst Set (DMAUSEBURSTSET) register. By setting the bit for a channel in this register, the
μDMA controller will only respond to burst requests for that channel.
8.2.5
Channel Configuration
The μDMA controller uses an area of system memory to store a set of channel control structures
in a table. The control table may have one or two entries for each DMA channel. Each entry in the
table structure contains source and destination pointers, transfer size, and transfer mode. The
control table can be located anywhere in system memory, but it must be contiguous and aligned on
a 1024-byte boundary.
Table 8-3 on page 291 shows the layout in memory of the channel control table. Each channel may
have one or two control structures in the contol table: a primary control structure and an optional
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alternate control structure. The table is organized so that all of the primary entries are in the first
half of the table and all the alternate structures are in the second half of the table. The primary entry
is used for simple transfer modes where transfers can be reconfigured and restarted after each
transfer is complete. In this case, the alternate control structures are not used and therefore only
the first half of the table needs to be allocated in memory. The second half of the control table is
not needed and that memory can be used for something else. If a more complex transfer mode is
used such as ping-pong or scatter-gather, then the alternate control structure is also used and
memory space should be allocated for the entire table.
Any unused memory in the control table may be used by the application. This includes the control
structures for any channels that are unused by the application as well as the unused control word
for each channel.
Table 8-3. Control Structure Memory Map
Offset
Channel
0x0
0, Primary
0x10
1, Primary
...
...
0x1F0
31, Primary
0x200
0, Alternate
0x210
1, Alternate
...
...
0x3F0
31, Alternate
Table 8-4 on page 291 shows an individual control structure entry in the control table. Each entry
has a source and destination end pointer. These pointers point to the ending address of the transfer
and are inclusive. If the source or destination is non-incrementing (as for a peripheral register), then
the pointer should point to the transfer address.
Table 8-4. Channel Control Structure
Offset
Description
0x000
Source End Pointer
0x004
Destination End Pointer
0x008
Control Word
0x00C
Unused
The remaining part of the control structure is the control word. The control word contains the following
fields:
■ Source and destination data sizes
■ Source and destination address increment size
■ Number of transfers before bus arbitration
■ Total number of items to transfer
■ Useburst flag
■ Transfer mode
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The control word and each field are described in detail in “μDMA Channel Control
Structure” on page 308. The μDMA controller updates the transfer size and transfer mode fields as
the transfer is performed. At the end of a transfer, the transfer size will indicate 0, and the transfer
mode will indicate "stopped". Since the control word is modified by the μDMA controller, it must be
reconfigured before each new transfer. The source and destination end pointers are not modified
so they can be left unchanged if the source or destination addresses remain the same.
Prior to starting a transfer, a μDMA channel must be enabled by setting the appropriate bit in the
DMA Channel Enable Set ((DMAENASET) register. A channel can be disabled by setting the
channel bit in the DMA Channel Enable Clear (DMAENACLR) register. At the end of a complete
DMA transfer, the controller will automatically disable the channel.
8.2.6
Transfer Modes
The μDMA controller supports several transfer modes. Two of the modes support simple one-time
transfers. There are several complex modes that are meant to support a continuous flow of data.
8.2.6.1
Stop Mode
While Stop is not actually a transfer mode, it is a valid value for the mode field of the control word.
When the mode field has this value, the μDMA controller will not perform a transfer and will disable
the channel if it is enabled. At the end of a transfer, the μDMA controller will update the control word
to set the mode to Stop.
8.2.6.2
Basic Mode
In Basic mode, the μDMA controller will perform transfers as long as there are more items to transfer
and a transfer request is present. This mode is used with peripherals that assert a DMA request
signal whenever the peripheral is ready for a data transfer. Basic mode should not be used in any
situation where the request is momentary but the entire transfer should be completed. For example,
for a software initiated transfer, the request is momentary, and if Basic mode is used then only one
item will be transferred on a software request.
When all of the items have been transferred using Basic mode, the μDMA controller will set the
mode for that channel to Stop.
8.2.6.3
Auto Mode
Auto mode is similar to Basic mode, except that once a transfer request is received the transfer will
run to completion, even if the DMA request is removed. This mode is suitable for software-triggered
transfers. Generally, you would not use Auto mode with a peripheral.
When all the items have been transferred using Auto mode, the μDMA controller will set the mode
for that channel to Stop.
8.2.6.4
Ping-Pong
Ping-Pong mode is used to support a continuous data flow to or from a peripheral. To use Ping-Pong
mode, both the primary and alternate data structures are used. Both are set up by the processor
for data transfer between memory and a peripheral. Then the transfer is started using the primary
control structure. When the transfer using the primary control structure is complete, the μDMA
controller will then read the alternate control structure for that channel to continue the transfer. Each
time this happens, an interrupt is generated and the processor can reload the control structure for
the just-completed transfer. Data flow can continue indefinitely this way, using the primary and
alternate control structures to switch back and forth between buffers as the data flows to or from
the peripheral.
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Refer to Figure 8-2 on page 293 for an example showing operation in Ping-Pong mode.
Figure 8-2. Example of Ping-Pong DMA Transaction
μDMA Controller
SOURCE
DEST
transfers using BUFFER A
transfer continues using alternate
Primary Structure
Cortex-M3 Processor
SOURCE
DEST
Pe
rip
Time
transfers using BUFFER B
SOURCE
DEST
Alternate Structure
SOURCE
DEST
ral
/uD
MA
Int
up
t
BUFFER B
· Process data in BUFFER A
· Reload primary structure
Pe
rip
he
ral
/uD
MA
Int
err
transfers using BUFFER A
up
t
BUFFER A
· Process data in BUFFER B
· Reload alternate structure
transfer continues using alternate
Primary Structure
he
err
transfer continues using primary
Alternate Structure
BUFFER A
Pe
rip
he
ral
/uD
MA
I
transfers using BUFFER B
nte
rru
p
t
BUFFER B
· Process data in BUFFER B
· Reload alternate structure
8.2.6.5
Memory Scatter-Gather
Memory Scatter-Gather mode is a complex mode used when data needs to be transferred to or
from varied locations in memory instead of a set of contiguous locations in a memory buffer. For
example, a gather DMA operation could be used to selectively read the payload of several stored
packets of a communication protocol, and store them together in sequence in a memory buffer.
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In Memory Scatter-Gather mode, the primary control structure is used to program the alternate
control structure from a table in memory. The table is set up by the processor software and contains
a list of control structures, each containing the source and destination end pointers, and the control
word for a specific transfer. The mode of each control word must be set to Scatter-Gather mode.
Each entry in the table is copied in turn to the alternate structure where it is then executed. The
μDMA controller alternates between using the primary control structure to copy the next transfer
instruction from the list, and then executing the new transfer instruction. The end of the list is marked
by setting the control word for the last entry to use Basic transfer mode. Once the last transfer is
performed using Basic mode, the μDMA controller will stop. A completion interrupt will only be
generated after the last transfer. It is possible to loop the list by having the last entry copy the primary
control structure to point back to the beginning of the list (or to a new list). It is also possible to trigger
a set of other channels to perform a transfer, either directly by programming a write to the software
trigger for another channel, or indirectly by causing a peripheral action that will result in a μDMA
request.
By programming the μDMA controller using this method, a set of arbitrary transfers can be performed
based on a single DMA request.
Refer to Figure 8-3 on page 295 and Figure 8-4 on page 296, which show an example of operation
in Memory Scatter-Gather mode. This example shows a gather operation, where data in three
separate buffers in memory will be copied together into one buffer. Figure 8-3 on page 295 shows
how the application sets up a μDMA task list in memory that is used by the controller to perform
three sets of copy operations from different locations in memory. The primary control structure for
the channel that will be used for the operation is configured to copy from the task list to the alternate
control structure.
Figure 8-4 on page 296 shows the sequence as the μDMA controller peforms the three sets of copy
operations. First, using the primary control structure, the μDMA controller loads the alternate control
structure with task A. It then peforms the copy operation specified by task A, copying the data from
the source buffer A to the destination buffer. Next, the μDMA controller again uses the primary
control structure to load task B into the alternate control structure, and then performs the B operation
with the alternate control structure. The process is repeated for task C.
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Figure 8-3. Memory Scatter-Gather, Setup and Configuration
1
2
3
Source and Destination
Buffer in Memory
Task List in Memory
Channel Control
Table in Memory
4 WORDS (SRC A)
SRC
A
DST
“TASK” A
ITEMS=4
SRC
SRC
DST
DST
“TASK” B
ITEMS=12
Channel Primary
Control Structure
ITEMS=16
16 WORDS (SRC B)
B
SRC
DST
“TASK” C
ITEMS=1
SRC
DST
Channel Alternate
Control Structure
ITEMS=n
1 WORD (SRC C)
C
4 (DEST A)
16 (DEST B)
1 (DEST C)
NOTES:
1. Application has a need to copy data items from three separate location in memory into one combined buffer.
2. Application sets up uDMA “task list” in memory, which contains the pointers and control configuration for three
uDMA copy “tasks.”
3. Application sets up the channel primary control structure to copy each task configuration, one at a time, to the
alternate control structure, where it will be executed by the uDMA controller.
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Figure 8-4. Memory Scatter-Gather, μDMA Copy Sequence
Task List
in Memory
μDMA Control Table
in Memory
Buffers
in Memory
SRC A
SRC
SRC B
PRI
COPIED
DST
TASK A
TASK B
SRC
SRC C
ALT
COPIED
DST
TASK C
DEST A
DEST B
DEST C
Using the channel’s primary control structure, the μDMA
controller copies task A configuration to the channel’s
alternate control structure.
Task List
in Memory
Then, using the channel’s alternate control structure, the
μDMA controller copies data from the source buffer A to
the destination buffer.
μDMA Control Table
in Memory
Buffers
in Memory
SRC A
SRC B
SRC
PRI
DST
TASK A
SRC
TASK B
TASK C
SRC C
COPIED
ALT
COPIED
DST
DEST A
DEST B
DEST C
Using the channel’s primary control structure, the μDMA
controller copies task B configuration to the channel’s
alternate control structure.
Task List
in Memory
Then, using the channel’s alternate control structure, the
μDMA controller copies data from the source buffer B to
the destination buffer.
μDMA Control Table
in Memory
Buffers
in Memory
SRC A
SRC
SRC B
PRI
DST
TASK A
SRC
TASK B
TASK C
SRC C
ALT
DST
DEST A
COPIED
COPIED
DEST B
DEST C
Using the channel’s primary control structure, the μDMA
controller copies task C configuration to the channel’s
alternate control structure.
Then, using the channel’s alternate control structure, the
μDMA controller copies data from the source buffer C to
the destination buffer.
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8.2.6.6
Peripheral Scatter-Gather
Peripheral Scatter-Gather mode is very similar to Memory Scatter-Gather, except that the transfers
are controlled by a peripheral making a DMA request. Upon detecting a DMA request from the
peripheral, the μDMA controller will use the primary control structure to copy one entry from the list
to the alternate control structure, and then perform the transfer. At the end of this transfer, the next
transfer will only be started if the peripheral again asserts a DMA request. The μDMA controller will
continue to perform transfers from the list only when the peripheral is making a request, until the
last transfer is complete. A completion interrupt will only be generated after the last transfer.
By programming the μDMA controller using this method, data can be transferred to or from a
peripheral from a set of arbitrary locations whenever the peripheral is ready to transfer data.
Refer to Figure 8-5 on page 298 and Figure 8-6 on page 299, which show an example of operation
in Peripheral Scatter-Gather mode. This example shows a gather operation, where data from three
separate buffers in memory will be copied to a single peripheral data register. Figure 8-5 on page 298
shows how the application sets up a µDMA task list in memory that is used by the controller to
perform three sets of copy operations from different locations in memory. The primary control
structure for the channel that will be used for the operation is configured to copy from the task list
to the alternate control structure.
Figure 8-6 on page 299 shows the sequence as the µDMA controller peforms the three sets of copy
operations. First, using the primary control structure, the µDMA controller loads the alternate control
structure with task A. It then peforms the copy operation specified by task A, copying the data from
the source buffer A to the peripheral data register. Next, the µDMA controller again uses the primary
control structure to load task B into the alternate control structure, and then performs the B operation
with the alternate control structure. The process is repeated for task C.
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Figure 8-5. Peripheral Scatter-Gather, Setup and Configuration
1
2
3
Source Buffer
in Memory
Task List in Memory
Channel Control
Table in Memory
4 WORDS (SRC A)
SRC
A
DST
“TASK” A
ITEMS=4
SRC
SRC
DST
DST
“TASK” B
ITEMS=12
Channel Primary
Control Structure
ITEMS=16
16 WORDS (SRC B)
B
SRC
DST
“TASK” C
ITEMS=1
SRC
DST
Channel Alternate
Control Structure
ITEMS=n
1 WORD (SRC C)
C
Peripheral Data
Register
DEST
NOTES:
1. Application has a need to copy data items from three separate location in memory into a peripheral data
register.
2. Application sets up μDMA “task list” in memory, which contains the pointers and control configuration for three
uDMA copy “tasks.”
3. Application sets up the channel primary control structure to copy each task configuration, one at a time, to the
alternate control structure, where it will be executed by the μDMA controller.
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Figure 8-6. Peripheral Scatter-Gather, μDMA Copy Sequence
μDMA Control
Table
in Memory
Task List
in Memory
Buffers
in Memory
SRC A
SRC
SRC B
PRI
TASK A
TASK B
COPIED
DST
SRC C
SRC
ALT
COPIED
TASK C
DST
Then, using the channel’s alternate control structure,
the μDMA controller copies data from the source
buffer A to the peripheral data register.
Using the channel’s primary control structure, the
μDMA controller copies task A configuration to the
channel’s alternate control structure.
Task List
in Memory
Peripheral
Data
Register
Buffers
in Memory
μDMA Control
Table
in Memory
SRC A
SRC
SRC B
PRI
DST
TASK A
TASK B
TASK C
SRC C
SRC
ALT
COPIED
DST
Peripheral
Data
Register
Then, using the channel’s alternate control structure,
the μDMA controller copies data from the source
buffer B to the peripheral data register.
Using the channel’s primary control structure, the
μDMA controller copies task B configuration to the
channel’s alternate control structure.
Task List
in Memory
COPIED
Buffers
in Memory
μDMA Control
Table
in Memory
SRC A
SRC
SRC B
PRI
DST
TASK A
TASK B
TASK C
SRC C
SRC
ALT
COPIED
DST
COPIED
Peripheral
Data
Register
Using the channel’s primary control structure, the
μDMA controller copies task C configuration to the
channel’s alternate control structure.
Then, using the channel’s alternate control structure,
the μDMA controller copies data from the source
buffer C to the peripheral data register.
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8.2.7
Transfer Size and Increment
The μDMA controller supports transfer data sizes of 8, 16, or 32 bits. The source and destination
data size must be the same for any given transfer. The source and destination address can be
auto-incremented by bytes, half-words, or words, or can be set to no increment. The source and
destination address increment values can be set independently, and it is not necessary for the
address increment to match the data size as long as the increment is the same or larger than the
data size. For example, it is possible to perform a transfer using 8-bit data size, but using an address
increment of full words (4 bytes). The data to be transferred must be aligned in memory according
to the data size (8, 16, or 32 bits).
Table 8-5 on page 300 shows the configuration to read from a peripheral that supplies 8-bit data.
Table 8-5. μDMA Read Example: 8-Bit Peripheral
8.2.8
Field
Configuration
Source data size
8 bits
Destination data size
8 bits
Source address increment
No increment
Destination address increment
Byte
Source end pointer
Peripheral read FIFO register
Destination end pointer
End of the data buffer in memory
Peripheral Interface
Each peripheral that supports μDMA has a DMA single request and/or burst request signal that is
asserted when the device is ready to transfer data. The request signal can be disabled or enabled
by using the DMA Channel Request Mask Set (DMAREQMASKSET) and DMA Channel Request
Mask Clear (DMAREQMASKCLR) registers. The DMA request signal is disabled, or masked, when
the channel request mask bit is set. When the request is not masked, the DMA channel is configured
correctly and enabled, and the peripheral asserts the DMA request signal, the μDMA controller will
begin the transfer.
When a DMA transfer is complete, the μDMA controller asserts a DMA Done signal, which is routed
through the interrupt vector of the peripheral. Therefore, if DMA is used to transfer data for a
peripheral and interrupts are used, then the interrupt handler for that peripheral must be designed
to handle the μDMA transfer completion interrupt. When DMA is enabled for a peripheral, the μDMA
controller will mask the normal interrupts for a peripheral. This means that when a large amount of
data is transferred using DMA, instead of receiving multiple interrupts from the peripheral as data
flows, the processor will only receive one interrupt when the transfer is complete.
The interrupt request from the μDMA controller is automatically cleared when the interrupt handler
is activated.
8.2.9
Software Request
There is a dedicated μDMA channel for software-initiated transfers. This channel also has a dedicated
interrupt to signal completion of a DMA transfer. A transfer is initiated by software by first configuring
and enabling the transfer, and then issuing a software request using the DMA Channel Software
Request (DMASWREQ) register. For software-based transfers, the Auto transfer mode should be
used.
It is possible to initiate a transfer on any channel using the DMASWREQ register. If a request is
initiated by software using a peripheral DMA channel, then the completion interrupt will occur on
the interrupt vector for the peripheral instead of the software interrupt vector. This means that any
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channel may be used for software requests as long as the corresponding peripheral is not using
μDMA.
8.2.10
Interrupts and Errors
When a DMA transfer is complete, the μDMA controller will generate a completion interrupt on the
interrupt vector of the peripheral. If the transfer uses the software DMA channel, then the completion
interrupt will occur on the dedicated software DMA interrupt vector.
If the μDMA controller encounters a bus or memory protection error as it attempts to perform a data
transfer, it will disable the DMA channel that caused the error, and generate an interrupt on the
μDMA Error interrupt vector. The processor can read the DMA Bus Error Clear (DMAERRCLR)
register to determine if an error is pending. The ERRCLR bit will be set if an error occurred. The error
can be cleared by writing a 1 to the ERRCLR bit.
If the peripheral generates an error that causes an interrupt, the interrupt will be generated on the
interrupt vector for that peripheral. This is the same whether or not μDMA is being used with the
peripheral.
Table 8-6 on page 301 shows the dedicated interrupt assignments for the μDMA controller.
Table 8-6. μDMA Interrupt Assignments
Interrupt
Assignment
46
μDMA Software Channel Transfer
47
μDMA Error
8.3
Initialization and Configuration
8.3.1
Module Initialization
Before the μDMA controller can be used, it must be enabled in the System Control block and in the
peripheral. The location of the channel control structure must also be programmed.
The following steps should be performed one time during system initialization:
1. The μDMA peripheral must be enabled in the System Control block. To do this, set the UDMA
bit of the System Control RCGC2 register.
2. Enable the μDMA controller by setting the MASTEREN bit of the DMA Configuration (DMACFG)
register.
3. Program the location of the channel control table by writing the base address of the table to the
DMA Channel Control Base Pointer (DMACTLBASE) register. The base address must be
aligned on a 1024-byte boundary.
8.3.2
Configuring a Memory-to-Memory Transfer
μDMA channel 30 is dedicated for software-initiated transfers. However, any channel can be used
for software-initiated, memory-to-memory transfer if the associated peripheral is not being used.
8.3.2.1
Configure the Channel Attributes
First, configure the channel attributes:
1. Set bit 30 of the DMA Channel Priority Set (DMAPRIOSET) or DMA Channel Priority Clear
(DMAPRIOCLR) registers to set the channel to High priority or Default priority.
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2. Set bit 30 of the DMA Channel Primary Alternate Clear (DMAALTCLR) register to select the
primary channel control structure for this transfer.
3. Set bit 30 of the DMA Channel Useburst Clear (DMAUSEBURSTCLR) register to allow the
μDMA controller to respond to single and burst requests.
4. Set bit 30 of the DMA Channel Request Mask Clear (DMAREQMASKCLR) register to allow
the μDMA controller to recognize requests for this channel.
8.3.2.2
Configure the Channel Control Structure
Now the channel control structure must be configured.
This example will transfer 256 32-bit words from one memory buffer to another. Channel 30 is used
for a software transfer, and the control structure for channel 30 is at offset 0x1E0 of the channel
control table. The channel control structure for channel 30 is located at the offsets shown in Table
8-7 on page 302.
Table 8-7. Channel Control Structure Offsets for Channel 30
Offset
Description
Control Table Base + 0x1E0
Channel 30 Source End Pointer
Control Table Base + 0x1E4
Channel 30 Destination End Pointer
Control Table Base + 0x1E8
Channel 30 Control Word
Configure the Source and Destination
The source and destination end pointers must be set to the last address for the transfer (inclusive).
1. Set the source end pointer at offset 0x1E0 to the address of the source buffer + 0x3FC.
2. Set the destination end pointer at offset 0x1E4 to the address of the destination buffer + 0x3FC.
The control word at offset 0x1E8 must be programmed according to Table 8-8 on page 302.
Table 8-8. Channel Control Word Configuration for Memory Transfer Example
Field in DMACHCTL
Bits
Value
DSTINC
31:30
2
32-bit destination address increment
DSTSIZE
29:28
2
32-bit destination data size
SRCINC
27:26
2
32-bit source address increment
SRCSIZE
25:24
2
32-bit source data size
reserved
23:18
0
Reserved
ARBSIZE
17:14
3
Arbitrates after 8 transfers
XFERSIZE
13:4
255
3
0
N/A for this transfer type
2:0
2
Use Auto-request transfer mode
NXTUSEBURST
XFERMODE
8.3.2.3
Description
Transfer 256 items
Start the Transfer
Now the channel is configured and is ready to start.
1. Enable the channel by setting bit 30 of the DMA Channel Enable Set (DMAENASET) register.
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2. Issue a transfer request by setting bit 30 of the DMA Channel Software Request (DMASWREQ)
register.
The DMA transfer will now take place. If the interrupt is enabled, then the processor will be notified
by interrupt when the transfer is complete. If needed, the status can be checked by reading bit 30
of the DMAENASET register. This bit will be automatically cleared when the transfer is complete.
The status can also be checked by reading the XFERMODE field of the channel control word at offset
0x1E8. This field will automatically be set to 0 at the end of the transfer.
8.3.3
Configuring a Peripheral for Simple Transmit
This example will set up the μDMA controller to transmit a buffer of data to a peripheral. The peripheral
has a transmit FIFO with a trigger level of 4. The example peripheral will use μDMA channel 7.
8.3.3.1
Configure the Channel Attributes
First, configure the channel attributes:
1. Set bit 7 of the DMA Channel Priority Set (DMAPRIOSET) or DMA Channel Priority Clear
(DMAPRIOCLR) registers to set the channel to High priority or Default priority.
2. Set bit 7 of the DMA Channel Primary Alternate Clear (DMAALTCLR) register to select the
primary channel control structure for this transfer.
3. Set bit 7 of the DMA Channel Useburst Clear (DMAUSEBURSTCLR) register to allow the
μDMA controller to respond to single and burst requests.
4. Set bit 7 of the DMA Channel Request Mask Clear (DMAREQMASKCLR) register to allow
the μDMA controller to recognize requests for this channel.
8.3.3.2
Configure the Channel Control Structure
Now the channel control structure must be configured. This example will transfer 64 8-bit bytes from
a memory buffer to the peripheral's transmit FIFO register. This example uses μDMA channel 7,
and the control structure for channel 7 is at offset 0x070 of the channel control table. The channel
control structure for channel 7 is located at the offsets shown in Table 8-9 on page 303.
Table 8-9. Channel Control Structure Offsets for Channel 7
Offset
Description
Control Table Base + 0x070
Channel 7 Source End Pointer
Control Table Base + 0x074
Channel 7 Destination End Pointer
Control Table Base + 0x078
Channel 7 Control Word
Configure the Source and Destination
The source and destination end pointers must be set to the last address for the transfer (inclusive).
Since the peripheral pointer does not change, it simply points to the peripheral's data register.
1. Set the source end pointer at offset 0x070 to the address of the source buffer + 0x3F.
2. Set the destination end pointer at offset 0x074 to the address of the peripheral's transmit FIFO
register.
The control word at offset 0x078 must be programmed according to Table 8-10 on page 304.
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Table 8-10. Channel Control Word Configuration for Peripheral Transmit Example
Field in DMACHCTL
Bits
Value
DSTINC
31:30
3
Destination address does not increment
DSTSIZE
29:28
0
8-bit destination data size
SRCINC
27:26
0
8-bit source address increment
SRCSIZE
25:24
0
8-bit source data size
reserved
23:18
0
Reserved
ARBSIZE
17:14
2
Arbitrates after 4 transfers
XFERSIZE
13:4
63
Transfer 64 items
3
0
N/A for this transfer type
2:0
1
Use Basic transfer mode
NXTUSEBURST
XFERMODE
Note:
8.3.3.3
Description
In this example, it is not important if the peripheral makes a single request or a burst request.
Since the peripheral has a FIFO that will trigger at a level of 4, the arbitration size is set to
4. If the peripheral does make a burst request, then 4 bytes will be transferred, which is
what the FIFO can accomodate. If the peripheral makes a single request (if there is any
space in the FIFO), then one byte will be transferred at a time. If it is important to the
application that transfers only be made in bursts, then the channel useburst SET[n] bit
should be set by writing a 1 to bit 7 of the DMA Channel Useburst Set
(DMAUSEBURSTSET) register.
Start the Transfer
Now the channel is configured and is ready to start.
1. Enable the channel by setting bit 7 of the DMA Channel Enable Set (DMAENASET) register.
The μDMA controller is now configured for transfer on channel 7. The controller will make transfers
to the peripheral whenever the peripheral asserts a DMA request. The transfers will continue until
the entire buffer of 64 bytes has been transferred. When that happens, the μDMA controller will
disable the channel and set the XFERMODE field of the channel control word to 0 (Stopped). The
status of the transfer can be checked by reading bit 7 of the DMA Channel Enable Set
(DMAENASET) register. This bit will be automatically cleared when the transfer is complete. The
status can also be checked by reading the XFERMODE field of the channel control word at offset
0x078. This field will automatically be set to 0 at the end of the transfer.
If peripheral interrupts were enabled, then the peripheral interrupt handler would receive an interrupt
when the entire transfer was complete.
8.3.4
Configuring a Peripheral for Ping-Pong Receive
This example will set up the μDMA controller to continuously receive 8-bit data from a peripheral
into a pair of 64 byte buffers. The peripheral has a receive FIFO with a trigger level of 8. The example
peripheral will use μDMA channel 8.
8.3.4.1
Configure the Channel Attributes
First, configure the channel attributes:
1. Set bit 8 of the DMA Channel Priority Set (DMAPRIOSET) or DMA Channel Priority Clear
(DMAPRIOCLR) registers to set the channel to High priority or Default priority.
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2. Set bit 8 of the DMA Channel Primary Alternate Clear (DMAALTCLR) register to select the
primary channel control structure for this transfer.
3. Set bit 8 of the DMA Channel Useburst Clear (DMAUSEBURSTCLR) register to allow the
μDMA controller to respond to single and burst requests.
4. Set bit 8 of the DMA Channel Request Mask Clear (DMAREQMASKCLR) register to allow
the μDMA controller to recognize requests for this channel.
8.3.4.2
Configure the Channel Control Structure
Now the channel control structure must be configured. This example will transfer 8-bit bytes from
the peripheral's receive FIFO register into two memory buffers of 64 bytes each. As data is received,
when one buffer is full, the μDMA controller switches to use the other.
To use Ping-Pong buffering, both primary and alternate channel control structures must be used.
The primary control structure for channel 8 is at offset 0x080 of the channel control table, and the
alternate channel control structure is at offset 0x280. The channel control structures for channel 8
are located at the offsets shown in Table 8-11 on page 305.
Table 8-11. Primary and Alternate Channel Control Structure Offsets for Channel 8
Offset
Description
Control Table Base + 0x080
Channel 8 Primary Source End Pointer
Control Table Base + 0x084
Channel 8 Primary Destination End Pointer
Control Table Base + 0x088
Channel 8 Primary Control Word
Control Table Base + 0x280
Channel 8 Alternate Source End Pointer
Control Table Base + 0x284
Channel 8 Alternate Destination End Pointer
Control Table Base + 0x288
Channel 8 Alternate Control Word
Configure the Source and Destination
The source and destination end pointers must be set to the last address for the transfer (inclusive).
Since the peripheral pointer does not change, it simply points to the peripheral's data register. Both
the primary and alternate sets of pointers must be configured.
1. Set the primary source end pointer at offset 0x080 to the address of the peripheral's receive
buffer.
2. Set the primary destination end pointer at offset 0x084 to the address of ping-pong buffer A +
0x3F.
3. Set the alternate source end pointer at offset 0x280 to the address of the peripheral's receive
buffer.
4. Set the alternate destination end pointer at offset 0x284 to the address of ping-pong buffer B +
0x3F.
The primary control word at offset 0x088, and the alternate control word at offset 0x288 must be
programmed according to Table 8-10 on page 304. Both control words are initially programmed the
same way.
1. Program the primary channel control word at offset 0x088 according to Table 8-12 on page 306.
2. Program the alternate channel control word at offset 0x288 according to Table 8-12 on page 306.
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Table 8-12. Channel Control Word Configuration for Peripheral Ping-Pong Receive Example
Field in DMACHCTL
Bits
Value
DSTINC
31:30
0
8-bit destination address increment
DSTSIZE
29:28
0
8-bit destination data size
SRCINC
27:26
3
Source address does not increment
SRCSIZE
25:24
0
8-bit source data size
reserved
23:18
0
Reserved
ARBSIZE
17:14
3
Arbitrates after 8 transfers
XFERSIZE
13:4
63
Transfer 64 items
3
0
N/A for this transfer type
2:0
3
Use Ping-Pong transfer mode
NXTUSEBURST
XFERMODE
Note:
8.3.4.3
Description
In this example, it is not important if the peripheral makes a single request or a burst request.
Since the peripheral has a FIFO that will trigger at a level of 8, the arbitration size is set to
8. If the peripheral does make a burst request, then 8 bytes will be transferred, which is
what the FIFO can accomodate. If the peripheral makes a single request (if there is any
data in the FIFO), then one byte will be transferred at a time. If it is important to the
application that transfers only be made in bursts, then the channel useburst SET[n] bit
should be set by writing a 1 to bit 8 of the DMA Channel Useburst Set
(DMAUSEBURSTSET) register.
Configure the Peripheral Interrupt
In order to use μDMA Ping-Pong mode, it is best to use an interrupt handler. (It is also possible to
use ping-pong mode without interrupts by polling). The interrupt handler will be triggered after each
buffer is complete.
1. Configure and enable an interrupt handler for the peripheral.
8.3.4.4
Enable the μDMA Channel
Now the channel is configured and is ready to start.
1. Enable the channel by setting bit 8 of the DMA Channel Enable Set (DMAENASET) register.
8.3.4.5
Process Interrupts
The μDMA controller is now configured and enabled for transfer on channel 8. When the peripheral
asserts the DMA request signal, the μDMA controller will make transfers into buffer A using the
primary channel control structure. When the primary transfer to buffer A is complete, it will switch
to the alternate channel control structure and make transfers into buffer B. At the same time, the
primary channel control word mode field will be set to indicate Stopped, and an interrupt will be
triggered.
When an interrupt is triggered, the interrupt handler must determine which buffer is complete and
process the data, or set a flag that the data needs to be processed by non-interrupt buffer processing
code. Then the next buffer transfer must be set up.
In the interrupt handler:
1. Read the primary channel control word at offset 0x088 and check the XFERMODE field. If the
field is 0, this means buffer A is complete. If buffer A is complete, then:
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a. Process the newly received data in buffer A, or signal the buffer processing code that buffer
A has data available.
b. Reprogram the primary channel control word at offset 0x88 according to Table
8-12 on page 306.
2. Read the alternate channel control word at offset 0x288 and check the XFERMODE field. If the
field is 0, this means buffer B is complete. If buffer B is complete, then:
a. Process the newly received data in buffer B, or signal the buffer processing code that buffer
B has data available.
b. Reprogram the alternate channel control word at offset 0x288 according to Table
8-12 on page 306.
8.4
Register Map
Table 8-13 on page 307 lists the μDMA channel control structures and registers. The channel control
structure shows the layout of one entry in the channel control table. The channel control table is
located in system memory, and the location is determined by the application, that is, the base
address is n/a (not applicable). In the table below, the offset for the channel control structures is the
offset from the entry in the channel control table. See “Channel Configuration” on page 290 and Table
8-3 on page 291 for a description of how the entries in the channel control table are located in memory.
The μDMA register addresses are given as a hexadecimal increment, relative to the μDMA base
address of 0x400F.F000. Note that the μDMA module clock must be enabled before the registers
can be programmed (see page 227). There must be a delay of 3 system clocks after the μDMA
module clock is enabled before any μDMA module registers are accessed.
Table 8-13. μDMA Register Map
Offset
Name
Type
Reset
Description
See
page
μDMA Channel Control Structure
0x000
DMASRCENDP
R/W
-
DMA Channel Source Address End Pointer
309
0x004
DMADSTENDP
R/W
-
DMA Channel Destination Address End Pointer
310
0x008
DMACHCTL
R/W
-
DMA Channel Control Word
311
DMA Status
315
DMA Configuration
317
μDMA Registers
0x000
DMASTAT
RO
0x001F.0000
0x004
DMACFG
WO
-
0x008
DMACTLBASE
R/W
0x0000.0000
DMA Channel Control Base Pointer
318
0x00C
DMAALTBASE
RO
0x0000.0200
DMA Alternate Channel Control Base Pointer
319
0x010
DMAWAITSTAT
RO
0x0000.0000
DMA Channel Wait on Request Status
320
0x014
DMASWREQ
WO
-
DMA Channel Software Request
321
0x018
DMAUSEBURSTSET
R/W
0x0000.0000
DMA Channel Useburst Set
322
0x01C
DMAUSEBURSTCLR
WO
-
DMA Channel Useburst Clear
324
0x020
DMAREQMASKSET
R/W
0x0000.0000
DMA Channel Request Mask Set
325
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Table 8-13. μDMA Register Map (continued)
Offset
Name
Type
Reset
0x024
DMAREQMASKCLR
WO
-
0x028
DMAENASET
R/W
0x0000.0000
0x02C
DMAENACLR
WO
-
0x030
DMAALTSET
R/W
0x0000.0000
0x034
DMAALTCLR
WO
-
0x038
DMAPRIOSET
R/W
0x0000.0000
0x03C
DMAPRIOCLR
WO
-
0x04C
DMAERRCLR
R/W
0xFD0
DMAPeriphID4
0xFE0
Description
See
page
DMA Channel Request Mask Clear
327
DMA Channel Enable Set
328
DMA Channel Enable Clear
330
DMA Channel Primary Alternate Set
331
DMA Channel Primary Alternate Clear
333
DMA Channel Priority Set
334
DMA Channel Priority Clear
336
0x0000.0000
DMA Bus Error Clear
337
RO
0x0000.0004
DMA Peripheral Identification 4
343
DMAPeriphID0
RO
0x0000.0030
DMA Peripheral Identification 0
339
0xFE4
DMAPeriphID1
RO
0x0000.00B2
DMA Peripheral Identification 1
340
0xFE8
DMAPeriphID2
RO
0x0000.000B
DMA Peripheral Identification 2
341
0xFEC
DMAPeriphID3
RO
0x0000.0000
DMA Peripheral Identification 3
342
0xFF0
DMAPCellID0
RO
0x0000.000D
DMA PrimeCell Identification 0
344
0xFF4
DMAPCellID1
RO
0x0000.00F0
DMA PrimeCell Identification 1
345
0xFF8
DMAPCellID2
RO
0x0000.0005
DMA PrimeCell Identification 2
346
0xFFC
DMAPCellID3
RO
0x0000.00B1
DMA PrimeCell Identification 3
347
8.5
μDMA Channel Control Structure
The μDMA Channel Control Structure holds the DMA transfer settings for a DMA channel. Each
channel has two control structures, which are located in a table in system memory. Refer to “Channel
Configuration” on page 290 for an explanation of the Channel Control Table and the Channel Control
Structure.
The channel control structure is one entry in the channel control table. There is a primary and
alternate structure for each channel. The primary control structures are located at offsets 0x0, 0x10,
0x20 and so on. The alternate control structures are located at offsets 0x200, 0x210, 0x220, and
so on.
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Register 1: DMA Channel Source Address End Pointer (DMASRCENDP), offset
0x000
DMA Channel Source Address End Pointer (DMASRCENDP) is part of the Channel Control
Structure, and is used to specify the source address for a DMA transfer.
DMA Channel Source Address End Pointer (DMASRCENDP)
Base n/a
Offset 0x000
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
8
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
31:0
ADDR
R/W
-
R/W
-
Description
Source Address End Pointer
Points to the last address of the DMA transfer source (inclusive). If the
source address is not incrementing, then this points at the source
location itself (such as a peripheral data register).
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Register 2: DMA Channel Destination Address End Pointer (DMADSTENDP),
offset 0x004
DMA Channel Destination Address End Pointer (DMADSTENDP) is part of the Channel Control
Structure, and is used to specify the destination address for a DMA transfer.
DMA Channel Destination Address End Pointer (DMADSTENDP)
Base n/a
Offset 0x004
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
8
ADDR
Type
Reset
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
31:0
ADDR
R/W
-
R/W
-
Description
Destination Address End Pointer
Points to the last address of the DMA transfer destination (inclusive). If
the destination address is not incrementing, then this points at the
destination location itself (such as a peripheral data register).
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Register 3: DMA Channel Control Word (DMACHCTL), offset 0x008
DMA Channel Control Word (DMACHCTL) is part of the Channel Control Structure, and is used
to specify parameters of a DMA transfer.
DMA Channel Control Word (DMACHCTL)
Base n/a
Offset 0x008
Type R/W, reset 31
30
29
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
15
14
13
12
11
10
9
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
DSTINC
Type
Reset
28
27
DSTSIZE
26
SRCINC
ARBSIZE
Type
Reset
R/W
-
R/W
-
25
24
23
22
21
19
18
17
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
8
7
6
5
4
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
SRCSIZE
20
reserved
ARBSIZE
XFERSIZE
Bit/Field
Name
Type
Reset
31:30
DSTINC
R/W
-
XFERMODE
NXTUSEBURST
R/W
-
16
R/W
-
R/W
-
R/W
-
R/W
-
Description
Destination Address Increment
Sets the bits to control the destination address increment.
The address increment value must be equal or greater than the value
of the destination size (DSTSIZE).
Value Description
0x0
Byte
Increment by 8-bit locations.
0x1
Half-word
Increment by 16-bit locations.
0x2
Word
Increment by 32-bit locations.
0x3
No increment
Address remains set to the value of the Destination Address
End Pointer (DMADSTENDP) for the channel.
29:28
DSTSIZE
R/W
-
Destination Data Size
Sets the destination item data size.
Note:
You must set DSTSIZE to be the same as SRCSIZE.
Value Description
0x0
Byte
8-bit data size.
0x1
Half-word
16-bit data size.
0x2
Word
32-bit data size.
0x3
Reserved
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Bit/Field
Name
Type
Reset
27:26
SRCINC
R/W
-
Description
Source Address Increment
Sets the bits to control the source address increment.
The address increment value must be equal or greater than the value
of the source size (SRCSIZE).
Value Description
0x0
Byte
Increment by 8-bit locations.
0x1
Half-word
Increment by 16-bit locations.
0x2
Word
Increment by 32-bit locations.
0x3
No increment
Address remains set to the value of the Source Address End
Pointer (DMASRCENDP) for the channel.
25:24
SRCSIZE
R/W
-
Source Data Size
Sets the source item data size.
Note:
You must set DSTSIZE to be the same as SRCSIZE.
Value Description
0x0
Byte
8-bit data size.
0x1
Half-word
16-bit data size.
0x2
Word
32-bit data size.
0x3
23:18
reserved
R/W
-
Reserved
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Bit/Field
Name
Type
Reset
17:14
ARBSIZE
R/W
-
Description
Arbitration Size
Sets the number of DMA transfers that can occur before the controller
re-arbitrates. The possible arbitration rate settings represent powers of
2 and are shown below.
Value
Description
0x0
1 Transfer
Arbitrates after each DMA transfer.
0x1
2 Transfers
0x2
4 Transfers
0x3
8 Transfers
0x4
16 Transfers
0x5
32 Transfers
0x6
64 Transfers
0x7
128 Transfers
0x8
256 Transfers
0x9
512 Transfers
0xA-0xF 1024 Transfers
This means that no arbitration occurs during the DMA transfer
because the maximum transfer size is 1024.
13:4
XFERSIZE
R/W
-
Transfer Size (minus 1)
Sets the total number of items to transfer. The value of this field is 1
less than the number to transfer (value 0 means transfer 1 item). The
maximum value for this 10-bit field is 1023 which represents a transfer
size of 1024 items.
The transfer size is the number of items, not the number of bytes. If the
data size is 32 bits, then this value is the number of 32-bit words to
transfer.
The controller updates this field immediately prior to it entering the
arbitration process, so it contains the number of outstanding DMA items
that are necessary to complete the DMA cycle.
3
NXTUSEBURST
R/W
-
Next Useburst
Controls whether the useburst SET[n] bit is automatically set for the
last transfer of a peripheral scatter-gather operation. Normally, for the
last transfer, if the number of remaining items to transfer is less than
the arbitration size, the controller will use single transfers to complete
the transaction. If this bit is set, then the controller will only use a burst
transfer to complete the last transfer.
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Bit/Field
Name
Type
Reset
2:0
XFERMODE
R/W
-
Description
DMA Transfer Mode
Since this register is in system RAM, it has no reset value. Therefore,
this field should be initialized to 0 before the channel is enabled.
The operating mode of the DMA cycle. Refer to “Transfer
Modes” on page 292 for a detailed explanation of transfer modes.
Value Description
0x0
Stop
Channel is stopped, or configuration data is invalid.
0x1
Basic
The controller must receive a new request, prior to it entering
the arbitration process, to enable the DMA cycle to complete.
0x2
Auto-Request
The initial request (software- or peripheral-initiated) is sufficient
to complete the entire transfer of XFERSIZE items without any
further requests.
0x3
Ping-Pong
The controller performs a DMA cycle using one of the channel
control structures. After the DMA cycle completes, it performs
a DMA cycle using the other channel control structure. After the
next DMA cycle completes (and provided that the host processor
has updated the original channel control data structure), it
performs a DMA cycle using the original channel control data
structure. The controller continues to perform DMA cycles until
it either reads an invalid data structure or the host processor
changes this field to 0x1 or 0x2. See “Ping-Pong” on page 292.
0x4
Memory Scatter-Gather
When the controller operates in Memory Scatter-Gather mode,
you must only use this value in the primary channel control data
structure. See “Memory Scatter-Gather” on page 293.
0x5
Alternate Memory Scatter-Gather
When the controller operates in Memory Scatter-Gather mode,
you must only use this value in the alternate channel control
data structure.
0x6
Peripheral Scatter-Gather
When the controller operates in Peripheral Scatter-Gather mode,
you must only use this value in the primary channel control data
structure. See “Peripheral Scatter-Gather” on page 297.
0x7
Alternate Peripheral Scatter-Gather
When the controller operates in Peripheral Scatter-Gather mode,
you must only use this value in the alternate channel control
data structure.
8.6
μDMA Register Descriptions
The register addresses given are relative to the μDMA base address of 0x400F.F000.
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Register 4: DMA Status (DMASTAT), offset 0x000
The DMA Status (DMASTAT) register returns the status of the controller. You cannot read this
register when the controller is in the reset state.
DMA Status (DMASTAT)
Base 0x400F.F000
Offset 0x000
Type RO, reset 0x001F.0000
31
30
29
28
27
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
RO
0
RO
0
RO
0
RO
0
26
25
24
23
22
21
20
19
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
10
9
8
7
6
5
4
3
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
STATE
RO
0
17
16
RO
1
RO
1
RO
1
2
1
0
DMACHANS
reserved
Type
Reset
18
reserved
RO
0
MASTEN
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:21
reserved
RO
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.
20:16
DMACHANS
RO
0x1F
Available DMA Channels Minus 1
This bit contains a value equal to the number of DMA channels the
controller is configured to use, minus one. That is, 32 DMA channels.
15:8
reserved
RO
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.
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Bit/Field
Name
Type
Reset
Description
7:4
STATE
RO
0x00
Control State Machine State
Current state of the control state machine. State can be one of the
following.
Value
Description
0x0
Idle
0x1
Read Chan Control Data
Reading channel controller data.
0x2
Read Source End Ptr
Reading source end pointer.
0x3
Read Dest End Ptr
Reading destination end pointer.
0x4
Read Source Data
Reading source data.
0x5
Write Dest Data
Writing destination data.
0x6
Wait for Req Clear
Waiting for DMA request to clear.
0x7
Write Chan Control Data
Writing channel controller data.
0x8
Stalled
0x9
Done
0xA-0xF Undefined
3:1
reserved
RO
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.
0
MASTEN
RO
0x00
Master Enable
Returns status of the controller.
Value Description
0
Disabled
1
Enabled
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Register 5: DMA Configuration (DMACFG), offset 0x004
The DMACFG register controls the configuration of the controller.
DMA Configuration (DMACFG)
Base 0x400F.F000
Offset 0x004
Type WO, reset 31
30
29
28
27
26
25
24
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
reserved
Type
Reset
reserved
Type
Reset
WO
-
MASTEN
WO
-
Bit/Field
Name
Type
Reset
Description
31:1
reserved
WO
-
Software should not rely on the value of 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
MASTEN
WO
-
Controller Master Enable
Enables the controller.
Value Description
0
Disables
1
Enables
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Register 6: DMA Channel Control Base Pointer (DMACTLBASE), offset 0x008
The DMACTLBASE register must be configured so that the base pointer points to a location in
system memory.
The amount of system memory that you must assign to the controller depends on the number of
DMA channels used and whether you configure it to use the alternate channel control data structure.
See “Channel Configuration” on page 290 for details about the Channel Control Table. The base
address must be aligned on a 1024-byte boundary. You cannot read this register when the controller
is in the reset state.
DMA Channel Control Base Pointer (DMACTLBASE)
Base 0x400F.F000
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
ADDR
Type
Reset
R/W
0
R/W
0
R/W
0
15
14
13
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
ADDR
Type
Reset
R/W
0
R/W
0
R/W
0
reserved
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:10
ADDR
R/W
0x00
Channel Control Base Address
Pointer to the base address of the channel control table. The base
address must be 1024-byte aligned.
9:0
reserved
RO
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.
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Register 7: DMA Alternate Channel Control Base Pointer (DMAALTBASE),
offset 0x00C
The DMAALTBASE register returns the base address of the alternate channel control data. This
register removes the necessity for application software to calculate the base address of the alternate
channel control structures. You cannot read this register when the controller is in the reset state.
DMA Alternate Channel Control Base Pointer (DMAALTBASE)
Base 0x400F.F000
Offset 0x00C
Type RO, reset 0x0000.0200
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
ADDR
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
ADDR
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
Bit/Field
Name
Type
Reset
Description
31:0
ADDR
RO
0x200
Alternate Channel Address Pointer
Provides the base address of the alternate channel control structures.
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Register 8: DMA Channel Wait on Request Status (DMAWAITSTAT), offset
0x010
This read-only register indicates that the μDMA channel is waiting on a request. A peripheral can
pull this Low to hold off the μDMA from performing a single request until the peripheral is ready for
a burst request. The use of this feature is dependent on the design of the peripheral and is used to
enhance performance of the μDMA with that peripheral. You cannot read this register when the
controller is in the reset state.
DMA Channel Wait on Request Status (DMAWAITSTAT)
Base 0x400F.F000
Offset 0x010
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WAITREQ[n]
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
WAITREQ[n]
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:0
WAITREQ[n]
RO
0x00
Channel [n] Wait Status
Channel wait on request status. For each channel 0 through 31, a 1 in
the corresponding bit field indicates that the channel is waiting on a
request.
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Stellaris® LM3S5737 Microcontroller
Register 9: DMA Channel Software Request (DMASWREQ), offset 0x014
Each bit of the DMASWREQ register represents the corresponding DMA channel. When you set a
bit, it generates a request for the specified DMA channel.
DMA Channel Software Request (DMASWREQ)
Base 0x400F.F000
Offset 0x014
Type WO, reset 31
30
29
28
27
26
25
24
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
SWREQ[n]
Type
Reset
SWREQ[n]
Type
Reset
Bit/Field
Name
Type
Reset
31:0
SWREQ[n]
WO
-
WO
-
Description
Channel [n] Software Request
For each channel 0 through 31, write a 1 to the corresponding bit field
to generate a software DMA request for that DMA channel. Writing a 0
does not create a DMA request for the corresponding channel.
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Micro Direct Memory Access (μDMA)
Register 10: DMA Channel Useburst Set (DMAUSEBURSTSET), offset 0x018
Each bit of the DMAUSEBURSTSET register represents the corresponding DMA channel. Writing
a 1 disables the peripheral's single request input from generating requests, and therefore only the
peripheral's burst request generates requests. Reading the register returns the status of useburst.
When there are fewer items remaining to transfer than the arbitration (burst) size, the controller
automatically clears the useburst bit to 0. This enables the remaining items to transfer using single
requests. This bit should not be set for a peripheral's channel that does not support the burst request
model.
Refer to “Request Types” on page 290 for more details about request types.
Reads
DMA Channel Useburst Set (DMAUSEBURSTSET)
Base 0x400F.F000
Offset 0x018
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
R
0x00
Channel [n] Useburst Status
Returns the useburst status of channel [n].
Value Description
0
Single and Burst
DMA channel [n] responds to single or burst requests.
1
Burst Only
DMA channel [n] responds only to burst requests.
Writes
DMA Channel Useburst Set (DMAUSEBURSTSET)
Base 0x400F.F000
Offset 0x018
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
SET[n]
Type
Reset
SET[n]
Type
Reset
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
W
0x00
Channel [n] Useburst Set
Sets useburst bit on channel [n].
Value Description
0
No Effect
Use the DMAUSEBURSTCLR register to clear bit [n] to 0.
1
Burst Only
DMA channel [n] responds only to burst requests.
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Micro Direct Memory Access (μDMA)
Register 11: DMA Channel Useburst Clear (DMAUSEBURSTCLR), offset 0x01C
Each bit of the DMAUSEBURSTCLR register represents the corresponding DMA channel. Writing
a 1 enables dma_sreq[n] to generate requests.
DMA Channel Useburst Clear (DMAUSEBURSTCLR)
Base 0x400F.F000
Offset 0x01C
Type WO, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
CLR[n]
Type
Reset
CLR[n]
Type
Reset
Bit/Field
Name
Type
Reset
31:0
CLR[n]
WO
-
Description
Channel [n] Useburst Clear
Clears useburst bit on channel [n].
Value Description
0
No Effect
Use the DMAUSEBURSTSET to set bit [n] to 1.
1
Single and Burst
DMA channel [n] responds to single and burst requests.
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Stellaris® LM3S5737 Microcontroller
Register 12: DMA Channel Request Mask Set (DMAREQMASKSET), offset
0x020
Each bit of the DMAREQMASKSET register represents the corresponding DMA channel. Writing
a 1 disables DMA requests for the channel. Reading the register returns the request mask status.
When a μDMA channel's request is masked, that means the peripheral can no longer request μDMA
transfers. The channel can then be used for software-initiated transfers.
Reads
DMA Channel Request Mask Set (DMAREQMASKSET)
Base 0x400F.F000
Offset 0x020
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SET[n]
Type
Reset
SET[n]
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
R
0x00
Channel [n] Request Mask Status
Returns the channel request mask status.
Value Description
0
Enabled
External requests are not masked for channel [n].
1
Masked
External requests are masked for channel [n].
Writes
DMA Channel Request Mask Set (DMAREQMASKSET)
Base 0x400F.F000
Offset 0x020
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
7
6
5
4
3
2
1
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
SET[n]
Type
Reset
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
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Micro Direct Memory Access (μDMA)
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
W
0x00
Channel [n] Request Mask Set
Masks (disables) the corresponding channel [n] from generating DMA
requests.
Value Description
0
No Effect
1
Masked
Use the DMAREQMASKCLR register to clear the request mask.
Masks (disables) DMA requests on channel [n].
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Stellaris® LM3S5737 Microcontroller
Register 13: DMA Channel Request Mask Clear (DMAREQMASKCLR), offset
0x024
Each bit of the DMAREQMASKCLR register represents the corresponding DMA channel. Writing
a 1 clears the request mask for the channel, and enables the channel to receive DMA requests.
DMA Channel Request Mask Clear (DMAREQMASKCLR)
Base 0x400F.F000
Offset 0x024
Type WO, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
CLR[n]
Type
Reset
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
CLR[n]
Type
Reset
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
Bit/Field
Name
Type
Reset
31:0
CLR[n]
WO
-
WO
-
Description
Channel [n] Request Mask Clear
Set the appropriate bit to clear the DMA request mask for channel [n].
This will enable DMA requests for the channel.
Value Description
0
No Effect
Use the DMAREQMASKSET register to set the request mask.
1
Clear Mask
Clears the request mask for the DMA channel. This enables
DMA requests for the channel.
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Micro Direct Memory Access (μDMA)
Register 14: DMA Channel Enable Set (DMAENASET), offset 0x028
Each bit of the DMAENASET register represents the corresponding DMA channel. Writing a 1
enables the DMA channel. Reading the register returns the enable status of the channels. If a
channel is enabled but the request mask is set (DMAREQMASKSET), then the channel can be
used for software-initiated transfers.
Reads
DMA Channel Enable Set (DMAENASET)
Base 0x400F.F000
Offset 0x028
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
R
0x00
Channel [n] Enable Status
Returns the enable status of the channels.
Value Description
0
Disabled
1
Enabled
Writes
DMA Channel Enable Set (DMAENASET)
Base 0x400F.F000
Offset 0x028
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
7
6
5
4
3
2
1
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
SET[n]
Type
Reset
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
W
0x00
Channel [n] Enable Set
Enables the corresponding channels.
Note:
The controller disables a channel when it completes the DMA
cycle.
Value Description
0
No Effect
1
Enable
Use the DMAENACLR register to disable a channel.
Enables channel [n].
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Micro Direct Memory Access (μDMA)
Register 15: DMA Channel Enable Clear (DMAENACLR), offset 0x02C
Each bit of the DMAENACLR register represents the corresponding DMA channel. Writing a 1
disables the specified DMA channel.
DMA Channel Enable Clear (DMAENACLR)
Base 0x400F.F000
Offset 0x02C
Type WO, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
CLR[n]
Type
Reset
CLR[n]
Type
Reset
Bit/Field
Name
Type
Reset
31:0
CLR[n]
WO
-
Description
Clear Channel [n] Enable
Set the appropriate bit to disable the corresponding DMA channel.
Note:
The controller disables a channel when it completes the DMA
cycle.
Value Description
0
No Effect
1
Disable
Use the DMAENASET register to enable DMA channels.
Disables channel [n].
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Stellaris® LM3S5737 Microcontroller
Register 16: DMA Channel Primary Alternate Set (DMAALTSET), offset 0x030
Each bit of the DMAALTSET register represents the corresponding DMA channel. Writing a 1
configures the DMA channel to use the alternate control data structure. Reading the register returns
the status of which control data structure is in use for the corresponding DMA channel.
Reads
DMA Channel Primary Alternate Set (DMAALTSET)
Base 0x400F.F000
Offset 0x030
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
R
0x00
Channel [n] Alternate Status
Returns the channel control data structure status.
Value Description
0
Primary
DMA channel [n] is using the primary control structure.
1
Alternate
DMA channel [n] is using the alternate control structure.
Writes
DMA Channel Primary Alternate Set (DMAALTSET)
Base 0x400F.F000
Offset 0x030
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
SET[n]
Type
Reset
SET[n]
Type
Reset
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Micro Direct Memory Access (μDMA)
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
W
0x00
Channel [n] Alternate Set
Selects the alternate channel control data structure for the corresponding
DMA channel.
Note:
For Ping-Pong and Scatter-Gather DMA cycle types, the
controller automatically sets these bits to select the alternate
channel control data structure.
Value Description
0
No Effect
Use the DMAALTCLR register to set bit [n] to 0.
1
Alternate
Selects the alternate control data structure for channel [n].
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Stellaris® LM3S5737 Microcontroller
Register 17: DMA Channel Primary Alternate Clear (DMAALTCLR), offset
0x034
Each bit of the DMAALTCLR register represents the corresponding DMA channel. Writing a 1
configures the DMA channel to use the primary control data structure.
DMA Channel Primary Alternate Clear (DMAALTCLR)
Base 0x400F.F000
Offset 0x034
Type WO, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
CLR[n]
Type
Reset
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
CLR[n]
Type
Reset
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
Bit/Field
Name
Type
Reset
31:0
CLR[n]
WO
-
WO
-
Description
Channel [n] Alternate Clear
Set the appropriate bit to select the primary control data structure for
the corresponding DMA channel.
Note:
For Ping-Pong and Scatter-Gather DMA cycle types, the
controller sets these bits to select the primary channel control
data structure.
Value Description
0
No Effect
Use the DMAALTSET register to select the alternate control
data structure.
1
Primary
Selects the primary control data structure for channel [n].
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Micro Direct Memory Access (μDMA)
Register 18: DMA Channel Priority Set (DMAPRIOSET), offset 0x038
Each bit of the the DMAPRIOSET register represents the corresponding DMA channel. Writing a
1 configures the DMA channel to have a high priority level. Reading the register returns the status
of the channel priority mask.
Reads
DMA Channel Priority Set (DMAPRIOSET)
Base 0x400F.F000
Offset 0x038
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
7
6
5
4
3
2
1
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
15
14
13
12
11
10
9
8
SET[n]
Type
Reset
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
R
0x00
Channel [n] Priority Status
Returns the channel priority status.
Value Description
0
Default Priority
DMA channel [n] is using the default priority level.
1
High Priority
DMA channel [n] is using a High Priority level.
Writes
DMA Channel Priority Set (DMAPRIOSET)
Base 0x400F.F000
Offset 0x038
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
SET[n]
Type
Reset
SET[n]
Type
Reset
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
Description
31:0
SET[n]
W
0x00
Channel [n] Priority Set
Sets the channel priority to high.
Value Description
0
No Effect
Use the DMAPRIOCLR register to set channel [n] to the default
priority level.
1
High Priority
Sets DMA channel [n] to a High Priority level.
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Register 19: DMA Channel Priority Clear (DMAPRIOCLR), offset 0x03C
Each bit of the DMAPRIOCLR register represents the corresponding DMA channel. Writing a 1
configures the DMA channel to have the default priority level.
DMA Channel Priority Clear (DMAPRIOCLR)
Base 0x400F.F000
Offset 0x03C
Type WO, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
CLR[n]
Type
Reset
CLR[n]
Type
Reset
Bit/Field
Name
Type
Reset
31:0
CLR[n]
WO
-
Description
Channel [n] Priority Clear
Set the appropriate bit to clear the high priority level for the specified
DMA channel.
Value Description
0
No Effect
Use the DMAPRIOSET register to set channel [n] to the High
priority level.
1
Default Priority
Sets DMA channel [n] to a Default priority level.
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Register 20: DMA Bus Error Clear (DMAERRCLR), offset 0x04C
The DMAERRCLR register is used to read and clear the DMA bus error status. The error status
will be set if the μDMA controller encountered a bus error while performing a DMA transfer. If a bus
error occurs on a channel, that channel will be automatically disabled by the μDMA controller. The
other channels are unaffected.
Reads
DMA Bus Error Clear (DMAERRCLR)
Base 0x400F.F000
Offset 0x04C
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
0
ERRCLR
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R
0
Bit/Field
Name
Type
Reset
Description
31:1
reserved
RO
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.
0
ERRCLR
R
0
DMA Bus Error Status
Value Description
0
Low
No bus error is pending.
1
High
Bus error is pending.
Writes
DMA Bus Error Clear (DMAERRCLR)
Base 0x400F.F000
Offset 0x04C
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
ERRCLR
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0
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Micro Direct Memory Access (μDMA)
Bit/Field
Name
Type
Reset
Description
31:1
reserved
RO
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.
0
ERRCLR
W
0
DMA Bus Error Clear
Clears the bus error.
Value Description
0
No Effect
Bus error status is unchanged.
1
Clear
Clears a pending bus error.
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Register 21: DMA Peripheral Identification 0 (DMAPeriphID0), offset 0xFE0
The DMAPeriphIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA Peripheral Identification 0 (DMAPeriphID0)
Base 0x400F.F000
Offset 0xFE0
Type RO, reset 0x0000.0030
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID0
RO
0x30
DMA Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
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Micro Direct Memory Access (μDMA)
Register 22: DMA Peripheral Identification 1 (DMAPeriphID1), offset 0xFE4
The DMAPeriphIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA Peripheral Identification 1 (DMAPeriphID1)
Base 0x400F.F000
Offset 0xFE4
Type RO, reset 0x0000.00B2
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
1
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID1
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID1
RO
0xB2
DMA Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
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Register 23: DMA Peripheral Identification 2 (DMAPeriphID2), offset 0xFE8
The DMAPeriphIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA Peripheral Identification 2 (DMAPeriphID2)
Base 0x400F.F000
Offset 0xFE8
Type RO, reset 0x0000.000B
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
reserved
Type
Reset
reserved
Type
Reset
PID2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID2
RO
0x0B
DMA Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
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Micro Direct Memory Access (μDMA)
Register 24: DMA Peripheral Identification 3 (DMAPeriphID3), offset 0xFEC
The DMAPeriphIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA Peripheral Identification 3 (DMAPeriphID3)
Base 0x400F.F000
Offset 0xFEC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID3
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID3
RO
0x00
DMA Peripheral ID Register[31:24]
Can be used by software to identify the presence of this peripheral.
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Stellaris® LM3S5737 Microcontroller
Register 25: DMA Peripheral Identification 4 (DMAPeriphID4), offset 0xFD0
The DMAPeriphIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA Peripheral Identification 4 (DMAPeriphID4)
Base 0x400F.F000
Offset 0xFD0
Type RO, reset 0x0000.0004
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID4
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID4
RO
0x04
DMA Peripheral ID Register
Can be used by software to identify the presence of this peripheral.
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Micro Direct Memory Access (μDMA)
Register 26: DMA PrimeCell Identification 0 (DMAPCellID0), offset 0xFF0
The DMAPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA PrimeCell Identification 0 (DMAPCellID0)
Base 0x400F.F000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID0
RO
0x0D
DMA PrimeCell ID Register[7:0]
Provides software a standard cross-peripheral identification system.
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Register 27: DMA PrimeCell Identification 1 (DMAPCellID1), offset 0xFF4
The DMAPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA PrimeCell Identification 1 (DMAPCellID1)
Base 0x400F.F000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
CID1
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID1
RO
0xF0
DMA PrimeCell ID Register[15:8]
Provides software a standard cross-peripheral identification system.
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Micro Direct Memory Access (μDMA)
Register 28: DMA PrimeCell Identification 2 (DMAPCellID2), offset 0xFF8
The DMAPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA PrimeCell Identification 2 (DMAPCellID2)
Base 0x400F.F000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID2
RO
0x05
DMA PrimeCell ID Register[23:16]
Provides software a standard cross-peripheral identification system.
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Register 29: DMA PrimeCell Identification 3 (DMAPCellID3), offset 0xFFC
The DMAPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
DMA PrimeCell Identification 3 (DMAPCellID3)
Base 0x400F.F000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID3
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID3
RO
0xB1
DMA PrimeCell ID Register[31:24]
Provides software a standard cross-peripheral identification system.
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General-Purpose Input/Outputs (GPIOs)
9
General-Purpose Input/Outputs (GPIOs)
The GPIO module is composed of eight physical GPIO blocks, each corresponding to an individual
GPIO port (Port A, Port B, Port C, Port D, Port E, Port F, Port G, Port H). The GPIO module supports
27-61 programmable input/output pins, depending on the peripherals being used.
The GPIO module has the following features:
■ 27-61 GPIOs, depending on configuration
■ 5-V-tolerant in input configuration
■ Two means of port access: either Advanced High-Performance Bus (AHB) with better back-to-back
access performance, or the legacy Advanced Peripheral Bus (APB) for backwards-compatibility
with existing code
■ Fast toggle capable of a change every clock cycle for ports on AHB, every two clock cycles for
ports on APB
■ Programmable control for GPIO interrupts
– Interrupt generation masking
– Edge-triggered on rising, falling, or both
– Level-sensitive on High or Low values
■ Bit masking in both read and write operations through address lines
■ Can initiate an ADC sample sequence
■ Pins configured as digital inputs are Schmitt-triggered.
■ Programmable control for GPIO pad configuration
– Weak pull-up or pull-down resistors
– 2-mA, 4-mA, and 8-mA pad drive for digital communication; up to four pads can be configured
with an 18-mA pad drive for high-current applications
– Slew rate control for the 8-mA drive
– Open drain enables
– Digital input enables
9.1
Signal Description
GPIO signals have alternate hardware functions. Table 9-3 on page 350 lists the GPIO pins and their
analog and digital alternate functions. The AINx analog signals are not 5-V tolerant and go through
an isolation circuit before reaching their circuitry. These signals are configured by clearing the
corresponding DEN bit in the GPIO Digital Enable (GPIODEN) register and setting the corresponding
AMSEL bit in the GPIO Analog Mode Select (GPIOAMSEL) register. Other analog signals are 5-V
tolerant and are connected directly to their circuitry (). These signals are configured by clearing the
DEN bit in the GPIO Digital Enable (GPIODEN) register. The digital alternate hardware functions
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are enabled by setting the appropriate bit in the GPIO Alternate Function Select (GPIOAFSEL)
and GPIODEN registers and configuring the PMCx bit field in the GPIO Port Control (GPIOPCTL)
register to the numeric enoding shown in the table below. Note that each pin must be programmed
individually; no type of grouping is implied by the columns in the table.
Important: All GPIO pins are configured as GPIOs and tri-stated by default (GPIOAFSEL=0,
GPIODEN=0, GPIOPDR=0, GPIOPUR=0, and GPIOPCTL=0, with the exception of the
four JTAG/SWD pins (shown in the table below). A Power-On-Reset (POR) or asserting
RST puts the pins back to their default state.
Table 9-1. GPIO Pins With Non-Zero Reset Values
GPIO Pins
Default State
PA[1:0]
UART0
GPIOAFSEL GPIODEN GPIOPDR GPIOPUR
1
1
0
0
GPIOPCTL
0x1
PA[5:2]
SSI0
1
1
0
0
0x1
PB[3:2]
I2C0
1
1
0
0
0x1
PC[3:0]
JTAG/SWD
1
1
0
1
0x3
Table 9-2. GPIO Pins and Alternate Functions (100LQFP)
IO
Pin Number
Multiplexed Function
Multiplexed Function
PA0
26
U0Rx
PA1
27
U0Tx
PA2
28
SSI0Clk
PA3
29
SSI0Fss
PA4
30
SSI0Rx
PA5
31
SSI0Tx
PA6
34
I2C1SCL
PA7
35
I2C1SDA
PB0
66
CCP0
PB1
67
CCP1
PB2
72
I2C0SCL
PB3
65
I2C0SDA
PB4
92
PB5
91
PB6
90
PB7
89
NMI
PC0
80
TCK
SWCLK
PC1
79
TMS
SWDIO
PC2
78
TDI
PC3
77
TDO
PC4
25
PC5
24
USB0EPEN
PC6
23
USB0PFLT
PC7
22
PD0
10
CCP2
SWO
CAN0Rx
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General-Purpose Input/Outputs (GPIOs)
Table 9-2. GPIO Pins and Alternate Functions (100LQFP) (continued)
IO
Pin Number
Multiplexed Function
PD1
11
CAN0Tx
PD2
12
PD3
13
PD4
97
ADC7
PD5
98
ADC6
PD6
99
ADC5
PD7
100
ADC4
PE0
74
SSI1Clk
PE1
75
SSI1Fss
PE2
95
SSI1Rx
PE3
96
SSI1Tx
PE4
6
ADC3
PE5
5
ADC2
PE6
2
ADC1
PE7
1
ADC0
PF0
47
PF1
61
PF2
60
PF3
59
PF4
58
PF5
46
PF6
43
PF7
42
PG0
19
PG1
18
PG2
17
PG3
16
PG4
41
PG5
40
PG6
37
PG7
36
PH0
86
PH1
85
PH2
84
PH3
83
PH4
76
Multiplexed Function
Table 9-3. GPIO Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
PA0
26
I/O
TTL
GPIO port A bit 0.
PA1
27
I/O
TTL
GPIO port A bit 1.
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Table 9-3. GPIO Signals (100LQFP) (continued)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
PA2
28
I/O
TTL
GPIO port A bit 2.
PA3
29
I/O
TTL
GPIO port A bit 3.
PA4
30
I/O
TTL
GPIO port A bit 4.
PA5
31
I/O
TTL
GPIO port A bit 5.
PA6
34
I/O
TTL
GPIO port A bit 6.
PA7
35
I/O
TTL
GPIO port A bit 7.
PB0
66
I/O
TTL
GPIO port B bit 0.
PB1
67
I/O
TTL
GPIO port B bit 1.
PB2
72
I/O
TTL
GPIO port B bit 2.
PB3
65
I/O
TTL
GPIO port B bit 3.
PB4
92
I/O
TTL
GPIO port B bit 4.
PB5
91
I/O
TTL
GPIO port B bit 5.
PB6
90
I/O
TTL
GPIO port B bit 6.
PB7
89
I/O
TTL
GPIO port B bit 7.
PC0
80
I/O
TTL
GPIO port C bit 0.
PC1
79
I/O
TTL
GPIO port C bit 1.
PC2
78
I/O
TTL
GPIO port C bit 2.
PC3
77
I/O
TTL
GPIO port C bit 3.
PC4
25
I/O
TTL
GPIO port C bit 4.
PC5
24
I/O
TTL
GPIO port C bit 5.
PC6
23
I/O
TTL
GPIO port C bit 6.
PC7
22
I/O
TTL
GPIO port C bit 7.
PD0
10
I/O
TTL
GPIO port D bit 0.
PD1
11
I/O
TTL
GPIO port D bit 1.
PD2
12
I/O
TTL
GPIO port D bit 2.
PD3
13
I/O
TTL
GPIO port D bit 3.
PD4
97
I/O
TTL
GPIO port D bit 4.
PD5
98
I/O
TTL
GPIO port D bit 5.
PD6
99
I/O
TTL
GPIO port D bit 6.
PD7
100
I/O
TTL
GPIO port D bit 7.
PE0
74
I/O
TTL
GPIO port E bit 0.
PE1
75
I/O
TTL
GPIO port E bit 1.
PE2
95
I/O
TTL
GPIO port E bit 2.
PE3
96
I/O
TTL
GPIO port E bit 3.
PE4
6
I/O
TTL
GPIO port E bit 4.
PE5
5
I/O
TTL
GPIO port E bit 5.
PE6
2
I/O
TTL
GPIO port E bit 6.
PE7
1
I/O
TTL
GPIO port E bit 7.
PF0
47
I/O
TTL
GPIO port F bit 0.
PF1
61
I/O
TTL
GPIO port F bit 1.
PF2
60
I/O
TTL
GPIO port F bit 2.
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Table 9-3. GPIO Signals (100LQFP) (continued)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
PF3
59
I/O
TTL
GPIO port F bit 3.
PF4
58
I/O
TTL
GPIO port F bit 4.
PF5
46
I/O
TTL
GPIO port F bit 5.
PF6
43
I/O
TTL
GPIO port F bit 6.
PF7
42
I/O
TTL
GPIO port F bit 7.
PG0
19
I/O
TTL
GPIO port G bit 0.
PG1
18
I/O
TTL
GPIO port G bit 1.
PG2
17
I/O
TTL
GPIO port G bit 2.
PG3
16
I/O
TTL
GPIO port G bit 3.
PG4
41
I/O
TTL
GPIO port G bit 4.
PG5
40
I/O
TTL
GPIO port G bit 5.
PG6
37
I/O
TTL
GPIO port G bit 6.
PG7
36
I/O
TTL
GPIO port G bit 7.
PH0
86
I/O
TTL
GPIO port H bit 0.
PH1
85
I/O
TTL
GPIO port H bit 1.
PH2
84
I/O
TTL
GPIO port H bit 2.
PH3
83
I/O
TTL
GPIO port H bit 3.
PH4
76
I/O
TTL
GPIO port H bit 4.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
9.2
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 four JTAG/SWD pins (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 353 and Figure 9-2 on page 354). The LM3S5737 microcontroller contains eight ports
and thus eight of these physical GPIO blocks.
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Figure 9-1. Digital I/O Pads
Commit
Control
GPIOLOCK
GPIOCR
Mode
Control
GPIOAFSEL
Alternate Input
DEMUX
Alternate Output
Alternate output Enable
GPIO Output
GPIO Output Enable
Interrupt
Control
Pad
Control
GPIOIS
GPIOIBE
GPIOIEV
GPIOIM
GPIORIS
GPIOMIS
GPIOICR
GPIODR2R
GPIODR4R
GPIODR8R
GPIOSLR
GPIOPUR
GPIOPDR
GPIOODR
GPIODEN
MUX
GPIODATA
GPIODIR
Interrupt
MUX
GPIO Input
Data
Control
Pad Input
Pad Output
Digital
I/O
Pad
Package I/O Pin
Pad Output
Enable
Identification Registers
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
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Figure 9-2. Analog/Digital I/O Pads
Commit
Control
Mode
Control
GPIOLOCK
GPIOCR
GPIOAFSEL
DEMUX
Alternate Input
Alternate Output
Alternate Output Enable
MUX
Data
Control
Pad Input
Pad Output
Analog/Digital
I/O Pad
Package I/O Pin
GPIO Input
GPIO Output
Interrupt
MUX
GPIODATA
GPIODIR
GPIO Output Enable
Interrupt
Control
GPIOIS
GPIOIBE
GPIOIEV
GPIOIM
GPIORIS
GPIOMIS
GPIOICR
Pad Output Enable
Pad
Control
GPIODR2R
GPIODR4R
GPIODR8R
GPIOSLR
GPIOPUR
GPIOPDR
GPIOODR
GPIODEN
GPIOAMSEL
Analog Circuitry
Identification Registers
ADC
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
9.2.1
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
(for PortE4 – 7 and
PortD4 – 7 pins that
connect to the ADC
input MUX)
Isolation
Circuit
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.
9.2.1.1
Data Direction Operation
The GPIO Direction (GPIODIR) register (see page 362) 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.
9.2.1.2
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 361) 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
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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.
For example, writing a value of 0xEB to the address GPIODATA + 0x098 would yield as shown in
Figure 9-3 on page 355, where u is data unchanged by the write.
Figure 9-3. GPIODATA Write Example
ADDR[9:2]
0x098
9
8
7
6
5
4
3
2
1
0
0
0
1
0
0
1
1
0
0
0
0xEB
1
1
1
0
1
0
1
1
GPIODATA
u
u
1
u
u
0
1
u
7
6
5
4
3
2
1
0
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 9-4 on page 355.
Figure 9-4. GPIODATA Read Example
9.2.2
ADDR[9:2]
0x0C4
9
8
7
6
5
4
3
2
1
0
0
0
1
1
0
0
0
1
0
0
GPIODATA
1
0
1
1
1
1
1
0
Returned Value
0
0
1
1
0
0
0
0
7
6
5
4
3
2
1
0
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 363)
■ GPIO Interrupt Both Edges (GPIOIBE) register (see page 364)
■ GPIO Interrupt Event (GPIOIEV) register (see page 365)
Interrupts are enabled/disabled via the GPIO Interrupt Mask (GPIOIM) register (see page 366).
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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 367 and page 368). 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.
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 (the appropriate bit of 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 Interrupt 0-31 Set Enable (EN0)
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 PB4,
and wait for the ADC interrupt or the ADC interrupt must be disabled in the EN0 register and the
PortB interrupt handler must poll the ADC registers until the conversion is completed. See page 108
for more information.
Interrupts are cleared by writing a 1 to the appropriate bit of the GPIO Interrupt Clear (GPIOICR)
register (see page 370).
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.
9.2.3
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 371), 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.
Note:
9.2.4
If any pin is to be used as an ADC input, the appropriate bit in GPIOAMSEL must be written
to 1 to disable the analog isolation circuit.
Commit Control
The GPIO commit control registers provide a layer of protection against accidental programming of
critical hardware peripherals. Protection is currently provided for the NMI pin (PB7) and the four
JTAG/SWD pins (PC[3:0]). Writes to protected bits of the GPIO Alternate Function Select
(GPIOAFSEL) register (see page 371), GPIO Pull-Up Select (GPIOPUR) register (see page 377),
and GPIO Digital Enable (GPIODEN) register (see page 381) are not committed to storage unless
the GPIO Lock (GPIOLOCK) register (see page 383) has been unlocked and the appropriate bits
of the GPIO Commit (GPIOCR) register (see page 384) have been set to 1.
9.2.5
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. These registers control drive strength,
open-drain configuration, pull-up and pull-down resistors, slew-rate control and digital enable.
For special high-current applications, the GPIO output buffers may be used with the following
restrictions. With the GPIO pins configured as 8-mA output drivers, a total of four GPIO outputs may
be used to sink current loads up to 18 mA each. At 18-mA sink current loading, the VOL value is
specified as 1.2 V. The high-current GPIO package pins must be selected such that there are only
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a maximum of two per side of the physical package with the total number of high-current GPIO
outputs not exceeding four for the entire package.
9.2.6
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.
9.3
Initialization and Configuration
The GPIO modules may be accessed via two different memory apertures. The legacy aperture, the
®
Advanced Peripheral Bus (APB), is backwards-compatible with previous Stellaris parts. The other
aperture, the Advanced High-Performance Bus (AHB), offers the same register map but provides
better back-to-back access performance than the APB bus. These apertures are mutually exclusive.
The aperture enabled for a given GPIO port is controlled by the appropriate bit in the GPIOHBCTL
register (see page 197).
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 four JTAG pins) are configured out of reset to be undriven
(tristate): GPIOAFSEL=0, GPIODEN=0, GPIOPDR=0, and GPIOPUR=0. Table 9-4 on page 357
shows all possible configurations of the GPIO pads and the control register settings required to
achieve them. Table 9-5 on page 358 shows how a rising edge interrupt would be configured for pin
2 of a GPIO port.
Table 9-4. GPIO Pad Configuration Examples
a
Configuration
GPIO Register Bit Value
DR2R
DR4R
DR8R
Digital Input (GPIO)
AFSEL
0
DIR
0
ODR
0
DEN
1
PUR
?
PDR
?
X
X
X
SLR
X
Digital Output (GPIO)
0
1
0
1
?
?
?
?
?
?
Open Drain Output
(GPIO)
0
1
1
1
X
X
?
?
?
?
Open Drain
Input/Output (I2C)
1
X
1
1
X
X
?
?
?
?
Digital Input (Timer
CCP)
1
X
0
1
?
?
X
X
X
X
Digital Output (Timer
PWM)
1
X
0
1
?
?
?
?
?
?
Digital Input/Output
(SSI)
1
X
0
1
?
?
?
?
?
?
Digital Input/Output
(UART)
1
X
0
1
?
?
?
?
?
?
a. X=Ignored (don’t care bit)
?=Can be either 0 or 1, depending on the configuration
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Table 9-5. GPIO Interrupt Configuration Example
Register
GPIOIS
Desired
Interrupt
Event
Trigger
a
Pin 2 Bit Value
7
0=edge
6
5
4
3
2
1
0
X
X
X
X
X
0
X
X
X
X
X
X
X
0
X
X
X
X
X
X
X
1
X
X
0
0
0
0
0
1
0
0
1=level
GPIOIBE
0=single
edge
1=both
edges
GPIOIEV
0=Low level,
or negative
edge
1=High level,
or positive
edge
GPIOIM
0=masked
1=not
masked
a. X=Ignored (don’t care bit)
9.4
Register Map
Table 9-6 on page 359 lists the GPIO registers. Each GPIO port can be accessed through one of
two bus apertures. The legacy aperture, the Advanced Peripheral Bus (APB), is backwards-compatible
with previous Stellaris parts. The other aperture, the Advanced High-Performance Bus (AHB), offers
the same register map but provides better back-to-back access performance than the APB bus.
The offset listed is a hexadecimal increment to the register’s address, relative to that GPIO port’s
base address:
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
GPIO Port A (APB): 0x4000.4000
GPIO Port A (AHB): 0x4005.8000
GPIO Port B (APB): 0x4000.5000
GPIO Port B (AHB): 0x4005.9000
GPIO Port C (APB): 0x4000.6000
GPIO Port C (AHB): 0x4005.A000
GPIO Port D (APB): 0x4000.7000
GPIO Port D (AHB): 0x4005.B000
GPIO Port E (APB): 0x4002.4000
GPIO Port E (AHB): 0x4005.C000
GPIO Port F (APB): 0x4002.5000
GPIO Port F (AHB): 0x4005.D000
GPIO Port G (APB): 0x4002.6000
GPIO Port G (AHB): 0x4005.E000
GPIO Port H (APB): 0x4002.7000
GPIO Port H (AHB): 0x4005.F000
Note that the GPIO module clock must be enabled before the registers can be programmed (see
page 227). There must be a delay of 3 system clocks after the GPIO module clock is enabled before
any GPIO module registers are accessed.
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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 four JTAG/SWD pins (PC[3:0]).
These four pins default to JTAG/SWD functionality. Because of this, the default reset value
of these registers 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 NMI pin and the four 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 NMI pin and the four JTAG/SWD pins (PB7 and PC[3:0]). To ensure that
the JTAG port is not accidentally programmed as a GPIO, these four pins default to
non-committable. To ensure that the NMI pin is not accidentally programmed as the
non-maskable interrupt pin, it defaults to non-committable. 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 9-6. GPIO Register Map
Description
See
page
Offset
Name
Type
Reset
0x000
GPIODATA
R/W
0x0000.0000
GPIO Data
361
0x400
GPIODIR
R/W
0x0000.0000
GPIO Direction
362
0x404
GPIOIS
R/W
0x0000.0000
GPIO Interrupt Sense
363
0x408
GPIOIBE
R/W
0x0000.0000
GPIO Interrupt Both Edges
364
0x40C
GPIOIEV
R/W
0x0000.0000
GPIO Interrupt Event
365
0x410
GPIOIM
R/W
0x0000.0000
GPIO Interrupt Mask
366
0x414
GPIORIS
RO
0x0000.0000
GPIO Raw Interrupt Status
367
0x418
GPIOMIS
RO
0x0000.0000
GPIO Masked Interrupt Status
368
0x41C
GPIOICR
W1C
0x0000.0000
GPIO Interrupt Clear
370
0x420
GPIOAFSEL
R/W
-
GPIO Alternate Function Select
371
0x500
GPIODR2R
R/W
0x0000.00FF
GPIO 2-mA Drive Select
373
0x504
GPIODR4R
R/W
0x0000.0000
GPIO 4-mA Drive Select
374
0x508
GPIODR8R
R/W
0x0000.0000
GPIO 8-mA Drive Select
375
0x50C
GPIOODR
R/W
0x0000.0000
GPIO Open Drain Select
376
0x510
GPIOPUR
R/W
-
GPIO Pull-Up Select
377
0x514
GPIOPDR
R/W
0x0000.0000
GPIO Pull-Down Select
379
0x518
GPIOSLR
R/W
0x0000.0000
GPIO Slew Rate Control Select
380
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Table 9-6. GPIO Register Map (continued)
Offset
Name
Type
Reset
0x51C
GPIODEN
R/W
-
0x520
GPIOLOCK
R/W
0x0000.0001
0x524
GPIOCR
-
-
0x528
GPIOAMSEL
R/W
0xFD0
GPIOPeriphID4
0xFD4
Description
See
page
GPIO Digital Enable
381
GPIO Lock
383
GPIO Commit
384
0x0000.0000
GPIO Analog Mode Select
386
RO
0x0000.0000
GPIO Peripheral Identification 4
388
GPIOPeriphID5
RO
0x0000.0000
GPIO Peripheral Identification 5
389
0xFD8
GPIOPeriphID6
RO
0x0000.0000
GPIO Peripheral Identification 6
390
0xFDC
GPIOPeriphID7
RO
0x0000.0000
GPIO Peripheral Identification 7
391
0xFE0
GPIOPeriphID0
RO
0x0000.0061
GPIO Peripheral Identification 0
392
0xFE4
GPIOPeriphID1
RO
0x0000.0000
GPIO Peripheral Identification 1
393
0xFE8
GPIOPeriphID2
RO
0x0000.0018
GPIO Peripheral Identification 2
394
0xFEC
GPIOPeriphID3
RO
0x0000.0001
GPIO Peripheral Identification 3
395
0xFF0
GPIOPCellID0
RO
0x0000.000D
GPIO PrimeCell Identification 0
396
0xFF4
GPIOPCellID1
RO
0x0000.00F0
GPIO PrimeCell Identification 1
397
0xFF8
GPIOPCellID2
RO
0x0000.0005
GPIO PrimeCell Identification 2
398
0xFFC
GPIOPCellID3
RO
0x0000.00B1
GPIO PrimeCell Identification 3
399
9.5
Register Descriptions
The remainder of this section lists and describes the GPIO registers, in numerical order by address
offset.
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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 362).
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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
DATA
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
DATA
R/W
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 354 for examples of
reads and writes.
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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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x400
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
DIR
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
DIR
R/W
0x00
GPIO Data Direction
The DIR values are defined as follows:
Value Description
0
Pins are inputs.
1
Pins are outputs.
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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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x404
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
IS
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
IS
R/W
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).
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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 363) 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 365). 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x408
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
IBE
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
IBE
R/W
0x00
GPIO Interrupt Both Edges
The IBE values are defined as follows:
Value Description
0
Interrupt generation is controlled by the GPIO Interrupt Event
(GPIOIEV) register (see page 365).
1
Both edges on the corresponding pin trigger an interrupt.
Note:
Single edge is determined by the corresponding bit
in GPIOIEV.
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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 363). 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x40C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
IEV
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
IEV
R/W
0x00
GPIO Interrupt Event
The IEV values are defined as follows:
Value Description
0
Falling edge or Low levels on corresponding pins trigger
interrupts.
1
Rising edge or High levels on corresponding pins trigger
interrupts.
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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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x410
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
IME
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
IME
R/W
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.
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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 366). 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x414
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RIS
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
RIS
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.
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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 (the appropriate bit of 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 Interrupt 0-31 Set Enable (EN0)
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 PB4,
and wait for the ADC interrupt or the ADC interrupt must be disabled in the EN0 register and the
PortB interrupt handler must poll the ADC registers until the conversion is completed. See page 108
for more information.
GPIOMIS is the state of the interrupt after masking.
GPIO Masked Interrupt Status (GPIOMIS)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x418
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
MIS
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
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Bit/Field
Name
Type
Reset
Description
7:0
MIS
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.
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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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x41C
Type W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
reserved
Type
Reset
reserved
Type
Reset
IC
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
IC
W1C
0x00
GPIO Interrupt Clear
The IC values are defined as follows:
Value Description
0
Corresponding interrupt is unaffected.
1
Corresponding interrupt is cleared.
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Stellaris® LM3S5737 Microcontroller
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 GPIO commit control registers provide a layer of protection against accidental programming of
critical hardware peripherals. Protection is currently provided for the NMI pin (PB7) and the four
JTAG/SWD pins (PC[3:0]). Writes to protected bits of the GPIO Alternate Function Select
(GPIOAFSEL) register (see page 371), GPIO Pull-Up Select (GPIOPUR) register (see page 377),
and GPIO Digital Enable (GPIODEN) register (see page 381) are not committed to storage unless
the GPIO Lock (GPIOLOCK) register (see page 383) has been unlocked and the appropriate bits
of the GPIO Commit (GPIOCR) register (see page 384) 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 four JTAG/SWD pins (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 – 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x420
Type R/W, reset 31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
reserved
Type
Reset
reserved
Type
Reset
RO
0
AFSEL
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General-Purpose Input/Outputs (GPIOs)
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
AFSEL
R/W
-
GPIO Alternate Function Select
The AFSEL values are defined as follows:
Value Description
0
Software control of corresponding GPIO line (GPIO mode).
1
Hardware control of corresponding GPIO line (alternate
hardware function).
Note:
The default reset value for the GPIOAFSEL,
GPIOPUR, and GPIODEN registers are 0x0000.0000
for all GPIO pins, with the exception of the four
JTAG/SWD pins (PC[3:0]). These four pins default
to JTAG/SWD functionality. Because of this, the
default reset value of these registers for Port C is
0x0000.000F.
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Stellaris® LM3S5737 Microcontroller
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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x500
Type R/W, reset 0x0000.00FF
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
reserved
Type
Reset
reserved
Type
Reset
DRV2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
DRV2
R/W
0xFF
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 if accessing GPIO via the APB memory
aperture. If using AHB access, the change is effective on the next clock
cycle.
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General-Purpose Input/Outputs (GPIOs)
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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x504
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
DRV4
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
DRV4
R/W
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 if accessing GPIO via the APB memory
aperture. If using AHB access, the change is effective on the next clock
cycle.
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Stellaris® LM3S5737 Microcontroller
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. The 8-mA setting is also used for high-current
operation.
Note:
There is no configuration difference between 8-mA and high-current operation. The additional
current capacity results from a shift in the VOH/VOL levels. See “Recommended DC Operating
Conditions” on page 768 for further information.
GPIO 8-mA Drive Select (GPIODR8R)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x508
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
DRV8
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
DRV8
R/W
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 if accessing GPIO via the APB memory
aperture. If using AHB access, the change is effective on the next clock
cycle.
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General-Purpose Input/Outputs (GPIOs)
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 Enable (GPIODEN) register (see page 381).
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 cleared. If open drain is selected while the
GPIO is configured as an input, the GPIO will remain an input and the open-drain selection has no
effect until the GPIO is changed to an output.
When using the I2C module, in addition to configuring the pin to open drain, the GPIO Alternate
Function Select (GPIOAFSEL) register bits for the I2C clock and data pins should be set to 1 (see
examples in “Initialization and Configuration” on page 357).
GPIO Open Drain Select (GPIOODR)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x50C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
ODE
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
ODE
R/W
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.
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Stellaris® LM3S5737 Microcontroller
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 379). Write access
to this register is protected with the GPIOCR register. Bits in GPIOCR that are set to 0 will prevent
writes to the equivalent bit in this register.
Note:
The GPIO commit control registers provide a layer of protection against accidental
programming of critical hardware peripherals. Protection is currently provided for the NMI
pin (PB7) and the four JTAG/SWD pins (PC[3:0]). Writes to protected bits of the GPIO
Alternate Function Select (GPIOAFSEL) register (see page 371), GPIO Pull-Up Select
(GPIOPUR) register (see page 377), and GPIO Digital Enable (GPIODEN) register (see
page 381) are not committed to storage unless the GPIO Lock (GPIOLOCK) register (see
page 383) has been unlocked and the appropriate bits of the GPIO Commit (GPIOCR)
register (see page 384) have been set to 1.
GPIO Pull-Up Select (GPIOPUR)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x510
Type R/W, reset 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
3
2
1
0
R/W
-
R/W
-
R/W
-
R/W
-
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PUE
RO
0
RO
0
RO
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
November 17, 2011
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General-Purpose Input/Outputs (GPIOs)
Bit/Field
Name
Type
Reset
7:0
PUE
R/W
-
Description
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 four JTAG/SWD pins (PC[3:0]). These
four pins default to JTAG/SWD functionality. Because of this,
the default reset value of these registers for Port C is
0x0000.000F.
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Stellaris® LM3S5737 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 377).
GPIO Pull-Down Select (GPIOPDR)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x514
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
PDE
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PDE
R/W
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.
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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 375).
GPIO Slew Rate Control Select (GPIOSLR)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x518
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
SRL
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
SRL
R/W
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.
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Stellaris® LM3S5737 Microcontroller
Register 18: GPIO Digital Enable (GPIODEN), offset 0x51C
Note:
Pins configured as digital inputs are Schmitt-triggered.
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.
Note:
The GPIO commit control registers provide a layer of protection against accidental
programming of critical hardware peripherals. Protection is currently provided for the NMI
pin (PB7) and the four JTAG/SWD pins (PC[3:0]). Writes to protected bits of the GPIO
Alternate Function Select (GPIOAFSEL) register (see page 371), GPIO Pull-Up Select
(GPIOPUR) register (see page 377), and GPIO Digital Enable (GPIODEN) register (see
page 381) are not committed to storage unless the GPIO Lock (GPIOLOCK) register (see
page 383) has been unlocked and the appropriate bits of the GPIO Commit (GPIOCR)
register (see page 384) have been set to 1.
GPIO Digital Enable (GPIODEN)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x51C
Type R/W, reset 31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
reserved
Type
Reset
reserved
Type
Reset
DEN
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
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General-Purpose Input/Outputs (GPIOs)
Bit/Field
Name
Type
Reset
7:0
DEN
R/W
-
Description
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 four
JTAG/SWD pins (PC[3:0]). These four pins default
to JTAG/SWD functionality. Because of this, the
default reset value of these registers for Port C is
0x0000.000F.
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Stellaris® LM3S5737 Microcontroller
Register 19: GPIO Lock (GPIOLOCK), offset 0x520
The GPIOLOCK register enables write access to the GPIOCR register (see page 384). Writing
0x0x4C4F.434B 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x520
Type R/W, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
1
LOCK
Type
Reset
LOCK
Type
Reset
Bit/Field
Name
Type
31:0
LOCK
R/W
Reset
Description
0x0000.0001 GPIO Lock
A write of the value 0x4C4F.434B unlocks the GPIO Commit (GPIOCR)
register for write access.
A write of any other value or a write to the GPIOCR register reapplies
the lock, preventing any register updates. A read of this register returns
the following values:
Value
Description
0x0000.0001 Locked
0x0000.0000 Unlocked
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General-Purpose Input/Outputs (GPIOs)
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, GPIOPUR, and GPIODEN registers are committed when a write to these
registers is performed. If a bit in the GPIOCR register is zero, the data being written to the
corresponding bit in the GPIOAFSEL, GPIOPUR, or GPIODEN registers cannot be committed and
retains its previous value. If a bit in the GPIOCR register is set, the data being written to the
corresponding bit of the GPIOAFSEL, GPIOPUR, or GPIODEN registers is committed to the register
and reflects the new value.
The contents of the GPIOCR register can only be modified if the GPIOLOCK register is unlocked.
Writes to the GPIOCR register are ignored if the GPIOLOCK register is locked.
Important: This register is designed to prevent accidental programming of the registers that control
connectivity to the NMI and JTAG/SWD debug hardware. By initializing the bits of the
GPIOCR register to 0 for PB7 and PC[3:0], the NMI and JTAG/SWD debug port can
only be converted to GPIOs through a deliberate set of writes to the GPIOLOCK,
GPIOCR, and the corresponding registers.
Because this protection is currently only implemented on the NMI and 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, GPIOPUR, or GPIODEN register bits of these other
pins.
GPIO Commit (GPIOCR)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x524
Type -, reset 31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
-
-
-
-
-
-
-
-
reserved
Type
Reset
reserved
Type
Reset
CR
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
384
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
7:0
CR
-
-
Description
GPIO Commit
On a bit-wise basis, any bit set allows the corresponding GPIOAFSEL,
GPIOPUR, or GPIODEN registers to be written.
Note:
The default register type for the GPIOCR register is RO for
all GPIO pins with the exception of the NMI pin and the four
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 NMI
pin and the four JTAG/SWD pins (PB7 and PC[3:0]). To
ensure that the JTAG port is not accidentally programmed as
a GPIO, these four pins default to non-committable. To ensure
that the NMI pin is not accidentally programmed as the
non-maskable interrupt pin, it defaults to non-committable.
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.
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General-Purpose Input/Outputs (GPIOs)
Register 21: GPIO Analog Mode Select (GPIOAMSEL), offset 0x528
Important: This register is only valid for ports D and E.
If any pin is to be used as an ADC input, the appropriate bit in GPIOAMSEL must be
written to 1 to disable the analog isolation circuit.
The GPIOAMSEL register controls isolation circuits to the analog side of a unified I/O pad. Because
the GPIOs may be driven by a 5V source and affect analog operation, analog circuitry requires
isolation from the pins when not used in their analog function.
Each bit of this register controls the isolation circuitry for circuits that share the same pin as the
GPIO bit lane.
GPIO Analog Mode Select (GPIOAMSEL)
GPIO Port A (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0x528
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
GPIOAMSEL
RO
0
R/W
0
reserved
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:4
GPIOAMSEL
R/W
0x00
GPIO Analog Mode Select
Value Description
0
Analog function of the pin is disabled, the isolation is enabled,
and the pin is capable of digital functions as specified by the
other GPIO configuration registers.
1
Analog function of the pin is enabled, the isolation is disabled,
and the pin is capable of analog functions.
Note:
This register and bits are required only for GPIO bit lanes that
share analog function through a unified I/O pad.
The reset state of this register is 0 for all bit lanes.
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Bit/Field
Name
Type
Reset
Description
3:0
reserved
RO
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.
November 17, 2011
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Texas Instruments-Production Data
General-Purpose Input/Outputs (GPIOs)
Register 22: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFD0
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID4
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID4
RO
0x00
GPIO Peripheral ID Register[7:0]
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Register 23: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFD4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID5
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID5
RO
0x00
GPIO Peripheral ID Register[15:8]
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General-Purpose Input/Outputs (GPIOs)
Register 24: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFD8
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID6
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID6
RO
0x00
GPIO Peripheral ID Register[23:16]
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Stellaris® LM3S5737 Microcontroller
Register 25: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFDC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID7
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID7
RO
0x00
GPIO Peripheral ID Register[31:24]
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General-Purpose Input/Outputs (GPIOs)
Register 26: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFE0
Type RO, reset 0x0000.0061
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
PID0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID0
RO
0x61
GPIO Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
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November 17, 2011
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Stellaris® LM3S5737 Microcontroller
Register 27: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFE4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID1
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID1
RO
0x00
GPIO Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
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Texas Instruments-Production Data
General-Purpose Input/Outputs (GPIOs)
Register 28: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFE8
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID2
RO
0x18
GPIO Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
394
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 29: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFEC
Type RO, reset 0x0000.0001
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
PID3
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID3
RO
0x01
GPIO Peripheral ID Register[31:24]
Can be used by software to identify the presence of this peripheral.
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General-Purpose Input/Outputs (GPIOs)
Register 30: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID0
RO
0x0D
GPIO PrimeCell ID Register[7:0]
Provides software a standard cross-peripheral identification system.
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November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 31: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
CID1
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID1
RO
0xF0
GPIO PrimeCell ID Register[15:8]
Provides software a standard cross-peripheral identification system.
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Texas Instruments-Production Data
General-Purpose Input/Outputs (GPIOs)
Register 32: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID2
RO
0x05
GPIO PrimeCell ID Register[23:16]
Provides software a standard cross-peripheral identification system.
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November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Register 33: 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 (APB) base: 0x4000.4000
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (APB) base: 0x4000.5000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (APB) base: 0x4000.6000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (APB) base: 0x4000.7000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (APB) base: 0x4002.4000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (APB) base: 0x4002.5000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (APB) base: 0x4002.6000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (APB) base: 0x4002.7000
GPIO Port H (AHB) base: 0x4005.F000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID3
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID3
RO
0xB1
GPIO PrimeCell ID Register[31:24]
Provides software a standard cross-peripheral identification system.
November 17, 2011
399
Texas Instruments-Production Data
General-Purpose Timers
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).
In addition, timers can be used to trigger analog-to-digital conversions (ADC). The ADC 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.
The GPT Module is one timing resource available on the Stellaris microcontrollers. Other timer
resources include the System Timer (SysTick) (see 93).
The General-Purpose Timers provide the following features:
■ Three General-Purpose Timer Modules (GPTM), each of which provides two 16-bit
timers/counters. 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
– User-enabled stalling when the controller asserts CPU Halt flag during debug
– ADC event trigger
■ 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
– User-enabled stalling when the controller asserts CPU Halt flag during debug
– ADC event trigger
■ 16-bit Input Capture modes
– Input edge count capture
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– 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 401, the specific CCP pins available depend on the Stellaris device.
See Table 10-1 on page 401 for the available CCPs.
Figure 10-1. GPTM Module Block Diagram
0x0000 (Down Counter Modes)
TimerA Control
TA Comparator
GPTMTAPR
Clock / Edge
Detect
GPTMTAMATCHR
Interrupt / Config
TimerA
Interrupt
GPTMCFG
GPTMTAILR
GPTMAR
En
GPTMTAMR
GPTMCTL
GPTMIMR
TimerB
Interrupt
32 KHz or
Even CCP Pin
RTC Divider
GPTMRIS
GPTMMIS
TimerB Control
GPTMICR
GPTMTBR En
Clock / Edge
Detect
GPTMTBPR
GPTMTBMATCHR
GPTMTBILR
Odd CCP Pin
TB Comparator
GPTMTBMR
0x0000 (Down Counter Modes)
System
Clock
Table 10-1. Available CCP Pins
Timer
16-Bit Up/Down Counter
Even CCP Pin
Odd CCP Pin
Timer 0
TimerA
CCP0
-
TimerB
-
CCP1
TimerA
CCP2
-
TimerB
-
-
TimerA
-
-
TimerB
-
-
Timer 1
Timer 2
10.2
Signal Description
Table 10-2 on page 402 lists the external signals of the GP Timer module and describes the function
of each. The GP Timer signals are alternate functions for some GPIO signals and default to be
GPIO signals at reset. The column in the table below titled "Pin Assignment" lists the possible GPIO
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pin placements for these GP Timer signals. The AFSEL bit in the GPIO Alternate Function Select
(GPIOAFSEL) register (page 371) should be set to choose the GP Timer function. For more information
on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 348.
Table 10-2. General-Purpose Timers Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
CCP0
66
I/O
TTL
Capture/Compare/PWM 0.
CCP1
67
I/O
TTL
Capture/Compare/PWM 1.
CCP2
91
I/O
TTL
Capture/Compare/PWM 2.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
10.3
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, 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 412),
the GPTM TimerA Mode (GPTMTAMR) register (see page 413), and the GPTM TimerB Mode
(GPTMTBMR) register (see page 415). 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.
10.3.1
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
(GPTMTAILR) register (see page 426) and the GPTM TimerB Interval Load (GPTMTBILR) register
(see page 427). The prescale counters are initialized to 0x00: the GPTM TimerA Prescale
(GPTMTAPR) register (see page 430) and the GPTM TimerB Prescale (GPTMTBPR) register (see
page 431).
10.3.2
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 426
■ GPTM TimerB Interval Load (GPTMTBILR) register [15:0], see page 427
■ GPTM TimerA (GPTMTAR) register [15:0], see page 432
■ GPTM TimerB (GPTMTBR) register [15:0], see page 433
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:
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GPTMTBILR[15:0]:GPTMTAILR[15:0]
Likewise, a read access to GPTMTAR returns the value:
GPTMTBR[15:0]:GPTMTAR[15:0]
10.3.2.1
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 413), 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 417), 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 triggers when it reaches
the 0x000.0000 state. The GPTM sets the TATORIS bit in the GPTM Raw Interrupt Status
(GPTMRIS) register (see page 422), and holds it until it is cleared by writing the GPTM Interrupt
Clear (GPTMICR) register (see page 424). If the time-out interrupt is enabled in the GPTM Interrupt
Mask (GPTMIMR) register (see page 420), the GPTM also sets the TATOMIS bit in the GPTM Masked
Interrupt Status (GPTMMIS) register (see page 423). The ADC trigger is enabled by setting the
TAOTE bit in GPTMCTL.
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.
If the TASTALL bit in the GPTMCTL register is set, the timer freezes counting while the processor
is halted by the debugger. The timer resumes counting when the processor resumes execution.
10.3.2.2
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 428) by the controller.
The input clock on an even CCP input 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 GPTMIMR, the
GPTM also sets the RTCMIS bit in GPTMMIS 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.
10.3.3
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 412). This section describes each of the GPTM 16-bit modes of
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operation. TimerA and TimerB have identical modes, so a single description is given using an n to
reference both.
10.3.3.1
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 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 GPTMIMR, the GPTM
also sets the TnTOMIS bit in GPTMISR and generates a controller interrupt. The ADC trigger is
enabled by setting the TnOTE bit in the GPTMCTL register.
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.
If the TnSTALL bit in the GPTMCTL register is set, the timer freezes counting while the processor
is halted by the debugger. The timer resumes counting when the processor resumes execution.
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 10-3. 16-Bit Timer With Prescaler Configurations
a
Prescale
#Clock (T c)
Max Time
Units
00000000
1
1.3107
mS
00000001
2
2.6214
mS
00000010
3
3.9322
mS
------------
--
--
--
11111101
254
332.9229
mS
11111110
255
334.2336
mS
11111111
256
335.5443
mS
a. Tc is the clock period.
10.3.3.2
16-Bit Input Edge Count Mode
Note:
For rising-edge detection, the input signal must be High for at least two system clock periods
following the rising edge. Similarly, for falling-edge detection, the input signal must be Low
for at least two system clock periods following the falling edge. Based on this criteria, the
maximum input frequency for edge detection is 1/4 of the system frequency.
Note:
The prescaler is not available in 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
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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 405 shows how input edge count mode works. In this case, the timer start value
is set to GPTMTnILR =0x000A and the match value is set to GPTMTnMATCHR =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 GPTMTnMATCHR register.
Figure 10-2. 16-Bit Input Edge Count Mode Example
Timer stops,
flags
asserted
Count
Timer reload
on next cycle
Ignored
Ignored
0x000A
0x0009
0x0008
0x0007
0x0006
Input Signal
10.3.3.3
16-Bit Input Edge Time Mode
Note:
For rising-edge detection, the input signal must be High for at least two system clock periods
following the rising edge. Similarly, for falling edge detection, the input signal must be Low
for at least two system clock periods following the falling edge. Based on this criteria, the
maximum input frequency for edge detection is 1/4 of the system frequency.
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). The timer is capable of capturing three
types of events: rising edge, falling edge, or both. The timer is placed into Edge Time mode by
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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 GPTMCTL 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
GPTMTnILR register.
Figure 10-3 on page 406 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).
Figure 10-3. 16-Bit Input Edge Time Mode Example
Count
0xFFFF
GPTMTnR=X
GPTMTnR=Y
GPTMTnR=Z
Z
X
Y
Time
Input Signal
10.3.3.4
16-Bit PWM Mode
Note:
The prescaler is not available in 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. In this mode, the PWM
frequency and period are synchronous events and therefore guaranteed to be glitch free. 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 continues counting until disabled by software clearing the TnEN bit in the GPTMCTL
register. No interrupts or status bits are asserted in PWM mode.
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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 (GPTMTnMATCHR). Software has the capability of inverting the output PWM signal by
setting the TnPWML bit in the GPTMCTL register.
Figure 10-4 on page 407 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 GPTMTnIRL=0xC350 and the match value is
GPTMTnMATCHR=0x411A.
Figure 10-4. 16-Bit PWM Mode Example
Count
GPTMTnR=GPTMnMR
GPTMTnR=GPTMnMR
0xC350
0x411A
Time
TnEN set
TnPWML = 0
Output
Signal
TnPWML = 1
10.4
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.
10.4.1
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):
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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.
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 408. To re-enable the timer, repeat
the sequence. A timer configured in Periodic mode does not stop counting after it times out.
10.4.2
32-Bit Real-Time Clock (RTC) Mode
To use the RTC mode, the timer must have a 32.768-KHz input signal on an even CCP input. 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 GPTM asserts the
RTCRIS bit in the GPTMRIS register and continues counting until Timer A is disabled or a hardware
reset. The interrupt is cleared by writing the RTCCINT bit in the GPTMICR register.
10.4.3
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).
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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).
In One-Shot mode, the timer stops counting after step 8 on page 409. To re-enable the timer, repeat
the sequence. A timer configured in Periodic mode does not stop counting after it times out.
10.4.4
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 409
through step 9 on page 409.
10.4.5
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.
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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
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.
10.4.6
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 TnPWML 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. 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.
10.5
Register Map
Table 10-4 on page 411 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
Note that the Timer module clock must be enabled before the registers can be programmed (see
page 221). There must be a delay of 3 system clocks after the Timer module clock is enabled before
any Timer module registers are accessed.
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Table 10-4. Timers Register Map
Name
Type
Reset
0x000
GPTMCFG
R/W
0x0000.0000
GPTM Configuration
412
0x004
GPTMTAMR
R/W
0x0000.0000
GPTM TimerA Mode
413
0x008
GPTMTBMR
R/W
0x0000.0000
GPTM TimerB Mode
415
0x00C
GPTMCTL
R/W
0x0000.0000
GPTM Control
417
0x018
GPTMIMR
R/W
0x0000.0000
GPTM Interrupt Mask
420
0x01C
GPTMRIS
RO
0x0000.0000
GPTM Raw Interrupt Status
422
0x020
GPTMMIS
RO
0x0000.0000
GPTM Masked Interrupt Status
423
0x024
GPTMICR
W1C
0x0000.0000
GPTM Interrupt Clear
424
0x028
GPTMTAILR
R/W
0xFFFF.FFFF
GPTM TimerA Interval Load
426
0x02C
GPTMTBILR
R/W
0x0000.FFFF
GPTM TimerB Interval Load
427
0x030
GPTMTAMATCHR
R/W
0xFFFF.FFFF
GPTM TimerA Match
428
0x034
GPTMTBMATCHR
R/W
0x0000.FFFF
GPTM TimerB Match
429
0x038
GPTMTAPR
R/W
0x0000.0000
GPTM TimerA Prescale
430
0x03C
GPTMTBPR
R/W
0x0000.0000
GPTM TimerB Prescale
431
0x048
GPTMTAR
RO
0xFFFF.FFFF
GPTM TimerA
432
0x04C
GPTMTBR
RO
0x0000.FFFF
GPTM TimerB
433
10.6
Description
See
page
Offset
Register Descriptions
The remainder of this section lists and describes the GPTM registers, in numerical order by address
offset.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
GPTMCFG
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:3
reserved
RO
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.
2:0
GPTMCFG
R/W
0x0
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
0x4-0x7 16-bit timer configuration, function is controlled by bits 1:0 of
GPTMTAMR and GPTMTBMR.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
TAAMS
TACMR
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
TAMR
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:4
reserved
RO
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.
3
TAAMS
R/W
0
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:
2
TACMR
R/W
0
To enable PWM mode, you must also clear the TACMR
bit and set the TAMR field to 0x2.
GPTM TimerA Capture Mode
The TACMR values are defined as follows:
Value Description
0
Edge-Count mode
1
Edge-Time mode
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Bit/Field
Name
Type
Reset
1:0
TAMR
R/W
0x0
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
TBAMS
TBCMR
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
TBMR
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:4
reserved
RO
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.
3
TBAMS
R/W
0
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:
2
TBCMR
R/W
0
To enable PWM mode, you must also clear the TBCMR
bit and set the TBMR field to 0x2.
GPTM TimerB Capture Mode
The TBCMR values are defined as follows:
Value Description
0
Edge-Count mode
1
Edge-Time mode
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Bit/Field
Name
Type
Reset
1:0
TBMR
R/W
0x0
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
11
10
9
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
TBSTALL
TBEN
reserved
TAPWML
TAOTE
RTCEN
TASTALL
TAEN
R/W
0
R/W
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
Type
Reset
15
14
13
12
reserved
TBPWML
TBOTE
reserved
RO
0
R/W
0
R/W
0
RO
0
TBEVENT
R/W
0
R/W
0
TAEVENT
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:15
reserved
RO
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.
14
TBPWML
R/W
0
GPTM TimerB PWM Output Level
The TBPWML values are defined as follows:
Value Description
13
TBOTE
R/W
0
0
Output is unaffected.
1
Output is inverted.
GPTM TimerB Output Trigger Enable
The TBOTE values are defined as follows:
Value Description
0
The output TimerB ADC trigger is disabled.
1
The output TimerB ADC trigger is enabled.
In addition, the ADC must be enabled and the timer selected as a trigger
source with the EMn bit in the ADCEMUX register (see page 473).
12
reserved
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.
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Bit/Field
Name
Type
Reset
11:10
TBEVENT
R/W
0x0
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
9
TBSTALL
R/W
0
GPTM Timer B Stall Enable
The TBSTALL values are defined as follows:
Value Description
0
Timer B continues counting while the processor is halted by the
debugger.
1
Timer B freezes counting while the processor is halted by the
debugger.
If the processor is executing normally, the TBSTALL bit is ignored.
8
TBEN
R/W
0
GPTM TimerB Enable
The TBEN values are defined as follows:
Value Description
0
TimerB is disabled.
1
TimerB is enabled and begins counting or the capture logic is
enabled based on the GPTMCFG register.
7
reserved
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.
6
TAPWML
R/W
0
GPTM TimerA PWM Output Level
The TAPWML values are defined as follows:
Value Description
5
TAOTE
R/W
0
0
Output is unaffected.
1
Output is inverted.
GPTM TimerA Output Trigger Enable
The TAOTE values are defined as follows:
Value Description
0
The output TimerA ADC trigger is disabled.
1
The output TimerA ADC trigger is enabled.
In addition, the ADC must be enabled and the timer selected as a trigger
source with the EMn bit in the ADCEMUX register (see page 473).
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Bit/Field
Name
Type
Reset
4
RTCEN
R/W
0
Description
GPTM RTC Enable
The RTCEN values are defined as follows:
Value Description
3:2
TAEVENT
R/W
0x0
0
RTC counting is disabled.
1
RTC counting is enabled.
GPTM TimerA Event Mode
The TAEVENT values are defined as follows:
Value Description
0x0 Positive edge
0x1 Negative edge
0x2 Reserved
0x3 Both edges
1
TASTALL
R/W
0
GPTM Timer A Stall Enable
The TASTALL values are defined as follows:
Value Description
0
Timer A continues counting while the processor is halted by the
debugger.
1
Timer A freezes counting while the processor is halted by the
debugger.
If the processor is executing normally, the TASTALL bit is ignored.
0
TAEN
R/W
0
GPTM TimerA Enable
The TAEN values are defined as follows:
Value Description
0
TimerA is disabled.
1
TimerA is enabled and begins counting or the capture logic is
enabled based on the GPTMCFG register.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
CBEIM
CBMIM
TBTOIM
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RTCIM
CAEIM
CAMIM
TATOIM
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
reserved
Bit/Field
Name
Type
Reset
Description
31:11
reserved
RO
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.
10
CBEIM
R/W
0
GPTM CaptureB Event Interrupt Mask
The CBEIM values are defined as follows:
Value Description
9
CBMIM
R/W
0
0
Interrupt is disabled.
1
Interrupt is enabled.
GPTM CaptureB Match Interrupt Mask
The CBMIM values are defined as follows:
Value Description
8
TBTOIM
R/W
0
0
Interrupt is disabled.
1
Interrupt is enabled.
GPTM TimerB Time-Out Interrupt Mask
The TBTOIM values are defined as follows:
Value Description
7:4
reserved
RO
0
0
Interrupt is disabled.
1
Interrupt is enabled.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Bit/Field
Name
Type
Reset
3
RTCIM
R/W
0
Description
GPTM RTC Interrupt Mask
The RTCIM values are defined as follows:
Value Description
2
CAEIM
R/W
0
0
Interrupt is disabled.
1
Interrupt is enabled.
GPTM CaptureA Event Interrupt Mask
The CAEIM values are defined as follows:
Value Description
1
CAMIM
R/W
0
0
Interrupt is disabled.
1
Interrupt is enabled.
GPTM CaptureA Match Interrupt Mask
The CAMIM values are defined as follows:
Value Description
0
TATOIM
R/W
0
0
Interrupt is disabled.
1
Interrupt is enabled.
GPTM TimerA Time-Out Interrupt Mask
The TATOIM values are defined as follows:
Value Description
0
Interrupt is disabled.
1
Interrupt is enabled.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RTCRIS
CAERIS
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
CBERIS
RO
0
CBMRIS TBTORIS
RO
0
RO
0
reserved
CAMRIS TATORIS
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:11
reserved
RO
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.
10
CBERIS
RO
0
GPTM CaptureB Event Raw Interrupt
This is the CaptureB Event interrupt status prior to masking.
9
CBMRIS
RO
0
GPTM CaptureB Match Raw Interrupt
This is the CaptureB Match interrupt status prior to masking.
8
TBTORIS
RO
0
GPTM TimerB Time-Out Raw Interrupt
This is the TimerB time-out interrupt status prior to masking.
7:4
reserved
RO
0x0
3
RTCRIS
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.
GPTM RTC Raw Interrupt
This is the RTC Event interrupt status prior to masking.
2
CAERIS
RO
0
GPTM CaptureA Event Raw Interrupt
This is the CaptureA Event interrupt status prior to masking.
1
CAMRIS
RO
0
GPTM CaptureA Match Raw Interrupt
This is the CaptureA Match interrupt status prior to masking.
0
TATORIS
RO
0
GPTM TimerA Time-Out Raw Interrupt
This the TimerA time-out interrupt status prior to masking.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
CBEMIS CBMMIS TBTOMIS
RO
0
RO
0
RO
0
reserved
RTCMIS
RO
0
CAEMIS CAMMIS TATOMIS
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:11
reserved
RO
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.
10
CBEMIS
RO
0
GPTM CaptureB Event Masked Interrupt
This is the CaptureB event interrupt status after masking.
9
CBMMIS
RO
0
GPTM CaptureB Match Masked Interrupt
This is the CaptureB match interrupt status after masking.
8
TBTOMIS
RO
0
GPTM TimerB Time-Out Masked Interrupt
This is the TimerB time-out interrupt status after masking.
7:4
reserved
RO
0x0
3
RTCMIS
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.
GPTM RTC Masked Interrupt
This is the RTC event interrupt status after masking.
2
CAEMIS
RO
0
GPTM CaptureA Event Masked Interrupt
This is the CaptureA event interrupt status after masking.
1
CAMMIS
RO
0
GPTM CaptureA Match Masked Interrupt
This is the CaptureA match interrupt status after masking.
0
TATOMIS
RO
0
GPTM TimerA Time-Out Masked Interrupt
This is the TimerA time-out interrupt status after masking.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
RO
0
CBECINT CBMCINT
RO
0
RO
0
W1C
0
W1C
0
reserved
TBTOCINT
W1C
0
RO
0
RO
0
RO
0
RTCCINT CAECINT CAMCINT
RO
0
W1C
0
W1C
0
W1C
0
0
TATOCINT
W1C
0
Bit/Field
Name
Type
Reset
Description
31:11
reserved
RO
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.
10
CBECINT
W1C
0
GPTM CaptureB Event Interrupt Clear
The CBECINT values are defined as follows:
Value Description
9
CBMCINT
W1C
0
0
The interrupt is unaffected.
1
The interrupt is cleared.
GPTM CaptureB Match Interrupt Clear
The CBMCINT values are defined as follows:
Value Description
8
TBTOCINT
W1C
0
0
The interrupt is unaffected.
1
The interrupt is cleared.
GPTM TimerB Time-Out Interrupt Clear
The TBTOCINT values are defined as follows:
Value Description
7:4
reserved
RO
0x0
0
The interrupt is unaffected.
1
The interrupt is cleared.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
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Bit/Field
Name
Type
Reset
3
RTCCINT
W1C
0
Description
GPTM RTC Interrupt Clear
The RTCCINT values are defined as follows:
Value Description
2
CAECINT
W1C
0
0
The interrupt is unaffected.
1
The interrupt is cleared.
GPTM CaptureA Event Interrupt Clear
The CAECINT values are defined as follows:
Value Description
1
CAMCINT
W1C
0
0
The interrupt is unaffected.
1
The interrupt is cleared.
GPTM CaptureA Match Interrupt Clear
The CAMCINT values are defined as follows:
Value Description
0
TATOCINT
W1C
0
0
The interrupt is unaffected.
1
The interrupt is cleared.
GPTM TimerA Time-Out Interrupt Clear
The TATOCINT values are defined as follows:
Value Description
0
The interrupt is unaffected.
1
The interrupt is cleared.
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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 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
TAILRH
Type
Reset
TAILRL
Type
Reset
Bit/Field
Name
Type
Reset
31:16
TAILRH
R/W
0xFFFF
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.
15:0
TAILRL
R/W
0xFFFF
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
reserved
Type
Reset
TBILRL
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
TBILRL
R/W
0xFFFF
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.
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General-Purpose Timers
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 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
TAMRH
Type
Reset
TAMRL
Type
Reset
Bit/Field
Name
Type
Reset
31:16
TAMRH
R/W
0xFFFF
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.
15:0
TAMRL
R/W
0xFFFF
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.
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Register 12: GPTM TimerB Match (GPTMTBMATCHR), offset 0x034
This register is used in 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
reserved
Type
Reset
TBMRL
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
TBMRL
R/W
0xFFFF
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.
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General-Purpose Timers
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
TAPSR
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
TAPSR
R/W
0x00
GPTM TimerA Prescale
The register loads this value on a write. A read returns the current value
of the register.
Refer to Table 10-3 on page 404 for more details and an example.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
TBPSR
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
TBPSR
R/W
0x00
GPTM TimerB Prescale
The register loads this value on a write. A read returns the current value
of this register.
Refer to Table 10-3 on page 404 for more details and an example.
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Register 15: 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 number of edges that have occurred.
GPTM TimerA (GPTMTAR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x048
Type RO, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
TARH
Type
Reset
TARL
Type
Reset
Bit/Field
Name
Type
Reset
31:16
TARH
RO
0xFFFF
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.
15:0
TARL
RO
0xFFFF
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 number of edges
that have occurred.
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Register 16: 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 number of edges that have occurred.
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
reserved
Type
Reset
TBRL
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
0x0000
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
15:0
TBRL
RO
0xFFFF
GPTM TimerB
A read returns the current value of the GPTM TimerB Count Register,
except in Input Edge-Count mode, when it returns the number of edges
that have occurred.
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Watchdog Timer
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 has the following features:
■ 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
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.
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11.1
Block Diagram
Figure 11-1. WDT Module Block Diagram
WDTLOAD
Control / Clock /
Interrupt
Generation
WDTCTL
WDTICR
Interrupt
WDTRIS
32-Bit Down
Counter
WDTMIS
0x00000000
WDTLOCK
System Clock
WDTTEST
Comparator
WDTVALUE
Identification Registers
11.2
WDTPCellID0
WDTPeriphID0
WDTPeriphID4
WDTPCellID1
WDTPeriphID1
WDTPeriphID5
WDTPCellID2
WDTPeriphID2
WDTPeriphID6
WDTPCellID3
WDTPeriphID3
WDTPeriphID7
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
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.
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Watchdog Timer
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 436 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
Description
See
page
Offset
Name
Type
Reset
0x000
WDTLOAD
R/W
0xFFFF.FFFF
Watchdog Load
438
0x004
WDTVALUE
RO
0xFFFF.FFFF
Watchdog Value
439
0x008
WDTCTL
R/W
0x0000.0000
Watchdog Control
440
0x00C
WDTICR
WO
-
Watchdog Interrupt Clear
441
0x010
WDTRIS
RO
0x0000.0000
Watchdog Raw Interrupt Status
442
0x014
WDTMIS
RO
0x0000.0000
Watchdog Masked Interrupt Status
443
0x418
WDTTEST
R/W
0x0000.0000
Watchdog Test
444
0xC00
WDTLOCK
R/W
0x0000.0000
Watchdog Lock
445
0xFD0
WDTPeriphID4
RO
0x0000.0000
Watchdog Peripheral Identification 4
446
0xFD4
WDTPeriphID5
RO
0x0000.0000
Watchdog Peripheral Identification 5
447
0xFD8
WDTPeriphID6
RO
0x0000.0000
Watchdog Peripheral Identification 6
448
0xFDC
WDTPeriphID7
RO
0x0000.0000
Watchdog Peripheral Identification 7
449
0xFE0
WDTPeriphID0
RO
0x0000.0005
Watchdog Peripheral Identification 0
450
0xFE4
WDTPeriphID1
RO
0x0000.0018
Watchdog Peripheral Identification 1
451
0xFE8
WDTPeriphID2
RO
0x0000.0018
Watchdog Peripheral Identification 2
452
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Table 11-1. Watchdog Timer Register Map (continued)
Offset
Name
0xFEC
Reset
WDTPeriphID3
RO
0x0000.0001
Watchdog Peripheral Identification 3
453
0xFF0
WDTPCellID0
RO
0x0000.000D
Watchdog PrimeCell Identification 0
454
0xFF4
WDTPCellID1
RO
0x0000.00F0
Watchdog PrimeCell Identification 1
455
0xFF8
WDTPCellID2
RO
0x0000.0005
Watchdog PrimeCell Identification 2
456
0xFFC
WDTPCellID3
RO
0x0000.00B1
Watchdog PrimeCell Identification 3
457
11.5
Description
See
page
Type
Register Descriptions
The remainder of this section lists and describes the WDT registers, in numerical order by address
offset.
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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
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
15
14
13
12
11
10
9
8
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
23
22
21
20
19
18
17
16
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
7
6
5
4
3
2
1
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
WDTLoad
Type
Reset
WDTLoad
Type
Reset
Bit/Field
Name
Type
31:0
WDTLoad
R/W
Reset
R/W
1
Description
0xFFFF.FFFF Watchdog Load Value
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Stellaris® LM3S5737 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
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
15
14
13
12
11
10
9
8
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
23
22
21
20
19
18
17
16
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
7
6
5
4
3
2
1
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
WDTValue
Type
Reset
WDTValue
Type
Reset
Bit/Field
Name
Type
31:0
WDTValue
RO
Reset
RO
1
Description
0xFFFF.FFFF Watchdog Value
Current value of the 32-bit down counter.
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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
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
1
0
RESEN
INTEN
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:2
reserved
RO
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.
1
RESEN
R/W
0
Watchdog Reset Enable
The RESEN values are defined as follows:
Value Description
0
INTEN
R/W
0
0
Disabled.
1
Enable the Watchdog module reset output.
Watchdog Interrupt Enable
The INTEN values are defined as follows:
Value Description
0
Interrupt event disabled (once this bit is set, it can only be
cleared by a hardware reset).
1
Interrupt event enabled. Once enabled, all writes are ignored.
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Stellaris® LM3S5737 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
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
15
14
13
12
11
10
9
8
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
23
22
21
20
19
18
17
16
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
7
6
5
4
3
2
1
0
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WDTIntClr
Type
Reset
WDTIntClr
Type
Reset
Bit/Field
Name
Type
Reset
31:0
WDTIntClr
WO
-
WO
-
Description
Watchdog Interrupt Clear
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
WDTRIS
RO
0
Bit/Field
Name
Type
Reset
Description
31:1
reserved
RO
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.
0
WDTRIS
RO
0
Watchdog Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of WDTINTR.
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Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
WDTMIS
RO
0
Bit/Field
Name
Type
Reset
Description
31:1
reserved
RO
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.
0
WDTMIS
RO
0
Watchdog Masked Interrupt Status
Gives the masked interrupt state (after masking) of the WDTINTR
interrupt.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
STALL
R/W
0
reserved
Bit/Field
Name
Type
Reset
Description
31:9
reserved
RO
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
STALL
R/W
0
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.
7:0
reserved
RO
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.
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Stellaris® LM3S5737 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
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
WDTLock
Type
Reset
WDTLock
Type
Reset
Bit/Field
Name
Type
Reset
31:0
WDTLock
R/W
0x0000
R/W
0
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
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
PID4
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID4
RO
0x00
WDT Peripheral ID Register[7:0]
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Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID5
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID5
RO
0x00
WDT Peripheral ID Register[15:8]
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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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID6
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID6
RO
0x00
WDT Peripheral ID Register[23:16]
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Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID7
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID7
RO
0x00
WDT Peripheral ID Register[31:24]
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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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
1
RO
0
RO
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID0
RO
0x05
Watchdog Peripheral ID Register[7:0]
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Texas Instruments-Production Data
Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
1
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID1
RO
0x18
Watchdog Peripheral ID Register[15:8]
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Texas Instruments-Production Data
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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
1
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID2
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID2
RO
0x18
Watchdog Peripheral ID Register[23:16]
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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
RO
0
RO
0
RO
0
RO
0
3
2
1
0
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
PID3
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
PID3
RO
0x01
Watchdog Peripheral ID Register[31:24]
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID0
RO
0x0D
Watchdog PrimeCell ID Register[7:0]
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
CID1
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID1
RO
0xF0
Watchdog PrimeCell ID Register[15:8]
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID2
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID2
RO
0x05
Watchdog PrimeCell ID Register[23:16]
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
reserved
Type
Reset
reserved
Type
Reset
CID3
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
RO
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.
7:0
CID3
RO
0xB1
Watchdog PrimeCell ID Register[31:24]
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Analog-to-Digital Converter (ADC)
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 eight input channels,
plus an internal temperature sensor. The ADC module contains four 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 module provides the following features:
■ Eight analog input channels
■ Single-ended and differential-input configurations
■ On-chip internal temperature sensor
■ 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
■ Flexible trigger control
– Controller (software)
– Timers
– GPIO
■ Hardware averaging of up to 64 samples for improved accuracy
■ Converter uses an internal 3-V reference
■ Power and ground for the analog circuitry is separate from the digital power and ground
12.1
Block Diagram
Figure 12-1 on page 459 provides details on the internal configuration of the ADC controls and data
registers.
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Figure 12-1. ADC Module Block Diagram
Trigger Events
Comparator
GPIO (PB4)
Timer
PWM
Analog Inputs
SS3
Comparator
GPIO (PB4)
Timer
PWM
Control/Status
Sample
Sequencer 0
ADCACTSS
ADCSSMUX0
ADCOSTAT
ADCSSCTL0
ADCUSTAT
ADCSSFSTAT0
Analog-to-Digital
Converter
ADCSSPRI
SS2
Sample
Sequencer 1
ADCSSMUX1
Comparator
GPIO (PB4)
Timer
PWM
ADCSSCTL1
SS1
Hardware Averager
ADCSSFSTAT1
ADCSAC
Sample
Sequencer 2
Comparator
GPIO (PB4)
Timer
PWM
SS0
ADCSSMUX2
ADCSSCTL2
FIFO Block
ADCSSFSTAT2
ADCSSFIFO0
ADCEMUX
ADCPSSI
ADCSSFIFO1
Interrupt Control
Sample
Sequencer 3
ADCIM
ADCSSMUX3
SS0 Interrupt
SS1 Interrupt
SS2 Interrupt
SS3 Interrupt
12.2
ADCSSFIFO2
ADCSSFIFO3
ADCRIS
ADCSSCTL3
ADCISC
ADCSSFSTAT3
Signal Description
Table 12-1 on page 459 lists the external signals of the ADC module and describes the function of
each. The signals are analog functions for some GPIO signals. The column in the table below titled
"Pin Assignment" lists the GPIO pin placement for the ADC signals. The AINx analog signals are
not 5-V tolerant and go through an isolation circuit before reaching their circuitry. These signals are
configured by clearing the corresponding DEN bit in the GPIO Digital Enable (GPIODEN) register
and setting the corresponding AMSEL bit in the GPIO Analog Mode Select (GPIOAMSEL) register.
For more information on configuring GPIOs, see “General-Purpose Input/Outputs
(GPIOs)” on page 348.
Table 12-1. ADC Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
ADC0
1
I
Analog
Description
Analog-to-digital converter input 0.
ADC1
2
I
Analog
Analog-to-digital converter input 1.
ADC2
5
I
Analog
Analog-to-digital converter input 2.
ADC3
6
I
Analog
Analog-to-digital converter input 3.
ADC4
100
I
Analog
Analog-to-digital converter input 4.
ADC5
99
I
Analog
Analog-to-digital converter input 5.
ADC6
98
I
Analog
Analog-to-digital converter input 6.
ADC7
97
I
Analog
Analog-to-digital converter input 7.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
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12.3
Functional Description
The Stellaris ADC collects sample data by using a programmable sequence-based approach instead
of the traditional single or double-sampling approaches 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.
12.3.1
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 12-2 on page 460 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 12-2. 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
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, and should 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 IEn 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.
12.3.2
Module Control
Outside of the sample sequencers, the remainder of the control logic is responsible for tasks such
as:
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■ Interrupt generation
■ Sequence prioritization
■ 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.
12.3.2.1
Interrupts
The register configurations of the sample sequencers dictate which events generate raw interrupts,
but do not have control over whether the interrupt is actually sent to the interrupt controller. The
ADC module's interrupt signals are 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 the various interrupt signals, and the ADC
Interrupt Status and Clear (ADCISC) register, which shows active interrupts that are enabled by
the ADCIM register. Sequencer interrupts are cleared by writing a 1 to the corresponding IN bit in
ADCISC.
12.3.2.2
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.
12.3.2.3
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,
but all devices share the "Controller" and "Always" triggers. Software can initiate sampling by setting
the SSx bits in the ADC Processor Sample Sequence Initiate (ADCPSSI) register.
Care must be taken when using the "Always" trigger. If a sequence's priority is too high, it is possible
to starve other lower priority sequences.
12.3.3
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 480). There is a single averaging circuit and all input channels receive the same
amount of averaging whether they are single-ended or differential.
12.3.4
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. An internal 3 V reference is used by the converter
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resulting in sample values ranging from 0x000 at 0 V input to 0x3FF at 3 V input when in single-ended
input mode.
12.3.5
Differential Sampling
In addition to traditional single-ended sampling, the ADC module supports differential sampling of
two analog input channels. To enable differential sampling, software must set the Dn bit in the
ADCSSCTL0n register in a step's configuration nibble.
When a sequence step is configured for differential sampling, its corresponding value in the
ADCSSMUXn register must be set to one of the four differential pairs, numbered 0-3. Differential
pair 0 samples analog inputs 0 and 1; differential pair 1 samples analog inputs 2 and 3; and so on
(see Table 12-3 on page 462). The ADC does not support other differential pairings such as analog
input 0 with analog input 3. The number of differential pairs supported is dependent on the number
of analog inputs (see Table 12-3 on page 462).
Table 12-3. Differential Sampling Pairs
Differential Pair
Analog Inputs
0
0 and 1
1
2 and 3
2
4 and 5
3
6 and 7
The voltage sampled in differential mode is the difference between the odd and even channels:
∆V (differential voltage) = VIN_EVEN (even channels) – VIN_ODD (odd channels), therefore:
■ If ∆V = 0, then the conversion result = 0x1FF
■ If ∆V > 0, then the conversion result > 0x1FF (range is 0x1FF–0x3FF)
■ If ∆V < 0, then the conversion result < 0x1FF (range is 0–0x1FF)
The differential pairs assign polarities to the analog inputs: the even-numbered input is always
positive, and the odd-numbered input is always negative. In order for a valid conversion result to
appear, the negative input must be in the range of ± 1.5 V of the positive input. If an analog input
is greater than 3 V or less than 0 V (the valid range for analog inputs), the input voltage is clipped,
meaning it appears as either 3 V or 0 V, respectively, to the ADC.
Figure 12-2 on page 463 shows an example of the negative input centered at 1.5 V. In this
configuration, the differential range spans from -1.5 V to 1.5 V. Figure 12-3 on page 463 shows an
example where the negative input is centered at -0.75 V, meaning inputs on the positive input
saturate past a differential voltage of -0.75 V since the input voltage is less than 0 V. Figure
12-4 on page 464 shows an example of the negative input centered at 2.25 V, where inputs on the
positive channel saturate past a differential voltage of 0.75 V since the input voltage would be greater
than 3 V.
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Figure 12-2. Differential Sampling Range, VIN_ODD = 1.5 V
ADC Conversion Result
0x3FF
0x1FF
0V
-1.5 V
1.5 V
0V
3.0 V VIN_EVEN
1.5 V DV
VIN_ODD = 1.5 V
- Input Saturation
Figure 12-3. Differential Sampling Range, VIN_ODD = 0.75 V
ADC Conversion Result
0x3FF
0x1FF
0x0FF
-1.5 V
0V
-0.75 V
+0.75 V
+2.25 V
+1.5 V
VIN_EVEN
DV
- Input Saturation
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Figure 12-4. Differential Sampling Range, VIN_ODD = 2.25 V
ADC Conversion Result
0x3FF
0x2FF
0x1FF
0.75 V
-1.5 V
2.25 V
3.0 V
0.75 V
1.5 V
VIN_EVEN
DV
- Input Saturation
12.3.6
Internal Temperature Sensor
The temperature sensor serves two primary purposes: 1) to notify the system that internal temperature
is too high or low for reliable operation, and 2) to provide temperature measurements for calibration
of the Hibernate module RTC trim value.
The temperature sensor does not have a separate enable, since it also contains the bandgap
reference and must always be enabled. The reference is supplied to other analog modules; not just
the ADC.
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 12-5 on page 465.
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Figure 12-5. Internal Temperature Sensor Characteristic
12.4
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.
12.4.1
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, disabling the analog isolation circuit associated with all inputs that
are to be used, 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 RCGC0 register (see page 215).
2. Disable the analog isolation circuit for all ADC input pins that are to be used by writing a 1 to
the appropriate bits of the GPIOAMSEL register (see page 386) in the associated GPIO block.
3. 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.
12.4.2
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 ASENn 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.
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3. For each sample in the sample sequence, configure the corresponding input source in the
ADCSSMUXn register.
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 ASENn bit in the
ADCACTSS register.
12.5
Register Map
Table 12-4 on page 466 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.
Note that the ADC module clock must be enabled before the registers can be programmed (see
page 215). There must be a delay of 3 system clocks after the ADC module clock is enabled before
any ADC module registers are accessed.
Table 12-4. ADC Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
ADCACTSS
R/W
0x0000.0000
ADC Active Sample Sequencer
468
0x004
ADCRIS
RO
0x0000.0000
ADC Raw Interrupt Status
469
0x008
ADCIM
R/W
0x0000.0000
ADC Interrupt Mask
470
0x00C
ADCISC
R/W1C
0x0000.0000
ADC Interrupt Status and Clear
471
0x010
ADCOSTAT
R/W1C
0x0000.0000
ADC Overflow Status
472
0x014
ADCEMUX
R/W
0x0000.0000
ADC Event Multiplexer Select
473
0x018
ADCUSTAT
R/W1C
0x0000.0000
ADC Underflow Status
476
0x020
ADCSSPRI
R/W
0x0000.3210
ADC Sample Sequencer Priority
477
0x028
ADCPSSI
WO
-
ADC Processor Sample Sequence Initiate
479
0x030
ADCSAC
R/W
0x0000.0000
ADC Sample Averaging Control
480
0x040
ADCSSMUX0
R/W
0x0000.0000
ADC Sample Sequence Input Multiplexer Select 0
481
0x044
ADCSSCTL0
R/W
0x0000.0000
ADC Sample Sequence Control 0
483
0x048
ADCSSFIFO0
RO
-
ADC Sample Sequence Result FIFO 0
486
0x04C
ADCSSFSTAT0
RO
0x0000.0100
ADC Sample Sequence FIFO 0 Status
487
0x060
ADCSSMUX1
R/W
0x0000.0000
ADC Sample Sequence Input Multiplexer Select 1
488
0x064
ADCSSCTL1
R/W
0x0000.0000
ADC Sample Sequence Control 1
489
0x068
ADCSSFIFO1
RO
-
ADC Sample Sequence Result FIFO 1
486
0x06C
ADCSSFSTAT1
RO
0x0000.0100
ADC Sample Sequence FIFO 1 Status
487
0x080
ADCSSMUX2
R/W
0x0000.0000
ADC Sample Sequence Input Multiplexer Select 2
488
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Table 12-4. ADC Register Map (continued)
Offset
Name
Type
Reset
0x084
ADCSSCTL2
R/W
0x0000.0000
0x088
ADCSSFIFO2
RO
0x08C
ADCSSFSTAT2
0x0A0
Description
See
page
ADC Sample Sequence Control 2
489
-
ADC Sample Sequence Result FIFO 2
486
RO
0x0000.0100
ADC Sample Sequence FIFO 2 Status
487
ADCSSMUX3
R/W
0x0000.0000
ADC Sample Sequence Input Multiplexer Select 3
491
0x0A4
ADCSSCTL3
R/W
0x0000.0002
ADC Sample Sequence Control 3
492
0x0A8
ADCSSFIFO3
RO
-
ADC Sample Sequence Result FIFO 3
486
0x0AC
ADCSSFSTAT3
RO
0x0000.0100
ADC Sample Sequence FIFO 3 Status
487
12.6
Register Descriptions
The remainder of this section lists and describes the ADC registers, in numerical order by address
offset.
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Analog-to-Digital Converter (ADC)
Register 1: ADC Active Sample Sequencer (ADCACTSS), offset 0x000
This register controls the activation of the sample sequencers. Each sample sequencer can be
enabled or 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
ASEN3
ASEN2
ASEN1
ASEN0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x0000.000
3
ASEN3
R/W
0
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.
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.
2
ASEN2
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.
1
ASEN1
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.
0
ASEN0
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.
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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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
INR3
INR2
INR1
INR0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:4
reserved
RO
0x000
Software should not rely on the value of 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
INR3
RO
0
SS3 Raw Interrupt Status
This bit is set by hardware when a sample with its respective
ADCSSCTL3 IE bit has completed conversion. This bit is cleared by
setting the IN3 bit in the ADCISC register.
2
INR2
RO
0
SS2 Raw Interrupt Status
This bit is set by hardware when a sample with its respective
ADCSSCTL2 IE bit has completed conversion. This bit is cleared by
setting the IN2 bit in the ADCISC register.
1
INR1
RO
0
SS1 Raw Interrupt Status
This bit is set by hardware when a sample with its respective
ADCSSCTL1 IE bit has completed conversion. This bit is cleared by
setting the IN1 bit in the ADCISC register.
0
INR0
RO
0
SS0 Raw Interrupt Status
This bit is set by hardware when a sample with its respective
ADCSSCTL0 IE bit has completed conversion. This bit is cleared by
setting the IN30 bit in the ADCISC register.
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Analog-to-Digital Converter (ADC)
Register 3: ADC Interrupt Mask (ADCIM), offset 0x008
This register controls whether the sample sequencer raw interrupt signals are promoted to controller
interrupts. Each raw interrupt signal 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
MASK3
MASK2
MASK1
MASK0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:4
reserved
RO
0x000
Software should not rely on the value of 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
MASK3
R/W
0
SS3 Interrupt Mask
When set, this bit allows the raw interrupt signal from Sample Sequencer
3 (ADCRIS register INR3 bit) to be promoted to a controller interrupt.
When clear, the status of Sample Sequencer 3 does not affect the SS3
interrupt status.
2
MASK2
R/W
0
SS2 Interrupt Mask
When set, this bit allows the raw interrupt signal from Sample Sequencer
2 (ADCRIS register INR2 bit) to be promoted to a controller interrupt.
When clear, the status of Sample Sequencer 2 does not affect the SS2
interrupt status.
1
MASK1
R/W
0
SS1 Interrupt Mask
When set, this bit allows the raw interrupt signal from Sample Sequencer
1 (ADCRIS register INR1 bit) to be promoted to a controller interrupt.
When clear, the status of Sample Sequencer 1 does not affect the SS1
interrupt status.
0
MASK0
R/W
0
SS0 Interrupt Mask
When set, this bit allows the raw interrupt signal from Sample Sequencer
0 (ADCRIS register INR0 bit) to be promoted to a controller interrupt.
When clear, the status of Sample Sequencer 0 does not affect the SS0
interrupt status.
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Stellaris® LM3S5737 Microcontroller
Register 4: ADC Interrupt Status and Clear (ADCISC), offset 0x00C
This register provides the mechanism for clearing sample sequence 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. Sample sequence nterrupts are cleared by
setting the corresponding bit position. If software is polling the ADCRIS instead of generating
interrupts, the sample sequence 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
IN3
IN2
IN1
IN0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:4
reserved
RO
0x000
Software should not rely on the value of 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
IN3
R/W1C
0
SS3 Interrupt Status and Clear
This bit is set when both the INR3 bit in the ADCRIS register and the
MASK3 bit in the ADCIM register are set, providing a level-based interrupt
to the controller.
This bit is cleared by writing a 1. Clearing this bit also clears the INR3
bit.
2
IN2
R/W1C
0
SS2 Interrupt Status and Clear
This bit is set when both the INR2 bit in the ADCRIS register and the
MASK2 bit in the ADCIM register are set, providing a level-based interrupt
to the controller.
This bit is cleared by writing a 1. Clearing this bit also clears the INR2
bit.
1
IN1
R/W1C
0
SS1 Interrupt Status and Clear
This bit is set when both the INR1 bit in the ADCRIS register and the
MASK1 bit in the ADCIM register are set, providing a level-based interrupt
to the controller.
This bit is cleared by writing a 1. Clearing this bit also clears the INR1
bit.
0
IN0
R/W1C
0
SS0 Interrupt Status and Clear
This bit is set when both the INR0 bit in the ADCRIS register and the
MASK0 bit in the ADCIM register are set, providing a level-based interrupt
to the controller.
This bit is cleared by writing a 1. Clearing this bit also clears the INR0
bit.
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Analog-to-Digital Converter (ADC)
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
OV3
OV2
OV1
OV0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x0000.000
3
OV3
R/W1C
0
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.
SS3 FIFO Overflow
When set, 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.
This bit is cleared by writing a 1.
2
OV2
R/W1C
0
SS2 FIFO Overflow
When set, 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.
This bit is cleared by writing a 1.
1
OV1
R/W1C
0
SS1 FIFO Overflow
When set, 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.
This bit is cleared by writing a 1.
0
OV0
R/W1C
0
SS0 FIFO Overflow
When set, 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.
This bit is cleared by writing a 1.
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Stellaris® LM3S5737 Microcontroller
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
EM3
Type
Reset
EM2
EM1
EM0
Bit/Field
Name
Type
Reset
Description
31:16
reserved
RO
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.
15:12
EM3
R/W
0x0
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
Reserved
0x2
Reserved
0x3
Reserved
0x4
External (GPIO PB4)
0x5
Timer
In addition, the trigger must be enabled with the TnOTE bit in
the GPTMCTL register (see page 417).
0x6
reserved
0x7
reserved
0x8
reserved
0x9-0xE reserved
0xF
Always (continuously sample)
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Analog-to-Digital Converter (ADC)
Bit/Field
Name
Type
Reset
11:8
EM2
R/W
0x0
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
Reserved
0x2
Reserved
0x3
Reserved
0x4
External (GPIO PB4)
0x5
Timer
In addition, the trigger must be enabled with the TnOTE bit in
the GPTMCTL register (see page 417).
0x6
reserved
0x7
reserved
0x8
reserved
0x9-0xE reserved
0xF
7:4
EM1
R/W
0x0
Always (continuously sample)
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
Reserved
0x2
Reserved
0x3
Reserved
0x4
External (GPIO PB4)
0x5
Timer
In addition, the trigger must be enabled with the TnOTE bit in
the GPTMCTL register (see page 417).
0x6
reserved
0x7
reserved
0x8
reserved
0x9-0xE reserved
0xF
Always (continuously sample)
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Bit/Field
Name
Type
Reset
3:0
EM0
R/W
0x0
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
Reserved
0x2
Reserved
0x3
Reserved
0x4
External (GPIO PB4)
0x5
Timer
In addition, the trigger must be enabled with the TnOTE bit in
the GPTMCTL register (see page 417).
0x6
reserved
0x7
reserved
0x8
reserved
0x9-0xE reserved
0xF
Always (continuously sample)
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Analog-to-Digital Converter (ADC)
Register 7: ADC Underflow Status (ADCUSTAT), offset 0x018
This register indicates underflow conditions in the sample sequencer FIFOs. The corresponding
underflow condition is 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
UV3
UV2
UV1
UV0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x0000.000
3
UV3
R/W1C
0
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.
SS3 FIFO Underflow
When set, 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.
2
UV2
R/W1C
0
SS2 FIFO Underflow
When set, 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.
1
UV1
R/W1C
0
SS1 FIFO Underflow
When set, 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.
0
UV0
R/W1C
0
SS0 FIFO Underflow
When set, 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.
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Stellaris® LM3S5737 Microcontroller
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 Sequencer 3 has the lowest priority. When reconfiguring sequence priorities,
each sequence must have a unique priority for the ADC to operate properly.
ADC Sample Sequencer Priority (ADCSSPRI)
Base 0x4003.8000
Offset 0x020
Type R/W, reset 0x0000.3210
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
R/W
1
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
R/W
0
RO
0
RO
0
R/W
0
R/W
1
RO
0
RO
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
SS3
R/W
1
reserved
RO
0
SS2
R/W
1
Bit/Field
Name
Type
Reset
31:14
reserved
RO
0x0000.0
13:12
SS3
R/W
0x3
reserved
SS1
reserved
SS0
R/W
0
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.
SS3 Priority
This 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. The ADC may not operate properly if two or more
fields are equal.
11:10
reserved
RO
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.
9:8
SS2
R/W
0x2
SS2 Priority
This field contains a binary-encoded value that specifies the priority
encoding of Sample Sequencer 2. A priority encoding of 0 is highest
and 3 is lowest. The priorities assigned to the sequencers must be
uniquely mapped. The ADC may not operate properly if two or more
fields are equal.
7:6
reserved
RO
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.
5:4
SS1
R/W
0x1
SS1 Priority
This field contains a binary-encoded value that specifies the priority
encoding of Sample Sequencer 1. A priority encoding of 0 is highest
and 3 is lowest. The priorities assigned to the sequencers must be
uniquely mapped. The ADC may not operate properly if two or more
fields are equal.
3:2
reserved
RO
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.
November 17, 2011
477
Texas Instruments-Production Data
Analog-to-Digital Converter (ADC)
Bit/Field
Name
Type
Reset
Description
1:0
SS0
R/W
0x0
SS0 Priority
This field contains a binary-encoded value that specifies the priority
encoding of Sample Sequencer 0. A priority encoding of 0 is highest
and 3 is lowest. The priorities assigned to the sequencers must be
uniquely mapped. The ADC may not operate properly if two or more
fields are equal.
478
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
SS3
SS2
SS1
SS0
RO
0
RO
0
RO
0
RO
0
RO
0
WO
-
WO
-
WO
-
WO
-
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
Description
31:4
reserved
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
SS3
WO
-
SS3 Initiate
When set, this bit triggers sampling on Sample Sequencer 3 if the
sequencer is enabled in the ADCACTSS register.
Only a write by software is valid; a read of this register returns no
meaningful data.
2
SS2
WO
-
SS2 Initiate
When set, this bit triggers sampling on Sample Sequencer 2 if the
sequencer is enabled in the ADCACTSS register.
Only a write by software is valid; a read of this register returns no
meaningful data.
1
SS1
WO
-
SS1 Initiate
When set, this bit triggers sampling on Sample Sequencer 1 if the
sequencer is enabled in the ADCACTSS register.
Only a write by software is valid; a read of this register returns no
meaningful data.
0
SS0
WO
-
SS0 Initiate
When set, this bit triggers sampling on Sample Sequencer 0 if the
sequencer is enabled in the ADCACTSS register.
Only a write by software is valid; a read of this register returns no
meaningful data.
November 17, 2011
479
Texas Instruments-Production Data
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
Bit/Field
Name
Type
Reset
31:3
reserved
RO
0x0000.000
2:0
AVG
R/W
0x0
AVG
R/W
0
R/W
0
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.
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
480
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 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
Type
Reset
RO
0
R/W
0
15
14
RO
0
28
R/W
0
R/W
0
R/W
0
13
12
R/W
0
27
26
RO
0
R/W
0
11
10
24
RO
0
R/W
0
R/W
0
R/W
0
9
8
R/W
0
Bit/Field
Name
Type
Reset
31
reserved
RO
0
30:28
MUX7
R/W
0x0
23
22
RO
0
R/W
0
7
6
RO
0
20
R/W
0
R/W
0
R/W
0
5
4
R/W
0
19
18
RO
0
R/W
0
3
2
RO
0
16
R/W
0
R/W
0
1
0
MUX0
reserved
R/W
0
17
MUX4
reserved
MUX1
reserved
R/W
0
21
MUX5
reserved
MUX2
reserved
R/W
0
25
MUX6
reserved
MUX3
reserved
Type
Reset
29
MUX7
reserved
R/W
0
R/W
0
R/W
0
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.
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.
27
reserved
RO
0
26:24
MUX6
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.
7th Sample Input Select
The MUX6 field is used during the seventh sample of a sequence
executed with the sample sequencer. It specifies which of the analog
inputs is sampled for the analog-to-digital conversion.
23
reserved
RO
0
22:20
MUX5
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.
6th Sample Input Select
The MUX5 field is used during the sixth sample of a sequence executed
with the sample sequencer. It specifies which of the analog inputs is
sampled for the analog-to-digital conversion.
19
reserved
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.
November 17, 2011
481
Texas Instruments-Production Data
Analog-to-Digital Converter (ADC)
Bit/Field
Name
Type
Reset
18:16
MUX4
R/W
0x0
Description
5th Sample Input Select
The MUX4 field is used during the fifth sample of a sequence executed
with the sample sequencer. It specifies which of the analog inputs is
sampled for the analog-to-digital conversion.
15
reserved
RO
0
14:12
MUX3
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.
4th Sample Input Select
The MUX3 field is used during the fourth sample of a sequence executed
with the sample sequencer. It specifies which of the analog inputs is
sampled for the analog-to-digital conversion.
11
reserved
RO
0
10:8
MUX2
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.
3rd Sample Input Select
The MUX72 field is used during the third sample of a sequence executed
with the sample sequencer. It specifies which of the analog inputs is
sampled for the analog-to-digital conversion.
7
reserved
RO
0
6:4
MUX1
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.
2nd Sample Input Select
The MUX1 field is used during the second sample of a sequence
executed with the sample sequencer. It specifies which of the analog
inputs is sampled for the analog-to-digital conversion.
3
reserved
RO
0
2:0
MUX0
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.
1st Sample Input Select
The MUX0 field is used during the first sample of a sequence executed
with the sample sequencer. It specifies which of the analog inputs is
sampled for the analog-to-digital conversion.
482
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 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
a sample sequencer. 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
Type
Reset
Type
Reset
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
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
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
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
31
TS7
R/W
0
Description
8th Sample Temp Sensor Select
This bit is used during the eighth sample of the sample sequence and
and specifies the input source of the sample.
When set, the temperature sensor is read.
When clear, the input pin specified by the ADCSSMUX register is read.
30
IE7
R/W
0
8th Sample Interrupt Enable
This 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.
When this bit is clear, the raw interrupt is not asserted.
It is legal to have multiple samples within a sequence generate interrupts.
29
END7
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.
28
D7
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.
27
TS6
R/W
0
7th Sample Temp Sensor Select
Same definition as TS7 but used during the seventh sample.
November 17, 2011
483
Texas Instruments-Production Data
Analog-to-Digital Converter (ADC)
Bit/Field
Name
Type
Reset
26
IE6
R/W
0
Description
7th Sample Interrupt Enable
Same definition as IE7 but used during the seventh sample.
25
END6
R/W
0
7th Sample is End of Sequence
Same definition as END7 but used during the seventh sample.
24
D6
R/W
0
7th Sample Diff Input Select
Same definition as D7 but used during the seventh sample.
23
TS5
R/W
0
6th Sample Temp Sensor Select
Same definition as TS7 but used during the sixth sample.
22
IE5
R/W
0
6th Sample Interrupt Enable
Same definition as IE7 but used during the sixth sample.
21
END5
R/W
0
6th Sample is End of Sequence
Same definition as END7 but used during the sixth sample.
20
D5
R/W
0
6th Sample Diff Input Select
Same definition as D7 but used during the sixth sample.
19
TS4
R/W
0
5th Sample Temp Sensor Select
Same definition as TS7 but used during the fifth sample.
18
IE4
R/W
0
5th Sample Interrupt Enable
Same definition as IE7 but used during the fifth sample.
17
END4
R/W
0
5th Sample is End of Sequence
Same definition as END7 but used during the fifth sample.
16
D4
R/W
0
5th Sample Diff Input Select
Same definition as D7 but used during the fifth sample.
15
TS3
R/W
0
4th Sample Temp Sensor Select
Same definition as TS7 but used during the fourth sample.
14
IE3
R/W
0
4th Sample Interrupt Enable
Same definition as IE7 but used during the fourth sample.
13
END3
R/W
0
4th Sample is End of Sequence
Same definition as END7 but used during the fourth sample.
12
D3
R/W
0
4th Sample Diff Input Select
Same definition as D7 but used during the fourth sample.
11
TS2
R/W
0
3rd Sample Temp Sensor Select
Same definition as TS7 but used during the third sample.
10
IE2
R/W
0
3rd Sample Interrupt Enable
Same definition as IE7 but used during the third sample.
9
END2
R/W
0
3rd Sample is End of Sequence
Same definition as END7 but used during the third sample.
484
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
8
D2
R/W
0
Description
3rd Sample Diff Input Select
Same definition as D7 but used during the third sample.
7
TS1
R/W
0
2nd Sample Temp Sensor Select
Same definition as TS7 but used during the second sample.
6
IE1
R/W
0
2nd Sample Interrupt Enable
Same definition as IE7 but used during the second sample.
5
END1
R/W
0
2nd Sample is End of Sequence
Same definition as END7 but used during the second sample.
4
D1
R/W
0
2nd Sample Diff Input Select
Same definition as D7 but used during the second sample.
3
TS0
R/W
0
1st Sample Temp Sensor Select
Same definition as TS7 but used during the first sample.
2
IE0
R/W
0
1st Sample Interrupt Enable
Same definition as IE7 but used during the first sample.
1
END0
R/W
0
1st Sample is End of Sequence
Same definition as END7 but used during the first sample.
0
D0
R/W
0
1st Sample Diff Input Select
Same definition as D7 but used during the first sample.
November 17, 2011
485
Texas Instruments-Production Data
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
Important: This register is read-sensitive. See the register description for details.
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 31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
-
RO
-
RO
-
RO
-
RO
-
4
3
2
1
0
RO
-
RO
-
RO
-
RO
-
RO
-
reserved
Type
Reset
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
15
14
13
12
11
10
9
8
7
6
5
reserved
Type
Reset
RO
-
RO
-
RO
-
RO
-
DATA
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
Bit/Field
Name
Type
Reset
Description
31:10
reserved
RO
-
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
9:0
DATA
RO
-
Conversion Result Data
486
November 17, 2011
Texas Instruments-Production Data
Stellaris® LM3S5737 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 FIFO0, 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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
RO
0
FULL
RO
0
RO
0
reserved
RO
0
RO
0
EMPTY
RO
0
Bit/Field
Name
Type
Reset
31:13
reserved
RO
0x0
12
FULL
RO
0
RO
1
HPTR
TPTR
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.
FIFO Full
When set, this bit indicates that the FIFO is currently full.
11:9
reserved
RO
0x0
8
EMPTY
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.
FIFO Empty
When set, this bit indicates that the FIFO is currently empty.
7:4
HPTR
RO
0x0
FIFO Head Pointer
This field contains the current "head" pointer index for the FIFO, that is,
the next entry to be written.
3:0
TPTR
RO
0x0
FIFO Tail Pointer
This field contains the current "tail" pointer index for the FIFO, that is,
the next entry to be read.
November 17, 2011
487
Texas Instruments-Production Data
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 481 for detailed bit descriptions. The ADCSSMUX1
register affects Sample Sequencer 1 and the ADCSSMUX2 register affects Sample Sequencer 2.
ADC Sample Sequence Input Multiplexer Select 1 (ADCSSMUX1)
Base 0x4003.8000
Offset 0x060
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
reserved
Type
Reset
MUX3
reserved
Type
Reset
RO
0
R/W
0
R/W
0
MUX2
reserved
R/W
0
RO
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
31:15
reserved
RO
0x0000
14:12
MUX3
R/W
0x0
11
reserved
RO
0
10:8
MUX2
R/W
0x0
7
reserved
RO
0
6:4
MUX1
R/W
0x0
3
reserved
RO
0
2:0
MUX0
R/W
0x0
MUX1
reserved
R/W
0
RO
0
R/W
0
R/W
0
MUX0
reserved
R/W
0
RO
0
R/W
0
R/W
0
R/W
0
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.
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.
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.
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.
1st Sample Input Select
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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. These registers
are 16-bits wide and contain information for four possible samples. See the ADCSSCTL0 register
on page 483 for detailed bit descriptions. The ADCSSCTL1 register configures Sample Sequencer
1 and the ADCSSCTL2 register configures Sample Sequencer 2.
ADC Sample Sequence Control 1 (ADCSSCTL1)
Base 0x4003.8000
Offset 0x064
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
TS3
IE3
END3
D3
TS2
IE2
END2
D2
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
TS1
IE1
END1
D1
TS0
IE0
END0
D0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
Type
Reset
Bit/Field
Name
Type
Reset
31:16
reserved
RO
0x0000
15
TS3
R/W
0
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.
4th Sample Temp Sensor Select
Same definition as TS7 but used during the fourth sample.
14
IE3
R/W
0
4th Sample Interrupt Enable
Same definition as IE7 but used during the fourth sample.
13
END3
R/W
0
4th Sample is End of Sequence
Same definition as END7 but used during the fourth sample.
12
D3
R/W
0
4th Sample Diff Input Select
Same definition as D7 but used during the fourth sample.
11
TS2
R/W
0
3rd Sample Temp Sensor Select
Same definition as TS7 but used during the third sample.
10
IE2
R/W
0
3rd Sample Interrupt Enable
Same definition as IE7 but used during the third sample.
9
END2
R/W
0
3rd Sample is End of Sequence
Same definition as END7 but used during the third sample.
8
D2
R/W
0
3rd Sample Diff Input Select
Same definition as D7 but used during the third sample.
7
TS1
R/W
0
2nd Sample Temp Sensor Select
Same definition as TS7 but used during the second sample.
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Bit/Field
Name
Type
Reset
6
IE1
R/W
0
Description
2nd Sample Interrupt Enable
Same definition as IE7 but used during the second sample.
5
END1
R/W
0
2nd Sample is End of Sequence
Same definition as END7 but used during the second sample.
4
D1
R/W
0
2nd Sample Diff Input Select
Same definition as D7 but used during the second sample.
3
TS0
R/W
0
1st Sample Temp Sensor Select
Same definition as TS7 but used during the first sample.
2
IE0
R/W
0
1st Sample Interrupt Enable
Same definition as IE7 but used during the first sample.
1
END0
R/W
0
1st Sample is End of Sequence
Same definition as END7 but used during the first sample.
0
D0
R/W
0
1st Sample Diff Input Select
Same definition as D7 but used during the first sample.
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Register 25: ADC Sample Sequence Input Multiplexer Select 3 (ADCSSMUX3),
offset 0x0A0
This register defines the analog input configuration for a sample executed with Sample Sequencer
3. This register is 4-bits wide and contains information for one possible sample. See the ADCSSMUX0
register on page 481 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
RO
0
RO
0
1
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
9
8
7
6
5
4
3
2
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:3
reserved
RO
0x0000.000
2:0
MUX0
R/W
0
MUX0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
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.
1st Sample Input Select
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Register 26: ADC Sample Sequence Control 3 (ADCSSCTL3), offset 0x0A4
This register contains the configuration information for a sample 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 483
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
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
TS0
IE0
END0
D0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
1
R/W
0
reserved
Type
Reset
reserved
Type
Reset
Bit/Field
Name
Type
Reset
31:4
reserved
RO
0x0000.000
3
TS0
R/W
0
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.
1st Sample Temp Sensor Select
Same definition as TS7 but used during the first sample.
2
IE0
R/W
0
1st Sample Interrupt Enable
Same definition as IE7 but used during the first sample.
1
END0
R/W
1
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.
0
D0
R/W
0
1st Sample Diff Input Select
Same definition as D7 but used during the first sample.
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13
Universal Asynchronous Receivers/Transmitters
(UARTs)
®
The Stellaris Universal Asynchronous Receiver/Transmitter (UART) has the following features:
■ Fully programmable 16C550-type UART with IrDA support
■ Separate 16x8 transmit (TX) and receive (RX) FIFOs to reduce CPU interrupt service loading
■ Programmable baud-rate generator allowing speeds up to 3.125 Mbps
■ 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
■ 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
■ Dedicated Direct Memory Access (DMA) transmit and receive channels
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13.1
Block Diagram
Figure 13-1. UART Module Block Diagram
System Clock
DMA Request
DMA Control
UARTDMACTL
Interrupt
Interrupt Control
UARTIFLS
UARTIM
UARTMIS
UARTRIS
UARTICR
Identification
Registers
UARTPCellID0
UARTPCellID1
UARTPCellID2
UARTPCellID3
UARTPeriphID0
UARTPeriphID1
UARTPeriphID2
UARTPeriphID3
UARTPeriphID4
UARTPeriphID5
UARTPeriphID6
UARTPeriphID7
13.2
TxFIFO
16 x 8
.
.
.
Baud Rate
Generator
Transmitter
(with SIR
Transmit
Encoder)
UnTx
UARTIBRD
UARTDR
UARTFBRD
RxFIFO
16 x 8
Control/Status
UARTRSR/ECR
UARTFR
UARTLCRH
UARTCTL
UARTILPR
Receiver
(with SIR
Receive
Decoder)
UnRx
.
.
.
Signal Description
Table 13-1 on page 494 lists the external signals of the UART module and describes the function of
each. The UART signals are alternate functions for some GPIO signals and default to be GPIO
signals at reset, with the exception of the U0Rx and U0Tx pins which default to the UART function.
The column in the table below titled "Pin Assignment" lists the possible GPIO pin placements for
these UART signals. The AFSEL bit in the GPIO Alternate Function Select (GPIOAFSEL) register
(page 371) should be set to choose the UART function. For more information on configuring GPIOs,
see “General-Purpose Input/Outputs (GPIOs)” on page 348.
Table 13-1. UART Signals (100LQFP)
a
Pin Name
Pin Number
Pin Type
Buffer Type
Description
U0Rx
26
I
TTL
UART module 0 receive. When in IrDA mode, this signal has
IrDA modulation.
U0Tx
27
O
TTL
UART module 0 transmit. When in IrDA mode, this signal has
IrDA modulation.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
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13.3
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 513). 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.
13.3.1
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
bits (LSB first), parity bit, and the stop bits according to the programmed configuration in the control
registers. See Figure 13-2 on page 495 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
UnTX
LSB
1
5-8 data bits
0
n
Parity bit
if enabled
Start
13.3.2
1-2
stop bits
MSB
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 509) and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate Divisor
(UARTFBRD) register (see page 510). 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 = UARTSysClk / (16 * Baud Rate)
where UARTSysClk is the system clock connected to the UART.
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)
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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 511), 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
13.3.3
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 506) 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 495).
The start bit is valid and recognized if UnRx is still low on the eighth cycle of Baud16, otherwise it
is ignored. After a valid start bit is detected, 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.
13.3.4
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
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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. See page 508 for more
information on IrDA low-power pulse-duration configuration.
Figure 13-3 on page 497 shows the UART transmit and receive signals, with and without IrDA
modulation.
Figure 13-3. IrDA Data Modulation
Data bits
Start
bit
UnTx
1
0
0
0
1
Stop
bit
0
0
1
1
1
UnTx with IrDA
3
16 Bit period
Bit period
UnRx with IrDA
UnRx
0
1
0
Start
1
0
0
1
1
Data bits
0
1
Stop
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.
If the application does not require the use of the UnRx signal, the GPIO pin that has the UnRx signal
as an alternate function must be configured as the UnRx signal and pulled High.
13.3.5
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 502). 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 511).
FIFO status can be monitored via the UART Flag (UARTFR) register (see page 506) and the UART
Receive Status (UARTRSR) register. Hardware monitors empty, full and overrun conditions. The
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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 515). 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.
13.3.6
Interrupts
The UART can generate interrupts when the following conditions are observed:
■ Overrun Error
■ Break Error
■ 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 520).
The interrupt events that can trigger a controller-level interrupt are defined in the UART Interrupt
Mask (UARTIM ) register (see page 517) 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 519).
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 521).
The receive interrupt changes state when one of the following events occurs:
■ If the FIFOs are enabled and the receive FIFO reaches the programmed trigger level, the RXRIS
bit is set. The receive interrupt is cleared by reading data from the receive FIFO until it becomes
less than the trigger level, or by clearing the interrupt by writing a 1 to the RXIC bit.
■ If the FIFOs are disabled (have a depth of one location) and data is received thereby filling the
location, the RXRIS bit is set. The receive interrupt is cleared by performing a single read of the
receive FIFO, or by clearing the interrupt by writing a 1 to the RXIC bit.
The transmit interrupt changes state when one of the following events occurs:
■ If the FIFOs are enabled and the transmit FIFO reaches the programmed trigger level, the TXRIS
bit is set. The transmit interrupt is cleared by writing data to the transmit FIFO until it becomes
greater than the trigger level, or by clearing the interrupt by writing a 1 to the TXIC bit.
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■ If the FIFOs are disabled (have a depth of one location) and there is no data present in the
transmitters single location, the TXRIS bit is set. It is cleared by performing a single write to the
transmit FIFO, or by clearing the interrupt by writing a 1 to the TXIC bit.
13.3.7
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 513). In loopback mode,
data transmitted on UnTx is received on the UnRx input.
13.3.8
DMA Operation
The UART provides an interface connected to the μDMA controller. The DMA operation of the UART
is enabled through the UART DMA Control (UARTDMACTL) register. When DMA operation is
enabled, the UART will assert a DMA request on the receive or transmit channel when the associated
FIFO can transfer data. For the receive channel, a single transfer request is asserted whenever
there is any data in the receive FIFO. A burst transfer request is asserted whenever the amount of
data in the receive FIFO is at or above the FIFO trigger level. For the transmit channel, a single
transfer request is asserted whenever there is at least one empty location in the transmit FIFO. The
burst request is asserted whenever the transmit FIFO contains fewer characters than the FIFO
trigger level. The single and burst DMA transfer requests are handled automatically by the μDMA
controller depending how the DMA channel is configured.
To enable DMA operation for the receive channel, the RXDMAE bit of the DMA Control
(UARTDMACTL) register should be set. To enable DMA operation for the transmit channel, the
TXDMAE bit of UARTDMACTL should be set. The UART can also be configured to stop using DMA
for the receive channel if a receive error occurs. If the DMAERR bit of UARTDMACR is set, then
when a receive error occurs, the DMA receive requests will be automatically disabled. This error
condition can be cleared by clearing the UART error interrupt.
If DMA is enabled, then the μDMA controller will trigger an interrupt when a transfer is complete.
The interrupt will occur on the UART interrupt vector. Therefore, if interrupts are used for UART
operation and DMA is enabled, the UART interrupt handler must be designed to handle the μDMA
completion interrupt.
See “Micro Direct Memory Access (μDMA)” on page 287 for more details about programming the
μDMA controller.
13.3.9
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.
13.4
Initialization and Configuration
To use the UART, the peripheral clock must be enabled by setting the UART0 bit in the RCGC1
register.
This section discusses the steps that are required to use a UART module. For this example, the
UART clock is assumed to be 20 MHz and the desired UART configuration is:
■ 115200 baud rate
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■ Data length of 8 bits
■ One stop bit
■ 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 495, 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 509) should be set to 10.
The value to be loaded into the UARTFBRD register (see page 510) 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. Optionally, configure the uDMA channel (see “Micro Direct Memory Access (μDMA)” on page 287)
and enable the DMA option(s) in the UARTDMACTL register.
6. Enable the UART by setting the UARTEN bit in the UARTCTL register.
13.5
Register Map
Table 13-2 on page 501 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
Note that the UART module clock must be enabled before the registers can be programmed (see
page 221). There must be a delay of 3 system clocks after the UART module clock is enabled before
any UART module registers are accessed.
Note:
The UART must be disabled (see the UARTEN bit in the UARTCTL register on page 513)
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.
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Table 13-2. UART Register Map
Offset
Name
Type
Reset
Description
See
page
0x000
UARTDR
R/W
0x0000.0000
UART Data
502
0x004
UARTRSR/UARTECR
R/W
0x0000.0000
UART Receive Status/Error Clear
504
0x018
UARTFR
RO
0x0000.0090
UART Flag
506
0x020
UARTILPR
R/W
0x0000.0000
UART IrDA Low-Power Register
508
0x024
UARTIBRD
R/W
0x0000.0000
UART Integer Baud-Rate Divisor
509
0x028
UARTFBRD
R/W
0x0000.0000
UART Fractional Baud-Rate Divisor
510
0x02C
UARTLCRH
R/W
0x0000.0000
UART Line Control
511
0x030
UARTCTL
R/W
0x0000.0300
UART Control
513
0x034
UARTIFLS
R/W
0x0000.0012
UART Interrupt FIFO Level Select
515
0x038
UARTIM
R/W
0x0000.0000
UART Interrupt Mask
517
0x03C
UARTRIS
RO
0x0000.000F
UART Raw Interrupt Status
519
0x040
UARTMIS
RO
0x0000.0000
UART Masked Interrupt Status
520
0x044
UARTICR
W1C
0x0000.0000
UART Interrupt Clear
521
0x048
UARTDMACTL
R/W
0x0000.0000
UART DMA Control
523
0xFD0
UARTPeriphID4
RO
0x0000.0000
UART Peripheral Identification 4
524
0xFD4
UARTPeriphID5
RO
0x0000.0000
UART Peripheral Identification 5
525
0xFD8
UARTPeriphID6
RO
0x0000.0000
UART Peripheral Identification 6
526
0xFDC
UARTPeriphID7
RO
0x0000.0000
UART Peripheral Identification 7
527
0xFE0
UARTPeriphID0
RO
0x0000.0011
UART Peripheral Identification 0
528
0xFE4
UARTPeriphID1
RO
0x0000.0000
UART Peripheral Identification 1
529
0xFE8
UARTPeriphID2
RO
0x0000.0018
UART Peripheral Identification 2
530
0xFEC
UARTPeriphID3
RO
0x0000.0001
UART Peripheral Identification 3
531
0xFF0
UARTPCellID0
RO
0x0000.000D
UART PrimeCell Identification 0
532
0xFF4
UARTPCellID1
RO
0x0000.00F0
UART PrimeCell Identification 1
533
0xFF8
UARTPCellID2
RO
0x0000.0005
UART PrimeCell Identification 2
534
0xFFC
UARTPCellID3
RO
0x0000.00B1
UART PrimeCell Identification 3
535
13.6
Register Descriptions
The remainder of this section lists and describes the UART registers, in numerical order by address
offset.
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Universal Asynchronous Receivers/Transmitters (UARTs)
Register 1: UART Data (UARTDR), offset 0x000
Important: This register is read-sensitive. See the register description for details.
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
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
OE
BE
PE
FE
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
DATA
Bit/Field
Name
Type
Reset
Description
31:12
reserved
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
OE
RO
0
UART Overrun Error
The OE values are defined as follows:
Value Description
10
BE
RO
0
0
There has been no data loss due to a FIFO overrun.
1
New data was received when the FIFO was full, resulting in
data loss.
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.
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
9
PE
RO
0
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.
8
FE
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).
7:0
DATA
R/W
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.
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Universal Asynchronous Receivers/Transmitters (UARTs)
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.
Reads
UART Receive Status/Error Clear (UARTRSR/UARTECR)
UART0 base: 0x4000.C000
Offset 0x004
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
3
2
1
0
OE
BE
PE
FE
RO
0
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:4
reserved
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
OE
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.
2
BE
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.
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
1
PE
RO
0
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.
0
FE
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.
Writes
UART Receive Status/Error Clear (UARTRSR/UARTECR)
UART0 base: 0x4000.C000
Offset 0x004
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
15
14
13
12
11
10
9
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
23
22
21
20
19
18
17
16
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
8
7
6
5
4
3
2
1
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
WO
0
reserved
Type
Reset
reserved
Type
Reset
DATA
WO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
WO
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
DATA
WO
0
Error Clear
A write to this register of any data clears the framing, parity, break, and
overrun flags.
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Texas Instruments-Production Data
Universal Asynchronous Receivers/Transmitters (UARTs)
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
Offset 0x018
Type RO, reset 0x0000.0090
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
TXFE
RXFF
TXFF
RXFE
BUSY
RO
1
RO
0
RO
0
RO
1
RO
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
reserved
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
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
TXFE
RO
1
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.
6
RXFF
RO
0
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.
5
TXFF
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.
4
RXFE
RO
1
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.
506
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Stellaris® LM3S5737 Microcontroller
Bit/Field
Name
Type
Reset
Description
3
BUSY
RO
0
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).
2:0
reserved
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.
November 17, 2011
507
Texas Instruments-Production Data
Universal Asynchronous Receivers/Transmitters (UARTs)
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 derive the low-power SIR pulse width clock by dividing down the system clock (SysClk).
All the bits are cleared to 0 when reset.
The internal IrLPBaud16 clock is generated by dividing down SysClk according to the low-power
divisor value written to UARTILPR. The duration of SIR pulses generated when low-power mode
is enabled is three times the period of the IrLPBaud16 clock. The low-power divisor value is
calculated as follows:
ILPDVSR = SysClk / FIrLPBaud16
where FIrLPBaud16 is nominally 1.8432 MHz.
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
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
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
ILPDVSR
RO
0
RO
0
RO
0
Bit/Field
Name
Type
Reset
31:8
reserved
RO
0
7:0
ILPDVSR
R/W
0x00
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
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.
IrDA Low-Power Divisor
This is an 8-bit low-power divisor value.
508
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
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 495
for configuration details.
UART Integer Baud-Rate Divisor (UARTIBRD)
UART0 base: 0x4000.C000
Offset 0x024
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
5
4
3
2
1
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
DIVINT
Type
Reset
Bit/Field
Name
Type
Reset
31:16
reserved
RO
0
15:0
DIVINT
R/W
0x0000
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.
Integer Baud-Rate Divisor
November 17, 2011
509
Texas Instruments-Production Data
Universal Asynchronous Receivers/Transmitters (UARTs)
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 495
for configuration details.
UART Fractional Baud-Rate Divisor (UARTFBRD)
UART0 base: 0x4000.C000
Offset 0x028
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
8
7
6
5
4
3
2
1
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
DIVFRAC
R/W
0
Bit/Field
Name
Type
Reset
Description
31:6
reserved
RO
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.
5:0
DIVFRAC
R/W
0x000
Fractional Baud-Rate Divisor
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Texas Instruments-Production Data
Stellaris® LM3S5737 Microcontroller
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
Offset 0x02C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
7
6
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
SPS
RO
0
RO
0
RO
0
RO
0
R/W
0
5
WLEN
R/W
0
R/W
0
4
3
2
1
0
FEN
STP2
EPS
PEN
BRK
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
Name
Type
Reset
Description
31:8
reserved
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
SPS
R/W
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.
6:5
WLEN
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)
4
FEN
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.
3
STP2
R/W
0
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.
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Universal Asynchronous Receivers/Transmitters (UARTs)
Bit/Field
Name
Type
Reset
2
EPS
R/W
0
Description
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.
1
PEN
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.
0
BRK
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.
512
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Stellaris® LM3S5737 Microcontroller
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.
Note:
The UARTCTL register should not be changed while the UART is enabled or else the results
are unpredictable. The following sequence is recommended for making changes to the
UARTCTL register.
1. Disable the UART.
2. Wait for the end of transmission or reception of the current character.
3. Flush the transmit FIFO by disabling bit 4 (FEN) in the line control register (UARTLCRH).
4. Reprogram the control register.
5. Enable the UART.
UART Control (UARTCTL)
UART0 base: 0x4000.C000
Offset 0x030
Type R/W, reset 0x0000.0300
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RXE
TXE
LBE
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
1
R/W
1
R/W
0
SIRLP
SIREN
UARTEN
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
reserved
Type
Reset
reserved
Type
Reset
RO
0
reserved
Bit/Field
Name
Type
Reset
Description
31:10
reserved
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.
9
RXE
R/W
1
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:
8
TXE
R/W
1
To enable reception, the UARTEN bit must also be set.
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.
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Texas Instruments-Production Data
Universal Asynchronous R