LM3S300-IQN25-A1T [ETC]
Microcontroller; 微控制器
| 型号： | LM3S300-IQN25-A1T |
| 厂家： | 
ETC |
| 描述： | Microcontroller |
| 文件： | 总378页 (文件大小：3970K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRELIMINARY
LM3S300 Microcontroller
DATA SHEET
DS-LM3S300-1728
Copyright © 2007 Luminary Micro, Inc.
Legal Disclaimers and Trademark Information
INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH LUMINARY MICRO PRODUCTS. NO LICENSE, EXPRESS OR
IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT
AS PROVIDED IN LUMINARY MICRO'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, LUMINARY MICRO ASSUMES NO
LIABILITY WHATSOEVER, AND LUMINARY MICRO DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR
USE OF LUMINARY MICRO'S PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR
PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
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Luminary Micro may make changes to specifications and product descriptions at any time, without notice. Contact your local Luminary Micro sales office
or your distributor to obtain the latest specifications before placing your product order.
Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Luminary Micro reserves these
for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.
Copyright © 2007 Luminary Micro, Inc. All rights reserved. Stellaris is a registered trademark and Luminary Micro and the Luminary Micro logo are
trademarks of Luminary Micro, Inc. or its subsidiaries in the United States and other countries. ARM and Thumb are registered trademarks and Cortex
is a trademark of ARM Limited. Other names and brands may be claimed as the property of others.
Luminary Micro, Inc.
108 Wild Basin, Suite 350
Austin, TX 78746
Main: +1-512-279-8800
Fax: +1-512-279-8879
http://www.luminarymicro.com
2
October 01, 2007
Preliminary
LM3S300 Microcontroller
Table of Contents
About This Document .................................................................................................................... 15
Audience .............................................................................................................................................. 15
About This Manual ................................................................................................................................ 15
Related Documents ............................................................................................................................... 15
Documentation Conventions .................................................................................................................. 15
1
Architectural Overview ...................................................................................................... 17
Product Features ...................................................................................................................... 17
Target Applications .................................................................................................................... 21
High-Level Block Diagram ......................................................................................................... 21
Functional Overview .................................................................................................................. 22
1.1
1.2
1.3
1.4
1.4.1 ARM Cortex™-M3 ..................................................................................................................... 23
1.4.2 Motor Control Peripherals .......................................................................................................... 23
1.4.3 Analog Peripherals .................................................................................................................... 24
1.4.4 Serial Communications Peripherals ............................................................................................ 24
1.4.5 System Peripherals ................................................................................................................... 25
1.4.6 Memory Peripherals .................................................................................................................. 26
1.4.7 Additional Features ................................................................................................................... 27
1.4.8 Hardware Details ...................................................................................................................... 27
2
2.1
2.2
ARM Cortex-M3 Processor Core ...................................................................................... 28
Block Diagram .......................................................................................................................... 29
Functional Description ............................................................................................................... 29
2.2.1 Serial Wire and JTAG Debug ..................................................................................................... 29
2.2.2 Embedded Trace Macrocell (ETM) ............................................................................................. 30
2.2.3 Trace Port Interface Unit (TPIU) ................................................................................................. 30
2.2.4 ROM Table ............................................................................................................................... 30
2.2.5 Memory Protection Unit (MPU) ................................................................................................... 30
2.2.6 Nested Vectored Interrupt Controller (NVIC) ................................................................................ 30
3
4
Memory Map ....................................................................................................................... 34
Interrupts ............................................................................................................................ 36
5
5.1
5.2
JTAG Interface .................................................................................................................... 38
Block Diagram .......................................................................................................................... 39
Functional Description ............................................................................................................... 39
5.2.1 JTAG Interface Pins .................................................................................................................. 40
5.2.2 JTAG TAP Controller ................................................................................................................. 41
5.2.3 Shift Registers .......................................................................................................................... 42
5.2.4 Operational Considerations ........................................................................................................ 42
5.3
5.4
Initialization and Configuration ................................................................................................... 43
Register Descriptions ................................................................................................................ 44
5.4.1 Instruction Register (IR) ............................................................................................................. 44
5.4.2 Data Registers .......................................................................................................................... 46
6
6.1
System Control ................................................................................................................... 48
Functional Description ............................................................................................................... 48
6.1.1 Device Identification .................................................................................................................. 48
6.1.2 Reset Control ............................................................................................................................ 48
October 01, 2007
3
Preliminary
Table of Contents
6.1.3 Power Control ........................................................................................................................... 51
6.1.4 Clock Control ............................................................................................................................ 51
6.1.5 System Control ......................................................................................................................... 54
6.2
6.3
6.4
Initialization and Configuration ................................................................................................... 54
Register Map ............................................................................................................................ 55
Register Descriptions ................................................................................................................ 56
7
7.1
7.2
Internal Memory ............................................................................................................... 103
Block Diagram ........................................................................................................................ 103
Functional Description ............................................................................................................. 103
7.2.1 SRAM Memory ........................................................................................................................ 103
7.2.2 Flash Memory ......................................................................................................................... 104
7.3
Flash Memory Initialization and Configuration ........................................................................... 106
7.3.1 Changing Flash Protection Bits ................................................................................................ 106
7.3.2 Flash Programming ................................................................................................................. 107
7.4
7.5
7.6
Register Map .......................................................................................................................... 107
Flash Register Descriptions (Flash Control Offset) ..................................................................... 108
Flash Register Descriptions (System Control Offset) .................................................................. 115
8
8.1
General-Purpose Input/Outputs (GPIOs) ....................................................................... 119
Functional Description ............................................................................................................. 119
8.1.1 Data Control ........................................................................................................................... 120
8.1.2 Interrupt Control ...................................................................................................................... 121
8.1.3 Mode Control .......................................................................................................................... 122
8.1.4 Pad Control ............................................................................................................................. 122
8.1.5 Identification ........................................................................................................................... 122
8.2
8.3
8.4
Initialization and Configuration ................................................................................................. 122
Register Map .......................................................................................................................... 123
Register Descriptions .............................................................................................................. 125
9
9.1
9.2
General-Purpose Timers ................................................................................................. 157
Block Diagram ........................................................................................................................ 158
Functional Description ............................................................................................................. 158
9.2.1 GPTM Reset Conditions .......................................................................................................... 158
9.2.2 32-Bit Timer Operating Modes .................................................................................................. 158
9.2.3 16-Bit Timer Operating Modes .................................................................................................. 160
9.3
Initialization and Configuration ................................................................................................. 164
9.3.1 32-Bit One-Shot/Periodic Timer Mode ....................................................................................... 164
9.3.2 32-Bit Real-Time Clock (RTC) Mode ......................................................................................... 165
9.3.3 16-Bit One-Shot/Periodic Timer Mode ....................................................................................... 165
9.3.4 16-Bit Input Edge Count Mode ................................................................................................. 166
9.3.5 16-Bit Input Edge Timing Mode ................................................................................................ 166
9.3.6 16-Bit PWM Mode ................................................................................................................... 167
9.4
9.5
Register Map .......................................................................................................................... 167
Register Descriptions .............................................................................................................. 168
10
Watchdog Timer ............................................................................................................... 193
Block Diagram ........................................................................................................................ 193
Functional Description ............................................................................................................. 193
Initialization and Configuration ................................................................................................. 194
Register Map .......................................................................................................................... 194
10.1
10.2
10.3
10.4
4
October 01, 2007
Preliminary
LM3S300 Microcontroller
10.5
Register Descriptions .............................................................................................................. 195
11
11.1
11.2
Universal Asynchronous Receivers/Transmitters (UARTs) ......................................... 216
Block Diagram ........................................................................................................................ 217
Functional Description ............................................................................................................. 217
11.2.1 Transmit/Receive Logic ........................................................................................................... 217
11.2.2 Baud-Rate Generation ............................................................................................................. 218
11.2.3 Data Transmission .................................................................................................................. 219
11.2.4 FIFO Operation ....................................................................................................................... 219
11.2.5 Interrupts ................................................................................................................................ 219
11.2.6 Loopback Operation ................................................................................................................ 220
11.3
11.4
11.5
Initialization and Configuration ................................................................................................. 220
Register Map .......................................................................................................................... 221
Register Descriptions .............................................................................................................. 222
12
12.1
12.2
Synchronous Serial Interface (SSI) ................................................................................ 254
Block Diagram ........................................................................................................................ 254
Functional Description ............................................................................................................. 254
12.2.1 Bit Rate Generation ................................................................................................................. 255
12.2.2 FIFO Operation ....................................................................................................................... 255
12.2.3 Interrupts ................................................................................................................................ 255
12.2.4 Frame Formats ....................................................................................................................... 256
12.3
12.4
12.5
Initialization and Configuration ................................................................................................. 263
Register Map .......................................................................................................................... 264
Register Descriptions .............................................................................................................. 265
13
13.1
13.2
Inter-Integrated Circuit (I2C) Interface ............................................................................ 291
Block Diagram ........................................................................................................................ 291
Functional Description ............................................................................................................. 291
13.2.1 I2C Bus Functional Overview .................................................................................................... 292
13.2.2 Available Speed Modes ........................................................................................................... 294
13.2.3 Interrupts ................................................................................................................................ 295
13.2.4 Loopback Operation ................................................................................................................ 295
13.2.5 Command Sequence Flow Charts ............................................................................................ 295
13.3
13.4
13.5
13.6
Initialization and Configuration ................................................................................................. 302
I2C Register Map ..................................................................................................................... 303
Register Descriptions (I2C Master) ........................................................................................... 304
Register Descriptions (I2C Slave) ............................................................................................. 317
14
14.1
14.2
Analog Comparators ....................................................................................................... 326
Block Diagram ........................................................................................................................ 327
Functional Description ............................................................................................................. 327
14.2.1 Internal Reference Programming .............................................................................................. 329
14.3
14.4
14.5
Initialization and Configuration ................................................................................................. 330
Register Map .......................................................................................................................... 330
Register Descriptions .............................................................................................................. 331
October 01, 2007
5
Preliminary
Table of Contents
15
16
17
Pin Diagram ...................................................................................................................... 339
Signal Tables .................................................................................................................... 340
Operating Characteristics ............................................................................................... 347
18
18.1
Electrical Characteristics ................................................................................................ 348
DC Characteristics .................................................................................................................. 348
18.1.1 Maximum Ratings ................................................................................................................... 348
18.1.2 Recommended DC Operating Conditions .................................................................................. 348
18.1.3 On-Chip Low Drop-Out (LDO) Regulator Characteristics ............................................................ 349
18.1.4 Power Specifications ............................................................................................................... 349
18.1.5 Flash Memory Characteristics .................................................................................................. 350
18.2
AC Characteristics ................................................................................................................... 350
18.2.1 Load Conditions ...................................................................................................................... 350
18.2.2 Clocks .................................................................................................................................... 350
18.2.3 Analog Comparator ................................................................................................................. 351
18.2.4 I2C ......................................................................................................................................... 351
18.2.5 Synchronous Serial Interface (SSI) ........................................................................................... 352
18.2.6 JTAG and Boundary Scan ........................................................................................................ 353
18.2.7 General-Purpose I/O ............................................................................................................... 355
18.2.8 Reset ..................................................................................................................................... 355
19
Package Information ........................................................................................................ 358
A
A.1
A.2
Serial Flash Loader .......................................................................................................... 360
Serial Flash Loader ................................................................................................................. 360
Interfaces ............................................................................................................................... 360
A.2.1 UART ..................................................................................................................................... 360
A.2.2 SSI ......................................................................................................................................... 360
A.3
Packet Handling ...................................................................................................................... 361
A.3.1 Packet Format ........................................................................................................................ 361
A.3.2 Sending Packets ..................................................................................................................... 361
A.3.3 Receiving Packets ................................................................................................................... 361
A.4
Commands ............................................................................................................................. 362
A.4.1 COMMAND_PING (0X20) ........................................................................................................ 362
A.4.2 COMMAND_GET_STATUS (0x23) ........................................................................................... 362
A.4.3 COMMAND_DOWNLOAD (0x21) ............................................................................................. 362
A.4.4 COMMAND_SEND_DATA (0x24) ............................................................................................. 363
A.4.5 COMMAND_RUN (0x22) ......................................................................................................... 363
A.4.6 COMMAND_RESET (0x25) ..................................................................................................... 363
B
Register Quick Reference ............................................................................................... 365
C
Ordering and Contact Information ................................................................................. 377
Ordering Information ................................................................................................................ 377
Kits ......................................................................................................................................... 377
Company Information .............................................................................................................. 377
Support Information ................................................................................................................. 378
C.1
C.2
C.3
C.4
6
October 01, 2007
Preliminary
LM3S300 Microcontroller
List of Figures
Figure 1-1.
Figure 2-1.
Figure 2-2.
Figure 5-1.
Figure 5-2.
Figure 5-3.
Figure 5-4.
Figure 5-5.
Figure 6-1.
Figure 6-2.
Figure 7-1.
Figure 8-1.
Figure 8-2.
Figure 8-3.
Figure 9-1.
Figure 9-2.
Figure 9-3.
Figure 9-4.
Stellaris® 300 Series High-Level Block Diagram ................................................................ 22
CPU Block Diagram ......................................................................................................... 29
TPIU Block Diagram ........................................................................................................ 30
JTAG Module Block Diagram ............................................................................................ 39
Test Access Port State Machine ....................................................................................... 42
IDCODE Register Format ................................................................................................. 46
BYPASS Register Format ................................................................................................ 46
Boundary Scan Register Format ....................................................................................... 47
External Circuitry to Extend Reset .................................................................................... 49
Main Clock Tree .............................................................................................................. 52
Flash Block Diagram ...................................................................................................... 103
GPIO Port Block Diagram ............................................................................................... 120
GPIODATA Write Example ............................................................................................. 121
GPIODATA Read Example ............................................................................................. 121
GPTM Module Block Diagram ........................................................................................ 158
16-Bit Input Edge Count Mode Example .......................................................................... 162
16-Bit Input Edge Time Mode Example ........................................................................... 163
16-Bit PWM Mode Example ............................................................................................ 164
Figure 10-1. WDT Module Block Diagram .......................................................................................... 193
Figure 11-1. UART Module Block Diagram ......................................................................................... 217
Figure 11-2. UART Character Frame ................................................................................................. 218
Figure 12-1. SSI Module Block Diagram ............................................................................................. 254
Figure 12-2. TI Synchronous Serial Frame Format (Single Transfer) .................................................... 257
Figure 12-3. TI Synchronous Serial Frame Format (Continuous Transfer) ............................................ 257
Figure 12-4. Freescale SPI Format (Single Transfer) with SPO=0 and SPH=0 ...................................... 258
Figure 12-5. Freescale SPI Format (Continuous Transfer) with SPO=0 and SPH=0 .............................. 258
Figure 12-6. Freescale SPI Frame Format with SPO=0 and SPH=1 ..................................................... 259
Figure 12-7. Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0 ........................... 260
Figure 12-8. Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0 .................... 260
Figure 12-9. Freescale SPI Frame Format with SPO=1 and SPH=1 ..................................................... 261
Figure 12-10. MICROWIRE Frame Format (Single Frame) .................................................................... 262
Figure 12-11. MICROWIRE Frame Format (Continuous Transfer) ......................................................... 263
Figure 12-12. MICROWIRE Frame Format, SSIFss Input Setup and Hold Requirements ........................ 263
Figure 13-1. I2C Block Diagram ......................................................................................................... 291
Figure 13-2. I2C Bus Configuration .................................................................................................... 292
Figure 13-3. START and STOP Conditions ......................................................................................... 292
Figure 13-4. Complete Data Transfer with a 7-Bit Address ................................................................... 293
Figure 13-5. R/S Bit in First Byte ........................................................................................................ 293
Figure 13-6. Data Validity During Bit Transfer on the I2C Bus ............................................................... 293
Figure 13-7. Master Single SEND ...................................................................................................... 296
Figure 13-8. Master Single RECEIVE ................................................................................................. 297
Figure 13-9. Master Burst SEND ....................................................................................................... 298
Figure 13-10. Master Burst RECEIVE .................................................................................................. 299
Figure 13-11. Master Burst RECEIVE after Burst SEND ........................................................................ 300
Figure 13-12. Master Burst SEND after Burst RECEIVE ........................................................................ 301
October 01, 2007
7
Preliminary
Table of Contents
Figure 13-13. Slave Command Sequence ............................................................................................ 302
Figure 14-1. Analog Comparator Module Block Diagram ..................................................................... 327
Figure 14-2. Structure of Comparator Unit .......................................................................................... 328
Figure 14-3. Comparator Internal Reference Structure ........................................................................ 329
Figure 15-1. Pin Connection Diagram ................................................................................................ 339
Figure 18-1. Load Conditions ............................................................................................................ 350
Figure 18-2. I2C Timing ..................................................................................................................... 352
Figure 18-3. SSI Timing for TI Frame Format (FRF=01), Single Transfer Timing Measurement .............. 352
Figure 18-4. SSI Timing for MICROWIRE Frame Format (FRF=10), Single Transfer ............................. 353
Figure 18-5. SSI Timing for SPI Frame Format (FRF=00), with SPH=1 ................................................. 353
Figure 18-6. JTAG Test Clock Input Timing ......................................................................................... 354
Figure 18-7. JTAG Test Access Port (TAP) Timing .............................................................................. 355
Figure 18-8. JTAG TRST Timing ........................................................................................................ 355
Figure 18-9. External Reset Timing (RST) .......................................................................................... 356
Figure 18-10. Power-On Reset Timing ................................................................................................. 356
Figure 18-11. Brown-Out Reset Timing ................................................................................................ 357
Figure 18-12. Software Reset Timing ................................................................................................... 357
Figure 18-13. Watchdog Reset Timing ................................................................................................. 357
Figure 18-14. LDO Reset Timing ......................................................................................................... 357
Figure 19-1. 48-Pin LQFP Package ................................................................................................... 358
8
October 01, 2007
Preliminary
LM3S300 Microcontroller
List of Tables
Table 1.
Documentation Conventions ............................................................................................ 15
Memory Map ................................................................................................................... 34
Exception Types .............................................................................................................. 36
Interrupts ........................................................................................................................ 37
JTAG Port Pins Reset State ............................................................................................. 40
JTAG Instruction Register Commands ............................................................................... 44
System Control Register Map ........................................................................................... 55
PLL Mode Control ........................................................................................................... 69
Flash Protection Policy Combinations ............................................................................. 105
Flash Register Map ........................................................................................................ 108
GPIO Pad Configuration Examples ................................................................................. 122
GPIO Interrupt Configuration Example ............................................................................ 123
GPIO Register Map ....................................................................................................... 124
16-Bit Timer With Prescaler Configurations ..................................................................... 161
Timers Register Map ...................................................................................................... 167
Watchdog Timer Register Map ........................................................................................ 194
UART Register Map ....................................................................................................... 221
SSI Register Map .......................................................................................................... 264
Examples of I2C Master Timer Period versus Speed Mode ............................................... 294
Inter-Integrated Circuit (I2C) Interface Register Map ......................................................... 303
Write Field Decoding for I2CMCS[3:0] Field (Sheet 1 of 3) ................................................ 308
Comparator 0 Operating Modes ...................................................................................... 328
Comparator 1 Operating Modes ...................................................................................... 328
Comparator 2 Operating Modes ...................................................................................... 329
Internal Reference Voltage and ACREFCTL Field Values ................................................. 329
Analog Comparators Register Map ................................................................................. 331
Signals by Pin Number ................................................................................................... 340
Signals by Signal Name ................................................................................................. 342
Signals by Function, Except for GPIO ............................................................................. 344
GPIO Pins and Alternate Functions ................................................................................. 345
Temperature Characteristics ........................................................................................... 347
Thermal Characteristics ................................................................................................. 347
Maximum Ratings .......................................................................................................... 348
Recommended DC Operating Conditions ........................................................................ 348
LDO Regulator Characteristics ....................................................................................... 349
Detailed Power Specifications ........................................................................................ 349
Flash Memory Characteristics ........................................................................................ 350
Phase Locked Loop (PLL) Characteristics ....................................................................... 350
Clock Characteristics ..................................................................................................... 350
Analog Comparator Characteristics ................................................................................. 351
Analog Comparator Voltage Reference Characteristics .................................................... 351
Table 3-1.
Table 4-1.
Table 4-2.
Table 5-1.
Table 5-2.
Table 6-1.
Table 6-2.
Table 7-1.
Table 7-2.
Table 8-1.
Table 8-2.
Table 8-3.
Table 9-1.
Table 9-2.
Table 10-1.
Table 11-1.
Table 12-1.
Table 13-1.
Table 13-2.
Table 13-3.
Table 14-1.
Table 14-2.
Table 14-3.
Table 14-4.
Table 14-5.
Table 16-1.
Table 16-2.
Table 16-3.
Table 16-4.
Table 17-1.
Table 17-2.
Table 18-1.
Table 18-2.
Table 18-3.
Table 18-4.
Table 18-5.
Table 18-6.
Table 18-7.
Table 18-8.
Table 18-9.
Table 18-10. I2C Characteristics ......................................................................................................... 351
Table 18-11. SSI Characteristics ........................................................................................................ 352
Table 18-12. JTAG Characteristics ..................................................................................................... 353
Table 18-13. GPIO Characteristics ..................................................................................................... 355
Table 18-14. Reset Characteristics ..................................................................................................... 355
October 01, 2007
9
Preliminary
Table of Contents
Table C-1.
Part Ordering Information ............................................................................................... 377
10
October 01, 2007
Preliminary
LM3S300 Microcontroller
List of Registers
System Control .............................................................................................................................. 48
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Device Identification 0 (DID0), offset 0x000 ....................................................................... 57
Power-On and Brown-Out Reset Control (PBORCTL), offset 0x030 .................................... 59
LDO Power Control (LDOPCTL), offset 0x034 ................................................................... 60
Raw Interrupt Status (RIS), offset 0x050 ........................................................................... 61
Interrupt Mask Control (IMC), offset 0x054 ........................................................................ 62
Masked Interrupt Status and Clear (MISC), offset 0x058 .................................................... 64
Reset Cause (RESC), offset 0x05C .................................................................................. 65
Run-Mode Clock Configuration (RCC), offset 0x060 .......................................................... 66
XTAL to PLL Translation (PLLCFG), offset 0x064 .............................................................. 70
Register 10: Deep Sleep Clock Configuration (DSLPCLKCFG), offset 0x144 .......................................... 71
Register 11: Clock Verification Clear (CLKVCLR), offset 0x150 ............................................................. 72
Register 12: Allow Unregulated LDO to Reset the Part (LDOARST), offset 0x160 ................................... 73
Register 13: Device Identification 1 (DID1), offset 0x004 ....................................................................... 74
Register 14: Device Capabilities 0 (DC0), offset 0x008 ......................................................................... 76
Register 15: Device Capabilities 1 (DC1), offset 0x010 ......................................................................... 77
Register 16: Device Capabilities 2 (DC2), offset 0x014 ......................................................................... 79
Register 17: Device Capabilities 3 (DC3), offset 0x018 ......................................................................... 81
Register 18: Device Capabilities 4 (DC4), offset 0x01C ......................................................................... 83
Register 19: Run Mode Clock Gating Control Register 0 (RCGC0), offset 0x100 .................................... 84
Register 20: Sleep Mode Clock Gating Control Register 0 (SCGC0), offset 0x110 .................................. 85
Register 21: Deep Sleep Mode Clock Gating Control Register 0 (DCGC0), offset 0x120 ......................... 86
Register 22: Run Mode Clock Gating Control Register 1 (RCGC1), offset 0x104 .................................... 87
Register 23: Sleep Mode Clock Gating Control Register 1 (SCGC1), offset 0x114 .................................. 89
Register 24: Deep Sleep Mode Clock Gating Control Register 1 (DCGC1), offset 0x124 ......................... 91
Register 25: Run Mode Clock Gating Control Register 2 (RCGC2), offset 0x108 .................................... 93
Register 26: Sleep Mode Clock Gating Control Register 2 (SCGC2), offset 0x118 .................................. 95
Register 27: Deep Sleep Mode Clock Gating Control Register 2 (DCGC2), offset 0x128 ......................... 97
Register 28: Software Reset Control 0 (SRCR0), offset 0x040 ............................................................... 99
Register 29: Software Reset Control 1 (SRCR1), offset 0x044 ............................................................. 100
Register 30: Software Reset Control 2 (SRCR2), offset 0x048 ............................................................. 102
Internal Memory ........................................................................................................................... 103
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Flash Memory Address (FMA), offset 0x000 .................................................................... 109
Flash Memory Data (FMD), offset 0x004 ......................................................................... 110
Flash Memory Control (FMC), offset 0x008 ..................................................................... 111
Flash Controller Raw Interrupt Status (FCRIS), offset 0x00C ............................................ 113
Flash Controller Interrupt Mask (FCIM), offset 0x010 ........................................................ 114
Flash Controller Masked Interrupt Status and Clear (FCMISC), offset 0x014 ..................... 115
USec Reload (USECRL), offset 0x140 ............................................................................ 116
Flash Memory Protection Read Enable (FMPRE), offset 0x130 ......................................... 117
Flash Memory Protection Program Enable (FMPPE), offset 0x134 .................................... 118
General-Purpose Input/Outputs (GPIOs) ................................................................................... 119
Register 1:
Register 2:
Register 3:
GPIO Data (GPIODATA), offset 0x000 ............................................................................ 126
GPIO Direction (GPIODIR), offset 0x400 ......................................................................... 127
GPIO Interrupt Sense (GPIOIS), offset 0x404 .................................................................. 128
October 01, 2007
11
Preliminary
Table of Contents
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
GPIO Interrupt Both Edges (GPIOIBE), offset 0x408 ........................................................ 129
GPIO Interrupt Event (GPIOIEV), offset 0x40C ................................................................ 130
GPIO Interrupt Mask (GPIOIM), offset 0x410 ................................................................... 131
GPIO Raw Interrupt Status (GPIORIS), offset 0x414 ........................................................ 132
GPIO Masked Interrupt Status (GPIOMIS), offset 0x418 ................................................... 133
GPIO Interrupt Clear (GPIOICR), offset 0x41C ................................................................ 134
Register 10: GPIO Alternate Function Select (GPIOAFSEL), offset 0x420 ............................................ 135
Register 11: GPIO 2-mA Drive Select (GPIODR2R), offset 0x500 ........................................................ 137
Register 12: GPIO 4-mA Drive Select (GPIODR4R), offset 0x504 ........................................................ 138
Register 13: GPIO 8-mA Drive Select (GPIODR8R), offset 0x508 ........................................................ 139
Register 14: GPIO Open Drain Select (GPIOODR), offset 0x50C ......................................................... 140
Register 15: GPIO Pull-Up Select (GPIOPUR), offset 0x510 ................................................................ 141
Register 16: GPIO Pull-Down Select (GPIOPDR), offset 0x514 ........................................................... 142
Register 17: GPIO Slew Rate Control Select (GPIOSLR), offset 0x518 ................................................ 143
Register 18: GPIO Digital Enable (GPIODEN), offset 0x51C ................................................................ 144
Register 19: GPIO Peripheral Identification 4 (GPIOPeriphID4), offset 0xFD0 ....................................... 145
Register 20: GPIO Peripheral Identification 5 (GPIOPeriphID5), offset 0xFD4 ....................................... 146
Register 21: GPIO Peripheral Identification 6 (GPIOPeriphID6), offset 0xFD8 ....................................... 147
Register 22: GPIO Peripheral Identification 7 (GPIOPeriphID7), offset 0xFDC ...................................... 148
Register 23: GPIO Peripheral Identification 0 (GPIOPeriphID0), offset 0xFE0 ....................................... 149
Register 24: GPIO Peripheral Identification 1 (GPIOPeriphID1), offset 0xFE4 ....................................... 150
Register 25: GPIO Peripheral Identification 2 (GPIOPeriphID2), offset 0xFE8 ....................................... 151
Register 26: GPIO Peripheral Identification 3 (GPIOPeriphID3), offset 0xFEC ...................................... 152
Register 27: GPIO PrimeCell Identification 0 (GPIOPCellID0), offset 0xFF0 .......................................... 153
Register 28: GPIO PrimeCell Identification 1 (GPIOPCellID1), offset 0xFF4 .......................................... 154
Register 29: GPIO PrimeCell Identification 2 (GPIOPCellID2), offset 0xFF8 .......................................... 155
Register 30: GPIO PrimeCell Identification 3 (GPIOPCellID3), offset 0xFFC ......................................... 156
General-Purpose Timers ............................................................................................................. 157
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
GPTM Configuration (GPTMCFG), offset 0x000 .............................................................. 169
GPTM TimerA Mode (GPTMTAMR), offset 0x004 ............................................................ 170
GPTM TimerB Mode (GPTMTBMR), offset 0x008 ............................................................ 172
GPTM Control (GPTMCTL), offset 0x00C ........................................................................ 174
GPTM Interrupt Mask (GPTMIMR), offset 0x018 .............................................................. 177
GPTM Raw Interrupt Status (GPTMRIS), offset 0x01C ..................................................... 179
GPTM Masked Interrupt Status (GPTMMIS), offset 0x020 ................................................ 180
GPTM Interrupt Clear (GPTMICR), offset 0x024 .............................................................. 181
GPTM TimerA Interval Load (GPTMTAILR), offset 0x028 ................................................. 183
Register 10: GPTM TimerB Interval Load (GPTMTBILR), offset 0x02C ................................................ 184
Register 11: GPTM TimerA Match (GPTMTAMATCHR), offset 0x030 ................................................... 185
Register 12: GPTM TimerB Match (GPTMTBMATCHR), offset 0x034 .................................................. 186
Register 13: GPTM TimerA Prescale (GPTMTAPR), offset 0x038 ........................................................ 187
Register 14: GPTM TimerB Prescale (GPTMTBPR), offset 0x03C ....................................................... 188
Register 15: GPTM TimerA Prescale Match (GPTMTAPMR), offset 0x040 ........................................... 189
Register 16: GPTM TimerB Prescale Match (GPTMTBPMR), offset 0x044 ........................................... 190
Register 17: GPTM TimerA (GPTMTAR), offset 0x048 ........................................................................ 191
Register 18: GPTM TimerB (GPTMTBR), offset 0x04C ....................................................................... 192
Watchdog Timer ........................................................................................................................... 193
Register 1:
Watchdog Load (WDTLOAD), offset 0x000 ...................................................................... 196
12
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Watchdog Value (WDTVALUE), offset 0x004 ................................................................... 197
Watchdog Control (WDTCTL), offset 0x008 ..................................................................... 198
Watchdog Interrupt Clear (WDTICR), offset 0x00C .......................................................... 199
Watchdog Raw Interrupt Status (WDTRIS), offset 0x010 .................................................. 200
Watchdog Masked Interrupt Status (WDTMIS), offset 0x014 ............................................. 201
Watchdog Test (WDTTEST), offset 0x418 ....................................................................... 202
Watchdog Lock (WDTLOCK), offset 0xC00 ..................................................................... 203
Watchdog Peripheral Identification 4 (WDTPeriphID4), offset 0xFD0 ................................. 204
Register 10: Watchdog Peripheral Identification 5 (WDTPeriphID5), offset 0xFD4 ................................. 205
Register 11: Watchdog Peripheral Identification 6 (WDTPeriphID6), offset 0xFD8 ................................. 206
Register 12: Watchdog Peripheral Identification 7 (WDTPeriphID7), offset 0xFDC ................................ 207
Register 13: Watchdog Peripheral Identification 0 (WDTPeriphID0), offset 0xFE0 ................................. 208
Register 14: Watchdog Peripheral Identification 1 (WDTPeriphID1), offset 0xFE4 ................................. 209
Register 15: Watchdog Peripheral Identification 2 (WDTPeriphID2), offset 0xFE8 ................................. 210
Register 16: Watchdog Peripheral Identification 3 (WDTPeriphID3), offset 0xFEC ................................. 211
Register 17: Watchdog PrimeCell Identification 0 (WDTPCellID0), offset 0xFF0 .................................... 212
Register 18: Watchdog PrimeCell Identification 1 (WDTPCellID1), offset 0xFF4 .................................... 213
Register 19: Watchdog PrimeCell Identification 2 (WDTPCellID2), offset 0xFF8 .................................... 214
Register 20: Watchdog PrimeCell Identification 3 (WDTPCellID3 ), offset 0xFFC .................................. 215
Universal Asynchronous Receivers/Transmitters (UARTs) ..................................................... 216
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
UART Data (UARTDR), offset 0x000 ............................................................................... 223
UART Receive Status/Error Clear (UARTRSR/UARTECR), offset 0x004 ........................... 225
UART Flag (UARTFR), offset 0x018 ................................................................................ 227
UART Integer Baud-Rate Divisor (UARTIBRD), offset 0x024 ............................................ 229
UART Fractional Baud-Rate Divisor (UARTFBRD), offset 0x028 ....................................... 230
UART Line Control (UARTLCRH), offset 0x02C ............................................................... 231
UART Control (UARTCTL), offset 0x030 ......................................................................... 233
UART Interrupt FIFO Level Select (UARTIFLS), offset 0x034 ........................................... 234
UART Interrupt Mask (UARTIM), offset 0x038 ................................................................. 236
Register 10: UART Raw Interrupt Status (UARTRIS), offset 0x03C ...................................................... 238
Register 11: UART Masked Interrupt Status (UARTMIS), offset 0x040 ................................................. 239
Register 12: UART Interrupt Clear (UARTICR), offset 0x044 ............................................................... 240
Register 13: UART Peripheral Identification 4 (UARTPeriphID4), offset 0xFD0 ..................................... 242
Register 14: UART Peripheral Identification 5 (UARTPeriphID5), offset 0xFD4 ..................................... 243
Register 15: UART Peripheral Identification 6 (UARTPeriphID6), offset 0xFD8 ..................................... 244
Register 16: UART Peripheral Identification 7 (UARTPeriphID7), offset 0xFDC ..................................... 245
Register 17: UART Peripheral Identification 0 (UARTPeriphID0), offset 0xFE0 ...................................... 246
Register 18: UART Peripheral Identification 1 (UARTPeriphID1), offset 0xFE4 ...................................... 247
Register 19: UART Peripheral Identification 2 (UARTPeriphID2), offset 0xFE8 ...................................... 248
Register 20: UART Peripheral Identification 3 (UARTPeriphID3), offset 0xFEC ..................................... 249
Register 21: UART PrimeCell Identification 0 (UARTPCellID0), offset 0xFF0 ........................................ 250
Register 22: UART PrimeCell Identification 1 (UARTPCellID1), offset 0xFF4 ........................................ 251
Register 23: UART PrimeCell Identification 2 (UARTPCellID2), offset 0xFF8 ........................................ 252
Register 24: UART PrimeCell Identification 3 (UARTPCellID3), offset 0xFFC ........................................ 253
Synchronous Serial Interface (SSI) ............................................................................................ 254
Register 1:
Register 2:
Register 3:
SSI Control 0 (SSICR0), offset 0x000 .............................................................................. 266
SSI Control 1 (SSICR1), offset 0x004 .............................................................................. 268
SSI Data (SSIDR), offset 0x008 ...................................................................................... 270
October 01, 2007
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Preliminary
Table of Contents
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
SSI Status (SSISR), offset 0x00C ................................................................................... 271
SSI Clock Prescale (SSICPSR), offset 0x010 .................................................................. 273
SSI Interrupt Mask (SSIIM), offset 0x014 ......................................................................... 274
SSI Raw Interrupt Status (SSIRIS), offset 0x018 .............................................................. 276
SSI Masked Interrupt Status (SSIMIS), offset 0x01C ........................................................ 277
SSI Interrupt Clear (SSIICR), offset 0x020 ....................................................................... 278
Register 10: SSI Peripheral Identification 4 (SSIPeriphID4), offset 0xFD0 ............................................. 279
Register 11: SSI Peripheral Identification 5 (SSIPeriphID5), offset 0xFD4 ............................................. 280
Register 12: SSI Peripheral Identification 6 (SSIPeriphID6), offset 0xFD8 ............................................. 281
Register 13: SSI Peripheral Identification 7 (SSIPeriphID7), offset 0xFDC ............................................ 282
Register 14: SSI Peripheral Identification 0 (SSIPeriphID0), offset 0xFE0 ............................................. 283
Register 15: SSI Peripheral Identification 1 (SSIPeriphID1), offset 0xFE4 ............................................. 284
Register 16: SSI Peripheral Identification 2 (SSIPeriphID2), offset 0xFE8 ............................................. 285
Register 17: SSI Peripheral Identification 3 (SSIPeriphID3), offset 0xFEC ............................................ 286
Register 18: SSI PrimeCell Identification 0 (SSIPCellID0), offset 0xFF0 ............................................... 287
Register 19: SSI PrimeCell Identification 1 (SSIPCellID1), offset 0xFF4 ............................................... 288
Register 20: SSI PrimeCell Identification 2 (SSIPCellID2), offset 0xFF8 ............................................... 289
Register 21: SSI PrimeCell Identification 3 (SSIPCellID3), offset 0xFFC ............................................... 290
Inter-Integrated Circuit (I2C) Interface ........................................................................................ 291
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 ........................................................... 305
I2C Master Control/Status (I2CMCS), offset 0x004 ........................................................... 306
I2C Master Data (I2CMDR), offset 0x008 ......................................................................... 310
I2C Master Timer Period (I2CMTPR), offset 0x00C ........................................................... 311
I2C Master Interrupt Mask (I2CMIMR), offset 0x010 ......................................................... 312
I2C Master Raw Interrupt Status (I2CMRIS), offset 0x014 ................................................. 313
I2C Master Masked Interrupt Status (I2CMMIS), offset 0x018 ........................................... 314
I2C Master Interrupt Clear (I2CMICR), offset 0x01C ......................................................... 315
I2C Master Configuration (I2CMCR), offset 0x020 ............................................................ 316
Register 10: I2C Slave Own Address (I2CSOAR), offset 0x000 ............................................................ 318
Register 11: I2C Slave Control/Status (I2CSCSR), offset 0x004 ........................................................... 319
Register 12: I2C Slave Data (I2CSDR), offset 0x008 ........................................................................... 321
Register 13: I2C Slave Interrupt Mask (I2CSIMR), offset 0x00C ........................................................... 322
Register 14: I2C Slave Raw Interrupt Status (I2CSRIS), offset 0x010 ................................................... 323
Register 15: I2C Slave Masked Interrupt Status (I2CSMIS), offset 0x014 .............................................. 324
Register 16: I2C Slave Interrupt Clear (I2CSICR), offset 0x018 ............................................................ 325
Analog Comparators ................................................................................................................... 326
Register 1:
Register 2:
Register 3:
Register 4:
Register 5:
Register 6:
Register 7:
Register 8:
Register 9:
Analog Comparator Masked Interrupt Status (ACMIS), offset 0x00 .................................... 332
Analog Comparator Raw Interrupt Status (ACRIS), offset 0x04 ......................................... 333
Analog Comparator Interrupt Enable (ACINTEN), offset 0x08 ........................................... 334
Analog Comparator Reference Voltage Control (ACREFCTL), offset 0x10 ......................... 335
Analog Comparator Status 0 (ACSTAT0), offset 0x20 ....................................................... 336
Analog Comparator Status 1 (ACSTAT1), offset 0x40 ....................................................... 336
Analog Comparator Status 2 (ACSTAT2), offset 0x60 ....................................................... 336
Analog Comparator Control 0 (ACCTL0), offset 0x24 ....................................................... 337
Analog Comparator Control 1 (ACCTL1), offset 0x44 ....................................................... 337
Register 10: Analog Comparator Control 2 (ACCTL2), offset 0x64 ...................................................... 337
14
October 01, 2007
Preliminary
LM3S300 Microcontroller
About This Document
This data sheet provides reference information for the LM3S300 microcontroller, describing the
functional blocks of the system-on-chip (SoC) device designed around the ARM® Cortex™-M3
core.
Audience
This manual is intended for system software developers, hardware designers, and application
developers.
About This Manual
This document is organized into sections that correspond to each major feature.
Related Documents
The following documents are referenced by the data sheet, and available on the documentation CD
or from the Luminary Micro web site at www.luminarymicro.com:
■ ARM® Cortex™-M3 Technical Reference Manual
■ ARM® CoreSight Technical Reference Manual
■ ARM® v7-M Architecture Application Level Reference Manual
The following related documents are also referenced:
■ IEEE Standard 1149.1-Test Access Port and Boundary-Scan Architecture
This documentation list was current as of publication date. Please check the Luminary Micro web
site for additional documentation, including application notes and white papers.
Documentation Conventions
This document uses the conventions shown in Table 1 on page 15.
Table 1. 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
offset 0xnnn
Two or more consecutive and related bits.
A hexadecimal increment to a register's address, relative to that module's base address as specified
in “Memory Map” on page 34.
Register N
Registers are numbered consecutively throughout the document to aid in referencing them. The
register number has no meaning to software.
October 01, 2007
15
Preliminary
About This Document
Notation
Meaning
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.
Software can read this field. Always write the chip reset value.
Software can read or write this field.
RO
R/W
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.
W1C
WO
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.
Only a write by software is valid; a read of the register returns no meaningful data.
This value in the register bit diagram shows the bit/field value after any reset, unless noted.
Register Bit/Field
Reset Value
0
Bit cleared to 0 on chip reset.
Bit set to 1 on chip reset.
Nondeterministic.
1
-
Pin/Signal Notation
[ ]
Pin alternate function; a pin defaults to the signal without the brackets.
Refers to the physical connection on the package.
pin
signal
Refers to the electrical signal encoding of a pin.
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.
16
October 01, 2007
Preliminary
LM3S300 Microcontroller
1
Architectural Overview
The Luminary Micro Stellaris® family of microcontrollers—the first ARM® Cortex™-M3 based
controllers—brings high-performance 32-bit computing to cost-sensitive embedded microcontroller
applications. These pioneering parts deliver customers 32-bit performance at a cost equivalent to
legacy 8- and 16-bit devices, all in a package with a small footprint.
The LM3S300 microcontroller is targeted for industrial applications, including test and measurement
equipment, factory automation, HVAC and building control, motion control, medical instrumentation,
fire and security, and power/energy.
In addition, the LM3S300 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 LM3S300 microcontroller is code-compatible
to all members of the extensive Stellaris® family; providing flexibility to fit our customers' precise
needs.
Luminary Micro offers a complete solution to get to market quickly, with evaluation and development
boards, white papers and application notes, an easy-to-use peripheral driver library, and a strong
support, sales, and distributor network.
1.1
Product Features
The LM3S300 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
25-MHz operation
Hardware-division and single-cycle-multiplication
Integrated Nested Vectored Interrupt Controller (NVIC) providing deterministic interrupt
handling
–
–
21 interrupts with eight priority levels
Memory protection unit (MPU), providing a privileged mode for protected operating system
functionality
–
–
Unaligned data access, enabling data to be efficiently packed into memory
Atomic bit manipulation (bit-banding), delivering maximum memory utilization and streamlined
peripheral control
■ Internal Memory
October 01, 2007
17
Preliminary
Architectural Overview
–
16 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
–
4 KB single-cycle SRAM
■ General-Purpose Timers
–
Three General-Purpose Timer Modules (GPTM), each of which provides two 16-bit
timer/counters. Each GPTM can be configured to operate independently as timers or event
counters as a single 32-bit timer, as one 32-bit Real-Time Clock (RTC) to event capture, or
for Pulse Width Modulation (PWM)
–
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 in periodic and one-shot mode when the controller asserts the CPU
Halt flag during debug
–
16-bit Timer modes
•
•
•
•
General-purpose timer function with an 8-bit prescaler
Programmable one-shot timer
Programmable periodic timer
User-enabled stalling when the controller asserts CPU Halt flag during debug
–
–
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
18
October 01, 2007
Preliminary
LM3S300 Microcontroller
–
–
Reset generation logic with an enable/disable
User-enabled stalling when the controller asserts the CPU Halt flag during debug
■ Synchronous Serial Interface (SSI)
–
–
–
–
Master or slave operation
Programmable clock bit rate and prescale
Separate transmit and receive FIFOs, 16 bits wide, 8 locations deep
Programmable interface operation for Freescale SPI, MICROWIRE, or Texas Instruments
synchronous serial interfaces
–
–
Programmable data frame size from 4 to 16 bits
Internal loopback test mode for diagnostic/debug testing
■ UART
–
–
Two fully programmable 16C550-type UARTs
Separate 16x8 transmit (TX) and 16x12 receive (RX) FIFOs to reduce CPU interrupt service
loading
–
–
Programmable baud-rate generator with fractional divider
Programmable FIFO length, including 1-byte deep operation providing conventional
double-buffered interface
–
–
–
–
FIFO trigger levels of 1/8, 1/4, 1/2, 3/4, and 7/8
Standard asynchronous communication bits for start, stop, and parity
False-start-bit detection
Line-break generation and detection
■ Analog Comparators
–
Three independent integrated analog comparators
–
Configurable for output to: drive an output pin or generate an interrupt
–
■ I2C
–
Compare external pin input to external pin input or to internal programmable voltage reference
Master and slave receive and transmit operation with transmission speed up to 100 Kbps in
Standard mode and 400 Kbps in Fast mode
–
–
Interrupt generation
Master with arbitration and clock synchronization, multimaster support, and 7-bit addressing
mode
October 01, 2007
19
Preliminary
Architectural Overview
■ GPIOs
–
–
–
–
–
8-36 GPIOs, depending on configuration
5-V-tolerant input/outputs
Programmable interrupt generation as either edge-triggered or level-sensitive
Bit masking in both read and write operations through address lines
Programmable control for GPIO pad configuration:
•
•
•
•
•
Weak pull-up or pull-down resistors
2-mA, 4-mA, and 8-mA pad drive
Slew rate control for the 8-mA drive
Open drain enables
Digital input enables
■ Power
–
On-chip Low Drop-Out (LDO) voltage regulator, with programmable output user-adjustable
from 2.25 V to 2.75 V
–
–
–
–
Low-power options on controller: Sleep and Deep-sleep modes
Low-power options for peripherals: software controls shutdown of individual peripherals
User-enabled LDO unregulated voltage detection and automatic reset
3.3-V supply brown-out detection and reporting via interrupt or reset
■ Flexible Reset Sources
–
–
–
–
–
–
Power-on reset (POR)
Reset pin assertion
Brown-out (BOR) detector alerts to system power drops
Software reset
Watchdog timer reset
Internal low drop-out (LDO) regulator output goes unregulated
■ Additional Features
–
–
–
Six reset sources
Programmable clock source control
Clock gating to individual peripherals for power savings
20
October 01, 2007
Preliminary
LM3S300 Microcontroller
–
–
–
IEEE 1149.1-1990 compliant Test Access Port (TAP) controller
Debug access via JTAG and Serial Wire interfaces
Full JTAG boundary scan
■ Industrial-range 48-pin RoHS-compliant LQFP package
1.2
Target Applications
■ Factory automation and control
■ Industrial control power devices
■ Building and home automation
■ Stepper motors
■ Brushless DC motors
■ AC induction motors
1.3
High-Level Block Diagram
Figure 1-1 on page 22 represents the full set of features in the Stellaris® 300 series of devices; not
all features may be available on the LM3S300 microcontroller.
October 01, 2007
21
Preliminary
Architectural Overview
Figure 1-1. Stellaris® 300 Series High-Level Block Diagram
1.4
Functional Overview
The following sections provide an overview of the features of the LM3S300 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 377.
22
October 01, 2007
Preliminary
LM3S300 Microcontroller
1.4.1
ARM Cortex™-M3
1.4.1.1 Processor Core (see page 28)
All members of the Stellaris® product family, including the LM3S300 microcontroller, are designed
around an ARM Cortex™-M3 processor core. The ARM Cortex-M3 processor provides the core for
a high-performance, low-cost platform that meets the needs of minimal memory implementation,
reduced pin count, and low-power consumption, while delivering outstanding computational
performance and exceptional system response to interrupts.
“ARM Cortex-M3 Processor Core” on page 28 provides an overview of the ARM core; the core is
detailed in the ARM® Cortex™-M3 Technical Reference Manual.
1.4.1.2 System Timer (SysTick)
Cortex-M3 includes an integrated system timer, SysTick. SysTick provides a simple, 24-bit
clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism. The counter
can be used in several different ways, for example:
■ An RTOS tick timer which fires at a programmable rate (for example, 100 Hz) and invokes a
SysTick routine.
■ A high-speed alarm timer using the system clock.
■ A variable rate alarm or signal timer—the duration is range-dependent on the reference clock
used and the dynamic range of the counter.
■ A simple counter. Software can use this to measure time to completion and time used.
■ An internal clock source control based on missing/meeting durations. The COUNTFLAG bit-field
in the control and status register can be used to determine if an action completed within a set
duration, as part of a dynamic clock management control loop.
1.4.1.3 Nested Vectored Interrupt Controller (NVIC)
The LM3S300 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 21 interrupts.
“Interrupts” on page 36 provides an overview of the NVIC controller and the interrupt map. Exceptions
and interrupts are detailed in the ARM® Cortex™-M3 Technical Reference Manual.
1.4.2
Motor Control Peripherals
To enhance motor control, the LM3S300 controller features Pulse Width Modulation (PWM) outputs.
1.4.2.1 PWM (see page 163)
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.
October 01, 2007
23
Preliminary
Architectural Overview
On the LM3S300, 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 163)
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
For support of analog signals, the LM3S300 microcontroller offers three analog comparators.
1.4.3.1 Analog Comparators (see page 326)
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S300 microcontroller provides three independent integrated analog comparators that can
be configured to drive an output or generate an interrupt .
A comparator can compare a test voltage against any one of these voltages:
■ An individual external reference voltage
■ A shared single external reference voltage
■ A shared internal reference voltage
The comparator can provide its output to a device pin, acting as a replacement for an analog
comparator on the board, or it can be used to signal the application via interrupts to cause it to start
capturing a sample sequence.
1.4.4
Serial Communications Peripherals
The LM3S300 controller supports both asynchronous and synchronous serial communications with:
■ Two fully programmable 16C550-type UARTs
■ One SSI module
■ One I2C module
1.4.4.1 UART (see page 216)
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 LM3S300 controller includes two fully programmable 16C550-type UARTs that support data
transfer speeds up to 460.8 Kbps. (Although similar in functionality to a 16C550 UART, it is not
register-compatible.)
Separate 16x8 transmit (TX) and 16x12 receive (RX) FIFOs reduce CPU interrupt service loading.
The UART can generate individually masked interrupts from the RX, TX, modem status, and error
conditions. The module provides a single combined interrupt when any of the interrupts are asserted
and are unmasked.
24
October 01, 2007
Preliminary
LM3S300 Microcontroller
1.4.4.2 SSI (see page 254)
Synchronous Serial Interface (SSI) is a four-wire bi-directional communications interface.
The LM3S300 controller includes one SSI module that provides the functionality for synchronous
serial communications with peripheral devices, and can be configured to use the Freescale SPI,
MICROWIRE, or TI synchronous serial interface frame formats. The size of the data frame is also
configurable, and can be set between 4 and 16 bits, inclusive.
The SSI module performs serial-to-parallel conversion on data received from a peripheral device,
and parallel-to-serial conversion on data transmitted to a peripheral device. The TX and RX paths
are buffered with internal FIFOs, allowing up to eight 16-bit values to be stored independently.
The SSI module can be configured as either a master or slave device. As a slave device, the SSI
module can also be configured to disable its output, which allows a master device to be coupled
with multiple slave devices.
The SSI module also includes a programmable bit rate clock divider and prescaler to generate the
output serial clock derived from the SSI module's input clock. Bit rates are generated based on the
input clock and the maximum bit rate is determined by the connected peripheral.
1.4.4.3 I2C (see page 291)
The Inter-Integrated Circuit (I2C) bus provides bi-directional data transfer through a two-wire design
(a serial data line SDA and a serial clock line SCL).
The I2C bus interfaces to external I2C devices such as serial memory (RAMs and ROMs), networking
devices, LCDs, tone generators, and so on. The I2C bus may also be used for system testing and
diagnostic purposes in product development and manufacture.
The LM3S300 controller includes one I2C module that provides the ability to communicate to other
IC devices over an I2C bus. The I2C bus supports devices that can both transmit and receive (write
and read) data.
Devices on the I2C bus can be designated as either a master or a slave. The I2C module supports
both sending and receiving data as either a master or a slave, and also supports the simultaneous
operation as both a master and a slave. The four I2C modes are: Master Transmit, Master Receive,
Slave Transmit, and Slave Receive.
A Stellaris® I2C module can operate at two speeds: Standard (100 Kbps) and Fast (400 Kbps).
Both the I2C master and slave can generate interrupts. The I2C master generates interrupts when
a transmit or receive operation completes (or aborts due to an error). The I2C slave generates
interrupts when data has been sent or requested by a master.
1.4.5
System Peripherals
1.4.5.1 Programmable GPIOs (see page 119)
General-purpose input/output (GPIO) pins offer flexibility for a variety of connections.
The Stellaris® GPIO module is composed of five 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 8-36 programmable input/output pins.
The number of GPIOs available depends on the peripherals being used (see “Signal Tables” on page
340 for the signals available to each GPIO pin).
October 01, 2007
25
Preliminary
Architectural Overview
The GPIO module features programmable interrupt generation as either edge-triggered or
level-sensitive on all pins, programmable control for GPIO pad configuration, and bit masking in
both read and write operations through address lines.
1.4.5.2 Three Programmable Timers (see page 157)
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 timer/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).
When configured in 32-bit mode, a timer can run as a one-shot timer, periodic timer, or Real-Time
Clock (RTC). 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 193)
A watchdog timer can generate nonmaskable interrupts (NMIs) or a reset when a time-out value is
reached. The watchdog timer is used to regain control when a system has failed due to a software
error or to the failure of an external device to respond in the expected way.
The Stellaris® Watchdog Timer module consists of a 32-bit down counter, a programmable load
register, interrupt generation logic, and a locking register.
The Watchdog Timer can be configured to generate an interrupt to the controller on its first time-out,
and to generate a reset signal on its second time-out. Once the Watchdog Timer has been configured,
the lock register can be written to prevent the timer configuration from being inadvertently altered.
1.4.6
Memory Peripherals
The LM3S300 controller offers both single-cycle SRAM and single-cycle Flash memory.
1.4.6.1 SRAM (see page 103)
The LM3S300 static random access memory (SRAM) controller supports 4 KB SRAM. The internal
SRAM of the Stellaris® devices is located at offset 0x0000.0000 of the device memory map. To
reduce the number of time-consuming read-modify-write (RMW) operations, ARM has introduced
bit-banding technology in the new Cortex-M3 processor. With a bit-band-enabled processor, certain
regions in the memory map (SRAM and peripheral space) can use address aliases to access
individual bits in a single, atomic operation.
1.4.6.2 Flash (see page 104)
The LM3S300 Flash controller supports 16 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.
26
October 01, 2007
Preliminary
LM3S300 Microcontroller
1.4.7
Additional Features
1.4.7.1 Memory Map (see page 34)
A memory map lists the location of instructions and data in memory. The memory map for the
LM3S300 controller can be found in “Memory Map” on page 34. Register addresses are given as
a hexadecimal increment, relative to the module's base address as shown in the memory map.
The ARM® Cortex™-M3 Technical Reference Manual provides further information on the memory
map.
1.4.7.2 JTAG TAP Controller (see page 38)
The Joint Test Action Group (JTAG) port provides a standardized serial interface for controlling the
Test Access Port (TAP) and associated test logic. The TAP, JTAG instruction register, and JTAG
data registers can be used to test the interconnects of assembled printed circuit boards, obtain
manufacturing information on the components, and observe and/or control the inputs and outputs
of the controller during normal operation. The JTAG port provides a high degree of testability and
chip-level access at a low cost.
The JTAG port is comprised of the standard five pins: TRST, TCK, TMS, TDI, and TDO. Data is
transmitted serially into the controller on TDI and out of the controller on TDO. The interpretation of
this data is dependent on the current state of the TAP controller. For detailed information on the
operation of the JTAG port and TAP controller, please refer to the IEEE Standard 1149.1-Test
Access Port and Boundary-Scan Architecture.
The Luminary Micro JTAG controller works with the ARM JTAG controller built into the Cortex-M3
core. This is implemented by multiplexing the TDO outputs from both JTAG controllers. ARM JTAG
instructions select the ARM TDO output while Luminary Micro JTAG instructions select the Luminary
Micro TDO outputs. The multiplexer is controlled by the Luminary Micro JTAG controller, which has
comprehensive programming for the ARM, Luminary Micro, and unimplemented JTAG instructions.
1.4.7.3 System Control and Clocks (see page 48)
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.
1.4.8
Hardware Details
Details on the pins and package can be found in the following sections:
■ “Pin Diagram” on page 339
■ “Signal Tables” on page 340
■ “Operating Characteristics” on page 347
■ “Electrical Characteristics” on page 348
■ “Package Information” on page 358
October 01, 2007
27
Preliminary
ARM Cortex-M3 Processor Core
2
ARM Cortex-M3 Processor Core
The ARM Cortex-M3 processor provides the core for a high-performance, low-cost platform that
meets the needs of minimal memory implementation, reduced pin count, and low power consumption,
while delivering outstanding computational performance and exceptional system response to
interrupts. Features include:
■ Compact core.
■ Thumb-2 instruction set, delivering the high-performance expected of an ARM core in the memory
size usually associated with 8- and 16-bit devices; typically in the range of a few kilobytes of
memory for microcontroller class applications.
■ Rapid application execution through Harvard architecture characterized by separate buses for
instruction and data.
■ Exceptional interrupt handling, by implementing the register manipulations required for handling
an interrupt in hardware.
■ Memory protection unit (MPU) to provide a privileged mode of operation for complex applications.
■ Migration from the ARM7™ processor family for better performance and power efficiency.
■ Full-featured debug solution with a:
–
–
–
Serial Wire JTAG Debug Port (SWJ-DP)
Flash Patch and Breakpoint (FPB) unit for implementing breakpoints
Data Watchpoint and Trigger (DWT) unit for implementing watchpoints, trigger resources,
and system profiling
–
–
Instrumentation Trace Macrocell (ITM) for support of printf style debugging
Trace Port Interface Unit (TPIU) for bridging to a Trace Port Analyzer
The Stellaris® family of microcontrollers builds on this core to bring high-performance 32-bit computing
to cost-sensitive embedded microcontroller applications, such as factory automation and control,
industrial control power devices, building and home automation, and stepper motors.
For more information on the ARM Cortex-M3 processor core, see the ARM® Cortex™-M3 Technical
Reference Manual. For information on SWJ-DP, see the ARM® CoreSight Technical Reference
Manual.
28
October 01, 2007
Preliminary
LM3S300 Microcontroller
2.1
Block Diagram
Figure 2-1. CPU Block Diagram
Nested
Vectored
Interrupt
Controller
Interrupts
Sleep
Serial
ARM
Cortex-M3
CM3 Core
Wire
Output
Trace
Port
Debug
Instructions Data
Trace
Port
Interface
Unit
Memory
Protection
Unit
(SWO)
Private
Peripheral
Bus
Instrumentation
Trace Macrocell
Data
Watchpoint
and Trace
Flash
Patch and
Breakpoint
(external)
ROM
Table
Private Peripheral
Bus
Adv. Peripheral
Bus
(internal)
I-code bus
D-code bus
System bus
Bus
Matrix
Adv. High-
Perf. Bus
Access Port
Serial Wire JTAG
Debug Port
2.2
Functional Description
Important: The ARM® Cortex™-M3 Technical Reference Manual describes all the features of an
ARM Cortex-M3 in detail. However, these features differ based on the implementation.
This section describes the Stellaris® implementation.
Luminary Micro has implemented the ARM Cortex-M3 core as shown in Figure 2-1 on page 29. As
noted in the ARM® Cortex™-M3 Technical Reference Manual, several Cortex-M3 components are
flexible in their implementation: SW/JTAG-DP, ETM, TPIU, the ROM table, the MPU, and the Nested
Vectored Interrupt Controller (NVIC). Each of these is addressed in the sections that follow.
2.2.1
Serial Wire and JTAG Debug
Luminary Micro has replaced the ARM SW-DP and JTAG-DP with the ARM CoreSight™-compliant
Serial Wire JTAG Debug Port (SWJ-DP) interface. This means Chapter 12, “Debug Port,” of the
ARM® Cortex™-M3 Technical Reference Manual does not apply to Stellaris® devices.
The SWJ-DP interface combines the SWD and JTAG debug ports into one module. See the
CoreSight™ Design Kit Technical Reference Manual for details on SWJ-DP.
October 01, 2007
29
Preliminary
ARM Cortex-M3 Processor Core
2.2.2
2.2.3
Embedded Trace Macrocell (ETM)
ETM was not implemented in the Stellaris® devices. This means Chapters 15 and 16 of the ARM®
Cortex™-M3 Technical Reference Manual can be ignored.
Trace Port Interface Unit (TPIU)
The TPIU acts as a bridge between the Cortex-M3 trace data from the ITM, and an off-chip Trace
Port Analyzer. The Stellaris® devices have implemented TPIU as shown in Figure 2-2 on page 30.
This is similar to the non-ETM version described in the ARM® Cortex™-M3 Technical Reference
Manual, however, SWJ-DP only provides SWV output for the TPIU.
Figure 2-2. TPIU Block Diagram
Debug
Serial Wire
Trace Port
(SWO)
ATB
Interface
Trace Out
(serializer)
ATB
Slave
Port
Asynchronous FIFO
APB
Slave
Port
APB
Interface
2.2.4
2.2.5
ROM Table
The default ROM table was implemented as described in the ARM® Cortex™-M3 Technical
Reference Manual.
Memory Protection Unit (MPU)
The Memory Protection Unit (MPU) is included on the LM3S300 controller and supports the standard
ARMv7 Protected Memory System Architecture (PMSA) model. The MPU provides full support for
protection regions, overlapping protection regions, access permissions, and exporting memory
attributes to the system.
2.2.6
Nested Vectored Interrupt Controller (NVIC)
The Nested Vectored Interrupt Controller (NVIC):
■ Facilitates low-latency exception and interrupt handling
■ Controls power management
■ Implements system control registers
30
October 01, 2007
Preliminary
LM3S300 Microcontroller
The NVIC supports up to 240 dynamically reprioritizable interrupts each with up to 256 levels of
priority. The NVIC and the processor core interface are closely coupled, which enables low latency
interrupt processing and efficient processing of late arriving interrupts. The NVIC maintains knowledge
of the stacked (nested) interrupts to enable tail-chaining of interrupts.
You can only fully access the NVIC from privileged mode, but you can pend interrupts in user-mode
if you enable the Configuration Control Register (see the ARM® Cortex™-M3 Technical Reference
Manual). Any other user-mode access causes a bus fault.
All NVIC registers are accessible using byte, halfword, and word unless otherwise stated.
All NVIC registers and system debug registers are little endian regardless of the endianness state
of the processor.
2.2.6.1 Interrupts
The ARM® Cortex™-M3 Technical Reference Manual describes the maximum number of interrupts
and interrupt priorities. The LM3S300 microcontroller supports 21 interrupts with eight priority levels.
2.2.6.2 System Timer (SysTick)
Cortex-M3 includes an integrated system timer, SysTick. SysTick provides a simple, 24-bit
clear-on-write, decrementing, wrap-on-zero counter with a flexible control mechanism. The counter
can be used in several different ways, for example:
■ An RTOS tick timer which fires at a programmable rate (for example, 100 Hz) and invokes a
SysTick routine.
■ A high-speed alarm timer using the system clock.
■ A variable rate alarm or signal timer—the duration is range-dependent on the reference clock
used and the dynamic range of the counter.
■ A simple counter. Software can use this to measure time to completion and time used.
■ An internal clock source control based on missing/meeting durations. The COUNTFLAG bit-field
in the control and status register can be used to determine if an action completed within a set
duration, as part of a dynamic clock management control loop.
Functional Description
The timer consists of three registers:
■ A control and status counter to configure its clock, enable the counter, enable the SysTick
interrupt, and determine counter status.
■ The reload value for the counter, used to provide the counter's wrap value.
■ The current value of the counter.
A fourth register, the SysTick Calibration Value Register, is not implemented in the Stellaris® devices.
When enabled, the timer counts down from the reload value to zero, reloads (wraps) to the value
in the SysTick Reload Value register on the next clock edge, then decrements on subsequent clocks.
Writing a value of zero to the Reload Value register disables the counter on the next wrap. When
the counter reaches zero, the COUNTFLAG status bit is set. The COUNTFLAG bit clears on reads.
October 01, 2007
31
Preliminary
ARM Cortex-M3 Processor Core
Writing to the Current Value register clears the register and the COUNTFLAG status bit. The write
does not trigger the SysTick exception logic. On a read, the current value is the value of the register
at the time the register is accessed.
If the core is in debug state (halted), the counter will not decrement. The timer is clocked with respect
to a reference clock. The reference clock can be the core clock or an external clock source.
SysTick Control and Status Register
Use the SysTick Control and Status Register to enable the SysTick features. The reset is
0x0000.0000.
Bit/Field
Name
Type Reset Description
31:17
reserved
RO
0
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
COUNTFLAG R/W
Returns 1 if timer counted to 0 since last time this was read. Clears on read by
application. If read by the debugger using the DAP, this bit is cleared on read-only
if the MasterType bit in the AHB-AP Control Register is set to 0. Otherwise, the
COUNTFLAG bit is not changed by the debugger read.
15:3
2
reserved
RO
0
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.
CLKSOURCE R/W
0 = external reference clock. (Not implemented for Stellaris microcontrollers.)
1 = core clock.
If no reference clock is provided, it is held at 1 and so gives the same time as the
core clock. The core clock must be at least 2.5 times faster than the reference clock.
If it is not, the count values are unpredictable.
1
0
TICKINT
ENABLE
R/W
R/W
0
0
1 = counting down to 0 pends the SysTick handler.
0 = counting down to 0 does not pend the SysTick handler. Software can use the
COUNTFLAG to determine if ever counted to 0.
1 = counter operates in a multi-shot way. That is, counter loads with the Reload
value and then begins counting down. On reaching 0, it sets the COUNTFLAG to
1 and optionally pends the SysTick handler, based on TICKINT. It then loads the
Reload value again, and begins counting.
0 = counter disabled.
SysTick Reload Value Register
Use the SysTick Reload Value Register to specify the start value to load into the current value
register when the counter reaches 0. It can be any value between 1 and 0x00FF.FFFF. A start value
of 0 is possible, but has no effect because the SysTick interrupt and COUNTFLAG are activated
when counting from 1 to 0.
Therefore, as a multi-shot timer, repeated over and over, it fires every N+1 clock pulse, where N is
any value from 1 to 0x00FF.FFFF. So, if the tick interrupt is required every 100 clock pulses, 99
must be written into the RELOAD. If a new value is written on each tick interrupt, so treated as single
shot, then the actual count down must be written. For example, if a tick is next required after 400
clock pulses, 400 must be written into the RELOAD.
Bit/Field Name Type Reset Description
31:24 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.
32
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field Name Type Reset Description
23:0 RELOAD W1C Value to load into the SysTick Current Value Register when the counter reaches 0.
-
SysTick Current Value Register
Use the SysTick Current Value Register to find the current value in the register.
Bit/Field
Name
Type Reset Description
31:24
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.
23:0
CURRENT W1C
Current value at the time the register is accessed. No read-modify-write protection is
provided, so change with care.
This register is write-clear. Writing to it with any value clears the register to 0. Clearing
this register also clears the COUNTFLAG bit of the SysTick Control and Status Register.
SysTick Calibration Value Register
The SysTick Calibration Value register is not implemented.
October 01, 2007
33
Preliminary
Memory Map
3
Memory Map
The memory map for the LM3S300 controller is provided in Table 3-1 on page 34.
In this manual, register addresses are given as a hexadecimal increment, relative to the module’s
base address as shown in the memory map. See also Chapter 4, “Memory Map” in the ARM®
Cortex™-M3 Technical Reference Manual.
Important: In Table 3-1 on page 34, addresses not listed are reserved.
Table 3-1. Memory Mapa
Start
End
Description
For details on
registers, see
page ...
Memory
0x0000.0000
0x2000.0000
0x2010.0000
0x2200.0000
0x2202.0000
FiRM Peripherals
0x4000.0000
0x4000.4000
0x4000.5000
0x4000.6000
0x4000.7000
0x4000.8000
0x4000.C000
0x4000.D000
Peripherals
0x4002.0000
0x4002.0800
0x4002.4000
0x4003.0000
0x4003.1000
0x4003.2000
0x4003.C000
0x400F.D000
0x400F.E000
0x4200.0000
Private Peripheral Bus
0x0000.3FFF
0x2000.0FFF
0x200F.FFFF
0x22001.FFFF
0x23FF.FFFF
On-chip flash b
Bit-banded on-chip SRAMc
108
108
-
Reserved
Bit-band alias of 0x2000.0000 through 0x200F.FFFF
Reserved
103
-
0x4000.0FFF
0x4000.4FFF
0x4000.5FFF
0x4000.6FFF
0x4000.7FFF
0x4000.8FFF
0x4000.CFFF
0x4000.DFFF
Watchdog timer
GPIO Port A
GPIO Port B
GPIO Port C
GPIO Port D
SSI0
195
125
125
125
125
265
222
222
UART0
UART1
0x4002.07FF
0x4002.0FFF
0x4002.7FFF
0x4003.0FFF
0x4003.1FFF
0x4003.2FFF
0x4003.CFFF
0x400F.DFFF
0x400F.FFFF
0x43FF.FFFF
I2C Master 0
304
317
125
168
168
168
326
108
56
I2C Slave 0
GPIO Port E
Timer0
Timer1
Timer2
Analog Comparators
Flash control
System control
Bit-banded alias of 0x4000.0000 through 0x400F.FFFF
-
34
October 01, 2007
Preliminary
LM3S300 Microcontroller
Start
End
Description
For details on
registers, see
page ...
0xE000.0000
0xE000.1000
0xE000.2000
0xE000.3000
0xE000.E000
0xE000.F000
0xE004.0000
0xE004.1000
0xE004.2000
0xE010.0000
0xE000.0FFF
0xE000.1FFF
0xE000.2FFF
0xE000.DFFF
0xE000.EFFF
0xE003.FFFF
0xE004.0FFF
0xE004.1FFF
0xE00F.FFFF
0xFFFF.FFFF
Instrumentation Trace Macrocell (ITM)
Data Watchpoint and Trace (DWT)
Flash Patch and Breakpoint (FPB)
Reserved
ARM®
Cortex™-M3
Technical
Reference
Manual
Nested Vectored Interrupt Controller (NVIC)
Reserved
Trace Port Interface Unit (TPIU)
Reserved
-
-
-
Reserved
Reserved for vendor peripherals
a. All reserved space returns a bus fault when read or written.
b. The unavailable flash will bus fault throughout this range.
c. The unavailable SRAM will bus fault throughout this range.
October 01, 2007
35
Preliminary
Interrupts
4
Interrupts
The ARM Cortex-M3 processor and the Nested Vectored Interrupt Controller (NVIC) prioritize and
handle all exceptions. All exceptions are handled in Handler Mode. The processor state is
automatically stored to the stack on an exception, and automatically restored from the stack at the
end of the Interrupt Service Routine (ISR). The vector is fetched in parallel to the state saving, which
enables efficient interrupt entry. The processor supports tail-chaining, which enables back-to-back
interrupts to be performed without the overhead of state saving and restoration.
Table 4-1 on page 36 lists all the exceptions. Software can set eight priority levels on seven of these
exceptions (system handlers) as well as on 21 interrupts (listed in Table 4-2 on page 37).
Priorities on the system handlers are set with the NVIC System Handler Priority registers. Interrupts
are enabled through the NVIC Interrupt Set Enable register and prioritized with the NVIC Interrupt
Priority registers. You can also group priorities by splitting priority levels into pre-emption priorities
and subpriorities. All the interrupt registers are described in Chapter 8, “Nested Vectored Interrupt
Controller” in the ARM® Cortex™-M3 Technical Reference Manual.
Internally, the highest user-settable priority (0) is treated as fourth priority, after a Reset, NMI, and
a Hard Fault. Note that 0 is the default priority for all the settable priorities.
If you assign the same priority level to two or more interrupts, their hardware priority (the lower the
position number) determines the order in which the processor activates them. For example, if both
GPIO Port A and GPIO Port B are priority level 1, then GPIO Port A has higher priority.
See Chapter 5, “Exceptions” and Chapter 8, “Nested Vectored Interrupt Controller” in the ARM®
Cortex™-M3 Technical Reference Manual for more information on exceptions and interrupts.
Note: In Table 4-2 on page 37 interrupts not listed are reserved.
Table 4-1. Exception Types
Exception Type
Position
Prioritya
Description
-
0
1
-
Stack top is loaded from first entry of vector table on reset.
Reset
-3 (highest) Invoked on power up and warm reset. On first instruction, drops to lowest
priority (and then is called the base level of activation). This is
asynchronous.
Non-Maskable
Interrupt (NMI)
2
-2
Cannot be stopped or preempted by any exception but reset. This is
asynchronous.
An NMI is only producible by software, using the NVIC Interrupt Control
State register.
Hard Fault
3
4
-1
All classes of Fault, when the fault cannot activate due to priority or the
configurable fault handler has been disabled. This is synchronous.
Memory Management
settable MPU mismatch, including access violation and no match. This is
synchronous.
The priority of this exception can be changed.
Bus Fault
5
settable Pre-fetch fault, memory access fault, and other address/memory related
faults. This is synchronous when precise and asynchronous when
imprecise.
You can enable or disable this fault.
Usage Fault
6
settable Usage fault, such as undefined instruction executed or illegal state
transition attempt. This is synchronous.
-
7-10
11
-
Reserved.
SVCall
settable System service call with SVC instruction. This is synchronous.
36
October 01, 2007
Preliminary
LM3S300 Microcontroller
Exception Type
Position
Prioritya
Description
Debug Monitor
12
settable Debug monitor (when not halting). This is synchronous, but only active
when enabled. It does not activate if lower priority than the current
activation.
-
13
14
-
Reserved.
PendSV
settable Pendable request for system service. This is asynchronous and only
pended by software.
SysTick
15
settable System tick timer has fired. This is asynchronous.
Interrupts
16 and
above
settable Asserted from outside the ARM Cortex-M3 core and fed through the NVIC
(prioritized). These are all asynchronous. Table 4-2 on page 37 lists the
interrupts on the LM3S300 controller.
a. 0 is the default priority for all the settable priorities.
Table 4-2. Interrupts
Interrupt (Bit in Interrupt Registers) Description
0
1
GPIO Port A
GPIO Port B
GPIO Port C
GPIO Port D
GPIO Port E
UART0
2
3
4
5
6
UART1
7
SSI0
8
I2C0
18
19
20
21
22
23
24
25
26
27
28
29
30-31
Watchdog timer
Timer0 A
Timer0 B
Timer1 A
Timer1 B
Timer2 A
Timer2 B
Analog Comparator 0
Analog Comparator 1
Analog Comparator 2
System Control
Flash Control
Reserved
October 01, 2007
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JTAG Interface
5
JTAG Interface
The Joint Test Action Group (JTAG) port is an IEEE standard that defines a Test Access Port and
Boundary Scan Architecture for digital integrated circuits and provides a standardized serial interface
for controlling the associated test logic. The TAP, Instruction Register (IR), and Data Registers (DR)
can be used to test the interconnections of assembled printed circuit boards and obtain manufacturing
information on the components. The JTAG Port also provides a means of accessing and controlling
design-for-test features such as I/O pin observation and control, scan testing, and debugging.
The JTAG port is comprised of the standard five pins: TRST, TCK, TMS, TDI, and TDO. Data is
transmitted serially into the controller on TDI and out of the controller on TDO. The interpretation of
this data is dependent on the current state of the TAP controller. For detailed information on the
operation of the JTAG port and TAP controller, please refer to the IEEE Standard 1149.1-Test
Access Port and Boundary-Scan Architecture.
The Luminary Micro JTAG controller works with the ARM JTAG controller built into the Cortex-M3
core. This is implemented by multiplexing the TDO outputs from both JTAG controllers. ARM JTAG
instructions select the ARM TDO output while Luminary Micro JTAG instructions select the Luminary
Micro TDO outputs. The multiplexer is controlled by the Luminary Micro JTAG controller, which has
comprehensive programming for the ARM, Luminary Micro, and unimplemented JTAG instructions.
The JTAG module has the following features:
■ IEEE 1149.1-1990 compatible Test Access Port (TAP) controller
■ Four-bit Instruction Register (IR) chain for storing JTAG instructions
■ IEEE standard instructions:
–
–
–
–
–
BYPASS instruction
IDCODE instruction
SAMPLE/PRELOAD instruction
EXTEST instruction
INTEST instruction
■ ARM additional instructions:
–
–
–
APACC instruction
DPACC instruction
ABORT instruction
■ Integrated ARM Serial Wire Debug (SWD)
See the ARM® Cortex™-M3 Technical Reference Manual for more information on the ARM JTAG
controller.
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5.1
Block Diagram
Figure 5-1. JTAG Module Block Diagram
TRST
TCK
TMS
TAP Controller
TDI
Instruction Register (IR)
BYPASS Data Register
Boundary Scan Data Register
IDCODE Data Register
ABORT Data Register
DPACC Data Register
APACC Data Register
TDO
Cortex-M3
Debug
Port
5.2
Functional Description
A high-level conceptual drawing of the JTAG module is shown in Figure 5-1 on page 39. The JTAG
module is composed of the Test Access Port (TAP) controller and serial shift chains with parallel
update registers. The TAP controller is a simple state machine controlled by the TRST, TCK and
TMS inputs. The current state of the TAP controller depends on the current value of TRST and the
sequence of values captured on TMS at the rising edge of TCK. The TAP controller determines when
the serial shift chains capture new data, shift data from TDI towards TDO, and update the parallel
load registers. The current state of the TAP controller also determines whether the Instruction
Register (IR) chain or one of the Data Register (DR) chains is being accessed.
The serial shift chains with parallel load registers are comprised of a single Instruction Register (IR)
chain and multiple Data Register (DR) chains. The current instruction loaded in the parallel load
register determines which DR chain is captured, shifted, or updated during the sequencing of the
TAP controller.
Some instructions, like EXTEST and INTEST, operate on data currently in a DR chain and do not
capture, shift, or update any of the chains. Instructions that are not implemented decode to the
BYPASS instruction to ensure that the serial path between TDI and TDO is always connected (see
Table 5-2 on page 44 for a list of implemented instructions).
See “JTAG and Boundary Scan” on page 353 for JTAG timing diagrams.
October 01, 2007
39
Preliminary
JTAG Interface
5.2.1
JTAG Interface Pins
The JTAG interface consists of five standard pins: TRST, TCK, TMS, TDI, and TDO. These pins and
their associated reset state are given in Table 5-1 on page 40. Detailed information on each pin
follows.
Table 5-1. JTAG Port Pins Reset State
Pin Name
TRST
TCK
Data Direction
Input
Internal Pull-Up Internal Pull-Down Drive Strength
Drive Value
N/A
Enabled
Enabled
Enabled
Enabled
Enabled
Disabled
Disabled
Disabled
Disabled
Disabled
N/A
N/A
Input
N/A
TMS
Input
N/A
N/A
TDI
Input
N/A
N/A
TDO
Output
2-mA driver
High-Z
5.2.1.1 Test Reset Input (TRST)
The TRST pin is an asynchronous active Low input signal for initializing and resetting the JTAG TAP
controller and associated JTAG circuitry. When TRST is asserted, the TAP controller resets to the
Test-Logic-Reset state and remains there while TRST is asserted. When the TAP controller enters
the Test-Logic-Reset state, the JTAG Instruction Register (IR) resets to the default instruction,
IDCODE.
By default, the internal pull-up resistor on the TRST pin is enabled after reset. Changes to the pull-up
resistor settings on GPIO Port B should ensure that the internal pull-up resistor remains enabled
on PB7/TRST; otherwise JTAG communication could be lost.
5.2.1.2 Test Clock Input (TCK)
The TCK pin is the clock for the JTAG module. This clock is provided so the test logic can operate
independently of any other system clocks. In addition, it ensures that multiple JTAG TAP controllers
that are daisy-chained together can synchronously communicate serial test data between
components. During normal operation, TCK is driven by a free-running clock with a nominal 50%
duty cycle. When necessary, TCK can be stopped at 0 or 1 for extended periods of time. While TCK
is stopped at 0 or 1, the state of the TAP controller does not change and data in the JTAG Instruction
and Data Registers is not lost.
By default, the internal pull-up resistor on the TCK pin is enabled after reset. This assures that no
clocking occurs if the pin is not driven from an external source. The internal pull-up and pull-down
resistors can be turned off to save internal power as long as the TCK pin is constantly being driven
by an external source.
5.2.1.3 Test Mode Select (TMS)
The TMS pin selects the next state of the JTAG TAP controller. TMS is sampled on the rising edge
of TCK. Depending on the current TAP state and the sampled value of TMS, the next state is entered.
Because the TMS pin is sampled on the rising edge of TCK, the IEEE Standard 1149.1 expects the
value on TMS to change on the falling edge of TCK.
Holding TMS high for five consecutive TCK cycles drives the TAP controller state machine to the
Test-Logic-Reset state. When the TAP controller enters the Test-Logic-Reset state, the JTAG
Instruction Register (IR) resets to the default instruction, IDCODE. Therefore, this sequence can
be used as a reset mechanism, similar to asserting TRST. The JTAG Test Access Port state machine
can be seen in its entirety in Figure 5-2 on page 42.
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October 01, 2007
Preliminary
LM3S300 Microcontroller
By default, the internal pull-up resistor on the TMS pin is enabled after reset. Changes to the pull-up
resistor settings on GPIO Port C should ensure that the internal pull-up resistor remains enabled
on PC1/TMS; otherwise JTAG communication could be lost.
5.2.1.4 Test Data Input (TDI)
The TDI pin provides a stream of serial information to the IR chain and the DR chains. TDI is
sampled on the rising edge of TCK and, depending on the current TAP state and the current
instruction, presents this data to the proper shift register chain. Because the TDI pin is sampled on
the rising edge of TCK, the IEEE Standard 1149.1 expects the value on TDI to change on the falling
edge of TCK.
By default, the internal pull-up resistor on the TDI pin is enabled after reset. Changes to the pull-up
resistor settings on GPIO Port C should ensure that the internal pull-up resistor remains enabled
on PC2/TDI; otherwise JTAG communication could be lost.
5.2.1.5 Test Data Output (TDO)
The TDO pin provides an output stream of serial information from the IR chain or the DR chains.
The value of TDO depends on the current TAP state, the current instruction, and the data in the
chain being accessed. In order to save power when the JTAG port is not being used, the TDO pin
is placed in an inactive drive state when not actively shifting out data. Because TDO can be connected
to the TDI of another controller in a daisy-chain configuration, the IEEE Standard 1149.1 expects
the value on TDO to change on the falling edge of TCK.
By default, the internal pull-up resistor on the TDO pin is enabled after reset. This assures that the
pin remains at a constant logic level when the JTAG port is not being used. The internal pull-up and
pull-down resistors can be turned off to save internal power if a High-Z output value is acceptable
during certain TAP controller states.
5.2.2
JTAG TAP Controller
The JTAG TAP controller state machine is shown in Figure 5-2 on page 42. The TAP controller
state machine is reset to the Test-Logic-Reset state on the assertion of a Power-On-Reset (POR)
or the assertion of TRST. Asserting the correct sequence on the TMS pin allows the JTAG module
to shift in new instructions, shift in data, or idle during extended testing sequences. For detailed
information on the function of the TAP controller and the operations that occur in each state, please
refer to IEEE Standard 1149.1.
October 01, 2007
41
Preliminary
JTAG Interface
Figure 5-2. Test Access Port State Machine
Test Logic Reset
0
1
0
Run Test Idle
Select DR Scan
0
Select IR Scan
0
1
1
1
Capture DR
0
Capture IR
0
1
1
Shift DR
1
Shift IR
1
0
1
0
1
Exit 1 DR
0
Exit 1 IR
0
Pause DR
1
Pause IR
1
0
0
Exit 2 DR
1
Exit 2 IR
1
0
0
Update DR
Update IR
1
0
1
0
5.2.3
5.2.4
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 44.
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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October 01, 2007
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LM3S300 Microcontroller
5.2.4.1 GPIO Functionality
When the controller is reset with either a POR or RST, the JTAG port pins default to their JTAG
configurations. The default configuration includes enabling the pull-up resistors (setting GPIOPUR
to 1 for PB7 and PC[3:0]) and enabling the alternate hardware function (setting GPIOAFSEL to
1 for PB7 and PC[3:0]) on the JTAG pins.
It is possible for software to configure these pins as GPIOs after reset by writing 0s to PB7 and
PC[3:0] in the GPIOAFSEL register. If the user does not require the JTAG port for debugging or
board-level testing, this provides five more GPIOs for use in the design.
Caution – If the JTAG pins are used as GPIOs in a design, PB7 and PC2 cannot have external pull-down
resistors connected to both of them at the same time. If both pins are pulled Low during reset, the
controller has unpredictable behavior. If this happens, remove one or both of the pull-down resistors,
and apply RST or power-cycle the part.
In addition, it is possible to create a software sequence that prevents the debugger from connecting to
the Stellaris® microcontroller. If the program code loaded into flash immediately changes the JTAG
pins to their GPIO functionality, the debugger may not have enough time to connect and halt the
controller before the JTAG pin functionality switches. This may lock the debugger out of the part. This
can be avoided with a software routine that restores JTAG functionality based on an external or software
trigger.
5.2.4.2 ARM Serial Wire Debug (SWD)
In order to seamlessly integrate the ARM Serial Wire Debug (SWD) functionality, a serial-wire
debugger must be able to connect to the Cortex-M3 core without having to perform, or have any
knowledge of, JTAG cycles. This is accomplished with a SWD preamble that is issued before the
SWD session begins.
The preamble used to enable the SWD interface of the SWJ-DP module starts with the TAP controller
in the Test-Logic-Reset state. From here, the preamble sequences the TAP controller through the
following states: Run Test Idle, Select DR, Select IR, Capture IR, Exit1 IR, Update IR, Run Test
Idle, Select DR, Select IR, Capture IR, Exit1 IR, Update IR, Run Test Idle, Select DR, Select IR,
and Test-Logic-Reset states.
Stepping through the JTAG TAP Instruction Register (IR) load sequences of the TAP state machine
twice without shifting in a new instruction enables the SWD interface and disables the JTAG interface.
For more information on this operation and the SWD interface, see the ARM® Cortex™-M3 Technical
Reference Manual and the ARM® CoreSight Technical Reference Manual.
Because this sequence is a valid series of JTAG operations that could be issued, the ARM JTAG
TAP controller is not fully compliant to the IEEE Standard 1149.1. This is the only instance where
the ARM JTAG TAP controller does not meet full compliance with the specification. Due to the low
probability of this sequence occurring during normal operation of the TAP controller, it should not
affect normal performance of the JTAG interface.
5.3
Initialization and Configuration
After a Power-On-Reset or an external reset (RST), the JTAG pins are automatically configured for
JTAG communication. No user-defined initialization or configuration is needed. However, if the user
application changes these pins to their GPIO function, they must be configured back to their JTAG
functionality before JTAG communication can be restored. This is done by enabling the five JTAG
pins (PB7 and PC[3:0]) for their alternate function using the GPIOAFSEL register.
October 01, 2007
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Preliminary
JTAG Interface
5.4
Register Descriptions
There are no APB-accessible registers in the JTAG TAP Controller or Shift Register chains. The
registers within the JTAG controller are all accessed serially through the TAP Controller. The registers
can be broken down into two main categories: Instruction Registers and Data Registers.
5.4.1
Instruction Register (IR)
The JTAG TAP Instruction Register (IR) is a four-bit serial scan chain with a parallel load register
connected between the JTAG TDI and TDO pins. When the TAP Controller is placed in the correct
states, bits can be shifted into the Instruction Register. Once these bits have been shifted into the
chain and updated, they are interpreted as the current instruction. The decode of the Instruction
Register bits is shown in Table 5-2 on page 44. A detailed explanation of each instruction, along
with its associated Data Register, follows.
Table 5-2. JTAG Instruction Register Commands
IR[3:0]
Instruction
Description
0000
EXTEST
Drives the values preloaded into the Boundary Scan Chain by the SAMPLE/PRELOAD
instruction onto the pads.
0001
0010
INTEST
Drives the values preloaded into the Boundary Scan Chain by the SAMPLE/PRELOAD
instruction into the controller.
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
1010
1011
1110
ABORT
DPACC
APACC
IDCODE
Shifts data into the ARM Debug Port Abort Register.
Shifts data into and out of the ARM DP Access Register.
Shifts data into and out of the ARM AC Access Register.
Loads manufacturing information defined by the IEEE Standard 1149.1 into the IDCODE
chain and shifts it out.
1111
BYPASS
Reserved
Connects TDI to TDO through a single Shift Register chain.
All Others
Defaults to the BYPASS instruction to ensure that TDI is always connected to TDO.
5.4.1.1 EXTEST Instruction
The EXTEST instruction does not have an associated Data Register chain. The EXTEST instruction
uses the data that has been preloaded into the Boundary Scan Data Register using the
SAMPLE/PRELOAD instruction. When the EXTEST instruction is present in the Instruction Register,
the preloaded data in the Boundary Scan Data Register associated with the outputs and output
enables are used to drive the GPIO pads rather than the signals coming from the core. This allows
tests to be developed that drive known values out of the controller, which can be used to verify
connectivity.
5.4.1.2 INTEST Instruction
The INTEST instruction does not have an associated Data Register chain. The INTEST instruction
uses the data that has been preloaded into the Boundary Scan Data Register using the
SAMPLE/PRELOAD instruction. When the INTEST instruction is present in the Instruction Register,
the preloaded data in the Boundary Scan Data Register associated with the inputs are used to drive
the signals going into the core rather than the signals coming from the GPIO pads. This allows tests
to be developed that drive known values into the controller, which can be used for testing. It is
important to note that although the RST input pin is on the Boundary Scan Data Register chain, it
is only observable.
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October 01, 2007
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LM3S300 Microcontroller
5.4.1.3 SAMPLE/PRELOAD Instruction
The SAMPLE/PRELOAD instruction connects the Boundary Scan Data Register chain between
TDI and TDO. This instruction samples the current state of the pad pins for observation and preloads
new test data. Each GPIO pad has an associated input, output, and output enable signal. When the
TAP controller enters the Capture DR state during this instruction, the input, output, and output-enable
signals to each of the GPIO pads are captured. These samples are serially shifted out of TDO while
the TAP controller is in the Shift DR state and can be used for observation or comparison in various
tests.
While these samples of the inputs, outputs, and output enables are being shifted out of the Boundary
Scan Data Register, new data is being shifted into the Boundary Scan Data Register from TDI.
Once the new data has been shifted into the Boundary Scan Data Register, the data is saved in the
parallel load registers when the TAP controller enters the Update DR state. This update of the
parallel load register preloads data into the Boundary Scan Data Register that is associated with
each input, output, and output enable. This preloaded data can be used with the EXTEST and
INTEST instructions to drive data into or out of the controller. Please see “Boundary Scan Data
Register” on page 46 for more information.
5.4.1.4 ABORT Instruction
The ABORT instruction connects the associated ABORT Data Register chain between TDI and
TDO. This instruction provides read and write access to the ABORT Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this Data Register clears various error bits or initiates
a DAP abort of a previous request. Please see the “ABORT Data Register” on page 47 for more
information.
5.4.1.5 DPACC Instruction
The DPACC instruction connects the associated DPACC Data Register chain between TDI and
TDO. This instruction provides read and write access to the DPACC Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this register and reading the data output from this
register allows read and write access to the ARM debug and status registers. Please see “DPACC
Data Register” on page 47 for more information.
5.4.1.6 APACC Instruction
The APACC instruction connects the associated APACC Data Register chain between TDI and
TDO. This instruction provides read and write access to the APACC Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this register and reading the data output from this
register allows read and write access to internal components and buses through the Debug Port.
Please see “APACC Data Register” on page 47 for more information.
5.4.1.7 IDCODE Instruction
The IDCODE instruction connects the associated IDCODE Data Register chain between TDI and
TDO. This instruction provides information on the manufacturer, part number, and version of the
ARM core. This information can be used by testing equipment and debuggers to automatically
configure their input and output data streams. IDCODE is the default instruction that is loaded into
the JTAG Instruction Register when a power-on-reset (POR) is asserted, TRST is asserted, or the
Test-Logic-Reset state is entered. Please see “IDCODE Data Register” on page 46 for more
information.
October 01, 2007
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Preliminary
JTAG Interface
5.4.1.8 BYPASS Instruction
The BYPASS instruction connects the associated BYPASS Data Register chain between TDI and
TDO. This instruction is used to create a minimum length serial path between the TDI and TDO ports.
The BYPASS Data Register is a single-bit shift register. This instruction improves test efficiency by
allowing components that are not needed for a specific test to be bypassed in the JTAG scan chain
by loading them with the BYPASS instruction. Please see “BYPASS Data Register” on page 46 for
more information.
5.4.2
Data Registers
The JTAG module contains six Data Registers. These include: IDCODE, BYPASS, Boundary Scan,
APACC, DPACC, and ABORT serial Data Register chains. Each of these Data Registers is discussed
in the following sections.
5.4.2.1 IDCODE Data Register
The format for the 32-bit IDCODE Data Register defined by the IEEE Standard 1149.1 is shown in
Figure 5-3 on page 46. 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 0x1BA00477. This value indicates an ARM Cortex-M3, Version 1
processor. This allows the debuggers to automatically configure themselves to work correctly with
the Cortex-M3 during debug.
Figure 5-3. IDCODE Register Format
5.4.2.2 BYPASS Data Register
The format for the 1-bit BYPASS Data Register defined by the IEEE Standard 1149.1 is shown in
Figure 5-4 on page 46. 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 5-4. BYPASS Register Format
5.4.2.3 Boundary Scan Data Register
The format of the Boundary Scan Data Register is shown in Figure 5-5 on page 47. Each GPIO
pin, in a counter-clockwise direction from the JTAG port pins, is included in the Boundary Scan Data
Register. Each GPIO pin has three associated digital signals that are included in the chain. These
46
October 01, 2007
Preliminary
LM3S300 Microcontroller
signals are input, output, and output enable, and are arranged in that order as can be seen in the
figure. In addition to the GPIO pins, the controller reset pin, RST, is included in the chain. Because
the reset pin is always an input, only the input signal is included in the Data Register chain.
When the Boundary Scan Data Register is accessed with the SAMPLE/PRELOAD instruction, the
input, output, and output enable from each digital pad are sampled and then shifted out of the chain
to be verified. The sampling of these values occurs on the rising edge of TCK in the Capture DR
state of the TAP controller. While the sampled data is being shifted out of the Boundary Scan chain
in the Shift DR state of the TAP controller, new data can be preloaded into the chain for use with
the EXTEST and INTEST instructions. These instructions either force data out of the controller, with
the EXTEST instruction, or into the controller, with the INTEST instruction.
Figure 5-5. Boundary Scan Register Format
O
U
T
O
U
T
O
U
T
O
U
T
TDI
TDO
I
N
O
E
I
N
O
E
I
I
N
O
E
I
N
O
E
...
...
N
GPIO PB6
GPIO m
RST
GPIO m+1
GPIO n
For detailed information on the order of the input, output, and output enable bits for each of the
GPIO ports, please refer to the Stellaris® Family Boundary Scan Description Language (BSDL) files,
downloadable from www.luminarymicro.com.
5.4.2.4 APACC Data Register
The format for the 35-bit APACC Data Register defined by ARM is described in the ARM®
Cortex™-M3 Technical Reference Manual.
5.4.2.5 DPACC Data Register
The format for the 35-bit DPACC Data Register defined by ARM is described in the ARM®
Cortex™-M3 Technical Reference Manual.
5.4.2.6 ABORT Data Register
The format for the 35-bit ABORT Data Register defined by ARM is described in the ARM®
Cortex™-M3 Technical Reference Manual.
October 01, 2007
47
Preliminary
System Control
6
System Control
System control determines the overall operation of the device. It provides information about the
device, controls the clocking to the core and individual peripherals, and handles reset detection and
reporting.
6.1
Functional Description
The System Control module provides the following capabilities:
■ Device identification, see “Device Identification” on page 48
■ Local control, such as reset (see “Reset Control” on page 48), power (see “Power
Control” on page 51) and clock control (see “Clock Control” on page 51)
■ System control (Run, Sleep, and Deep-Sleep modes), see “System Control” on page 54
6.1.1
6.1.2
Device Identification
Seven read-only registers provide software with information on the microcontroller, such as version,
part number, SRAM size, flash size, and other features. See the DID0, DID1, and DC0-DC4 registers.
Reset Control
This section discusses aspects of hardware functions during reset as well as system software
requirements following the reset sequence.
6.1.2.1 Reset Sources
The controller has six sources of reset:
1. External reset input pin (RST) assertion, see “RST Pin Assertion” on page 48.
2. Power-on reset (POR), see “Power-On Reset (POR)” on page 49.
3. Internal brown-out (BOR) detector, see “Brown-Out Reset (BOR)” on page 49.
4. Software-initiated reset (with the software reset registers), see “Software Reset” on page 50.
5. A watchdog timer reset condition violation, see “Watchdog Timer Reset” on page 51.
6. Internal low drop-out (LDO) regulator output
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 external reset
is the cause, and then all the other bits in the RESC register are cleared.
Note: The main oscillator is used for external resets and power-on resets; the internal oscillator
is used during the internal process by internal reset and clock verification circuitry.
6.1.2.2 RST Pin Assertion
The external reset pin (RST) resets the controller. This resets the core and all the peripherals except
the JTAG TAP controller (see “JTAG Interface” on page 38). The external reset sequence is as
follows:
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LM3S300 Microcontroller
1. The external reset pin (RST) is asserted and then de-asserted.
2. After RST is de-asserted, the main crystal oscillator is allowed to settle and there is an internal
main oscillator counter that takes from 15-30 ms to account for this. During this time, internal
reset to the rest of the controller is held active.
3. The internal reset is released and the core fetches and loads the initial stack pointer, the initial
program counter, the first instruction designated by the program counter, and begins execution.
The external reset timing is shown in Figure 18-9 on page 356.
6.1.2.3 Power-On Reset (POR)
The Power-On Reset (POR) circuitry detects a rise in power-supply voltage (VDD) and generates
an on-chip reset pulse. To use the on-chip circuitry, the RST input needs to be connected to the
power supply (VDD) through a pull-up resistor (1K to 10K Ω).
The device must be operating within the specified operating parameters at the point when the on-chip
power-on reset pulse is complete. The specified operating parameters include supply voltage,
frequency, temperature, and so on. If the operating conditions are not met at the point of POR end,
the Stellaris® controller does not operate correctly. In this case, the reset must be extended using
external circuitry. The RST input may be used with the circuit as shown in Figure 6-1 on page 49.
Figure 6-1. External Circuitry to Extend Reset
Stellaris
D1
R1
RST
R2
C1
The R1 and C1 components define the power-on delay. The R2 resistor mitigates any leakage from
the RST input. The diode (D1) discharges C1 rapidly when the power supply is turned off.
The Power-On Reset sequence is as follows:
1. The controller waits for the later of external reset (RST) or internal POR to go inactive.
2. After the resets are inactive, the main crystal oscillator is allowed to settle and there is an internal
main oscillator counter that takes from 15-30 ms to account for this. During this time, internal
reset to the rest of the controller is held active.
3. The internal reset is released and the core fetches and loads the initial stack pointer, the initial
program counter, the first instruction designated by the program counter, and begins execution.
The internal POR is only active on the initial power-up of the controller. The Power-On Reset timing
is shown in Figure 18-10 on page 356.
Note: The power-on reset also resets the JTAG controller. An external reset does not.
6.1.2.4 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.
October 01, 2007
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Preliminary
System Control
The system provides a brown-out detection circuit that triggers if the power supply (VDD) drops
below a brown-out threshold voltage (VBTH). The circuit is provided to guard against improper
operation of logic and peripherals that operate off the power supply voltage (VDD) and not the LDO
voltage. If a brown-out condition is detected, the system may generate a controller interrupt or a
system reset. The BOR circuit has a digital filter that protects against noise-related detection for the
interrupt condition. This feature may be optionally enabled.
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 sequence is as follows:
1. When VDD drops below VBTH, an internal BOR condition is set.
2. If the BORWT bit in the PBORCTL register is set and BORIOR is not set, the BOR condition is
resampled again, after a delay specified by BORTIM, to determine if the original condition was
caused by noise. If the BOR condition is not met the second time, then no further action is taken.
3. If the BOR condition exists, an internal reset is asserted.
4. The internal reset is released and the controller fetches and loads the initial stack pointer, the
initial program counter, the first instruction designated by the program counter, and begins
execution.
5. The internal BOR condition is reset after 500 µs to prevent another BOR condition from being
set before software has a chance to investigate the original cause.
The internal Brown-Out Reset timing is shown in Figure 18-11 on page 357.
6.1.2.5 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 54). Note that all reset signals for all clocks of the specified unit are asserted as
a result of a software-initiated reset.
The entire system can be reset by software by setting the SYSRESETREQ bit in the Cortex-M3
Application Interrupt and Reset Control register resets the entire system including the core. The
software-initiated system reset sequence is as follows:
1. A software system reset is initiated by writing the SYSRESETREQ bit in the ARM Cortex-M3
Application Interrupt and Reset Control register.
2. An internal reset is asserted.
3. The internal reset is deasserted and the controller loads from memory the initial stack pointer,
the initial program counter, and the first instruction designated by the program counter, and
then begins execution.
The software-initiated system reset timing is shown in Figure 18-12 on page 357.
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October 01, 2007
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6.1.2.6 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 18-13 on page 357.
6.1.2.7 Low Drop-Out
A reset can be initiated when the internal low drop-out (LDO) regulator output goes unregulated.
This is initially disabled and may be enabled by software. LDO is controlled with the LDO Power
Control (LDOPCTL) register. The LDO reset sequence is as follows:
1. LDO goes unregulated and the LDOARST bit in the LDOARST register is set.
2. An internal reset is asserted.
3. The internal reset is released and the controller fetches and loads the initial stack pointer, the
initial program counter, the first instruction designated by the program counter, and begins
execution.
The LDO reset timing is shown in Figure 18-14 on page 357.
6.1.3
6.1.4
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. 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.
Clock Control
System control determines the control of clocks in this part.
6.1.4.1 Fundamental Clock Sources
There are two 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%.
October 01, 2007
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Preliminary
System Control
Applications that do not depend on accurate clock sources may use this clock source to reduce
system cost.
■ Main Oscillator: The main oscillator provides a frequency-accurate clock source by one of two
means: an external single-ended clock source is connected to the OSC0 input pin, or an external
crystal is connected across the OSC0 input and OSC1 output pins. The crystal value allowed
depends on whether the main oscillator is used as the clock reference source to the PLL. If so,
the crystal must be one of the supported frequencies between 3.579545 MHz through 8.192
MHz (inclusive). If the PLL is not being used, the crystal may be any one of the supported
frequencies between 1 MHz and 8.192 MHz. The single-ended clock source range is from DC
through the specified speed of the device. The supported crystals are listed in the XTAL bit in
the RCC register (see page 66).
The internal system clock (sysclk), is derived from any of the two sources plus two others: the output
of the internal PLL, and the internal oscillator divided by four (3 MHz ± 30%). The frequency of the
PLL clock reference must be in the range of 3.579545 MHz to 8.192 MHz (inclusive).
Nearly all of the control for the clocks is provided by the Run-Mode Clock Configuration (RCC)
register.
Figure 6-2 on page 52 shows the logic for the main clock tree. The peripheral blocks are driven by
the system clock signal and can be programmatically enabled/disabled.
Figure 6-2. Main Clock Tree
USESYSDIVa
OSC1
OSC2
Main
Osc
1-8 MHz
System Clock
SYSDIVa
PLL
(200 MHz
output)
Internal
Osc
12 MHz
÷4
OSCSRCa
OENa
XTALa
BYPASSa
PWRDNa
a. These are bit fields within the Run-Mode Clock Configuration (RCC) register.
6.1.4.2 Crystal Configuration for the Main Oscillator (MOSC)
The main oscillator supports the use of a select number of crystals. If the main oscillator is used by
the PLL as a reference clock, the supported range of crystals is 3.579545 to 8.192 MHz, otherwise,
the range of supported crystals is 1 to 8.192 MHz.
The XTAL bit in the RCC register (see page 66) 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.
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October 01, 2007
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6.1.4.3 PLL Frequency Configuration
The PLL is disabled by default during power-on reset and is enabled later by software if required.
Software configures the PLL input reference clock source, specifies the output divisor to set the
system clock frequency, and enables the PLL to drive the output.
If the main oscillator provides the clock reference to the PLL, the translation provided by hardware
and used to program the PLL is available for software in the XTAL to PLL Translation (PLLCFG)
register (see page 70). The internal translation provides a translation within ± 1% of the targeted
PLL VCO frequency.
The XTAL bit in the RCC register (see page 66) describes the available crystal choices and default
programming of the PLLCFG register. The crystal number is written into the XTAL field of the
Run-Mode Clock Configuration (RCC) register. Any time the XTAL field changes, the new settings
are translated and the internal PLL settings are updated.
6.1.4.4 PLL Modes
The PLL has two modes of operation: Normal and Power-Down
■ Normal: The PLL multiplies the input clock reference and drives the output.
■ Power-Down: Most of the PLL internal circuitry is disabled and the PLL does not drive the output.
The modes are programmed using the RCC register fields (see page 66).
6.1.4.5 PLL Operation
If the PLL configuration is changed, the PLL output frequency is unstable until it reconverges (relocks)
to the new setting. The time between the configuration change and relock is TREADY (see Table
18-6 on page 350). During this time, the PLL is not usable as a clock reference.
The PLL is changed by one of the following:
■ Change to the XTAL value in the RCC register—writes of the same value do not cause a relock.
■ Change in the PLL from Power-Down to Normal mode.
A counter is defined to measure the TREADY requirement. The counter is clocked by the main
oscillator. The range of the main oscillator has been taken into account and the down counter is set
to 0x1200 (that is, ~600 μs at an 8.192 MHz external oscillator clock). Hardware is provided to keep
the PLL from being used as a system clock until the TREADY condition is met after one of the two
changes above. It is the user's responsibility to have a stable clock source (like the main oscillator)
before the RCC register is switched to use the PLL.
6.1.4.6 Clock Verification Timers
There are three identical clock verification circuits that can be enabled though software. The circuit
checks the faster clock by a slower clock using timers:
■ The main oscillator checks the PLL.
■ The main oscillator checks the internal oscillator.
■ The internal oscillator divided by 64 checks the main oscillator.
If the verification timer function is enabled and a failure is detected, the main clock tree is immediately
switched to a working clock and an interrupt is generated to the controller. Software can then
October 01, 2007
53
Preliminary
System Control
determine the course of action to take. The actual failure indication and clock switching does not
clear without a write to the CLKVCLR register, an external reset, or a POR reset. The clock
verification timers are controlled by the PLLVER , IOSCVER , and MOSCVER bits in the RCC register.
6.1.5
System Control
For power-savings purposes, the RCGCn , SCGCn , and DCGCn registers control the clock gating
logic for each peripheral or block in the system while the controller is in Run, Sleep, and Deep-Sleep
mode, respectively. The DC1 , DC2 and DC4 registers act as a write mask for the RCGCn , SCGCn,
and DCGCn registers.
In Run mode, the controller is actively executing code. In Sleep mode, the clocking of the device is
unchanged but the controller no longer executes code (and is no longer clocked). In Deep-Sleep
mode, the clocking of the device may change (depending on the Run mode clock configuration)
and the controller no longer executes code (and is no longer clocked). An interrupt returns the device
to Run mode from one of the sleep modes. Each mode is described in more detail in this section.
There are four levels of operation for the device defined as:
■ Run Mode. Run mode provides normal operation of the processor and all of the peripherals that
are currently enabled by the RCGCn registers. The system clock can be any of the available
clock sources including the PLL.
■ Sleep Mode. Sleep mode is entered by the Cortex-M3 core executing a WFI (Wait for
Interrupt) instruction. Any properly configured interrupt event in the system will bring the
processor back into Run mode. See the system control NVIC section of the ARM® Cortex™-M3
Technical Reference Manual for more details.
In Sleep mode, the Cortex-M3 processor core and the memory subsystem are not clocked.
Peripherals are clocked that are enabled in the SCGCn register when auto-clock gating is enabled
(see the RCC register) or the RCGCn register when the auto-clock gating is disabled. The system
clock has the same source and frequency as that during Run mode.
■ Deep-Sleep Mode. Deep-Sleep mode is entered by first writing the Deep Sleep Enable bit in
the ARM Cortex-M3 NVIC system control register and then executing a WFI instruction. Any
properly configured interrupt event in the system will bring the processor back into Run mode.
See the system control NVIC section of the ARM® Cortex™-M3 Technical Reference Manual
for more details.
The Cortex-M3 processor core and the memory subsystem are not clocked. Peripherals are
clocked that are enabled in the DCGCn register when auto-clock gating is enabled (see the RCC
register) or the RCGCn register when auto-clock gating is disabled. The system clock source is
the main oscillator by default or the internal oscillator specified in the DSLPCLKCFG register if
one is enabled. When the DSLPCLKCFG register is used, the internal oscillator is powered up,
if necessary, and the main oscillator is powered down. If the PLL is running at the time of the
WFI instruction, hardware will power the PLL down and override the SYSDIV field of the active
RCC register to be /16 or /64, respectively. When the Deep-Sleep exit event occurs, hardware
brings the system clock back to the source and frequency it had at the onset of Deep-Sleep
mode before enabling the clocks that had been stopped during the Deep-Sleep duration.
6.2
Initialization and Configuration
The PLL is configured using direct register writes to the RCC register. The steps required to
successfully change the PLL-based system clock are:
54
October 01, 2007
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LM3S300 Microcontroller
1. Bypass the PLL and system clock divider by setting the BYPASS bit and clearing the USESYS
bit in the RCC register. This configures the system to run off a “raw” clock source (using the
main oscillator or internal oscillator) and allows for the new PLL configuration to be validated
before switching the system clock to the PLL.
2. Select the crystal value (XTAL) and oscillator source (OSCSRC), and clear the PWRDN and OEN
bits in RCC. Setting the XTAL field automatically pulls valid PLL configuration data for the
appropriate crystal, and clearing the PWRDN and OEN bits powers and enables the PLL and its
output.
3. Select the desired system divider (SYSDIV) in RCC 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.
Note: If the BYPASS bit is cleared before the PLL locks, it is possible to render the device unusable.
6.3
Register Map
Table 6-1 on page 55 lists the System Control registers, grouped by function. The offset listed is a
hexadecimal increment to the register’s address, relative to the System Control base address of
0x400F.E000.
Note: Spaces in the System Control register space that are not used are reserved for future or
internal use by Luminary Micro, Inc. Software should not modify any reserved memory
address.
Table 6-1. System Control Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
0x004
0x008
0x010
0x014
0x018
0x01C
0x030
0x034
0x040
0x044
0x048
0x050
0x054
DID0
RO
RO
-
Device Identification 0
Device Identification 1
Device Capabilities 0
57
74
76
77
79
81
83
59
60
99
100
102
61
62
DID1
-
DC0
RO
0x000F.0007
0x0000.709F
0x0707.1013
0x3F00.7FC0
0x0000.001F
0x0000.7FFD
0x0000.0000
0x00000000
0x00000000
0x00000000
0x0000.0000
0x0000.0000
DC1
RO
Device Capabilities 1
DC2
RO
Device Capabilities 2
DC3
RO
Device Capabilities 3
DC4
RO
Device Capabilities 4
PBORCTL
LDOPCTL
SRCR0
SRCR1
SRCR2
RIS
R/W
R/W
R/W
R/W
R/W
RO
Power-On and Brown-Out Reset Control
LDO Power Control
Software Reset Control 0
Software Reset Control 1
Software Reset Control 2
Raw Interrupt Status
IMC
R/W
Interrupt Mask Control
October 01, 2007
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Preliminary
System Control
See
page
Offset
Name
Type
Reset
Description
0x058
0x05C
0x060
0x064
0x100
0x104
0x108
0x110
0x114
0x118
0x120
0x124
0x128
0x144
0x150
0x160
MISC
R/W1C
R/W
R/W
RO
0x0000.0000
-
Masked Interrupt Status and Clear
64
65
66
70
84
87
93
85
89
95
86
91
97
71
72
73
RESC
Reset Cause
RCC
0x07A0.3AD1
-
Run-Mode Clock Configuration
PLLCFG
RCGC0
RCGC1
RCGC2
SCGC0
SCGC1
SCGC2
DCGC0
DCGC1
DCGC2
DSLPCLKCFG
CLKVCLR
LDOARST
XTAL to PLL Translation
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0x00000040
0x00000000
0x00000000
0x00000040
0x00000000
0x00000000
0x00000040
0x00000000
0x00000000
0x0780.0000
0x0000.0000
0x0000.0000
Run Mode Clock Gating Control Register 0
Run Mode Clock Gating Control Register 1
Run Mode Clock Gating Control Register 2
Sleep Mode Clock Gating Control Register 0
Sleep Mode Clock Gating Control Register 1
Sleep Mode Clock Gating Control Register 2
Deep Sleep Mode Clock Gating Control Register 0
Deep Sleep Mode Clock Gating Control Register 1
Deep Sleep Mode Clock Gating Control Register 2
Deep Sleep Clock Configuration
Clock Verification Clear
Allow Unregulated LDO to Reset the Part
6.4
Register Descriptions
All addresses given are relative to the System Control base address of 0x400F.E000.
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October 01, 2007
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LM3S300 Microcontroller
Register 1: Device Identification 0 (DID0), offset 0x000
This register identifies the version of the device.
Device Identification 0 (DID0)
Base 0x400F.E000
Offset 0x000
Type RO, reset -
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
VER
reserved
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
MAJOR
MINOR
Type
Reset
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
Bit/Field
31
Name
Type
RO
Reset
0
Description
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.
30:28
VER
RO
0x0
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
0x0 Initial DID0 register format definition for Stellaris®
Sandstorm-class devices.
27:16
15:8
reserved
MAJOR
RO
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.
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.
October 01, 2007
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Preliminary
System Control
Bit/Field
7:0
Name
Type
RO
Reset
-
Description
MINOR
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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October 01, 2007
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LM3S300 Microcontroller
Register 2: Power-On and Brown-Out Reset Control (PBORCTL), offset 0x030
This register is responsible for controlling reset conditions after initial power-on reset.
Power-On and Brown-Out Reset Control (PBORCTL)
Base 0x400F.E000
Offset 0x030
Type R/W, reset 0x0000.7FFD
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
BORTIM
BORIOR BORWT
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
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
R/W
1
Bit/Field
31:16
Name
Type
RO
Reset
0x0
Description
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.
15:2
BORTIM
R/W
0x1FFF
BOR Time Delay
This field specifies the number of internal oscillator clocks delayed before
the BOR output is resampled if the BORWT bit is set.
The width of this field is derived by the t BOR width of 500 μs and the
internal oscillator (IOSC) frequency of 12 MHz ± 30%. At +30%, the
counter value has to exceed 7,800.
1
0
BORIOR
BORWT
R/W
R/W
0
1
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.
BOR Wait and Check for Noise
This bit specifies the response to a brown-out signal assertion if BORIOR
is not set.
If BORWT is set to 1 and BORIOR is cleared to 0, the controller waits
BORTIM IOSC periods and resamples the BOR output. If still asserted,
a BOR interrupt is signalled. If no longer asserted, the initial assertion
is suppressed (attributable to noise).
If BORWT is 0, BOR assertions do not resample the output and any
condition is reported immediately if enabled.
October 01, 2007
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Preliminary
System Control
Register 3: LDO Power Control (LDOPCTL), offset 0x034
The VADJ field in this register adjusts the on-chip output voltage (VOUT).
LDO Power Control (LDOPCTL)
Base 0x400F.E000
Offset 0x034
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
VADJ
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:6
Name
Type
RO
Reset
0
Description
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.
5:0
VADJ
R/W
0x0
LDO Output Voltage
This field sets the on-chip output voltage. The programming values for
the VADJ field are provided below.
Value
0x00
0x01
0x02
0x03
0x04
0x05
VOUT (V)
2.50
2.45
2.40
2.35
2.30
2.25
0x06-0x3F Reserved
0x1B
0x1C
0x1D
0x1E
0x1F
2.75
2.70
2.65
2.60
2.55
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October 01, 2007
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LM3S300 Microcontroller
Register 4: Raw Interrupt Status (RIS), offset 0x050
Central location for system control raw interrupts. These are set and cleared by hardware.
Raw Interrupt Status (RIS)
Base 0x400F.E000
Offset 0x050
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PLLLRIS CLRIS
IOFRIS MOFRIS LDORIS BORRIS PLLFRIS
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
Bit/Field
31:7
Name
Type
RO
Reset
0
Description
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.
6
5
4
3
2
1
PLLLRIS
CLRIS
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
PLL Lock Raw Interrupt Status
This bit is set when the PLL TREADY Timer asserts.
Current Limit Raw Interrupt Status
This bit is set if the LDO’s CLE output asserts.
IOFRIS
MOFRIS
LDORIS
BORRIS
Internal Oscillator Fault Raw Interrupt Status
This bit is set if an internal oscillator fault is detected.
Main Oscillator Fault Raw Interrupt Status
This bit is set if a main oscillator fault is detected.
LDO Power Unregulated Raw Interrupt Status
This bit is set if a LDO voltage is unregulated.
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
PLLFRIS
RO
0
PLL Fault Raw Interrupt Status
This bit is set if a PLL fault is detected (stops oscillating).
October 01, 2007
61
Preliminary
System Control
Register 5: Interrupt Mask Control (IMC), offset 0x054
Central location for system control interrupt masks.
Interrupt Mask Control (IMC)
Base 0x400F.E000
Offset 0x054
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PLLLIM
CLIM
IOFIM
MOFIM
LDOIM
BORIM PLLFIM
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:7
Name
Type
RO
Reset
0
Description
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.
6
5
4
3
2
1
PLLLIM
CLIM
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
PLL Lock Interrupt Mask
This bit specifies whether a current limit detection is promoted to a
controller interrupt. If set, an interrupt is generated if PLLLRIS in RIS
is set; otherwise, an interrupt is not generated.
Current Limit Interrupt Mask
This bit specifies whether a current limit detection is promoted to a
controller interrupt. If set, an interrupt is generated if CLRIS is set;
otherwise, an interrupt is not generated.
IOFIM
Internal Oscillator Fault Interrupt Mask
This bit specifies whether an internal oscillator fault detection is promoted
to a controller interrupt. If set, an interrupt is generated if IOFRIS is set;
otherwise, an interrupt is not generated.
MOFIM
LDOIM
BORIM
Main Oscillator Fault Interrupt Mask
This bit specifies whether a main oscillator fault detection is promoted
to a controller interrupt. If set, an interrupt is generated if MOFRIS is set;
otherwise, an interrupt is not generated.
LDO Power Unregulated Interrupt Mask
This bit specifies whether an LDO unregulated power situation is
promoted to a controller interrupt. If set, an interrupt is generated if
LDORIS is set; otherwise, an interrupt is not generated.
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.
62
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
0
Name
Type
R/W
Reset
0
Description
PLLFIM
PLL Fault Interrupt Mask
This bit specifies whether a PLL fault detection is promoted to a controller
interrupt. If set, an interrupt is generated if PLLFRIS is set; otherwise,
an interrupt is not generated.
October 01, 2007
63
Preliminary
System Control
Register 6: Masked Interrupt Status and Clear (MISC), offset 0x058
Central location for system control result of RIS AND IMC to generate an interrupt to the controller.
All of the bits are R/W1C and this action also clears the corresponding raw interrupt bit in the RIS
register (see page 61).
Masked Interrupt Status and Clear (MISC)
Base 0x400F.E000
Offset 0x058
Type R/W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PLLLMIS CLMIS
IOFMIS MOFMIS LDOMIS BORMIS reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
R/W1C
0
RO
0
Bit/Field
31:7
Name
Type
RO
Reset
0
Description
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.
6
5
4
3
2
1
PLLLMIS
CLMIS
R/W1C
R/W1C
R/W1C
R/W1C
R/W1C
R/W1C
0
0
0
0
0
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.
Current Limit Masked Interrupt Status
This bit is set if the LDO’s CLE output asserts. The interrupt is cleared
by writing a 1 to this bit.
IOFMIS
MOFMIS
LDOMIS
BORMIS
Internal Oscillator Fault Masked Interrupt Status
This bit is set if an internal oscillator fault is detected. The interrupt is
cleared by writing a 1 to this bit.
Main Oscillator Fault Masked Interrupt Status
This bit is set if a main oscillator fault is detected. The interrupt is cleared
by writing a 1 to this bit.
LDO Power Unregulated Masked Interrupt Status
This bit is set if LDO power is unregulated. The interrupt is cleared by
writing a 1 to this bit.
BOR Masked Interrupt Status
This bit is the masked interrupt status for any brown-out conditions. If
set, a brown-out condition was detected. An interrupt is reported if the
BORIM bit in the IMC register is set and the BORIOR bit in the PBORCTL
register is cleared. The interrupt is cleared by writing a 1 to this bit.
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.
64
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 7: Reset Cause (RESC), offset 0x05C
This field specifies the cause of the reset event to software. The reset value is determined by the
cause of the reset. When an external reset is the cause (EXT is set), all other reset bits are cleared.
However, if the reset is due to any other cause, the remaining bits are sticky, allowing software to
see all causes.
Reset Cause (RESC)
Base 0x400F.E000
Offset 0x05C
Type R/W, reset -
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
LDO
SW
WDT
BOR
POR
EXT
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
31:6
Name
Type
RO
Reset
0
Description
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.
5
LDO
R/W
-
LDO Reset
When set, indicates the LDO circuit has lost regulation and has
generated a reset event.
4
3
2
1
0
SW
WDT
BOR
POR
EXT
R/W
R/W
R/W
R/W
R/W
-
-
-
-
-
Software Reset
When set, indicates a software reset is the cause of the reset event.
Watchdog Timer Reset
When set, indicates a watchdog reset is the cause of the reset event.
Brown-Out Reset
When set, indicates a brown-out reset is the cause of the reset event.
Power-On Reset
When set, indicates a power-on reset is the cause of the reset event.
External Reset
When set, indicates an external reset (RST assertion) is the cause of
the reset event.
October 01, 2007
65
Preliminary
System Control
Register 8: Run-Mode Clock Configuration (RCC), offset 0x060
This register is defined to provide source control and frequency speed.
Run-Mode Clock Configuration (RCC)
Base 0x400F.E000
Offset 0x060
Type R/W, reset 0x07A0.3AD1
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
USESYSDIV
reserved
ACG
SYSDIV
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
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
reserved
PWRDN
OEN
BYPASS PLLVER
XTAL
OSCSRC
IOSCVER MOSCVER IOSCDIS MOSCDIS
Type
Reset
RO
0
RO
0
R/W
1
R/W
1
R/W
1
R/W
0
R/W
1
R/W
0
R/W
1
R/W
1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
1
Bit/Field
31:28
Name
Type
RO
Reset
0x0
Description
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.
27
ACG
R/W
0
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.
66
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
26:23
Name
Type
R/W
Reset
0xF
Description
SYSDIV
System Clock Divisor
Specifies which divisor is used to generate the system clock from the
PLL output.
The PLL VCO frequency is 200 MHz.
Value Divisor (BYPASS=1) Frequency (BYPASS=0)
0x0 reserved
0x1 /2
reserved
reserved
0x2 /3
reserved
0x3 /4
reserved
0x4 /5
reserved
0x5 /6
reserved
0x6 /7
reserved
0x7 /8
25 MHz
0x8 /9
22.22 MHz
20 MHz
0x9 /10
0xA /11
0xB /12
0xC /13
0xD /14
0xE /15
0xF /16
18.18 MHz
16.67 MHz
15.38 MHz
14.29 MHz
13.33 MHz
12.5 MHz (default)
When reading the Run-Mode Clock Configuration (RCC) register (see
page 66), the SYSDIV value is MINSYSDIV if a lower divider was
requested and the PLL is being used. This lower value is allowed to
divide a non-PLL source.
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.
21:14
13
reserved
PWRDN
RO
0
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.
R/W
PLL Power Down
This bit connects to the PLL PWRDN input. The reset value of 1 powers
down the PLL. See Table 6-2 on page 69 for PLL mode control.
12
OEN
R/W
1
PLL Output Enable
This bit specifies whether the PLL output driver is enabled. If cleared,
the driver transmits the PLL clock to the output. Otherwise, the PLL
clock does not oscillate outside the PLL module.
Note:
Both PWRDN and OEN must be cleared to run the PLL.
October 01, 2007
67
Preliminary
System Control
Bit/Field
11
Name
Type
R/W
Reset
1
Description
PLL Bypass
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.
10
PLLVER
XTAL
R/W
R/W
0
PLL Verification
This bit controls the PLL verification timer function. If set, the verification
timer is enabled and an interrupt is generated if the PLL becomes
inoperative. Otherwise, the verification timer is not enabled.
9:6
0xB
Crystal Value
This field specifies the crystal value attached to the main oscillator. The
encoding for this field is provided below.
Value
Crystal Frequency (MHz) Crystal Frequency (MHz)
Not Using the PLL
Using the PLL
0x0
1.000
reserved
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
0xC
0xD
0xE
0xF
1.8432
reserved
reserved
reserved
2.000
2.4576
3.579545 MHz
3.6864 MHz
4 MHz
4.096 MHz
4.9152 MHz
5 MHz
5.12 MHz
6 MHz (reset value)
6.144 MHz
7.3728 MHz
8 MHz
8.192 MHz
5:4
OSCSRC
R/W
0x0
Oscillator Source
Picks among the four input sources for the OSC. The values are:
Value Input Source
0x0 Main oscillator (default)
0x1 Internal oscillator (default)
0x2 Internal oscillator / 4 (this is necessary if used as input to PLL)
0x3 reserved
3
IOSCVER
R/W
0
Internal Oscillator Verification Timer
This bit controls the internal oscillator verification timer function. If set,
the verification timer is enabled and an interrupt is generated if the timer
becomes inoperative. Otherwise, the verification timer is not enabled.
68
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
2
Name
Type
R/W
Reset
0
Description
MOSCVER
Main Oscillator Verification Timer
This bit controls the main oscillator verification timer function. If set, the
verification timer is enabled and an interrupt is generated if the timer
becomes inoperative. Otherwise, the verification timer is not enabled.
1
0
IOSCDIS
R/W
R/W
0
1
Internal Oscillator Disable
0: Internal oscillator (IOSC) is enabled.
1: Internal oscillator is disabled.
MOSCDIS
Main Oscillator Disable
0: Main oscillator is enabled.
1: Main oscillator is disabled (default).
Table 6-2. PLL Mode Control
PWRDN OEN Mode
1
0
X
0
Power down
Normal
October 01, 2007
69
Preliminary
System Control
Register 9: XTAL to PLL Translation (PLLCFG), offset 0x064
This register provides a means of translating external crystal frequencies into the appropriate PLL
settings. This register is initialized during the reset sequence and updated anytime that the XTAL
field changes in the Run-Mode Clock Configuration (RCC) register (see page 66).
The PLL frequency is calculated using the PLLCFG field values, as follows:
PLLFreq = OSCFreq * (F + 2) / (R + 2)
XTAL to PLL Translation (PLLCFG)
Base 0x400F.E000
Offset 0x064
Type RO, reset -
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
F
8
7
6
5
4
3
2
1
0
OD
R
Type
Reset
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
RO
-
Bit/Field
31:16
Name
Type
RO
Reset
0x0
Description
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.
15:14
OD
RO
-
PLL OD Value
This field specifies the value supplied to the PLL’s OD input.
Value Description
0x0 Divide by 1
0x1 Divide by 2
0x2 Divide by 4
0x3 Reserved
13:5
4:0
F
RO
RO
-
-
PLL F Value
This field specifies the value supplied to the PLL’s F input.
R
PLL R Value
This field specifies the value supplied to the PLL’s R input.
70
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 10: Deep Sleep Clock Configuration (DSLPCLKCFG), offset 0x144
This register is used to automatically switch from the main oscillator to the internal oscillator when
entering Deep-Sleep mode. The system clock source is the main oscillator by default. When this
register is set, the internal oscillator is powered up and the main oscillator is powered down. 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.
Deep Sleep Clock Configuration (DSLPCLKCFG)
Base 0x400F.E000
Offset 0x144
Type R/W, reset 0x0780.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
IOSC
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
R/W
0
Bit/Field
31:1
Name
Type
RO
Reset
0x0
Description
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.
0
IOSC
R/W
0
IOSC Clock Source
When set, forces IOSC to be clock source during Deep-Sleep (overrides
DSOSCSRC field if set)
October 01, 2007
71
Preliminary
System Control
Register 11: Clock Verification Clear (CLKVCLR), offset 0x150
This register is provided as a means of clearing the clock verification circuits by software. Since the
clock verification circuits force a known good clock to control the process, the controller is allowed
the opportunity to solve the problem and clear the verification fault. This register clears all clock
verification faults. To clear a clock verification fault, the VERCLR bit must be set and then cleared
by software. This bit is not self-clearing.
Clock Verification Clear (CLKVCLR)
Base 0x400F.E000
Offset 0x150
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
reserved
VERCLR
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
R/W
0
Bit/Field
31:1
Name
Type
RO
Reset
0
Description
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.
0
VERCLR
R/W
0
Clock Verification Clear
Clears clock verification faults.
72
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 12: Allow Unregulated LDO to Reset the Part (LDOARST), offset
0x160
This register is provided as a means of allowing the LDO to reset the part if the voltage goes
unregulated. Use this register to choose whether to automatically reset the part if the LDO goes
unregulated, based on the design tolerance for LDO fluctuation.
Allow Unregulated LDO to Reset the Part (LDOARST)
Base 0x400F.E000
Offset 0x160
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
Reserved
LDOARST
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
R/W
0
Bit/Field
31:1
Name
Type
RO
Reset
0
Description
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.
0
LDOARST
R/W
0
LDO Reset
When set, allows unregulated LDO output to reset the part.
October 01, 2007
73
Preliminary
System Control
Register 13: Device Identification 1 (DID1), offset 0x004
This register identifies the device family, part number, temperature range, and package type.
Device Identification 1 (DID1)
Base 0x400F.E000
Offset 0x004
Type RO, reset -
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
VER
FAM
PARTNO
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
0
RO
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
reserved
TEMP
PKG
ROHS
QUAL
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
-
RO
-
Bit/Field
31:28
Name
VER
Type
RO
Reset
0x0
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
0x0 Initial DID1 register format definition, indicating a Stellaris
LM3Snnn device.
27:24
FAM
RO
0x0
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 Stellaris family of microcontollers, that is, all devices with
external part numbers starting with LM3S.
23:16
PARTNO
RO
0x19
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
0x19 LM3S300
15:8
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.
74
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
7:5
Name
TEMP
Type
RO
Reset
0x1
Description
Temperature Range
This field specifies the temperature rating of the device. The value is
encoded as follows (all other encodings are reserved):
Value Description
0x1 Industrial temperature range (-40°C to 85°C)
4:3
PKG
RO
0x1
Package Type
This field specifies the package type. The value is encoded as follows
(all other encodings are reserved):
Value Description
0x1 48-pin LQFP package
2
ROHS
QUAL
RO
RO
1
-
RoHS-Compliance
This bit specifies whether the device is RoHS-compliant. A 1 indicates
the part is RoHS-compliant.
1:0
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
October 01, 2007
75
Preliminary
System Control
Register 14: 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 0x000F.0007
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
SRAMSZ
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
1
RO
1
RO
1
RO
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FLASHSZ
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
1
RO
1
RO
1
Bit/Field
31:16
Name
Type
RO
Reset
Description
SRAM Size
SRAMSZ
0x000F
Indicates the size of the on-chip SRAM memory.
Value Description
0x000F 4 KB of SRAM
15:0
FLASHSZ
RO
0x0007
Flash Size
Indicates the size of the on-chip flash memory.
Value Description
0x0007 16 KB of Flash
76
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 15: Device Capabilities 1 (DC1), offset 0x010
This register provides a list of features available in the system. The Stellaris family uses this register
format to indicate the availability of the following family features in the specific device: PWM, ADC,
Watchdog timer, and debug capabilities. This register also indicates the maximum clock frequency
and maximum ADC sample rate. The format of this register is consistent with the RCGC0, SCGC0,
and DCGC0 clock control registers and the SRCR0 software reset control register.
Device Capabilities 1 (DC1)
Base 0x400F.E000
Offset 0x010
Type RO, reset 0x0000.709F
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
MINSYSDIV
reserved
MPU
reserved
PLL
WDT
SWO
SWD
JTAG
Type
Reset
RO
0
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
1
Bit/Field
31:16
Name
Type
RO
Reset
0
Description
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.
15:12
MINSYSDIV
RO
0x7
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
0x7 Specifies a 25-MHz clock with a PLL divider of 8.
11:8
7
reserved
MPU
RO
RO
0
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.
MPU Present
When set, indicates that the Cortex-M3 Memory Protection Unit (MPU)
module is present. See the ARM Cortex-M3 Technical Reference Manual
for details on the MPU.
6:5
4
reserved
PLL
RO
RO
0
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.
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.
October 01, 2007
77
Preliminary
System Control
Bit/Field
2
Name
SWO
Type
RO
Reset
1
Description
SWO Trace Port Present
When set, indicates that the Serial Wire Output (SWO) trace port is
present.
1
0
SWD
JTAG
RO
RO
1
1
SWD Present
When set, indicates that the Serial Wire Debugger (SWD) is present.
JTAG Present
When set, indicates that the JTAG debugger interface is present.
78
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 16: Device Capabilities 2 (DC2), offset 0x014
This register provides a list of features available in the system. The Stellaris family uses this register
format to indicate the availability of the following family features in the specific device: Analog
Comparators, General-Purpose Timers, I2Cs, QEIs, SSIs, and UARTs. The format of this register
is consistent with the RCGC1, SCGC1, and DCGC1 clock control registers and the SRCR1 software
reset control register.
Device Capabilities 2 (DC2)
Base 0x400F.E000
Offset 0x014
Type RO, reset 0x0707.1013
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
COMP2 COMP1 COMP0
reserved
TIMER2 TIMER1 TIMER0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
RO
0
RO
0
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
1
0
reserved
I2C0
reserved
SSI0
reserved
UART1
UART0
Type
Reset
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
1
RO
1
Bit/Field
31:27
Name
Type
RO
Reset
0
Description
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.
26
25
COMP2
COMP1
COMP0
reserved
RO
RO
RO
RO
1
1
1
0
Analog Comparator 2 Present
When set, indicates that analog comparator 2 is present.
Analog Comparator 1 Present
When set, indicates that analog comparator 1 is present.
24
Analog Comparator 0 Present
When set, indicates that analog comparator 0 is present.
23:19
Software should not rely on the value of 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
17
TIMER2
TIMER1
TIMER0
reserved
RO
RO
RO
RO
1
1
1
0
Timer 2 Present
When set, indicates that General-Purpose Timer module 2 is present.
Timer 1 Present
When set, indicates that General-Purpose Timer module 1 is present.
16
Timer 0 Present
When set, indicates that General-Purpose Timer module 0 is present.
15:13
Software should not rely on the value of 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.
October 01, 2007
79
Preliminary
System Control
Bit/Field
11:5
Name
Type
RO
Reset
0
Description
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.
4
SSI0
RO
RO
1
0
SSI0 Present
When set, indicates that SSI module 0 is present.
3:2
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.
1
0
UART1
UART0
RO
RO
1
1
UART1 Present
When set, indicates that UART module 1 is present.
UART0 Present
When set, indicates that UART module 0 is present.
80
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 17: Device Capabilities 3 (DC3), offset 0x018
This register provides a list of features available in the system. The Stellaris family uses this register
format to indicate the availability of the following family features in the specific device: Analog
Comparator I/Os, CCP I/Os, ADC I/Os, and PWM I/Os.
Device Capabilities 3 (DC3)
Base 0x400F.E000
Offset 0x018
Type RO, reset 0x3F00.7FC0
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
CCP5
CCP4
CCP3
CCP2
CCP1
CCP0
reserved
Type
Reset
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
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
reserved
C2O
C2PLUS C2MINUS C1O
C1PLUS C1MINUS C0O
C0PLUS C0MINUS
reserved
Type
Reset
RO
0
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:30
Name
Type
RO
Reset
0
Description
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.
29
28
CCP5
CCP4
CCP3
CCP2
CCP1
CCP0
reserved
RO
RO
RO
RO
RO
RO
RO
1
1
1
1
1
1
0
CCP5 Pin Present
When set, indicates that Capture/Compare/PWM pin 5 is present.
CCP4 Pin Present
When set, indicates that Capture/Compare/PWM pin 4 is present.
27
CCP3 Pin Present
When set, indicates that Capture/Compare/PWM pin 3 is present.
26
CCP2 Pin Present
When set, indicates that Capture/Compare/PWM pin 2 is present.
25
CCP1 Pin Present
When set, indicates that Capture/Compare/PWM pin 1 is present.
24
CCP0 Pin Present
When set, indicates that Capture/Compare/PWM pin 0 is present.
23:15
Software should not rely on the value of 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
13
C2O
RO
RO
1
1
C2o Pin Present
When set, indicates that the analog comparator 2 output pin is present.
C2PLUS
C2+ Pin Present
When set, indicates that the analog comparator 2 (+) input pin is present.
October 01, 2007
81
Preliminary
System Control
Bit/Field
12
Name
Type
RO
Reset
1
Description
C2MINUS
C2- Pin Present
When set, indicates that the analog comparator 2 (-) input pin is present.
11
10
9
C1O
RO
RO
RO
RO
RO
RO
RO
1
1
1
1
1
1
0
C1o Pin Present
When set, indicates that the analog comparator 1 output pin is present.
C1PLUS
C1MINUS
C0O
C1+ Pin Present
When set, indicates that the analog comparator 1 (+) input pin is present.
C1- Pin Present
When set, indicates that the analog comparator 1 (-) input pin is present.
8
C0o Pin Present
When set, indicates that the analog comparator 0 output pin is present.
7
C0PLUS
C0MINUS
reserved
C0+ Pin Present
When set, indicates that the analog comparator 0 (+) input pin is present.
6
C0- Pin Present
When set, indicates that the analog comparator 0 (-) input pin is present.
5:0
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.
82
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 18: Device Capabilities 4 (DC4), offset 0x01C
This register provides a list of features available in the system. The Stellaris family uses this register
format to indicate the availability of GPIOs in the specific device. The format of this register is
consistent with the RCGC2, SCGC2, and DCGC2 clock control registers and the SRCR2 software
reset control register.
Device Capabilities 4 (DC4)
Base 0x400F.E000
Offset 0x01C
Type RO, reset 0x0000.001F
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
reserved
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
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
1
RO
1
RO
1
RO
1
RO
1
Bit/Field
31:5
Name
Type
RO
Reset
0
Description
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.
4
3
2
1
0
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
RO
RO
RO
RO
RO
1
1
1
1
1
GPIO Port E Present
When set, indicates that GPIO Port E is present.
GPIO Port D Present
When set, indicates that GPIO Port D is present.
GPIO Port C Present
When set, indicates that GPIO Port C is present.
GPIO Port B Present
When set, indicates that GPIO Port B is present.
GPIO Port A Present
When set, indicates that GPIO Port A is present.
October 01, 2007
83
Preliminary
System Control
Register 19: Run Mode Clock Gating Control Register 0 (RCGC0), offset 0x100
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the
clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Run Mode Clock Gating Control Register 0 (RCGC0)
Base 0x400F.E000
Offset 0x100
Type R/W, reset 0x00000040
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
WDT
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
R/W
0
RO
0
RO
0
RO
0
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
3
WDT
R/W
RO
0
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
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
84
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 20: Sleep Mode Clock Gating Control Register 0 (SCGC0), offset
0x110
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the
clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Sleep Mode Clock Gating Control Register 0 (SCGC0)
Base 0x400F.E000
Offset 0x110
Type R/W, reset 0x00000040
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
WDT
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
R/W
0
RO
0
RO
0
RO
0
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
3
WDT
R/W
RO
0
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
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
October 01, 2007
85
Preliminary
System Control
Register 21: Deep Sleep Mode Clock Gating Control Register 0 (DCGC0),
offset 0x120
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC0 is the
clock configuration register for running operation, SCGC0 for Sleep operation, and DCGC0 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Deep Sleep Mode Clock Gating Control Register 0 (DCGC0)
Base 0x400F.E000
Offset 0x120
Type R/W, reset 0x00000040
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
WDT
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
R/W
0
RO
0
RO
0
RO
0
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
3
WDT
R/W
RO
0
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
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
86
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 22: Run Mode Clock Gating Control Register 1 (RCGC1), offset 0x104
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the
clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Run Mode Clock Gating Control Register 1 (RCGC1)
Base 0x400F.E000
Offset 0x104
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
COMP2 COMP1 COMP0
reserved
TIMER2 TIMER1 TIMER0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
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
reserved
I2C0
reserved
SSI0
reserved
UART1
UART0
Type
Reset
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
Bit/Field
31:27
Name
Type
RO
Reset
0
Description
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.
26
25
COMP2
COMP1
COMP0
reserved
R/W
R/W
R/W
RO
0
0
0
0
Analog Comparator 2 Clock Gating
This bit controls the clock gating for analog comparator 2. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
Analog Comparator 1 Clock Gating
This bit controls the clock gating for analog comparator 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
24
Analog Comparator 0 Clock Gating
This bit controls the clock gating for analog comparator 0. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
23:19
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
October 01, 2007
87
Preliminary
System Control
Bit/Field
18
Name
Type
R/W
Reset
0
Description
TIMER2
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
16
TIMER1
TIMER0
R/W
R/W
0
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.
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.
15:13
12
reserved
I2C0
RO
0
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.
R/W
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.
11:5
4
reserved
SSI0
RO
0
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.
R/W
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.
3:2
1
reserved
UART1
RO
0
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.
R/W
UART1 Clock Gating Control
This bit controls the clock gating for UART module 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
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.
88
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 23: Sleep Mode Clock Gating Control Register 1 (SCGC1), offset
0x114
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the
clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Sleep Mode Clock Gating Control Register 1 (SCGC1)
Base 0x400F.E000
Offset 0x114
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
COMP2 COMP1 COMP0
reserved
TIMER2 TIMER1 TIMER0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
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
reserved
I2C0
reserved
SSI0
reserved
UART1
UART0
Type
Reset
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
Bit/Field
31:27
Name
Type
RO
Reset
0
Description
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.
26
25
COMP2
COMP1
COMP0
reserved
R/W
R/W
R/W
RO
0
0
0
0
Analog Comparator 2 Clock Gating
This bit controls the clock gating for analog comparator 2. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
Analog Comparator 1 Clock Gating
This bit controls the clock gating for analog comparator 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
24
Analog Comparator 0 Clock Gating
This bit controls the clock gating for analog comparator 0. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
23:19
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
October 01, 2007
89
Preliminary
System Control
Bit/Field
18
Name
Type
R/W
Reset
0
Description
TIMER2
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
16
TIMER1
TIMER0
R/W
R/W
0
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.
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.
15:13
12
reserved
I2C0
RO
0
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.
R/W
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.
11:5
4
reserved
SSI0
RO
0
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.
R/W
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.
3:2
1
reserved
UART1
RO
0
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.
R/W
UART1 Clock Gating Control
This bit controls the clock gating for UART module 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
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.
90
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 24: Deep Sleep Mode Clock Gating Control Register 1 (DCGC1),
offset 0x124
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC1 is the
clock configuration register for running operation, SCGC1 for Sleep operation, and DCGC1 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Deep Sleep Mode Clock Gating Control Register 1 (DCGC1)
Base 0x400F.E000
Offset 0x124
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
COMP2 COMP1 COMP0
reserved
TIMER2 TIMER1 TIMER0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
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
reserved
I2C0
reserved
SSI0
reserved
UART1
UART0
Type
Reset
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
Bit/Field
31:27
Name
Type
RO
Reset
0
Description
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.
26
25
COMP2
COMP1
COMP0
reserved
R/W
R/W
R/W
RO
0
0
0
0
Analog Comparator 2 Clock Gating
This bit controls the clock gating for analog comparator 2. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
Analog Comparator 1 Clock Gating
This bit controls the clock gating for analog comparator 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
24
Analog Comparator 0 Clock Gating
This bit controls the clock gating for analog comparator 0. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
23:19
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
October 01, 2007
91
Preliminary
System Control
Bit/Field
18
Name
Type
R/W
Reset
0
Description
TIMER2
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
16
TIMER1
TIMER0
R/W
R/W
0
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.
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.
15:13
12
reserved
I2C0
RO
0
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.
R/W
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.
11:5
4
reserved
SSI0
RO
0
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.
R/W
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.
3:2
1
reserved
UART1
RO
0
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.
R/W
UART1 Clock Gating Control
This bit controls the clock gating for UART module 1. If set, the unit
receives a clock and functions. Otherwise, the unit is unclocked and
disabled. If the unit is unclocked, reads or writes to the unit will generate
a bus fault.
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.
92
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 25: Run Mode Clock Gating Control Register 2 (RCGC2), offset 0x108
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the
clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Run Mode Clock Gating Control Register 2 (RCGC2)
Base 0x400F.E000
Offset 0x108
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:5
Name
Type
RO
Reset
0
Description
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.
4
3
2
1
GPIOE
GPIOD
GPIOC
GPIOB
R/W
R/W
R/W
R/W
0
0
0
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.
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.
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.
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.
October 01, 2007
93
Preliminary
System Control
Bit/Field
0
Name
Type
R/W
Reset
0
Description
GPIOA
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.
94
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 26: Sleep Mode Clock Gating Control Register 2 (SCGC2), offset
0x118
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the
clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Sleep Mode Clock Gating Control Register 2 (SCGC2)
Base 0x400F.E000
Offset 0x118
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:5
Name
Type
RO
Reset
0
Description
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.
4
3
2
1
GPIOE
GPIOD
GPIOC
GPIOB
R/W
R/W
R/W
R/W
0
0
0
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.
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.
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.
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.
October 01, 2007
95
Preliminary
System Control
Bit/Field
0
Name
Type
R/W
Reset
0
Description
GPIOA
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.
96
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 27: Deep Sleep Mode Clock Gating Control Register 2 (DCGC2),
offset 0x128
This register controls the clock gating logic. Each bit controls a clock enable for a given interface,
function, or unit. If set, the unit receives a clock and functions. Otherwise, the unit is unclocked and
disabled (saving power). If the unit is unclocked, reads or writes to the unit will generate a bus fault.
The reset state of these bits is 0 (unclocked) unless otherwise noted, so that all functional units are
disabled. It is the responsibility of software to enable the ports necessary for the application. Note
that these registers may contain more bits than there are interfaces, functions, or units to control.
This is to assure reasonable code compatibility with other family and future parts. RCGC2 is the
clock configuration register for running operation, SCGC2 for Sleep operation, and DCGC2 for
Deep-Sleep operation. Setting the ACG bit in the Run-Mode Clock Configuration (RCC) register
specifies that the system uses sleep modes.
Deep Sleep Mode Clock Gating Control Register 2 (DCGC2)
Base 0x400F.E000
Offset 0x128
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:5
Name
Type
RO
Reset
0
Description
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.
4
3
2
1
GPIOE
GPIOD
GPIOC
GPIOB
R/W
R/W
R/W
R/W
0
0
0
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.
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.
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.
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.
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Bit/Field
0
Name
Type
R/W
Reset
0
Description
GPIOA
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.
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Register 28: Software Reset Control 0 (SRCR0), offset 0x040
Writes to this register are masked by the bits in the Device Capabilities 1 (DC1) register.
Software Reset Control 0 (SRCR0)
Base 0x400F.E000
Offset 0x040
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
WDT
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
R/W
0
RO
0
RO
0
RO
0
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
3
WDT
R/W
RO
0
0
WDT Reset Control
Reset control for Watchdog unit.
2:0
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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Register 29: Software Reset Control 1 (SRCR1), offset 0x044
Writes to this register are masked by the bits in the Device Capabilities 2 (DC2) register.
Software Reset Control 1 (SRCR1)
Base 0x400F.E000
Offset 0x044
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
COMP2 COMP1 COMP0
reserved
TIMER2 TIMER1 TIMER0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
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
reserved
I2C0
reserved
SSI0
reserved
UART1
UART0
Type
Reset
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
R/W
0
R/W
0
Bit/Field
31:27
Name
Type
RO
Reset
0
Description
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.
26
25
COMP2
COMP1
COMP0
reserved
R/W
R/W
R/W
RO
0
0
0
0
Analog Comp 2 Reset Control
Reset control for analog comparator 2.
Analog Comp 1 Reset Control
Reset control for analog comparator 1.
24
Analog Comp 0 Reset Control
Reset control for analog comparator 0.
23:19
Software should not rely on the value of 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
17
TIMER2
TIMER1
TIMER0
reserved
R/W
R/W
R/W
RO
0
0
0
0
Timer 2 Reset Control
Reset control for General-Purpose Timer module 2.
Timer 1 Reset Control
Reset control for General-Purpose Timer module 1.
16
Timer 0 Reset Control
Reset control for General-Purpose Timer module 0.
15:13
Software should not rely on the value of 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
RO
0
0
I2C0 Reset Control
Reset control for I2C unit 0.
11:5
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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LM3S300 Microcontroller
Bit/Field
4
Name
SSI0
Type
R/W
Reset
0
Description
SSI0 Reset Control
Reset control for SSI unit 0.
3:2
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
0
UART1
UART0
R/W
R/W
0
0
UART1 Reset Control
Reset control for UART unit 1.
UART0 Reset Control
Reset control for UART unit 0.
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Register 30: Software Reset Control 2 (SRCR2), offset 0x048
Writes to this register are masked by the bits in the Device Capabilities 4 (DC4) register.
Software Reset Control 2 (SRCR2)
Base 0x400F.E000
Offset 0x048
Type R/W, reset 0x00000000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:5
Name
Type
RO
Reset
0
Description
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.
4
3
2
1
0
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
Port E Reset Control
Reset control for GPIO Port E.
Port D Reset Control
Reset control for GPIO Port D.
Port C Reset Control
Reset control for GPIO Port C.
Port B Reset Control
Reset control for GPIO Port B.
Port A Reset Control
Reset control for GPIO Port A.
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LM3S300 Microcontroller
7
Internal Memory
The LM3S300 microcontroller comes with 4 KB of bit-banded SRAM and 16 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. Flash Block Diagram
Flash Timing
USECRL
Flash Control
ICode
Cortex-M3
DCode
FMA
Flash Array
FMD
FMC
System Bus
FCRIS
FCIM
FCMISC
APB
Bridge
Flash Protection
FMPRE
SRAM Array
FMPPE
7.2
Functional Description
This section describes the functionality of both the flash and SRAM memories.
7.2.1
SRAM Memory
The internal SRAM of the Stellaris® devices is located at address 0x2000.0000 of the device memory
map. To reduce the number of time consuming read-modify-write (RMW) operations, ARM has
introduced bit-banding technology in the Cortex-M3 processor. With a bit-band-enabled processor,
certain regions in the memory map (SRAM and peripheral space) can use address aliases to access
individual bits in a single, atomic operation.
The bit-band alias is calculated by using the formula:
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bit-band alias = bit-band base + (byte offset * 32) + (bit number * 4)
For example, if bit 3 at address 0x2000.1000 is to be modified, the bit-band alias is calculated as:
0x2200.0000 + (0x1000 * 32) + (3 * 4) = 0x2202.000C
With the alias address calculated, an instruction performing a read/write to address 0x2202.000C
allows direct access to only bit 3 of the byte at address 0x2000.1000.
For details about bit-banding, please refer to Chapter 4, “Memory Map” in the ARM® Cortex™-M3
Technical Reference Manual.
7.2.2
Flash Memory
The flash is organized as a set of 1-KB blocks that can be individually erased. Erasing a block
causes the entire contents of the block to be reset to all 1s. An individual 32-bit word can be
programmed to change bits that are currently 1 to a 0. These blocks are paired into a set of 2-KB
blocks that can be individually protected. The protection allows blocks to be marked as read-only
or execute-only, providing different levels of code protection. Read-only blocks cannot be erased
or programmed, protecting the contents of those blocks from being modified. Execute-only blocks
cannot be erased or programmed, and can only be read by the controller instruction fetch mechanism,
protecting the contents of those blocks from being read by either the controller or by a debugger.
See also “Serial Flash Loader” on page 360 for a preprogrammed flash-resident utility used to
download code to the flash memory of a device without the use of a debug interface.
7.2.2.1 Flash Memory Timing
The timing for the flash is automatically handled by the flash controller. However, in order to do so,
it must know the clock rate of the system in order to time its internal signals properly. The number
of clock cycles per microsecond must be provided to the flash controller for it to accomplish this
timing. It is software's responsibility to keep the flash controller updated with this information via the
USec Reload (USECRL) register.
On reset, the USECRL register is loaded with a value that configures the flash timing so that it works
with the maximum clock rate of the part. If software changes the system operating frequency, the
new operating frequency minus 1 (in MHz) must be loaded into USECRL before any flash
modifications are attempted. For example, if the device is operating at a speed of 20 MHz, a value
of 0x13 (20-1) must be written to the USECRL register.
7.2.2.2 Flash Memory Protection
The user is provided two forms of flash protection per 2-KB flash blocks in two 32-bit wide
registers.The protection policy for each form is controlled by individual bits (per policy per block) in
the FMPPEn and FMPREn registers.
■ Flash Memory Protection Program Enable (FMPPEn): If set, the block may be programmed
(written) or erased. If cleared, the block may not be changed.
■ Flash Memory Protection Read Enable (FMPREn): If set, the block may be executed or read
by software or debuggers. If cleared, the block may only be executed. The contents of the memory
block are prohibited from being accessed as data and traversing the DCode bus.
The policies may be combined as shown in Table 7-1 on page 105.
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October 01, 2007
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LM3S300 Microcontroller
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
0
1
The block may be written, erased or executed, but not read. This combination is unlikely to be used.
Read-only protection. The block may be read or executed but may not be written or erased. This mode
is used to lock the block from further modification while allowing any read or execute access.
1
1
No protection. The block may be written, erased, executed or read.
An access that attempts to program or erase a PE-protected block is prohibited. A controller interrupt
may be optionally generated (by setting the AMASK bit in the FIM register) to alert software developers
of poorly behaving software during the development and debug phases.
An access that attempts to read an RE-protected block is prohibited. Such accesses return data
filled with all 0s. A controller interrupt may be optionally generated to alert software developers of
poorly behaving software during the development and debug phases.
The factory settings for the FMPREn and FMPPEn registers are a value of 1 for all implemented
banks. This implements a policy of open access and programmability. The register bits may be
changed by writing the specific register bit. The changes are not permanent until the register is
committed (saved), at which point the bit change is permanent. If a bit is changed from a 1 to a 0
and not committed, it may be restored by executing a power-on reset sequence.
7.2.2.3 Flash Protection by Disabling Debug Access
Flash memory may also be protected by permanently disabling access to the Debug Access Port
(DAP) through the JTAG and SWD interfaces. This is accomplished by clearing the DBG field of
the FMPRE register.
Flash Memory Protection Read Enable (DBG field): If set to 0x2, access to the DAP is enabled
through the JTAG and SWD interfaces. If clear, access to the DAP is disabled. The DBG field
programming becomes permanent, and irreversible, after a commit sequence is performed.
In the initial state, provided from the factory, access is enabled in order to facilitate code development
and debug. Access to the DAP may be disabled at the end of the manufacturing flow, once all tests
have passed and software loaded. This change will not take effect until the next power-up of the
device. Note that it is recommended that disabling access to the DAP be combined with a mechanism
for providing end-user installable updates (if necessary) such as the Stellaris boot loader.
Important: Once the DBG field is cleared and committed, this field can never be restored to the
factory-programmed value—which means JTAG/SWD interface to the debug module
can never be re-enabled. This sequence does NOT disable the JTAG controller, it only
disables the access of the DAP through the JTAG or SWD interfaces. The JTAG interface
remains functional and access to the Test Access Port remains enabled, allowing the
user to execute the IEEE JTAG-defined instructions (for example, to perform boundary
scan operations).
If the user will also be using the FMPRE bits to protect flash memory from being read as data (to
mark sets of 2 KB blocks of flash memory as execute-only), these one-time-programmable bits
should be written at the same time that the debug disable bits are programmed. Mechanisms to
execute the one-time code sequence to disable all debug access include:
■ Selecting the debug disable option in the Stellaris boot loader
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■ Loading the debug disable sequence into SRAM and running it once from SRAM after
programming the final end application code into flash
7.3
Flash Memory Initialization and Configuration
This section shows examples for using the flash controller to perform various operations on the
contents of the flash memory.
7.3.1
Changing Flash Protection Bits
As discussed in “Flash Memory Protection” on page 104, changes to the protection bits must be
committed before they take effect. The sequence below is used change and commit a block protection
bit in the FMPRE or FMPPE registers. The sequence to change and commit a bit in software is as
follows:
1. The Flash Memory Protection Read Enable (FMPRE) and Flash Memory Protection Program
Enable (FMPPE) registers are written, changing the intended bit(s). The action of these changes
can be tested by software while in this state.
2. The Flash Memory Address (FMA) register (see page 109) bit 0 is set to 1 if the FMPPE register
is to be committed; otherwise, a 0 commits the FMPRE register.
3. The Flash Memory Control (FMC) register (see page 111) is written with the COMT bit set. This
initiates a write sequence and commits the changes.
There is a special sequence to change and commit the DBG bits in the Flash Memory Protection
Read Enable (FMPRE) register. This sequence also sets and commits any changes from 1 to 0 in
the block protection bits (for execute-only) in the FMPRE register.
1. The Flash Memory Protection Read Enable (FMPRE) register is written, changing the intended
bit(s). The action of these changes can be tested by software while in this state.
2. The Flash Memory Address (FMA) register (see ppage 109) is written with a value of 0x900.
3. The Flash Memory Control (FMC) register (see page 111) is written with the COMT bit set. This
initiates a write sequence and commits the changes.
Below is an example code sequence to permanently disable the JTAG and SWD interface to the
debug module using Luminary Micro's DriverLib peripheral driver library:
#include "hw_types.h"
#include "hw_flash.h"
void
permanently_disable_jtag_swd(void)
{
//
// Clear the DBG field of the FMPRE register. Note that the value
// used in this instance does not affect the state of the BlockN
// bits, but were the value different, all bits in the FMPRE are
// affected by this function!
//
HWREG(FLASH_FMPRE) &= 0x3fffffff;
//
// The following sequence activates the one-time
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October 01, 2007
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LM3S300 Microcontroller
// programming of the FMPRE register.
//
HWREG(FLASH_FMA) = 0x900;
HWREG(FLASH_FMC) = (FLASH_FMC_WRKEY | FLASH_FMC_COMT);
//
// Wait until the operation is complete.
//
while (HWREG(FLASH_FMC) & FLASH_FMC_COMT)
{
}
}
7.3.2
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.
7.3.2.1 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.
7.3.2.2 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.
7.3.2.3 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.
7.4
Register Map
Table 7-2 on page 108 lists the Flash memory and control registers. The offset listed is a hexadecimal
increment to the register's address. The FMA, FMD, FMC, FCRIS, FCIM, and FCMISC registers
are relative to the Flash control base address of 0x400F.D000. The FMPREn, FMPPEn, USECRL,
USER_DBG, and USER_REGn registers are relative to the System Control base address of
0x400F.E000.
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Table 7-2. Flash Register Map
See
page
Offset
Name
Type
Reset
Description
Flash Control Offset
0x000
0x004
0x008
0x00C
0x010
0x014
FMA
R/W
R/W
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
Flash Memory Address
109
110
111
113
114
115
FMD
Flash Memory Data
FMC
R/W
Flash Memory Control
FCRIS
FCIM
FCMISC
RO
Flash Controller Raw Interrupt Status
Flash Controller Interrupt Mask
Flash Controller Masked Interrupt Status and Clear
R/W
R/W1C
System Control Offset
0x130
0x134
0x140
FMPRE
FMPPE
USECRL
R/W
R/W
R/W
0x8000.00FF
0x0000.00FF
0x16
Flash Memory Protection Read Enable
Flash Memory Protection Program Enable
USec Reload
117
118
116
7.5
Flash Register Descriptions (Flash Control Offset)
The remainder of this section lists and describes the Flash Memory registers, in numerical order by
address offset. Registers in this section are relative to the Flash control base address of 0x400F.D000.
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Register 1: Flash Memory Address (FMA), offset 0x000
During a write operation, this register contains a 4-byte-aligned address and specifies where the
data is written. During erase operations, this register contains a 1 KB-aligned address and specifies
which page is erased. Note that the alignment requirements must be met by software or the results
of the operation are unpredictable.
Flash Memory Address (FMA)
Base 0x400F.D000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
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
reserved
OFFSET
Type
Reset
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
Bit/Field
31:14
Name
Type
RO
Reset
0x0
Description
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.
13:0
OFFSET
R/W
0x0
Address Offset
Address offset in flash where operation is performed.
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Register 2: Flash Memory Data (FMD), offset 0x004
This register contains the data to be written during the programming cycle or read during the read
cycle. Note that the contents of this register are undefined for a read access of an execute-only
block. This register is not used during the erase cycles.
Flash Memory Data (FMD)
Base 0x400F.D000
Offset 0x004
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
DATA
DATA
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
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
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
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
31:0
Name
DATA
Type
R/W
Reset
0x0
Description
Data Value
Data value for write operation.
110
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 3: Flash Memory Control (FMC), offset 0x008
When this register is written, the flash controller initiates the appropriate access cycle for the location
specified by the Flash Memory Address (FMA) register (see page 109). If the access is a write
access, the data contained in the Flash Memory Data (FMD) register (see page 110) is written.
This is the final register written and initiates the memory operation. There are four control bits in the
lower byte of this register that, when set, initiate the memory operation. The most used of these
register bits are the ERASE and WRITE bits.
It is a programming error to write multiple control bits and the results of such an operation are
unpredictable.
Flash Memory Control (FMC)
Base 0x400F.D000
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WRKEY
Type
Reset
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
reserved
COMT MERASE ERASE WRITE
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:16
Name
Type
WO
Reset
0x0
Description
WRKEY
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
3
reserved
COMT
RO
0x0
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.
R/W
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.
Mass Erase Flash Memory
2
MERASE
R/W
0
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.
October 01, 2007
111
Preliminary
Internal Memory
Bit/Field
1
Name
Type
R/W
Reset
0
Description
ERASE
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.
112
October 01, 2007
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LM3S300 Microcontroller
Register 4: Flash Controller Raw Interrupt Status (FCRIS), offset 0x00C
This register indicates that the flash controller has an interrupt condition. An interrupt is only signaled
if the corresponding FCIM register bit is set.
Flash Controller Raw Interrupt Status (FCRIS)
Base 0x400F.D000
Offset 0x00C
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PRIS
ARIS
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
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
PRIS
ARIS
RO
0
Programming Raw Interrupt Status
This bit indicates the current state of the programming cycle. If set, the
programming cycle completed; if cleared, the programming cycle has
not completed. Programming cycles are either write or erase actions
generated through the Flash Memory Control (FMC) register bits (see
page 111).
0
RO
0
Access Raw Interrupt Status
This bit indicates if the flash was improperly accessed. If set, the program
tried to access the flash counter to the policy as set in the Flash Memory
Protection Read Enable (FMPREn) and Flash Memory Protection
Program Enable (FMPPEn) registers. Otherwise, no access has tried
to improperly access the flash.
October 01, 2007
113
Preliminary
Internal Memory
Register 5: Flash Controller Interrupt Mask (FCIM), offset 0x010
This register controls whether the flash controller generates interrupts to the controller.
Flash Controller Interrupt Mask (FCIM)
Base 0x400F.D000
Offset 0x010
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PMASK AMASK
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
R/W
0
R/W
0
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
0
PMASK
AMASK
R/W
R/W
0
0
Programming Interrupt Mask
This bit controls the reporting of the programming raw interrupt status
to the controller. If set, a programming-generated interrupt is promoted
to the controller. Otherwise, interrupts are recorded but suppressed from
the controller.
Access Interrupt Mask
This bit controls the reporting of the access raw interrupt status to the
controller. If set, an access-generated interrupt is promoted to the
controller. Otherwise, interrupts are recorded but suppressed from the
controller.
114
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 6: Flash Controller Masked Interrupt Status and Clear (FCMISC),
offset 0x014
This register provides two functions. First, it reports the cause of an interrupt by indicating which
interrupt source or sources are signalling the interrupt. Second, it serves as the method to clear the
interrupt reporting.
Flash Controller Masked Interrupt Status and Clear (FCMISC)
Base 0x400F.D000
Offset 0x014
Type R/W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PMISC
AMISC
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
R/W1C
0
R/W1C
0
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
0
PMISC
AMISC
R/W1C
R/W1C
0
0
Programming Masked Interrupt Status and Clear
This bit indicates whether an interrupt was signaled because a
programming cycle completed and was not masked. This bit is cleared
by writing a 1. The PRIS bit in the FCRIS register (see page 113) is also
cleared when the PMISC bit is cleared.
Access Masked Interrupt Status and Clear
This bit indicates whether an interrupt was signaled because an improper
access was attempted and was not masked. This bit is cleared by writing
a 1. The ARIS bit in the FCRIS register is also cleared when the AMISC
bit is cleared.
7.6
Flash Register Descriptions (System Control Offset)
The remainder of this section lists and describes the Flash Memory registers, in numerical order by
address offset. Registers in this section are relative to the System Control base address of
0x400F.E000.
October 01, 2007
115
Preliminary
Internal Memory
Register 7: USec Reload (USECRL), offset 0x140
Note: Offset is relative to System Control base address of 0x400F.E000
This register is provided as a means of creating a 1-μs tick divider reload value for the flash controller.
The internal flash has specific minimum and maximum requirements on the length of time the high
voltage write pulse can be applied. It is required that this register contain the operating frequency
(in MHz -1) whenever the flash is being erased or programmed. The user is required to change this
value if the clocking conditions are changed for a flash erase/program operation.
USec Reload (USECRL)
Base 0x400F.E000
Offset 0x140
Type R/W, reset 0x16
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
reserved
USEC
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
1
R/W
1
R/W
0
R/W
0
R/W
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
USEC
R/W
0x18
Microsecond Reload Value
MHz -1 of the controller clock when the flash is being erased or
programmed.
USEC should be set to 0x18 (24 MHz) whenever the flash is being erased
or programmed.
116
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 8: Flash Memory Protection Read Enable (FMPRE), offset 0x130
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 (see the FMPPE registers
for the execute-only protection bits). This register is loaded during the power-on reset sequence.
The factory settingsare a value of 1 for all implemented banks. This implements a policy of open
access and programmability. The register bits may be changed by writing the specific register bit.
However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may
NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at
which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it
may be restored by executing a power-on reset sequence. For additional information, see the “Flash
Memory Protection” section.
Flash Memory Protection Read Enable (FMPRE)
Base 0x400F.E000
Offset 0x130
Type R/W, reset 0x8000.00FF
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
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
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
R/W
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
Bit/Field
31:0
Name
Type
R/W
Reset
Description
READ_ENABLE
0x800000FF Flash Read Enable
Each bit position maps 2 Kbytes of Flash to be read-enabled.
Value
Description
0x800000FF Enables 16 KB of flash.
October 01, 2007
117
Preliminary
Internal Memory
Register 9: Flash Memory Protection Program Enable (FMPPE), offset 0x134
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 (see the FMPRE
registers for the read-only protection bits). This register is loaded during the power-on reset sequence.
The factory settings are a value of 1 for all implemented banks. This implements a policy of open
access and programmability. The register bits may be changed by writing the specific register bit.
However, this register is R/W0; the user can only change the protection bit from a 1 to a 0 (and may
NOT change a 0 to a 1). The changes are not permanent until the register is committed (saved), at
which point the bit change is permanent. If a bit is changed from a 1 to a 0 and not committed, it
may be restored by executing a power-on reset sequence. For additional information, see the “Flash
Memory Protection” section.
Flash Memory Protection Program Enable (FMPPE)
Base 0x400F.E000
Offset 0x134
Type R/W, reset 0x0000.00FF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
PROG_ENABLE
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
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
PROG_ENABLE
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
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
31:0
Name
Type
R/W
Reset
Description
PROG_ENABLE
0x000000FF Flash Programming Enable
Each bit position maps 2 Kbytes of Flash to be write-enabled.
Value
Description
0x000000FF Enables 16 KB of flash.
118
October 01, 2007
Preliminary
LM3S300 Microcontroller
8
General-Purpose Input/Outputs (GPIOs)
The GPIO module is composed of five physical GPIO blocks, each corresponding to an individual
GPIO port (Port A, Port B, Port C, Port D, and Port E, ). The GPIO module is FiRM-compliant and
supports 8-36 programmable input/output pins, depending on the peripherals being used.
The GPIO module has the following features:
■ Programmable control for GPIO interrupts
–
–
–
Interrupt generation masking
Edge-triggered on rising, falling, or both
Level-sensitive on High or Low values
■ 5-V-tolerant input/outputs
■ Bit masking in both read and write operations through address lines
■ Programmable control for GPIO pad configuration
–
–
–
–
–
Weak pull-up or pull-down resistors
2-mA, 4-mA, and 8-mA pad drive
Slew rate control for the 8-mA drive
Open drain enables
Digital input enables
8.1
Functional Description
Important: All GPIO pins are inputs by default (GPIODIR=0 and GPIOAFSEL=0), with the exception
of the five JTAG pins (PB7 and PC[3:0]). The JTAG pins default to their JTAG
functionality (GPIOAFSEL=1). A Power-On-Reset (POR) or asserting an external reset
(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
8-1 on page 120). The LM3S300 microcontroller contains five ports and thus five of these physical
GPIO blocks.
October 01, 2007
119
Preliminary
General-Purpose Input/Outputs (GPIOs)
Figure 8-1. GPIO Port Block Diagram
Mode
Control
GPIOAFSEL
Alternate Input
Pad Input
Alternate Output
Alternate Output Enable
Digital
I/O Pad
Pad Output
Package I/O Pin
GPIO Input
Data
Control
GPIO Output
GPIODATA
GPIODIR
Pad Output Enable
GPIO Output Enable
Interrupt
Control
Pad
Control
GPIOIS
GPIOIBE
GPIODR2R
GPIODR4R
GPIODR8R
GPIOSLR
GPIOPUR
GPIOPDR
GPIOODR
GPIODEN
Interrupt
GPIOIEV
GPIOIM
GPIORIS
GPIOMIS
GPIOICR
Identification Registers
GPIOPeriphID0 GPIOPeriphID4
GPIOPeriphID1 GPIOPeriphID5
GPIOPeriphID2 GPIOPeriphID6
GPIOPeriphID3 GPIOPeriphID7
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIOPCellID3
8.1.1
Data Control
The data control registers allow software to configure the operational modes of the GPIOs. The data
direction register configures the GPIO as an input or an output while the data register either captures
incoming data or drives it out to the pads.
8.1.1.1 Data Direction Operation
The GPIO Direction (GPIODIR) register (see page 127) 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.
8.1.1.2 Data Register Operation
To aid in the efficiency of software, the GPIO ports allow for the modification of individual bits in the
GPIO Data (GPIODATA) register (see page 126) by using bits [9:2] of the address bus as a mask.
This allows software drivers to modify individual GPIO pins in a single instruction, without affecting
the state of the other pins. This is in contrast to the "typical" method of doing a read-modify-write
operation to set or clear an individual GPIO pin. To accommodate this feature, the GPIODATA
register covers 256 locations in the memory map.
During a write, if the address bit associated with that data bit is set to 1, the value of the GPIODATA
register is altered. If it is cleared to 0, it is left unchanged.
120
October 01, 2007
Preliminary
LM3S300 Microcontroller
For example, writing a value of 0xEB to the address GPIODATA + 0x098 would yield as shown in
Figure 8-2 on page 121, where u is data unchanged by the write.
Figure 8-2. GPIODATA Write Example
9
0
8
0
7
1
6
0
5
0
4
1
3
1
2
0
1
1
0
0
ADDR[9:2]
0x098
1
1
1
0
1
0
1
1
0xEB
u
7
u
6
1
5
u
4
u
3
0
2
1
1
u
0
GPIODATA
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 8-3 on page 121.
Figure 8-3. GPIODATA Read Example
9
0
8
0
7
1
6
1
5
0
4
0
3
0
2
1
1
0
0
0
ADDR[9:2]
0x0C4
1
0
1
1
1
1
1
0
GPIODATA
0
7
0
6
1
5
1
4
0
3
0
2
0
1
0
0
Returned Value
8.1.2
Interrupt Control
The interrupt capabilities of each GPIO port are controlled by a set of seven registers. With these
registers, it is possible to select the source of the interrupt, its polarity, and the edge properties.
When one or more GPIO inputs cause an interrupt, a single interrupt output is sent to the interrupt
controller for the entire GPIO port. For edge-triggered interrupts, software must clear the interrupt
to enable any further interrupts. For a level-sensitive interrupt, it is assumed that the external source
holds the level constant for the interrupt to be recognized by the controller.
Three registers are required to define the edge or sense that causes interrupts:
■ GPIO Interrupt Sense (GPIOIS) register (see page 128)
■ GPIO Interrupt Both Edges (GPIOIBE) register (see page 129)
■ GPIO Interrupt Event (GPIOIEV) register (see page 130)
Interrupts are enabled/disabled via the GPIO Interrupt Mask (GPIOIM) register (see page 131).
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 132 and page 133). 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.
Interrupts are cleared by writing a 1 to the GPIO Interrupt Clear (GPIOICR) register (see page 134).
October 01, 2007
121
Preliminary
General-Purpose Input/Outputs (GPIOs)
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.
8.1.3
Mode Control
The GPIO pins can be controlled by either hardware or software. When hardware control is enabled
via the GPIO Alternate Function Select (GPIOAFSEL) register (see page 135), 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.
8.1.4
8.1.5
Pad Control
The pad control registers allow for GPIO pad configuration by software based on the application
requirements. The pad control registers include the GPIODR2R, GPIODR4R, GPIODR8R, GPIOODR,
GPIOPUR, GPIOPDR, GPIOSLR, and GPIODEN registers.
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.
8.2
Initialization and Configuration
To use the GPIO, the peripheral clock must be enabled by setting the appropriate GPIO Port bit
field (GPIOn) in the RCGC2 register.
On reset, all GPIO pins (except for the five JTAG pins) default to general-purpose inut mode
(GPIODIR=0 and GPIOAFSEL=0). Table 8-1 on page 122 shows all possible configurations of the
GPIO pads and the control register settings required to achieve them. Table 8-2 on page 123 shows
how a rising edge interrupt would be configured for pin 2 of a GPIO port.
Table 8-1. GPIO Pad Configuration Examples
Configuration
GPIO Register Bit Valuea
AFSEL
DIR
ODR
DEN
PUR
PDR
DR2R
DR4R
DR8R
SLR
Digital Input (GPIO)
Digital Output (GPIO)
0
0
0
0
1
0
0
1
?
?
X
?
X
?
X
?
X
0
1
1
1
?
?
?
Open Drain Input
(GPIO)
X
X
X
X
X
X
Open Drain Output
(GPIO)
0
1
1
1
1
1
1
X
X
X
X
X
1
1
0
0
0
0
1
1
1
1
1
1
X
X
?
?
?
?
X
X
?
?
?
?
?
?
X
?
?
?
?
?
X
?
?
?
?
?
X
?
?
?
?
?
X
?
?
?
Open Drain
Input/Output (I2C)
Digital Input (Timer
CCP)
Digital Output (Timer
PWM)
Digital Input/Output
(SSI)
Digital Input/Output
(UART)
122
October 01, 2007
Preliminary
LM3S300 Microcontroller
Configuration
GPIO Register Bit Valuea
AFSEL
DIR
ODR
DEN
PUR
PDR
DR2R
DR4R
DR8R
SLR
Analog Input
(Comparator)
0
0
0
0
0
0
X
X
X
X
Digital Output
(Comparator)
1
X
0
1
?
?
?
?
?
?
a. X=Ignored (don’t care bit)
?=Can be either 0 or 1, depending on the configuration
Table 8-2. GPIO Interrupt Configuration Example
Register
Desired
Interrupt
Event
Pin 2 Bit Valuea
7
6
5
4
3
2
1
0
Trigger
GPIOIS
0=edge
1=level
X
X
X
X
X
X
X
X
X
0
0
X
X
X
GPIOIBE
0=single
edge
X
X
X
X
1=both
edges
GPIOIEV
GPIOIM
0=Low level,
or negative
edge
X
0
X
0
X
0
X
0
1
1
X
0
1=High level,
or positive
edge
0=masked
0
0
1=not
masked
a. X=Ignored (don’t care bit)
8.3
Register Map
Table 8-3 on page 124 lists the GPIO registers. The offset listed is a hexadecimal increment to the
register’s address, relative to that GPIO port’s base address:
■ GPIO Port A: 0x4000.4000
■ GPIO Port B: 0x4000.5000
■ GPIO Port C: 0x4000.6000
■ GPIO Port D: 0x4000.7000
■ GPIO Port E: 0x4002.4000
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.
October 01, 2007
123
Preliminary
General-Purpose Input/Outputs (GPIOs)
Note: The default reset value for the GPIOAFSEL register is 0x0000.0000 for all GPIO pins, with
the exception of the five JTAG pins (PB7 and PC[3:0]). These five pins default to JTAG
functionality. Because of this, the default reset value of GPIOAFSEL for GPIO Port B is
0x0000.0080 while the default reset value for Port C is 0x0000.000F.
Table 8-3. GPIO Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
0x400
0x404
0x408
0x40C
0x410
0x414
0x418
0x41C
0x420
0x500
0x504
0x508
0x50C
0x510
0x514
0x518
0x51C
0xFD0
0xFD4
0xFD8
0xFDC
0xFE0
0xFE4
0xFE8
0xFEC
0xFF0
0xFF4
0xFF8
GPIODATA
GPIODIR
R/W
R/W
R/W
R/W
R/W
R/W
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
-
GPIO Data
126
127
128
129
130
131
132
133
134
135
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
GPIO Direction
GPIOIS
GPIO Interrupt Sense
GPIOIBE
GPIO Interrupt Both Edges
GPIO Interrupt Event
GPIOIEV
GPIOIM
GPIO Interrupt Mask
GPIORIS
GPIO Raw Interrupt Status
GPIO Masked Interrupt Status
GPIO Interrupt Clear
GPIOMIS
RO
GPIOICR
W1C
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RO
GPIOAFSEL
GPIODR2R
GPIODR4R
GPIODR8R
GPIOODR
GPIO Alternate Function Select
GPIO 2-mA Drive Select
GPIO 4-mA Drive Select
GPIO 8-mA Drive Select
GPIO Open Drain Select
GPIO Pull-Up Select
0x0000.00FF
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.00FF
0x0000.0000
0x0000.0000
0x0000.00FF
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0061
0x0000.0000
0x0000.0018
0x0000.0001
0x0000.000D
0x0000.00F0
0x0000.0005
GPIOPUR
GPIOPDR
GPIO Pull-Down Select
GPIOSLR
GPIO Slew Rate Control Select
GPIO Digital Enable
GPIODEN
GPIOPeriphID4
GPIOPeriphID5
GPIOPeriphID6
GPIOPeriphID7
GPIOPeriphID0
GPIOPeriphID1
GPIOPeriphID2
GPIOPeriphID3
GPIOPCellID0
GPIOPCellID1
GPIOPCellID2
GPIO Peripheral Identification 4
GPIO Peripheral Identification 5
GPIO Peripheral Identification 6
GPIO Peripheral Identification 7
GPIO Peripheral Identification 0
GPIO Peripheral Identification 1
GPIO Peripheral Identification 2
GPIO Peripheral Identification 3
GPIO PrimeCell Identification 0
GPIO PrimeCell Identification 1
GPIO PrimeCell Identification 2
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
124
October 01, 2007
Preliminary
LM3S300 Microcontroller
See
page
Offset
Name
Type
Reset
Description
0xFFC
GPIOPCellID3
RO
0x0000.00B1
GPIO PrimeCell Identification 3
156
8.4
Register Descriptions
The remainder of this section lists and describes the GPIO registers, in numerical order by address
offset.
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
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 127).
In order to write to GPIODATA, the corresponding bits in the mask, resulting from the address bus
bits [9:2], must be High. Otherwise, the bit values remain unchanged by the write.
Similarly, the values read from this register are determined for each bit by the mask bit derived from
the address used to access the data register, bits [9:2]. Bits that are 1 in the address mask cause
the corresponding bits in GPIODATA to be read, and bits that are 0 in the address mask cause the
corresponding bits in GPIODATA to be read as 0, regardless of their value.
A read from GPIODATA returns the last bit value written if the respective pins are configured as
outputs, or it returns the value on the corresponding input pin when these are configured as inputs.
All bits are cleared by a reset.
GPIO Data (GPIODATA)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DATA
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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 120 for examples of
reads and writes.
126
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 2: GPIO Direction (GPIODIR), offset 0x400
The GPIODIR register is the data direction register. Bits set to 1 in the GPIODIR register configure
the corresponding pin to be an output, while bits set to 0 configure the pins to be inputs. All bits are
cleared by a reset, meaning all GPIO pins are inputs by default.
GPIO Direction (GPIODIR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x400
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DIR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
DIR
R/W
0x00
GPIO Data Direction
The DIR values are defined as follows:
Value Description
0
1
Pins are inputs.
Pins are outputs.
October 01, 2007
127
Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 3: GPIO Interrupt Sense (GPIOIS), offset 0x404
The GPIOIS register is the interrupt sense register. Bits set to 1 in GPIOIS configure the
corresponding pins to detect levels, while bits set to 0 configure the pins to detect edges. All bits
are cleared by a reset.
GPIO Interrupt Sense (GPIOIS)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x404
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IS
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
IS
R/W
0x00
GPIO Interrupt Sense
The IS values are defined as follows:
Value Description
0
1
Edge on corresponding pin is detected (edge-sensitive).
Level on corresponding pin is detected (level-sensitive).
128
October 01, 2007
Preliminary
LM3S300 Microcontroller
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 128) 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 130). Clearing a bit
configures the pin to be controlled by GPIOIEV. All bits are cleared by a reset.
GPIO Interrupt Both Edges (GPIOIBE)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x408
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IBE
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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 130).
1
Both edges on the corresponding pin trigger an interrupt.
Note:
Single edge is determined by the corresponding bit
in GPIOIEV.
October 01, 2007
129
Preliminary
General-Purpose Input/Outputs (GPIOs)
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 128). Clearing a bit configures the pin to
detect falling edges or low levels, depending on the corresponding bit value in GPIOIS. All bits are
cleared by a reset.
GPIO Interrupt Event (GPIOIEV)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x40C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IEV
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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.
130
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 6: GPIO Interrupt Mask (GPIOIM), offset 0x410
The GPIOIM register is the interrupt mask register. Bits set to High in GPIOIM allow the corresponding
pins to trigger their individual interrupts and the combined GPIOINTR line. Clearing a bit disables
interrupt triggering on that pin. All bits are cleared by a reset.
GPIO Interrupt Mask (GPIOIM)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x410
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IME
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
IME
R/W
0x00
GPIO Interrupt Mask Enable
The IME values are defined as follows:
Value Description
0
1
Corresponding pin interrupt is masked.
Corresponding pin interrupt is not masked.
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
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 131). Bits read as zero indicate that corresponding input pins have not
initiated an interrupt. All bits are cleared by a reset.
GPIO Raw Interrupt Status (GPIORIS)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x414
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RIS
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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
1
Corresponding pin interrupt requirements not met.
Corresponding pin interrupt has met requirements.
132
October 01, 2007
Preliminary
LM3S300 Microcontroller
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.
GPIOMIS is the state of the interrupt after masking.
GPIO Masked Interrupt Status (GPIOMIS)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x418
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
MIS
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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
1
Corresponding GPIO line interrupt not active.
Corresponding GPIO line asserting interrupt.
October 01, 2007
133
Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 9: GPIO Interrupt Clear (GPIOICR), offset 0x41C
The GPIOICR register is the interrupt clear register. Writing a 1 to a bit in this register clears the
corresponding interrupt edge detection logic register. Writing a 0 has no effect.
GPIO Interrupt Clear (GPIOICR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x41C
Type W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IC
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
IC
W1C
0x00
GPIO Interrupt Clear
The IC values are defined as follows:
Value Description
0
1
Corresponding interrupt is unaffected.
Corresponding interrupt is cleared.
134
October 01, 2007
Preliminary
LM3S300 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.
Important: All GPIO pins are inputs by default (GPIODIR=0 and GPIOAFSEL=0), with the exception
of the five JTAG pins (PB7 and PC[3:0]). The JTAG pins default to their JTAG
functionality (GPIOAFSEL=1). A Power-On-Reset (POR) or asserting an external reset
(RST) puts both groups of pins back to their default state.
Caution – If the JTAG pins are used as GPIOs in a design, PB7 and PC2 cannot have external pull-down
resistors connected to both of them at the same time. If both pins are pulled Low during reset, the
controller has unpredictable behavior. If this happens, remove one or both of the pull-down resistors,
and apply RST or power-cycle the part.
In addition, it is possible to create a software sequence that prevents the debugger from connecting to
the Stellaris® microcontroller. If the program code loaded into flash immediately changes the JTAG
pins to their GPIO functionality, the debugger may not have enough time to connect and halt the
controller before the JTAG pin functionality switches. This may lock the debugger out of the part. This
can be avoided with a software routine that restores JTAG functionality based on an external or software
trigger.
GPIO Alternate Function Select (GPIOAFSEL)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x420
Type R/W, reset -
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
reserved
AFSEL
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
October 01, 2007
135
Preliminary
General-Purpose Input/Outputs (GPIOs)
Bit/Field
7:0
Name
Type
R/W
Reset
-
Description
AFSEL
GPIO Alternate Function Select
The AFSEL values are defined as follows:
Value Description
0
1
Software control of corresponding GPIO line (GPIO mode).
Hardware control of corresponding GPIO line (alternate
hardware function).
Note:
The default reset value for the GPIOAFSEL register
is 0x0000.0000 for all GPIO pins, with the exception
of the five JTAG pins (PB7 and PC[3:0]). These five
pins default to JTAG functionality. Because of this,
the default reset value of GPIOAFSEL for GPIO Port
B is 0x0000.0080 while the default reset value for
Port C is 0x0000.000F.
136
October 01, 2007
Preliminary
LM3S300 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 base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x500
Type R/W, reset 0x0000.00FF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DRV2
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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.
October 01, 2007
137
Preliminary
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 base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x504
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DRV4
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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.
138
October 01, 2007
Preliminary
LM3S300 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.
GPIO 8-mA Drive Select (GPIODR8R)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x508
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DRV8
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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.
October 01, 2007
139
Preliminary
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 Input Enable (GPIODEN) register (see
page 144). Corresponding bits in the drive strength registers (GPIODR2R, GPIODR4R, GPIODR8R,
and GPIOSLR ) can be set to achieve the desired rise and fall times. The GPIO acts as an open
drain input if the corresponding bit in the GPIODIR register is set to 0; and as an open drain output
when set to 1.
When using the I2C module, the GPIO Alternate Function Select (GPIOAFSEL) register bit for
PB2 and PB3 should be set to 1 (see examples in “Initialization and Configuration” on page 122).
GPIO Open Drain Select (GPIOODR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x50C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
ODE
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
ODE
R/W
0x00
Output Pad Open Drain Enable
The ODE values are defined as follows:
Value Description
0
1
Open drain configuration is disabled.
Open drain configuration is enabled.
140
October 01, 2007
Preliminary
LM3S300 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 142).
GPIO Pull-Up Select (GPIOPUR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x510
Type R/W, reset 0x0000.00FF
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
reserved
PUE
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PUE
R/W
0xFF
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.
October 01, 2007
141
Preliminary
General-Purpose Input/Outputs (GPIOs)
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 141).
GPIO Pull-Down Select (GPIOPDR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x514
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PDE
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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.
142
October 01, 2007
Preliminary
LM3S300 Microcontroller
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 139).
GPIO Slew Rate Control Select (GPIOSLR)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x518
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
SRL
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
SRL
R/W
0x00
Slew Rate Limit Enable (8-mA drive only)
The SRL values are defined as follows:
Value Description
0
1
Slew rate control disabled.
Slew rate control enabled.
October 01, 2007
143
Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 18: GPIO Digital Enable (GPIODEN), offset 0x51C
The GPIODEN register is the digital input enable register. By default, all GPIO signals are configured
as digital inputs at reset. If a pin is being used as a GPIO or its Alternate Hardware Function, it
should be configured as a digital input. The only time that a pin should not be configured as a digital
input is when the GPIO pin is configured to be one of the analog input signals for the analog
comparators.
GPIO Digital Enable (GPIODEN)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0x51C
Type R/W, reset 0x0000.00FF
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
reserved
DEN
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
DEN
R/W
0xFF
Digital Enable
The DEN values are defined as follows:
Value Description
0
1
Digital functions disabled.
Digital functions enabled.
144
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 19: GPIO Peripheral Identification 4 (GPIOPeriphID4), offset 0xFD0
The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 4 (GPIOPeriphID4)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFD0
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID4
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID4
RO
0x00
GPIO Peripheral ID Register[7:0]
October 01, 2007
145
Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 20: GPIO Peripheral Identification 5 (GPIOPeriphID5), offset 0xFD4
The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 5 (GPIOPeriphID5)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFD4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID5
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID5
RO
0x00
GPIO Peripheral ID Register[15:8]
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October 01, 2007
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LM3S300 Microcontroller
Register 21: GPIO Peripheral Identification 6 (GPIOPeriphID6), offset 0xFD8
The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 6 (GPIOPeriphID6)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFD8
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID6
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID6
RO
0x00
GPIO Peripheral ID Register[23:16]
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 22: GPIO Peripheral Identification 7 (GPIOPeriphID7), offset 0xFDC
The GPIOPeriphID4, GPIOPeriphID5, GPIOPeriphID6, and GPIOPeriphID7 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 7 (GPIOPeriphID7)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFDC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID7
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID7
RO
0x00
GPIO Peripheral ID Register[31:24]
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 23: GPIO Peripheral Identification 0 (GPIOPeriphID0), offset 0xFE0
The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 0 (GPIOPeriphID0)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFE0
Type RO, reset 0x0000.0061
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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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Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 24: GPIO Peripheral Identification 1 (GPIOPeriphID1), offset 0xFE4
The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 1 (GPIOPeriphID1)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFE4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID1
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID1
RO
0x00
GPIO Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
150
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 25: GPIO Peripheral Identification 2 (GPIOPeriphID2), offset 0xFE8
The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 2 (GPIOPeriphID2)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFE8
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID2
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
1
RO
1
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID2
RO
0x18
GPIO Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 26: GPIO Peripheral Identification 3 (GPIOPeriphID3), offset 0xFEC
The GPIOPeriphID0, GPIOPeriphID1, GPIOPeriphID2, and GPIOPeriphID3 registers can
conceptually be treated as one 32-bit register; each register contains eight bits of the 32-bit register,
used by software to identify the peripheral.
GPIO Peripheral Identification 3 (GPIOPeriphID3)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFEC
Type RO, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID3
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
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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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October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 27: GPIO PrimeCell Identification 0 (GPIOPCellID0), offset 0xFF0
The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide
registers, that can conceptually be treated as one 32-bit register. The register is used as a standard
cross-peripheral identification system.
GPIO PrimeCell Identification 0 (GPIOPCellID0)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID0
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
1
RO
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID0
RO
0x0D
GPIO PrimeCell ID Register[7:0]
Provides software a standard cross-peripheral identification system.
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 28: GPIO PrimeCell Identification 1 (GPIOPCellID1), offset 0xFF4
The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide
registers, that can conceptually be treated as one 32-bit register. The register is used as a standard
cross-peripheral identification system.
GPIO PrimeCell Identification 1 (GPIOPCellID1)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID1
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID1
RO
0xF0
GPIO PrimeCell ID Register[15:8]
Provides software a standard cross-peripheral identification system.
154
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 29: GPIO PrimeCell Identification 2 (GPIOPCellID2), offset 0xFF8
The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide
registers, that can conceptually be treated as one 32-bit register. The register is used as a standard
cross-peripheral identification system.
GPIO PrimeCell Identification 2 (GPIOPCellID2)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID2
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
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID2
RO
0x05
GPIO PrimeCell ID Register[23:16]
Provides software a standard cross-peripheral identification system.
October 01, 2007
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Preliminary
General-Purpose Input/Outputs (GPIOs)
Register 30: GPIO PrimeCell Identification 3 (GPIOPCellID3), offset 0xFFC
The GPIOPCellID0, GPIOPCellID1, GPIOPCellID2, and GPIOPCellID3 registers are four 8-bit wide
registers, that can conceptually be treated as one 32-bit register. The register is used as a standard
cross-peripheral identification system.
GPIO PrimeCell Identification 3 (GPIOPCellID3)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID3
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID3
RO
0xB1
GPIO PrimeCell ID Register[31:24]
Provides software a standard cross-peripheral identification system.
156
October 01, 2007
Preliminary
LM3S300 Microcontroller
9
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 timer/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).
Note: Timer2 is an internal timer and can only be used to generate internal interrupts.
The General-Purpose Timer Module is one timing resource available on the Stellaris® microcontrollers.
Other timer resources include the System Timer (SysTick) (see “System Timer
(SysTick)” on page 31).
The following modes are supported:
■ 32-bit Timer modes
–
–
–
–
Programmable one-shot timer
Programmable periodic timer
Real-Time Clock using 32.768-KHz input clock
Software-controlled event stalling (excluding RTC mode)
■ 16-bit Timer modes
–
–
–
–
General-purpose timer function with an 8-bit prescaler (for one-shot and periodic modes only)
Programmable one-shot timer
Programmable periodic timer
Software-controlled event stalling
■ 16-bit Input Capture modes
–
–
Input edge count capture
Input edge time capture
■ 16-bit PWM mode
Simple PWM mode with software-programmable output inversion of the PWM signal
–
October 01, 2007
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Preliminary
General-Purpose Timers
9.1
Block Diagram
Figure 9-1. GPTM Module Block Diagram
0x0000 (Down Counter Modes)
TimerA Control
GPTMTAPMR
GPTMTAPR
TA Comparator
GPTMAR En
Clock / Edge
Detect
GPTMTAMATCHR
Interrupt / Config
GPTMTAILR
GPTMTAMR
CCP (even)
GPTMCFG
GPTMCTL
GPTMIMR
GPTMRIS
GPTMMIS
GPTMICR
TimerA
Interrupt
RTC Divider
TimerB
Interrupt
TimerB Control
GPTMTBR En
TB Comparator
GPTMTBPMR
GPTMTBPR
Clock / Edge
Detect
CCP (odd)
GPTMTBMATCHR
GPTMTBILR
GPTMTBMR
0x0000 (Down Counter Modes)
System
Clock
9.2
Functional Description
The main components of each GPTM block are two free-running 16-bit up/down counters (referred
to as TimerA and TimerB), two 16-bit match registers, two prescaler match registers, and two 16-bit
load/initialization registers and their associated control functions. The exact functionality of each
GPTM is controlled by software and configured through the register interface.
Software configures the GPTM using the GPTM Configuration (GPTMCFG) register (see page 169),
the GPTM TimerA Mode (GPTMTAMR) register (see page 170), and the GPTM TimerB Mode
(GPTMTBMR) register (see page 172). 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.
9.2.1
GPTM Reset Conditions
After reset has been applied to the GPTM module, the module is in an inactive state, and all control
registers are cleared and in their default states. Counters TimerA and TimerB are initialized to
0xFFFF, along with their corresponding load registers: the GPTM TimerA Interval Load
(GPTMTAILR) register (see page 183) and the GPTM TimerB Interval Load (GPTMTBILR) register
(see page 184). The prescale counters are initialized to 0x00: the GPTM TimerA Prescale
(GPTMTAPR) register (see page 187) and the GPTM TimerB Prescale (GPTMTBPR) register (see
page 188).
9.2.2
32-Bit Timer Operating Modes
Note: Both the odd- and even-numbered CCP pins are used for 16-bit mode. Only the
even-numbered CCP pins are used for 32-bit mode.
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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 183
■ GPTM TimerB Interval Load (GPTMTBILR) register [15:0], see page 184
■ GPTM TimerA (GPTMTAR) register [15:0], see page 191
■ GPTM TimerB (GPTMTBR) register [15:0], see page 192
In the 32-bit modes, the GPTM translates a 32-bit write access to GPTMTAILR into a write access
to both GPTMTAILR and GPTMTBILR. The resulting word ordering for such a write operation is:
GPTMTBILR[15:0]:GPTMTAILR[15:0]
Likewise, a read access to GPTMTAR returns the value:
GPTMTBR[15:0]:GPTMTAR[15:0]
9.2.2.1 32-Bit One-Shot/Periodic Timer Mode
In 32-bit one-shot and periodic timer modes, the concatenated versions of the TimerA and TimerB
registers are configured as a 32-bit down-counter. The selection of one-shot or periodic mode is
determined by the value written to the TAMR field of the GPTM TimerA Mode (GPTMTAMR) register
(see page 170), 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 174), the
timer begins counting down from its preloaded value. Once the 0x0000.0000 state is reached, the
timer reloads its start value from the concatenated GPTMTAILR on the next cycle. If configured to
be a one-shot timer, the timer stops counting and clears the TAEN bit in the GPTMCTL register. If
configured as a periodic timer, it continues counting.
In addition to reloading the count value, the GPTM generates interrupts and output triggers when
it reaches the 0x0000000 state. The GPTM sets the TATORIS bit in the GPTM Raw Interrupt Status
(GPTMRIS) register (see page 179), and holds it until it is cleared by writing the GPTM Interrupt
Clear (GPTMICR) register (see page 181). If the time-out interrupt is enabled in the GPTM Interrupt
Mask (GPTIMR) register (see page 177), the GPTM also sets the TATOMIS bit in the GPTM Masked
Interrupt Status (GPTMMIS) register (see page 180).
The output trigger is a one-clock-cycle pulse that is asserted when the counter hits the 0x0000.0000
state, and deasserted on the following clock cycle. It is enabled by setting the TAOTE bit in GPTMCTL.
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 asserted, the timer freezes counting until the signal
is deasserted.
9.2.2.2 32-Bit Real-Time Clock Timer Mode
In Real-Time Clock (RTC) mode, the concatenated versions of the TimerA and TimerB registers
are configured as a 32-bit up-counter. When RTC mode is selected for the first time, the counter is
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loaded with a value of 0x0000.0001. All subsequent load values must be written to the GPTM TimerA
Match (GPTMTAMATCHR) register (see page 185) by the controller.
The input clock on the CCP0, CCP2, or CCP4 pins is required to be 32.768 KHz in RTC mode. The
clock signal is then divided down to a 1 Hz rate and is passed along to the input of the 32-bit counter.
When software writes the TAEN bit inthe GPTMCTL register, the counter starts counting up from its
preloaded value of 0x0000.0001. When the current count value matches the preloaded value in the
GPTMTAMATCHR register, it rolls over to a value of 0x0000.0000 and continues counting until
either a hardware reset, or it is disabled by software (clearing the TAEN bit). When a match occurs,
the GPTM asserts the RTCRIS bit in GPTMRIS. If the RTC interrupt is enabled in GPTIMR, the
GPTM also sets the RTCMIS bit in GPTMISR and generates a controller interrupt. The status flags
are cleared by writing the RTCCINT bit in GPTMICR.
If the TASTALL and/or TBSTALL bits in the GPTMCTL register are set, the timer does not freeze if
the RTCEN bit is set in GPTMCTL.
9.2.3
16-Bit Timer Operating Modes
The GPTM is placed into global 16-bit mode by writing a value of 0x4 to the GPTM Configuration
(GPTMCFG) register (see page 169). This section describes each of the GPTM 16-bit modes of
operation. TimerA and TimerB have identical modes, so a single description is given using an n to
reference both.
9.2.3.1 16-Bit One-Shot/Periodic Timer Mode
In 16-bit one-shot and periodic timer modes, the timer is configured as a 16-bit down-counter with
an optional 8-bit prescaler that effectively extends the counting range of the timer to 24 bits. The
selection of one-shot or periodic mode is determined by the value written to the TnMR field of the
GPTMTnMR register. The optional prescaler is loaded into the GPTM Timern Prescale (GPTMTnPR)
register.
When software writes the TnEN bit in the GPTMCTL register, the timer begins counting down from
its preloaded value. Once the 0x0000 state is reached, the timer reloads its start value from
GPTMTnILR and GPTMTnPR on the next cycle. If configured to be a one-shot timer, the timer stops
counting and clears the TnEN bit in the GPTMCTL register. If configured as a periodic timer, it
continues counting.
In addition to reloading the count value, the timer generates interrupts and output triggers when it
reaches the 0x0000 state. The GPTM sets the TnTORIS bit in the GPTMRIS register, and holds it
until it is cleared by writing the GPTMICR register. If the time-out interrupt is enabled in GPTIMR,
the GPTM also sets the TnTOMIS bit in GPTMISR and generates a controller interrupt.
The output trigger is a one-clock-cycle pulse that is asserted when the counter hits the 0x0000 state,
and deasserted on the following clock cycle. It is enabled by setting the TnOTE bit in the GPTMCTL
register, and can trigger SoC-level events.
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 enabled, the timer freezes counting until the signal
is deasserted.
The following example shows a variety of configurations for a 16-bit free running timer while using
the prescaler. All values assume a 25-MHz clock with Tc=20 ns (clock period).
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Table 9-1. 16-Bit Timer With Prescaler Configurations
Prescale #Clock (T c)a Max Time Units
00000000
00000001
00000010
------------
11111100
11111110
11111111
1
2
2.6214
5.2428
7.8642
--
mS
mS
mS
--
3
--
254
255
256
665.8458 mS
668.4672 mS
671.0886 mS
a. Tc is the clock period.
9.2.3.2 16-Bit Input Edge Count Mode
In Edge Count mode, the timer is configured as a down-counter capable of capturing three types
of events: rising edge, falling edge, or both. To place the timer in Edge Count mode, the TnCMR bit
of the GPTMTnMR register must be set to 0. The type of edge that the timer counts is determined
by the TnEVENT fields of the GPTMCTL register. During initialization, the GPTM Timern Match
(GPTMTnMATCHR) register is configured so that the difference between the value in the
GPTMTnILR register and the GPTMTnMATCHR register equals the number of edge events that
must be counted.
When software writes the TnEN bit in the GPTM Control (GPTMCTL) register, the timer is enabled
for event capture. Each input event on the CCP pin decrements the counter by 1 until the event count
matches GPTMTnMATCHR. When the counts match, the GPTM asserts the CnMRIS bit in the
GPTMRIS register (and the CnMMIS bit, if the interrupt is not masked). The counter is then reloaded
using the value in GPTMTnILR, and stopped since the GPTM automatically clears the TnEN bit in
the GPTMCTL register. Once the event count has been reached, all further events are ignored until
TnEN is re-enabled by software.
Figure 9-2 on page 162 shows how input edge count mode works. In this case, the timer start value
is set to GPTMnILR =0x000A and the match value is set to GPTMnMATCHR =0x0006 so that four
edge events are counted. The counter is configured to detect both edges of the input signal.
Note that the last two edges are not counted since the timer automatically clears the TnEN bit after
the current count matches the value in the GPTMnMR register.
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Figure 9-2. 16-Bit Input Edge Count Mode Example
Timer reload
on next cycle
Ignored
Ignored
Count
0x000A
0x0009
0x0008
0x0007
0x0006
Timer stops,
flags
asserted
Input Signal
9.2.3.3 16-Bit Input Edge Time Mode
Note: The prescaler is not available in 16-Bit Input Edge Time mode.
In Edge Time mode, the timer is configured as a free-running down-counter initialized to the value
loaded in the GPTMTnILR register (or 0xFFFF at reset). This mode allows for event capture of both
rising and falling edges. The timer is placed into Edge Time mode by setting the TnCMR bit in the
GPTMTnMR register, and the type of event that the timer captures is determined by the TnEVENT
fields of the GPTMCnTL register.
When software writes the TnEN bit in the GPTMCTL register, the timer is enabled for event capture.
When the selected input event is detected, the current Tn counter value is captured in the GPTMTnR
register and is available to be read by the controller. The GPTM then asserts the CnERIS bit (and
the CnEMIS bit, if the interrupt is not masked).
After an event has been captured, the timer does not stop counting. It continues to count until the
TnEN bit is cleared. When the timer reaches the 0x0000 state, it is reloaded with the value from the
GPTMnILR register.
Figure 9-3 on page 163 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).
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Figure 9-3. 16-Bit Input Edge Time Mode Example
Count
GPTMTnR=X
0xFFFF
GPTMTnR=Y
GPTMTnR=Z
Z
X
Y
Time
Input Signal
9.2.3.4 16-Bit PWM Mode
The GPTM supports a simple PWM generation mode. In PWM mode, the timer is configured as a
down-counter with a start value (and thus period) defined by GPTMTnILR. PWM mode is enabled
with the GPTMTnMR register by setting the TnAMS bit to 0x1, the TnCMR bit to 0x0, and the TnMR
field to 0x2.
When software writes the TnEN bit in the GPTMCTL register, the counter begins counting down
until it reaches the 0x0000 state. On the next counter cycle, the counter reloads its start value from
GPTMTnILR (and GPTMTnPR if using a prescaler) and continues counting until disabled by software
clearing the TnEN bit in the GPTMCTL register. No interrupts or status bits are asserted in PWM
mode.
The output PWM signal asserts when the counter is at the value of the GPTMTnILR register (its
start state), and is deasserted when the counter value equals the value in the GPTM Timern Match
Register (GPTMnMATCHR). Software has the capability of inverting the output PWM signal by
setting the TnPWML bit in the GPTMCTL register.
Figure 9-4 on page 164 shows how to generate an output PWM with a 1-ms period and a 66% duty
cycle assuming a 50-MHz input clock and TnPWML =0 (duty cycle would be 33% for the TnPWML
=1 configuration). For this example, the start value is GPTMnIRL=0xC350 and the match value is
GPTMnMR=0x411A.
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Figure 9-4. 16-Bit PWM Mode Example
GPTMTnR=GPTMnMR
GPTMTnR=GPTMnMR
Count
0xC350
0x411A
Time
TnEN set
TnPWML = 0
TnPWML = 1
Output
Signal
9.3
Initialization and Configuration
To use the general-purpose timers, the peripheral clock must be enabled by setting the TIMER0,
TIMER1, and TIMER2 bits in the RCGC1 register.
This section shows module initialization and configuration examples for each of the supported timer
modes.
9.3.1
32-Bit One-Shot/Periodic Timer Mode
The GPTM is configured for 32-bit One-Shot and Periodic modes by the following sequence:
1. Ensure the timer is disabled (the TAEN bit in the GPTMCTL register is cleared) before making
any changes.
2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x0.
3. Set the TAMR field in the GPTM TimerA Mode Register (GPTMTAMR):
a. Write a value of 0x1 for One-Shot mode.
b. Write a value of 0x2 for Periodic mode.
4. Load the start value into the GPTM TimerA Interval Load Register (GPTMTAILR).
5. If interrupts are required, set the TATOIM bit in the GPTM Interrupt Mask Register (GPTMIMR).
6. Set the TAEN bit in the GPTMCTL register to enable the timer and start counting.
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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 165. To re-enable the timer, repeat
the sequence. A timer configured in Periodic mode does not stop counting after it times out.
9.3.2
32-Bit Real-Time Clock (RTC) Mode
To use the RTC mode, the timer must have a 32.768-KHz input signal on its CCP0, CCP2, or CCP4
pins. To enable the RTC feature, follow these steps:
1. Ensure the timer is disabled (the TAEN bit is cleared) before making any changes.
2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x1.
3. Write the desired match value to the GPTM TimerA Match Register (GPTMTAMATCHR).
4. Set/clear the RTCEN bit in the GPTM Control Register (GPTMCTL) as desired.
5. If interrupts are required, set the RTCIM bit in the GPTM Interrupt Mask Register (GPTMIMR).
6. Set the TAEN bit in the GPTMCTL register to enable the timer and start counting.
When the timer count equals the value in the GPTMTAMATCHR register, the counter is re-loaded
with 0x0000.0000 and begins counting. If an interrupt is enabled, it does not have to be cleared.
9.3.3
16-Bit One-Shot/Periodic Timer Mode
A timer is configured for 16-bit One-Shot and Periodic modes by the following sequence:
1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes.
2. Write the GPTM Configuration Register (GPTMCFG) with a value of 0x4.
3. Set the TnMR field in the GPTM Timer Mode (GPTMTnMR) register:
a. Write a value of 0x1 for One-Shot mode.
b. Write a value of 0x2 for Periodic mode.
4. If a prescaler is to be used, write the prescale value to the GPTM Timern Prescale Register
(GPTMTnPR).
5. Load the start value into the GPTM Timer Interval Load Register (GPTMTnILR).
6. If interrupts are required, set the TnTOIM bit in the GPTM Interrupt Mask Register (GPTMIMR).
7. Set the TnEN bit in the GPTM Control Register (GPTMCTL) to enable the timer and start
counting.
8. Poll the TnTORIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled).
In both cases, the status flags are cleared by writing a 1 to the TnTOCINT bit of the GPTM
Interrupt Clear Register (GPTMICR).
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In One-Shot mode, the timer stops counting after step 8 on page 165. To re-enable the timer, repeat
the sequence. A timer configured in Periodic mode does not stop counting after it times out.
9.3.4
16-Bit Input Edge Count Mode
A timer is configured to Input Edge Count mode by the following sequence:
1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes.
2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4.
3. In the GPTM Timer Mode (GPTMTnMR) register, write the TnCMR field to 0x0 and the TnMR
field to 0x3.
4. Configure the type of event(s) that the timer captures by writing the TnEVENT field of the GPTM
Control (GPTMCTL) register.
5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register.
6. Load the desired event count into the GPTM Timern Match (GPTMTnMATCHR) register.
7. If interrupts are required, set the CnMIM bit in the GPTM Interrupt Mask (GPTMIMR) register.
8. Set the TnEN bit in the GPTMCTL register to enable the timer and begin waiting for edge events.
9. Poll the CnMRIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled).
In both cases, the status flags are cleared by writing a 1 to the CnMCINT bit of the GPTM
Interrupt Clear (GPTMICR) register.
In Input Edge Count Mode, the timer stops after the desired number of edge events has been
detected. To re-enable the timer, ensure that the TnEN bit is cleared and repeat step
4 on page 166-step 9 on page 166.
9.3.5
16-Bit Input Edge Timing Mode
A timer is configured to Input Edge Timing mode by the following sequence:
1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes.
2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4.
3. In the GPTM Timer Mode (GPTMTnMR) register, write the TnCMR field to 0x1 and the TnMR
field to 0x3.
4. Configure the type of event that the timer captures by writing the TnEVENT field of the GPTM
Control (GPTMCTL) register.
5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register.
6. If interrupts are required, set the CnEIM bit in the GPTM Interrupt Mask (GPTMIMR) register.
7. Set the TnEN bit in the GPTM Control (GPTMCTL) register to enable the timer and start counting.
8. Poll the CnERIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled).
In both cases, the status flags are cleared by writing a 1 to the CnECINT bit of the GPTM
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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.
9.3.6
16-Bit PWM Mode
A timer is configured to PWM mode using the following sequence:
1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes.
2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x4.
3. In the GPTM Timer Mode (GPTMTnMR) register, set the TnAMS bit to 0x1, the TnCMR bit to
0x0, and the TnMR field to 0x2.
4. Configure the output state of the PWM signal (whether or not it is inverted) in the TnEVENT field
of the GPTM Control (GPTMCTL) register.
5. Load the timer start value into the GPTM Timern Interval Load (GPTMTnILR) register.
6. Load the GPTM Timern Match (GPTMTnMATCHR) register with the desired value.
7. If a prescaler is going to be used, configure the GPTM Timern Prescale (GPTMTnPR) register
and the GPTM Timern Prescale Match (GPTMTnPMR) register.
8. Set the TnEN bit in the GPTM Control (GPTMCTL) register to enable the timer and begin
generation of the output PWM signal.
In PWM Timing mode, the timer continues running after the PWM signal has been generated. The
PWM period can be adjusted at any time by writing the GPTMTnILR register, and the change takes
effect at the next cycle after the write.
9.4
Register Map
Table 9-2 on page 167 lists the GPTM registers. The offset listed is a hexadecimal increment to the
register’s address, relative to that timer’s base address:
■ Timer0: 0x4003.0000
■ Timer1: 0x4003.1000
■ Timer2: 0x4003.2000
Table 9-2. Timers Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
0x004
0x008
GPTMCFG
GPTMTAMR
GPTMTBMR
R/W
R/W
R/W
0x0000.0000
0x0000.0000
0x0000.0000
GPTM Configuration
GPTM TimerA Mode
GPTM TimerB Mode
169
170
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See
page
Offset
Name
Type
Reset
Description
0x00C
0x018
0x01C
0x020
0x024
GPTMCTL
GPTMIMR
GPTMRIS
GPTMMIS
GPTMICR
R/W
R/W
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
GPTM Control
174
177
179
180
181
GPTM Interrupt Mask
GPTM Raw Interrupt Status
GPTM Masked Interrupt Status
GPTM Interrupt Clear
RO
W1C
0x0000.FFFF
(16-bit mode)
0xFFFF.FFFF
(32-bit mode)
0x028
0x02C
0x030
GPTMTAILR
R/W
R/W
R/W
GPTM TimerA Interval Load
GPTM TimerB Interval Load
GPTM TimerA Match
183
184
185
GPTMTBILR
0x0000.FFFF
0x0000.FFFF
(16-bit mode)
0xFFFF.FFFF
(32-bit mode)
GPTMTAMATCHR
0x034
0x038
0x03C
0x040
0x044
GPTMTBMATCHR
GPTMTAPR
R/W
R/W
R/W
R/W
R/W
0x0000.FFFF
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
GPTM TimerB Match
186
187
188
189
190
GPTM TimerA Prescale
GPTM TimerB Prescale
GPTM TimerA Prescale Match
GPTM TimerB Prescale Match
GPTMTBPR
GPTMTAPMR
GPTMTBPMR
0x0000.FFFF
(16-bit mode)
0xFFFF.FFFF
(32-bit mode)
0x048
0x04C
GPTMTAR
GPTMTBR
RO
RO
GPTM TimerA
GPTM TimerB
191
192
0x0000.FFFF
9.5
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
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
reserved
GPTMCFG
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
R/W
0
R/W
0
R/W
0
Bit/Field
31:3
Name
Type
RO
Reset
Description
reserved
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
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
reserved
TAAMS TACMR
TAMR
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:4
Name
Type
RO
Reset
0x00
Description
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.
3
TAAMS
R/W
0
GPTM TimerA Alternate Mode Select
The TAAMS values are defined as follows:
Value Description
0
1
Capture mode is enabled.
PWM mode is enabled.
Note:
To enable PWM mode, you must also clear the TACMR
bit and set the TAMR field to 0x2.
2
TACMR
R/W
0
GPTM TimerA Capture Mode
The TACMR values are defined as follows:
Value Description
0
1
Edge-Count mode.
Edge-Time mode.
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Bit/Field
1:0
Name
TAMR
Type
R/W
Reset
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
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
reserved
TBAMS TBCMR
TBMR
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:4
Name
Type
RO
Reset
0x00
Description
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.
3
TBAMS
R/W
0
GPTM TimerB Alternate Mode Select
The TBAMS values are defined as follows:
Value Description
0
1
Capture mode is enabled.
PWM mode is enabled.
Note:
To enable PWM mode, you must also clear the TBCMR
bit and set the TBMR field to 0x2.
2
TBCMR
R/W
0
GPTM TimerB Capture Mode
The TBCMR values are defined as follows:
Value Description
0
1
Edge-Count mode.
Edge-Time mode.
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Bit/Field
1:0
Name
TBMR
Type
R/W
Reset
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.
GPTM Control (GPTMCTL)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x00C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved TBPWML TBOTE reserved
TBEVENT
TBSTALL TBEN reserved TAPWML TAOTE RTCEN
TAEVENT
TASTALL TAEN
Type
Reset
RO
0
R/W
0
R/W
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:15
Name
Type
RO
Reset
0x00
Description
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.
14
TBPWML
R/W
0
GPTM TimerB PWM Output Level
The TBPWML values are defined as follows:
Value Description
0
1
Output is unaffected.
Output is inverted.
13
TBOTE
R/W
0
GPTM TimerB Output Trigger Enable
The TBOTE values are defined as follows:
Value Description
0
1
The output TimerB trigger is disabled.
The output TimerB trigger is enabled.
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.
11:10
TBEVENT
R/W
0x0
GPTM TimerB Event Mode
The TBEVENT values are defined as follows:
Value Description
0x0 Positive edge.
0x1 Negative edge.
0x2 Reserved
0x3 Both edges.
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Bit/Field
9
Name
Type
R/W
Reset
0
Description
TBSTALL
GPTM TimerB Stall Enable
The TBSTALL values are defined as follows:
Value Description
0
1
TimerB stalling is disabled.
TimerB stalling is enabled.
8
TBEN
R/W
0
GPTM TimerB Enable
The TBEN values are defined as follows:
Value Description
0
1
TimerB is disabled.
TimerB is enabled and begins counting or the capture logic is
enabled based on the GPTMCFG register.
7
6
reserved
TAPWML
RO
0
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.
R/W
GPTM TimerA PWM Output Level
The TAPWML values are defined as follows:
Value Description
0
1
Output is unaffected.
Output is inverted.
5
TAOTE
R/W
0
GPTM TimerA Output Trigger Enable
The TAOTE values are defined as follows:
Value Description
0
1
The output TimerA trigger is disabled.
The output TimerA trigger is enabled.
4
RTCEN
R/W
0
GPTM RTC Enable
The RTCEN values are defined as follows:
Value Description
0
1
RTC counting is disabled.
RTC counting is enabled.
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Bit/Field
3:2
Name
Type
R/W
Reset
0x0
Description
TAEVENT
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 TimerA Stall Enable
The TASTALL values are defined as follows:
Value Description
0
1
TimerA stalling is disabled.
TimerA stalling is enabled.
0
TAEN
R/W
0
GPTM TimerA Enable
The TAEN values are defined as follows:
Value Description
0
1
TimerA is disabled.
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
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
reserved
CBEIM
CBMIM TBTOIM
reserved
RTCIM
CAEIM
CAMIM TATOIM
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:11
Name
Type
RO
Reset
0x00
Description
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.
10
CBEIM
CBMIM
TBTOIM
reserved
R/W
R/W
R/W
RO
0
0
0
0
GPTM CaptureB Event Interrupt Mask
The CBEIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
9
GPTM CaptureB Match Interrupt Mask
The CBMIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
8
GPTM TimerB Time-Out Interrupt Mask
The TBTOIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
7:4
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.
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Bit/Field
3
Name
Type
R/W
Reset
0
Description
RTCIM
CAEIM
CAMIM
TATOIM
GPTM RTC Interrupt Mask
The RTCIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
2
1
0
R/W
R/W
R/W
0
0
0
GPTM CaptureA Event Interrupt Mask
The CAEIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
GPTM CaptureA Match Interrupt Mask
The CAMIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
Interrupt is enabled.
GPTM TimerA Time-Out Interrupt Mask
The TATOIM values are defined as follows:
Value Description
0
1
Interrupt is disabled.
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
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
reserved
CBERIS CBMRIS TBTORIS
reserved
RTCRIS CAERIS CAMRIS TATORIS
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
Bit/Field
31:11
Name
Type
RO
Reset
0x00
Description
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.
10
9
CBERIS
CBMRIS
TBTORIS
reserved
RO
RO
RO
RO
0
0
GPTM CaptureB Event Raw Interrupt
This is the CaptureB Event interrupt status prior to masking.
GPTM CaptureB Match Raw Interrupt
This is the CaptureB Match interrupt status prior to masking.
8
0
GPTM TimerB Time-Out Raw Interrupt
This is the TimerB time-out interrupt status prior to masking.
7:4
0x0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
3
2
1
0
RTCRIS
CAERIS
CAMRIS
TATORIS
RO
RO
RO
RO
0
0
0
0
GPTM RTC Raw Interrupt
This is the RTC Event interrupt status prior to masking.
GPTM CaptureA Event Raw Interrupt
This is the CaptureA Event interrupt status prior to masking.
GPTM CaptureA Match Raw Interrupt
This is the CaptureA Match interrupt status prior to masking.
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
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
reserved
CBEMIS CBMMIS TBTOMIS
reserved
RTCMIS CAEMIS CAMMIS TATOMIS
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
Bit/Field
31:11
Name
Type
RO
Reset
0x00
Description
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.
10
9
CBEMIS
CBMMIS
TBTOMIS
reserved
RO
RO
RO
RO
0
0
GPTM CaptureB Event Masked Interrupt
This is the CaptureB event interrupt status after masking.
GPTM CaptureB Match Masked Interrupt
This is the CaptureB match interrupt status after masking.
8
0
GPTM TimerB Time-Out Masked Interrupt
This is the TimerB time-out interrupt status after masking.
7:4
0x0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
3
2
1
0
RTCMIS
CAEMIS
CAMMIS
TATOMIS
RO
RO
RO
RO
0
0
0
0
GPTM RTC Masked Interrupt
This is the RTC event interrupt status after masking.
GPTM CaptureA Event Masked Interrupt
This is the CaptureA event interrupt status after masking.
GPTM CaptureA Match Masked Interrupt
This is the CaptureA match interrupt status after masking.
GPTM TimerA Time-Out Masked Interrupt
This is the TimerA time-out interrupt status after masking.
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October 01, 2007
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LM3S300 Microcontroller
Register 8: GPTM Interrupt Clear (GPTMICR), offset 0x024
This register is used to clear the status bits in the GPTMRIS and GPTMMIS registers. Writing a 1
to a bit clears the corresponding bit in the GPTMRIS and GPTMMIS registers.
GPTM Interrupt Clear (GPTMICR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x024
Type W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CBECINT CBMCINT TBTOCINT
reserved
RTCCINT CAECINT CAMCINT TATOCINT
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
W1C
0
W1C
0
W1C
0
RO
0
RO
0
RO
0
RO
0
W1C
0
W1C
0
W1C
0
W1C
0
Bit/Field
31:11
Name
Type
RO
Reset
Description
reserved
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
CBMCINT
TBTOCINT
reserved
W1C
W1C
W1C
RO
0
GPTM CaptureB Event Interrupt Clear
The CBECINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
9
0
GPTM CaptureB Match Interrupt Clear
The CBMCINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
8
0
GPTM TimerB Time-Out Interrupt Clear
The TBTOCINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
7:4
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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General-Purpose Timers
Bit/Field
3
Name
RTCCINT
Type
W1C
Reset
0
Description
GPTM RTC Interrupt Clear
The RTCCINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
2
CAECINT
W1C
0
GPTM CaptureA Event Interrupt Clear
The CAECINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
1
0
CAMCINT
TATOCINT
W1C
W1C
0
0
GPTM CaptureA Match Raw Interrupt
This is the CaptureA match interrupt status after masking.
GPTM TimerA Time-Out Raw Interrupt
The TATOCINT values are defined as follows:
Value Description
0
1
The interrupt is unaffected.
The interrupt is cleared.
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LM3S300 Microcontroller
Register 9: GPTM TimerA Interval Load (GPTMTAILR), offset 0x028
This register is used to load the starting count value into the timer. When GPTM is configured to
one of the 32-bit modes, GPTMTAILR appears as a 32-bit register (the upper 16-bits correspond
to the contents of the GPTM TimerB Interval Load (GPTMTBILR) register). In 16-bit mode, the
upper 16 bits of this register read as 0s and have no effect on the state of GPTMTBILR.
GPTM TimerA Interval Load (GPTMTAILR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x028
Type R/W, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
TAILRH
Type
Reset
R/W
0
R/W
1
R/W
1
R/W
0
R/W
1
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
TAILRL
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
Bit/Field
31:16
Name
Type
R/W
Reset
Description
GPTM TimerA Interval Load Register High
TAILRH
0xFFFF
(32-bit mode)
0x0000 (16-bit
mode)
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
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
TBILRL
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
Bit/Field
31:16
Name
Type
RO
Reset
Description
reserved
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.
184
October 01, 2007
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LM3S300 Microcontroller
Register 11: GPTM TimerA Match (GPTMTAMATCHR), offset 0x030
This register is used in 32-bit Real-Time Clock mode and 16-bit PWM and Input Edge Count modes.
GPTM TimerA Match (GPTMTAMATCHR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x030
Type R/W, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
TAMRH
Type
Reset
R/W
0
R/W
1
R/W
1
R/W
0
R/W
1
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
R/W
1
R/W
1
R/W
1
R/W
1
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
TAMRL
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
Bit/Field
31:16
Name
Type
R/W
Reset
Description
GPTM TimerA Match Register High
TAMRH
0xFFFF
(32-bit mode)
0x0000 (16-bit
mode)
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.
October 01, 2007
185
Preliminary
General-Purpose Timers
Register 12: GPTM TimerB Match (GPTMTBMATCHR), offset 0x034
This register is used in 32-bit Real-Time Clock mode and 16-bit PWM and Input Edge Count modes.
GPTM TimerB Match (GPTMTBMATCHR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x034
Type R/W, reset 0x0000.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
TBMRL
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
Bit/Field
31:16
Name
Type
RO
Reset
Description
reserved
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.
186
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 13: GPTM TimerA Prescale (GPTMTAPR), offset 0x038
This register allows software to extend the range of the 16-bit timers when operating in one-shot or
periodic mode.
GPTM TimerA Prescale (GPTMTAPR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x038
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TAPSR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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 9-1 on page 161 for more details and an example.
October 01, 2007
187
Preliminary
General-Purpose Timers
Register 14: GPTM TimerB Prescale (GPTMTBPR), offset 0x03C
This register allows software to extend the range of the 16-bit timers when operating in one-shot or
periodic mode.
GPTM TimerB Prescale (GPTMTBPR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x03C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TBPSR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
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 9-1 on page 161 for more details and an example.
188
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 15: GPTM TimerA Prescale Match (GPTMTAPMR), offset 0x040
This register effectively extends the range of GPTMTAMATCHR to 24 bits when operating in 16-bit
one-shot or periodic mode.
GPTM TimerA Prescale Match (GPTMTAPMR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x040
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TAPSMR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
TAPSMR
R/W
0x00
GPTM TimerA Prescale Match
This value is used alongside GPTMTAMATCHR to detect timer match
events while using a prescaler.
October 01, 2007
189
Preliminary
General-Purpose Timers
Register 16: GPTM TimerB Prescale Match (GPTMTBPMR), offset 0x044
This register effectively extends the range of GPTMTBMATCHR to 24 bits when operating in 16-bit
one-shot or periodic mode.
GPTM TimerB Prescale Match (GPTMTBPMR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x044
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TBPSMR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
TBPSMR
R/W
0x00
GPTM TimerB Prescale Match
This value is used alongside GPTMTBMATCHR to detect timer match
events while using a prescaler.
190
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 17: GPTM TimerA (GPTMTAR), offset 0x048
This register shows the current value of the TimerA counter in all cases except for Input Edge Count
mode. When in this mode, this register contains the time at which the last edge event took place.
GPTM TimerA (GPTMTAR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x048
Type RO, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
TARH
TARL
Type
Reset
RO
0
RO
1
RO
1
RO
0
RO
1
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Type
Reset
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
Bit/Field
31:16
Name
TARH
Type
RO
Reset
Description
GPTM TimerA Register High
0xFFFF
(32-bit mode)
0x0000 (16-bit
mode)
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 timestamp from
the last edge event.
October 01, 2007
191
Preliminary
General-Purpose Timers
Register 18: GPTM TimerB (GPTMTBR), offset 0x04C
This register shows the current value of the TimerB counter in all cases except for Input Edge Count
mode. When in this mode, this register contains the time at which the last edge event took place.
GPTM TimerB (GPTMTBR)
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
Offset 0x04C
Type RO, reset 0x0000.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
TBRL
Type
Reset
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
Bit/Field
31:16
Name
Type
RO
Reset
Description
reserved
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 timestamp from
the last edge event.
192
October 01, 2007
Preliminary
LM3S300 Microcontroller
10
Watchdog Timer
A watchdog timer can generate nonmaskable interrupts (NMIs) or a reset when a time-out value is
reached. The watchdog timer is used to regain control when a system has failed due to a software
error or due to the failure of an external device to respond in the expected way.
The Stellaris® Watchdog Timer module consists of a 32-bit down counter, a programmable load
register, interrupt generation logic, a locking register, and user-enabled stalling.
The Watchdog Timer can be configured to generate an interrupt to the controller on its first time-out,
and to generate a reset signal on its second time-out. Once the Watchdog Timer has been configured,
the lock register can be written to prevent the timer configuration from being inadvertently altered.
10.1
Block Diagram
Figure 10-1. WDT Module Block Diagram
WDTLOAD
Control / Clock /
Interrupt
Generation
WDTCTL
WDTICR
Interrupt
WDTRIS
32-Bit Down
Counter
WDTMIS
WDTLOCK
WDTTEST
0x00000000
System Clock
Comparator
WDTVALUE
Identification Registers
WDTPCellID0 WDTPeriphID0 WDTPeriphID4
WDTPCellID1 WDTPeriphID1 WDTPeriphID5
WDTPCellID2 WDTPeriphID2 WDTPeriphID6
WDTPCellID3 WDTPeriphID3 WDTPeriphID7
10.2
Functional Description
The Watchdog Timer module generates the first time-out signal when the 32-bit counter reaches
the zero state after being enabled; enabling the counter also enables the watchdog timer interrupt.
After the first time-out event, the 32-bit counter is re-loaded with the value of the Watchdog Timer
Load (WDTLOAD) register, and the timer resumes counting down from that value. Once the
October 01, 2007
193
Preliminary
Watchdog Timer
Watchdog Timer has been configured, the Watchdog Timer Lock (WDTLOCK) register is written,
which prevents the timer configuration from being inadvertently altered by software.
If the timer counts down to its zero state again before the first time-out interrupt is cleared, and the
reset signal has been enabled (via the WatchdogResetEnable function), the Watchdog timer
asserts its reset signal to the system. If the interrupt is cleared before the 32-bit counter reaches its
second time-out, the 32-bit counter is loaded with the value in the WDTLOAD register, and counting
resumes from that value.
If WDTLOAD is written with a new value while the Watchdog Timer counter is counting, then the
counter is loaded with the new value and continues counting.
Writing to WDTLOAD does not clear an active interrupt. An interrupt must be specifically cleared
by writing to the Watchdog Interrupt Clear (WDTICR) register.
The Watchdog module interrupt and reset generation can be enabled or disabled as required. When
the interrupt is re-enabled, the 32-bit counter is preloaded with the load register value and not its
last state.
10.3
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.
10.4
Register Map
Table 10-1 on page 194 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 10-1. Watchdog Timer Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
0x004
0x008
0x00C
0x010
0x014
0x418
0xC00
WDTLOAD
WDTVALUE
WDTCTL
WDTICR
R/W
RO
0xFFFF.FFFF
0xFFFF.FFFF
0x0000.0000
-
Watchdog Load
196
197
198
199
200
201
202
203
Watchdog Value
R/W
WO
RO
Watchdog Control
Watchdog Interrupt Clear
Watchdog Raw Interrupt Status
Watchdog Masked Interrupt Status
Watchdog Test
WDTRIS
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
WDTMIS
RO
WDTTEST
WDTLOCK
R/W
R/W
Watchdog Lock
194
October 01, 2007
Preliminary
LM3S300 Microcontroller
See
page
Offset
Name
Type
Reset
Description
0xFD0
0xFD4
0xFD8
0xFDC
0xFE0
0xFE4
0xFE8
0xFEC
0xFF0
0xFF4
0xFF8
0xFFC
WDTPeriphID4
WDTPeriphID5
WDTPeriphID6
WDTPeriphID7
WDTPeriphID0
WDTPeriphID1
WDTPeriphID2
WDTPeriphID3
WDTPCellID0
WDTPCellID1
WDTPCellID2
WDTPCellID3
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0005
0x0000.0018
0x0000.0018
0x0000.0001
0x0000.000D
0x0000.00F0
0x0000.0005
0x0000.00B1
Watchdog Peripheral Identification 4
Watchdog Peripheral Identification 5
Watchdog Peripheral Identification 6
Watchdog Peripheral Identification 7
Watchdog Peripheral Identification 0
Watchdog Peripheral Identification 1
Watchdog Peripheral Identification 2
Watchdog Peripheral Identification 3
Watchdog PrimeCell Identification 0
Watchdog PrimeCell Identification 1
Watchdog PrimeCell Identification 2
Watchdog PrimeCell Identification 3
204
205
206
207
208
209
210
211
212
213
214
215
10.5
Register Descriptions
The remainder of this section lists and describes the WDT registers, in numerical order by address
offset.
October 01, 2007
195
Preliminary
Watchdog Timer
Register 1: Watchdog Load (WDTLOAD), offset 0x000
This register is the 32-bit interval value used by the 32-bit counter. When this register is written, the
value is immediately loaded and the counter restarts counting down from the new value. If the
WDTLOAD register is loaded with 0x0000.0000, an interrupt is immediately generated.
Watchdog Load (WDTLOAD)
Base 0x4000.0000
Offset 0x000
Type R/W, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WDTLoad
Type
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
WDTLoad
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
Bit/Field
31:0
Name
Type
R/W
Reset
Description
WDTLoad
0xFFFF.FFFF Watchdog Load Value
196
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 2: Watchdog Value (WDTVALUE), offset 0x004
This register contains the current count value of the timer.
Watchdog Value (WDTVALUE)
Base 0x4000.0000
Offset 0x004
Type RO, reset 0xFFFF.FFFF
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WDTValue
Type
Reset
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
WDTValue
Type
Reset
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
Bit/Field
31:0
Name
Type
RO
Reset
Description
WDTValue
0xFFFF.FFFF Watchdog Value
Current value of the 32-bit down counter.
October 01, 2007
197
Preliminary
Watchdog Timer
Register 3: Watchdog Control (WDTCTL), offset 0x008
This register is the watchdog control register. The watchdog timer can be configured to generate a
reset signal (on second time-out) or an interrupt on time-out.
When the watchdog interrupt has been enabled, all subsequent writes to the control register are
ignored. The only mechanism that can re-enable writes is a hardware reset.
Watchdog Control (WDTCTL)
Base 0x4000.0000
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RESEN
INTEN
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
R/W
0
R/W
0
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
RESEN
R/W
0
Watchdog Reset Enable
The RESEN values are defined as follows:
Value Description
0
1
Disabled.
Enable the Watchdog module reset output.
0
INTEN
R/W
0
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.
198
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 4: Watchdog Interrupt Clear (WDTICR), offset 0x00C
This register is the interrupt clear register. A write of any value to this register clears the Watchdog
interrupt and reloads the 32-bit counter from the WDTLOAD register. Value for a read or reset is
indeterminate.
Watchdog Interrupt Clear (WDTICR)
Base 0x4000.0000
Offset 0x00C
Type WO, reset -
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WDTIntClr
Type
Reset
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
WDTIntClr
Type
Reset
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
WO
-
Bit/Field
31:0
Name
Type
WO
Reset
-
Description
Watchdog Interrupt Clear
WDTIntClr
October 01, 2007
199
Preliminary
Watchdog Timer
Register 5: Watchdog Raw Interrupt Status (WDTRIS), offset 0x010
This register is the raw interrupt status register. Watchdog interrupt events can be monitored via
this register if the controller interrupt is masked.
Watchdog Raw Interrupt Status (WDTRIS)
Base 0x4000.0000
Offset 0x010
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
WDTRIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
WDTRIS
RO
0
Watchdog Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of WDTINTR.
200
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 6: Watchdog Masked Interrupt Status (WDTMIS), offset 0x014
This register is the masked interrupt status register. The value of this register is the logical AND of
the raw interrupt bit and the Watchdog interrupt enable bit.
Watchdog Masked Interrupt Status (WDTMIS)
Base 0x4000.0000
Offset 0x014
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
WDTMIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
WDTMIS
RO
0
Watchdog Masked Interrupt Status
Gives the masked interrupt state (after masking) of the WDTINTR
interrupt.
October 01, 2007
201
Preliminary
Watchdog Timer
Register 7: Watchdog Test (WDTTEST), offset 0x418
This register provides user-enabled stalling when the microcontroller asserts the CPU halt flag
during debug.
Watchdog Test (WDTTEST)
Base 0x4000.0000
Offset 0x418
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
STALL
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:9
Name
Type
RO
Reset
0x00
Description
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.
8
STALL
R/W
RO
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
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.
202
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 8: Watchdog Lock (WDTLOCK), offset 0xC00
Writing 0x1ACC.E551 to the WDTLOCK register enables write access to all other registers. Writing
any other value to the WDTLOCK register re-enables the locked state for register writes to all the
other registers. Reading the WDTLOCK register returns the lock status rather than the 32-bit value
written. Therefore, when write accesses are disabled, reading the WDTLOCK register returns
0x0000.0001 (when locked; otherwise, the returned value is 0x0000.0000 (unlocked)).
Watchdog Lock (WDTLOCK)
Base 0x4000.0000
Offset 0xC00
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WDTLock
Type
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
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
WDTLock
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
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
31:0
Name
Type
R/W
Reset
Description
WDTLock
0x0000
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
October 01, 2007
203
Preliminary
Watchdog Timer
Register 9: Watchdog Peripheral Identification 4 (WDTPeriphID4), offset 0xFD0
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 4 (WDTPeriphID4)
Base 0x4000.0000
Offset 0xFD0
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID4
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID4
RO
0x00
WDT Peripheral ID Register[7:0]
204
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 10: Watchdog Peripheral Identification 5 (WDTPeriphID5), offset
0xFD4
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 5 (WDTPeriphID5)
Base 0x4000.0000
Offset 0xFD4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID5
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID5
RO
0x00
WDT Peripheral ID Register[15:8]
October 01, 2007
205
Preliminary
Watchdog Timer
Register 11: Watchdog Peripheral Identification 6 (WDTPeriphID6), offset
0xFD8
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 6 (WDTPeriphID6)
Base 0x4000.0000
Offset 0xFD8
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID6
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID6
RO
0x00
WDT Peripheral ID Register[23:16]
206
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 12: Watchdog Peripheral Identification 7 (WDTPeriphID7), offset
0xFDC
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 7 (WDTPeriphID7)
Base 0x4000.0000
Offset 0xFDC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID7
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID7
RO
0x00
WDT Peripheral ID Register[31:24]
October 01, 2007
207
Preliminary
Watchdog Timer
Register 13: Watchdog Peripheral Identification 0 (WDTPeriphID0), offset
0xFE0
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 0 (WDTPeriphID0)
Base 0x4000.0000
Offset 0xFE0
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID0
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
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID0
RO
0x05
Watchdog Peripheral ID Register[7:0]
208
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 14: Watchdog Peripheral Identification 1 (WDTPeriphID1), offset
0xFE4
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 1 (WDTPeriphID1)
Base 0x4000.0000
Offset 0xFE4
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID1
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
1
RO
1
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID1
RO
0x18
Watchdog Peripheral ID Register[15:8]
October 01, 2007
209
Preliminary
Watchdog Timer
Register 15: Watchdog Peripheral Identification 2 (WDTPeriphID2), offset
0xFE8
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 2 (WDTPeriphID2)
Base 0x4000.0000
Offset 0xFE8
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID2
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
1
RO
1
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID2
RO
0x18
Watchdog Peripheral ID Register[23:16]
210
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 16: Watchdog Peripheral Identification 3 (WDTPeriphID3), offset
0xFEC
The WDTPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog Peripheral Identification 3 (WDTPeriphID3)
Base 0x4000.0000
Offset 0xFEC
Type RO, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID3
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
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID3
RO
0x01
Watchdog Peripheral ID Register[31:24]
October 01, 2007
211
Preliminary
Watchdog Timer
Register 17: Watchdog PrimeCell Identification 0 (WDTPCellID0), offset 0xFF0
The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog PrimeCell Identification 0 (WDTPCellID0)
Base 0x4000.0000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID0
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
1
RO
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID0
RO
0x0D
Watchdog PrimeCell ID Register[7:0]
212
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 18: Watchdog PrimeCell Identification 1 (WDTPCellID1), offset 0xFF4
The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog PrimeCell Identification 1 (WDTPCellID1)
Base 0x4000.0000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID1
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID1
RO
0xF0
Watchdog PrimeCell ID Register[15:8]
October 01, 2007
213
Preliminary
Watchdog Timer
Register 19: Watchdog PrimeCell Identification 2 (WDTPCellID2), offset 0xFF8
The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog PrimeCell Identification 2 (WDTPCellID2)
Base 0x4000.0000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID2
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
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID2
RO
0x05
Watchdog PrimeCell ID Register[23:16]
214
October 01, 2007
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LM3S300 Microcontroller
Register 20: Watchdog PrimeCell Identification 3 (WDTPCellID3 ), offset 0xFFC
The WDTPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
Watchdog PrimeCell Identification 3 (WDTPCellID3)
Base 0x4000.0000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID3
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID3
RO
0xB1
Watchdog PrimeCell ID Register[31:24]
October 01, 2007
215
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
11
Universal Asynchronous Receivers/Transmitters
(UARTs)
The Stellaris® Universal Asynchronous Receiver/Transmitter (UART) provides fully programmable,
16C550-type serial interface characteristics. The LM3S300 controller is equipped with two UART
modules.
Each UART has the following features:
■ Separate transmit and receive FIFOs
■ Programmable FIFO length, including 1-byte deep operation providing conventional
double-buffered interface
■ FIFO trigger levels of 1/8, 1/4, 1/2, 3/4, and 7/8
■ Programmable baud-rate generator allowing rates up to 1.5625 Mbps
■ Standard asynchronous communication bits for start, stop, and parity
■ False start bit detection
■ Line-break generation and detection
■ Fully programmable serial interface characteristics:
–
–
–
5, 6, 7, or 8 data bits
Even, odd, stick, or no-parity bit generation/detection
1 or 2 stop bit generation
216
October 01, 2007
Preliminary
LM3S300 Microcontroller
11.1
Block Diagram
Figure 11-1. UART Module Block Diagram
System Clock
TXFIFO
16x8
Interrupt Control
Interrupt
UARTIFLS
UARTIM
.
.
.
UARTMIS
UARTRIS
Identification
Registers
UARTICR
Transmitter
UnTx
UARTPCellID0
Baud Rate
Generator
UARTPCellID1
UARTDR
UARTPCellID2
UARTPCellID3
UARTPeriphID0
UARTPeriphID1
UARTPeriphID2
UARTIBRD
UARTFBRD
Receiver
UnRx
UARTPeriphID3
Control / Status
UART PeriphID4
UARTRSR/ECR
UARTPeriphID5
UARTFR
RXFIFO
16x8
UARTPeriphID6
UARTLCRH
.
.
.
UARTPeriphID7
UARTCTL
UARTILPR
11.2
Functional Description
Each Stellaris® UART performs the functions of parallel-to-serial and serial-to-parallel conversions.
It is similar in functionality to a 16C550 UART, but is not register compatible.
The UART is configured for transmit and/or receive via the TXE and RXE bits of the UART Control
(UARTCTL) register (see page 233). 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.
11.2.1
Transmit/Receive Logic
The transmit logic performs parallel-to-serial conversion on the data read from the transmit FIFO.
The control logic outputs the serial bit stream beginning with a start bit, and followed by the data
bits (LSB first), parity bit, and the stop bits according to the programmed configuration in the control
registers. See Figure 11-2 on page 218 for details.
October 01, 2007
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Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
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 11-2. UART Character Frame
UnTX
1
1-2
stop bits
LSB
MSB
5-8 data bits
0
n
Parity bit
if enabled
Start
11.2.2
Baud-Rate Generation
The baud-rate divisor is a 22-bit number consisting of a 16-bit integer and a 6-bit fractional part.
The number formed by these two values is used by the baud-rate generator to determine the bit
period. Having a fractional baud-rate divider allows the UART to generate all the standard baud
rates.
The 16-bit integer is loaded through the UART Integer Baud-Rate Divisor (UARTIBRD) register
(see page 229) and the 6-bit fractional part is loaded with the UART Fractional Baud-Rate Divisor
(UARTFBRD) register (see page 230). The baud-rate divisor (BRD) has the following relationship
to the system clock (where BRDI is the integer part of the BRD and BRDF is the fractional part,
separated by a decimal place.):
BRD = BRDI + BRDF = SysClk / (16 * Baud Rate)
The 6-bit fractional number (that is to be loaded into the DIVFRAC bit field in the UARTFBRD register)
can be calculated by taking the fractional part of the baud-rate divisor, multiplying it by 64, and
adding 0.5 to account for rounding errors:
UARTFBRD[DIVFRAC] = integer(BRDF * 64 + 0.5)
The UART generates an internal baud-rate reference clock at 16x the baud-rate (referred to as
Baud16). This reference clock is divided by 16 to generate the transmit clock, and is used for error
detection during receive operations.
Along with the UART Line Control, High Byte (UARTLCRH) register (see page 231), 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
218
October 01, 2007
Preliminary
LM3S300 Microcontroller
11.2.3
Data Transmission
Data received or transmitted is stored in two 16-byte FIFOs, though the receive FIFO has an extra
four bits per character for status information. For transmission, data is written into the transmit FIFO.
If the UART is enabled, it causes a data frame to start transmitting with the parameters indicated
in the UARTLCRH register. Data continues to be transmitted until there is no data left in the transmit
FIFO. The BUSY bit in the UART Flag (UARTFR) register (see page 227) 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 217).
The start bit is valid if UnRx is still low on the eighth cycle of Baud16, otherwise a false start bit is
detected and it is ignored. Start bit errors can be viewed in the UART Receive Status (UARTRSR)
register (see page 225). If the start bit was valid, successive data bits are sampled on every 16th
cycle of Baud16 (that is, one bit period later) according to the programmed length of the data
characters. The parity bit is then checked if parity mode was enabled. Data length and parity are
defined in the UARTLCRH register.
Lastly, a valid stop bit is confirmed if UnRx is High, otherwise a framing error has occurred. When
a full word is received, the data is stored in the receive FIFO, with any error bits associated with
that word.
11.2.4
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 223). 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 231).
FIFO status can be monitored via the UART Flag (UARTFR) register (see page 227) and the UART
Receive Status (UARTRSR) register. Hardware monitors empty, full and overrun conditions. The
UARTFR register contains empty and full flags (TXFE, TXFF, RXFE, and RXFF bits) and the
UARTRSR register shows overrun status via the OE bit.
The trigger points at which the FIFOs generate interrupts is controlled via the UART Interrupt FIFO
Level Select (UARTIFLS) register (see page 234). 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.
11.2.5
Interrupts
The UART can generate interrupts when the following conditions are observed:
■ Overrun Error
■ Break Error
October 01, 2007
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Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
■ Parity Error
■ Framing Error
■ Receive Timeout
■ Transmit (when condition defined in the TXIFLSEL bit in the UARTIFLS register is met)
■ Receive (when condition defined in the RXIFLSEL bit in the UARTIFLS register is met)
All of the interrupt events are ORed together before being sent to the interrupt controller, so the
UART can only generate a single interrupt request to the controller at any given time. Software can
service multiple interrupt events in a single interrupt service routine by reading the UART Masked
Interrupt Status (UARTMIS) register (see page 239).
The interrupt events that can trigger a controller-level interrupt are defined in the UART Interrupt
Mask (UARTIM ) register (see page 236) 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 238).
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 240).
The receive timeout interrupt is asserted when the receive FIFO is not empty, and no further data
is received over a 32-bit period. The receive timeout interrupt is cleared either when the FIFO
becomes empty through reading all the data (or by reading the holding register), or when a 1 is
written to the corresponding bit in the UARTICR register.
11.2.6
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 233). In loopback mode,
data transmitted on UnTx is received on the UnRx input.
11.3
Initialization and Configuration
To use the UARTs, the peripheral clock must be enabled by setting the UART0 or UART1 bits in the
RCGC1 register.
This section discusses the steps that are required for using a UART module. For this example, the
system clock is assumed to be 20 MHz and the desired UART configuration is:
■ 115200 baud rate
■ Data length of 8 bits
■ One stop bit
■ 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 218, the BRD can be calculated:
220
October 01, 2007
Preliminary
LM3S300 Microcontroller
BRD = 20,000,000 / (16 * 115,200) = 10.8507
which means that the DIVINT field of the UARTIBRD register (see page 229) should be set to 10.
The value to be loaded into the UARTFBRD register (see page 230) is calculated by the equation:
UARTFBRD[DIVFRAC] = integer(0.8507 * 64 + 0.5) = 54
With the BRD values in hand, the UART configuration is written to the module in the following order:
1. Disable the UART by clearing the UARTEN bit in the UARTCTL register.
2. Write the integer portion of the BRD to the UARTIBRD register.
3. Write the fractional portion of the BRD to the UARTFBRD register.
4. Write the desired serial parameters to the UARTLCRH register (in this case, a value of
0x0000.0060).
5. Enable the UART by setting the UARTEN bit in the UARTCTL register.
11.4
Register Map
Table 11-1 on page 221 lists the UART registers. The offset listed is a hexadecimal increment to the
register’s address, relative to that UART’s base address:
■ UART0: 0x4000.C000
■ UART1: 0x4000.D000
Note: The UART must be disabled (see the UARTEN bit in the UARTCTL register on page 233)
before any of the control registers are reprogrammed. When the UART is disabled during
a TX or RX operation, the current transaction is completed prior to the UART stopping.
Table 11-1. UART Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
0x004
0x018
0x024
0x028
0x02C
0x030
0x034
0x038
0x03C
0x040
UARTDR
R/W
R/W
RO
0x0000.0000
0x0000.0000
0x0000.0090
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0300
0x0000.0012
0x0000.0000
0x0000.000F
0x0000.0000
UART Data
223
225
227
229
230
231
233
234
236
238
239
UARTRSR/UARTECR
UARTFR
UART Receive Status/Error Clear
UART Flag
UARTIBRD
UARTFBRD
UARTLCRH
UARTCTL
R/W
R/W
R/W
R/W
R/W
R/W
RO
UART Integer Baud-Rate Divisor
UART Fractional Baud-Rate Divisor
UART Line Control
UART Control
UARTIFLS
UARTIM
UART Interrupt FIFO Level Select
UART Interrupt Mask
UARTRIS
UART Raw Interrupt Status
UART Masked Interrupt Status
UARTMIS
RO
October 01, 2007
221
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
See
page
Offset
Name
Type
Reset
Description
0x044
0xFD0
0xFD4
0xFD8
0xFDC
0xFE0
0xFE4
0xFE8
0xFEC
0xFF0
0xFF4
0xFF8
0xFFC
UARTICR
W1C
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0011
0x0000.0000
0x0000.0018
0x0000.0001
0x0000.000D
0x0000.00F0
0x0000.0005
0x0000.00B1
UART Interrupt Clear
240
242
243
244
245
246
247
248
249
250
251
252
253
UARTPeriphID4
UARTPeriphID5
UARTPeriphID6
UARTPeriphID7
UARTPeriphID0
UARTPeriphID1
UARTPeriphID2
UARTPeriphID3
UARTPCellID0
UARTPCellID1
UARTPCellID2
UARTPCellID3
UART Peripheral Identification 4
UART Peripheral Identification 5
UART Peripheral Identification 6
UART Peripheral Identification 7
UART Peripheral Identification 0
UART Peripheral Identification 1
UART Peripheral Identification 2
UART Peripheral Identification 3
UART PrimeCell Identification 0
UART PrimeCell Identification 1
UART PrimeCell Identification 2
UART PrimeCell Identification 3
11.5
Register Descriptions
The remainder of this section lists and describes the UART registers, in numerical order by address
offset.
222
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 1: UART Data (UARTDR), offset 0x000
This register is the data register (the interface to the FIFOs).
When FIFOs are enabled, data written to this location is pushed onto the transmit FIFO. If FIFOs
are disabled, data is stored in the transmitter holding register (the bottom word of the transmit FIFO).
A write to this register initiates a transmission from the UART.
For received data, if the FIFO is enabled, the data byte and the 4-bit status (break, frame, parity,
and overrun) is pushed onto the 12-bit wide receive FIFO. If FIFOs are disabled, the data byte and
status are stored in the receiving holding register (the bottom word of the receive FIFO). The received
data can be retrieved by reading this register.
UART Data (UARTDR)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OE
BE
PE
FE
DATA
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:12
Name
Type
RO
Reset
0
Description
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.
11
OE
RO
0
UART Overrun Error
The OE values are defined as follows:
Value Description
0
1
There has been no data loss due to a FIFO overrun.
New data was received when the FIFO was full, resulting in
data loss.
10
BE
RO
0
UART Break Error
This bit is set to 1 when a break condition is detected, indicating that
the receive data input was held Low for longer than a full-word
transmission time (defined as start, data, parity, and stop bits).
In FIFO mode, this error is associated with the character at the top of
the FIFO. When a break occurs, only one 0 character is loaded into the
FIFO. The next character is only enabled after the received data input
goes to a 1 (marking state) and the next valid start bit is received.
October 01, 2007
223
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Bit/Field
9
Name
PE
Type
RO
Reset
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
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
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.
224
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 2: UART Receive Status/Error Clear (UARTRSR/UARTECR), offset
0x004
The UARTRSR/UARTECR register is the receive status register/error clear register.
In addition to the UARTDR register, receive status can also be read from the UARTRSR register.
If the status is read from this register, then the status information corresponds to the entry read from
UARTDR prior to reading UARTRSR. The status information for overrun is set immediately when
an overrun condition occurs.
A write of any value to the UARTECR register clears the framing, parity, break, and overrun errors.
All the bits are cleared to 0 on reset.
Read-Only Receive Status (UARTRSR) Register
UART Receive Status/Error Clear (UARTRSR/UARTECR)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x004
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OE
BE
PE
FE
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
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
The UARTRSR register cannot be written.
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.
October 01, 2007
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Universal Asynchronous Receivers/Transmitters (UARTs)
Bit/Field
1
Name
PE
Type
RO
Reset
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.
Write-Only Error Clear (UARTECR) Register
UART Receive Status/Error Clear (UARTRSR/UARTECR)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x004
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
Reset
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
reserved
DATA
Type
Reset
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
Bit/Field
31:8
Name
Type
WO
Reset
0
Description
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.
7:0
DATA
WO
0
Error Clear
A write to this register of any data clears the framing, parity, break, and
overrun flags.
226
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 3: UART Flag (UARTFR), offset 0x018
The UARTFR register is the flag register. After reset, the TXFF, RXFF, and BUSY bits are 0, and
TXFE and RXFE bits are 1.
UART Flag (UARTFR)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x018
Type RO, reset 0x0000.0090
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TXFE
RXFF
TXFF
RXFE
BUSY
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
1
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0
Description
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.
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.
UART Transmit FIFO Full
5
TXFF
RO
0
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.
October 01, 2007
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Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Bit/Field
4
Name
RXFE
Type
RO
Reset
1
Description
UART Receive FIFO Empty
The meaning of this bit depends on the state of the FEN bit in the
UARTLCRH register.
If the FIFO is disabled, this bit is set when the receive holding register
is empty.
If the FIFO is enabled, this bit is set when the receive FIFO is empty.
UART Busy
3
BUSY
RO
0
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.
228
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 4: 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 218
for configuration details.
UART Integer Baud-Rate Divisor (UARTIBRD)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x024
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
DIVINT
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
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
31:16
Name
Type
RO
Reset
0
Description
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.
15:0
DIVINT
R/W
0x0000
Integer Baud-Rate Divisor
October 01, 2007
229
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 5: 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 218
for configuration details.
UART Fractional Baud-Rate Divisor (UARTFBRD)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x028
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DIVFRAC
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:6
Name
Type
RO
Reset
0x00
Description
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.
5:0
DIVFRAC
R/W
0x000
Fractional Baud-Rate Divisor
230
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 6: UART Line Control (UARTLCRH), offset 0x02C
The UARTLCRH register is the line control register. Serial parameters such as data length, parity,
and stop bit selection are implemented in this register.
When updating the baud-rate divisor (UARTIBRD and/or UARTIFRD), the UARTLCRH register
must also be written. The write strobe for the baud-rate divisor registers is tied to the UARTLCRH
register.
UART Line Control (UARTLCRH)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x02C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
SPS
WLEN
FEN
STP2
EPS
PEN
BRK
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0
Description
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.
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.
UART Word Length
6:5
WLEN
R/W
0
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.
October 01, 2007
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Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Bit/Field
3
Name
STP2
Type
R/W
Reset
0
Description
UART Two Stop Bits Select
If this bit is set to 1, two stop bits are transmitted at the end of a frame.
The receive logic does not check for two stop bits being received.
2
EPS
R/W
0
UART Even Parity Select
If this bit is set to 1, even parity generation and checking is performed
during transmission and reception, which checks for an even number
of 1s in data and parity bits.
When cleared to 0, then odd parity is performed, which checks for an
odd number of 1s.
This bit has no effect when parity is disabled by the PEN bit.
1
0
PEN
BRK
R/W
R/W
0
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.
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.
232
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 7: UART Control (UARTCTL), offset 0x030
The UARTCTL register is the control register. All the bits are cleared on reset except for the
Transmit Enable (TXE) and Receive Enable (RXE) bits, which are set to 1.
To enable the UART module, the UARTEN bit must be set to 1. If software requires a configuration
change in the module, the UARTEN bit must be cleared before the configuration changes are written.
If the UART is disabled during a transmit or receive operation, the current transaction is completed
prior to the UART stopping.
UART Control (UARTCTL)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x030
Type R/W, reset 0x0000.0300
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RXE
TXE
LBE
reserved
UARTEN
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
1
R/W
1
R/W
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
Bit/Field
31:10
Name
Type
RO
Reset
Description
reserved
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
TXE
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:
To enable reception, the UARTEN bit must also be set.
8
R/W
1
UART Transmit Enable
If this bit is set to 1, the transmit section of the UART is enabled. When
the UART is disabled in the middle of a transmission, it completes the
current character before stopping.
Note:
To enable transmission, the UARTEN bit must also be set.
7
LBE
R/W
RO
0
0
UART Loop Back Enable
If this bit is set to 1, the UnTX path is fed through the UnRX path.
6:1
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.
0
UARTEN
R/W
0
UART Enable
If this bit is set to 1, the UART is enabled. When the UART is disabled
in the middle of transmission or reception, it completes the current
character before stopping.
October 01, 2007
233
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 8: UART Interrupt FIFO Level Select (UARTIFLS), offset 0x034
The UARTIFLS register is the interrupt FIFO level select register. You can use this register to define
the FIFO level at which the TXRIS and RXRIS bits in the UARTRIS register are triggered.
The interrupts are generated based on a transition through a level rather than being based on the
level. That is, the interrupts are generated when the fill level progresses through the trigger level.
For example, if the receive trigger level is set to the half-way mark, the interrupt is triggered as the
module is receiving the 9th character.
Out of reset, the TXIFLSEL and RXIFLSEL bits are configured so that the FIFOs trigger an interrupt
at the half-way mark.
UART Interrupt FIFO Level Select (UARTIFLS)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x034
Type R/W, reset 0x0000.0012
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RXIFLSEL
TXIFLSEL
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
1
R/W
0
R/W
0
R/W
1
R/W
0
Bit/Field
31:6
Name
Type
RO
Reset
0x00
Description
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.
5:3
RXIFLSEL
R/W
0x2
UART Receive Interrupt FIFO Level Select
The trigger points for the receive interrupt are as follows:
Value Description
0x0 RX FIFO ≥ 1/8 full
0x1 RX FIFO ≥ ¼ full
0x2 RX FIFO ≥ ½ full (default)
0x3 RX FIFO ≥ ¾ full
0x4 RX FIFO ≥ 7/8 full
0x5-0x7 Reserved
234
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
2:0
Name
Type
R/W
Reset
0x2
Description
TXIFLSEL
UART Transmit Interrupt FIFO Level Select
The trigger points for the transmit interrupt are as follows:
Value Description
0x0 TX FIFO ≤ 1/8 full
0x1 TX FIFO ≤ ¼ full
0x2 TX FIFO ≤ ½ full (default)
0x3 TX FIFO ≤ ¾ full
0x4 TX FIFO ≤ 7/8 full
0x5-0x7 Reserved
October 01, 2007
235
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 9: UART Interrupt Mask (UARTIM), offset 0x038
The UARTIM register is the interrupt mask set/clear register.
On a read, this register gives the current value of the mask on the relevant interrupt. Writing a 1 to
a bit allows the corresponding raw interrupt signal to be routed to the interrupt controller. Writing a
0 prevents the raw interrupt signal from being sent to the interrupt controller.
UART Interrupt Mask (UARTIM)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x038
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OEIM
BEIM
PEIM
FEIM
RTIM
TXIM
RXIM
reserved
Type
Reset
RO
0
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
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:11
Name
Type
RO
Reset
Description
reserved
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
9
OEIM
BEIM
PEIM
FEIM
RTIM
TXIM
R/W
R/W
R/W
R/W
R/W
R/W
0
UART Overrun Error Interrupt Mask
On a read, the current mask for the OEIM interrupt is returned.
Setting this bit to 1 promotes the OEIM interrupt to the interrupt controller.
0
0
0
0
0
UART Break Error Interrupt Mask
On a read, the current mask for the BEIM interrupt is returned.
Setting this bit to 1 promotes the BEIM interrupt to the interrupt controller.
8
UART Parity Error Interrupt Mask
On a read, the current mask for the PEIM interrupt is returned.
Setting this bit to 1 promotes the PEIM interrupt to the interrupt controller.
7
UART Framing Error Interrupt Mask
On a read, the current mask for the FEIM interrupt is returned.
Setting this bit to 1 promotes the FEIM interrupt to the interrupt controller.
6
UART Receive Time-Out Interrupt Mask
On a read, the current mask for the RTIM interrupt is returned.
Setting this bit to 1 promotes the RTIM interrupt to the interrupt controller.
5
UART Transmit Interrupt Mask
On a read, the current mask for the TXIM interrupt is returned.
Setting this bit to 1 promotes the TXIM interrupt to the interrupt controller.
236
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
4
Name
RXIM
Type
R/W
Reset
0
Description
UART Receive Interrupt Mask
On a read, the current mask for the RXIM interrupt is returned.
Setting this bit to 1 promotes the RXIM interrupt to the interrupt controller.
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.
October 01, 2007
237
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 10: UART Raw Interrupt Status (UARTRIS), offset 0x03C
The UARTRIS register is the raw interrupt status register. On a read, this register gives the current
raw status value of the corresponding interrupt. A write has no effect.
UART Raw Interrupt Status (UARTRIS)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x03C
Type RO, reset 0x0000.000F
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OERIS
BERIS
PERIS
FERIS
RTRIS
TXRIS
RXRIS
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
1
RO
1
RO
1
RO
1
Bit/Field
31:11
Name
Type
RO
Reset
Description
reserved
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
9
OERIS
BERIS
PERIS
FERIS
RTRIS
TXRIS
RXRIS
reserved
RO
RO
RO
RO
RO
RO
RO
RO
0
0
UART Overrun Error Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
UART Break Error Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
8
0
UART Parity Error Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
7
0
UART Framing Error Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
6
0
UART Receive Time-Out Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
5
0
UART Transmit Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
4
0
UART Receive Raw Interrupt Status
Gives the raw interrupt state (prior to masking) of this interrupt.
3:0
0xF
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
238
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 11: UART Masked Interrupt Status (UARTMIS), offset 0x040
The UARTMIS register is the masked interrupt status register. On a read, this register gives the
current masked status value of the corresponding interrupt. A write has no effect.
UART Masked Interrupt Status (UARTMIS)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x040
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OEMIS
BEMIS
PEMIS
FEMIS
RTMIS
TXMIS
RXMIS
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
Bit/Field
31:11
Name
Type
RO
Reset
Description
reserved
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
9
OEMIS
BEMIS
PEMIS
FEMIS
RTMIS
TXMIS
RXMIS
reserved
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
UART Overrun Error Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
UART Break Error Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
8
UART Parity Error Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
7
UART Framing Error Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
6
UART Receive Time-Out Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
5
UART Transmit Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
4
UART Receive Masked Interrupt Status
Gives the masked interrupt state of this interrupt.
3:0
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.
October 01, 2007
239
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 12: UART Interrupt Clear (UARTICR), offset 0x044
The UARTICR register is the interrupt clear register. On a write of 1, the corresponding interrupt
(both raw interrupt and masked interrupt, if enabled) is cleared. A write of 0 has no effect.
UART Interrupt Clear (UARTICR)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0x044
Type W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OEIC
BEIC
PEIC
FEIC
RTIC
TXIC
RXIC
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
W1C
0
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:11
Name
Type
RO
Reset
Description
reserved
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
OEIC
BEIC
PEIC
W1C
W1C
W1C
0
Overrun Error Interrupt Clear
The OEIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
9
0
Break Error Interrupt Clear
The BEIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
8
0
Parity Error Interrupt Clear
The PEIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
240
October 01, 2007
Preliminary
LM3S300 Microcontroller
Bit/Field
7
Name
FEIC
Type
W1C
Reset
0
Description
Framing Error Interrupt Clear
The FEIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
6
RTIC
W1C
W1C
W1C
RO
0
Receive Time-Out Interrupt Clear
The RTIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
5
TXIC
0
Transmit Interrupt Clear
The TXIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
4
RXIC
0
Receive Interrupt Clear
The RXIC values are defined as follows:
Value Description
0
1
No effect on the interrupt.
Clears interrupt.
3:0
reserved
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.
October 01, 2007
241
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 13: UART Peripheral Identification 4 (UARTPeriphID4), offset 0xFD0
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 4 (UARTPeriphID4)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFD0
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID4
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID4
RO
0x0000
UART Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
242
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 14: UART Peripheral Identification 5 (UARTPeriphID5), offset 0xFD4
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 5 (UARTPeriphID5)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFD4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID5
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID5
RO
0x0000
UART Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
243
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 15: UART Peripheral Identification 6 (UARTPeriphID6), offset 0xFD8
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 6 (UARTPeriphID6)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFD8
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID6
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID6
RO
0x0000
UART Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
244
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 16: UART Peripheral Identification 7 (UARTPeriphID7), offset 0xFDC
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 7 (UARTPeriphID7)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFDC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID7
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
Bit/Field
31:8
Name
Type
RO
Reset
0
Description
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.
7:0
PID7
RO
0x0000
UART Peripheral ID Register[31:24]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
245
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 17: UART Peripheral Identification 0 (UARTPeriphID0), offset 0xFE0
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 0 (UARTPeriphID0)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFE0
Type RO, reset 0x0000.0011
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID0
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
1
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID0
RO
0x11
UART Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
246
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 18: UART Peripheral Identification 1 (UARTPeriphID1), offset 0xFE4
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 1 (UARTPeriphID1)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFE4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID1
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID1
RO
0x00
UART Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
247
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 19: UART Peripheral Identification 2 (UARTPeriphID2), offset 0xFE8
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 2 (UARTPeriphID2)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFE8
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID2
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
1
RO
1
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID2
RO
0x18
UART Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
248
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 20: UART Peripheral Identification 3 (UARTPeriphID3), offset 0xFEC
The UARTPeriphIDn registers are hard-coded and the fields within the registers determine the
reset values.
UART Peripheral Identification 3 (UARTPeriphID3)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFEC
Type RO, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID3
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
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID3
RO
0x01
UART Peripheral ID Register[31:24]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
249
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 21: UART PrimeCell Identification 0 (UARTPCellID0), offset 0xFF0
The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
UART PrimeCell Identification 0 (UARTPCellID0)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID0
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
1
RO
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID0
RO
0x0D
UART PrimeCell ID Register[7:0]
Provides software a standard cross-peripheral identification system.
250
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 22: UART PrimeCell Identification 1 (UARTPCellID1), offset 0xFF4
The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
UART PrimeCell Identification 1 (UARTPCellID1)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID1
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID1
RO
0xF0
UART PrimeCell ID Register[15:8]
Provides software a standard cross-peripheral identification system.
October 01, 2007
251
Preliminary
Universal Asynchronous Receivers/Transmitters (UARTs)
Register 23: UART PrimeCell Identification 2 (UARTPCellID2), offset 0xFF8
The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
UART PrimeCell Identification 2 (UARTPCellID2)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID2
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
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID2
RO
0x05
UART PrimeCell ID Register[23:16]
Provides software a standard cross-peripheral identification system.
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Register 24: UART PrimeCell Identification 3 (UARTPCellID3), offset 0xFFC
The UARTPCellIDn registers are hard-coded and the fields within the registers determine the reset
values.
UART PrimeCell Identification 3 (UARTPCellID3)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID3
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID3
RO
0xB1
UART PrimeCell ID Register[31:24]
Provides software a standard cross-peripheral identification system.
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12
Synchronous Serial Interface (SSI)
The Stellaris® Synchronous Serial Interface (SSI) is a master or slave interface for synchronous
serial communication with peripheral devices that have either Freescale SPI, MICROWIRE, or Texas
Instruments synchronous serial interfaces.
The Stellaris® SSI module has the following features:
■ Master or slave operation
■ Programmable clock bit rate and prescale
■ Separate transmit and receive FIFOs, 16 bits wide, 8 locations deep
■ Programmable interface operation for Freescale SPI, MICROWIRE, or Texas Instruments
synchronous serial interfaces
■ Programmable data frame size from 4 to 16 bits
■ Internal loopback test mode for diagnostic/debug testing
12.1
Block Diagram
Figure 12-1. SSI Module Block Diagram
Interrupt
Interrupt Control
SSIIM
TxFIFO
8 x 16
SSIMIS
SSIRIS
Control / Status
.
.
SSIICR
SSICR0
.
SSICR1
SSITx
SSISR
SSIRx
SSIClk
SSIFss
Transmit/
Receive
Logic
SSIDR
RxFIFO
8 x 16
System Clock
.
.
.
Clock
Prescaler
Identification Registers
SSICPSR
SSIPCellID0
SSIPCellID1
SSIPCellID2
SSIPCellID3
SSIPeriphID0
SSIPeriphID1
SSIPeriphID2
SSIPeriphID3
SSIPeriphID4
SSIPeriphID5
SSIPeriphID6
SSIPeriphID7
12.2
Functional Description
The SSI performs serial-to-parallel conversion on data received from a peripheral device. The CPU
accesses data, control, and status information. The transmit and receive paths are buffered with
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internal FIFO memories allowing up to eight 16-bit values to be stored independently in both transmit
and receive modes.
12.2.1
Bit Rate Generation
The SSI includes a programmable bit rate clock divider and prescaler to generate the serial output
clock. Bit rates are supported to 2 MHz and higher, although maximum bit rate is determined by
peripheral devices.
The serial bit rate is derived by dividing down the 25-MHz input clock. The clock is first divided by
an even prescale value CPSDVSR from 2 to 254, which is programmed in the SSI Clock Prescale
(SSICPSR) register (see page 273). The clock is further divided by a value from 1 to 256, which is
1 + SCR, where SCR is the value programmed in the SSI Control0 (SSICR0) register (see page 266).
The frequency of the output clock SSIClk is defined by:
FSSIClk = FSysClk / (CPSDVSR * (1 + SCR))
Note that although the SSIClk transmit clock can theoretically be 12.5 MHz, the module may not
be able to operate at that speed. For master mode, the system clock must be at least two times
faster than the SSIClk. For slave mode, the system clock must be at least 12 times faster than the
SSIClk.
See “Synchronous Serial Interface (SSI)” on page 352 to view SSI timing parameters.
12.2.2
FIFO Operation
12.2.2.1 Transmit FIFO
The common transmit FIFO is a 16-bit wide, 8-locations deep, first-in, first-out memory buffer. The
CPU writes data to the FIFO by writing the SSI Data (SSIDR) register (see page 270), and data is
stored in the FIFO until it is read out by the transmission logic.
When configured as a master or a slave, parallel data is written into the transmit FIFO prior to serial
conversion and transmission to the attached slave or master, respectively, through the SSITx pin.
12.2.2.2 Receive FIFO
The common receive FIFO is a 16-bit wide, 8-locations deep, first-in, first-out memory buffer.
Received data from the serial interface is stored in the buffer until read out by the CPU, which
accesses the read FIFO by reading the SSIDR register.
When configured as a master or slave, serial data received through the SSIRx pin is registered
prior to parallel loading into the attached slave or master receive FIFO, respectively.
12.2.3
Interrupts
The SSI can generate interrupts when the following conditions are observed:
■ Transmit FIFO service
■ Receive FIFO service
■ Receive FIFO time-out
■ Receive FIFO overrun
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All of the interrupt events are ORed together before being sent to the interrupt controller, so the SSI
can only generate a single interrupt request to the controller at any given time. You can mask each
of the four individual maskable interrupts by setting the appropriate bits in the SSI Interrupt Mask
(SSIIM) register (see page 274). Setting the appropriate mask bit to 1 enables the interrupt.
Provision of the individual outputs, as well as a combined interrupt output, allows use of either a
global interrupt service routine, or modular device drivers to handle interrupts. The transmit and
receive dynamic dataflow interrupts have been separated from the status interrupts so that data
can be read or written in response to the FIFO trigger levels. The status of the individual interrupt
sources can be read from the SSI Raw Interrupt Status (SSIRIS) and SSI Masked Interrupt Status
(SSIMIS) registers (see page 276 and page 277, respectively).
12.2.4
Frame Formats
Each data frame is between 4 and 16 bits long, depending on the size of data programmed, and is
transmitted starting with the MSB. There are three basic frame types that can be selected:
■ Texas Instruments synchronous serial
■ Freescale SPI
■ MICROWIRE
For all three formats, the serial clock (SSIClk) is held inactive while the SSI is idle, and SSIClk
transitions at the programmed frequency only during active transmission or reception of data. The
idle state of SSIClk is utilized to provide a receive timeout indication that occurs when the receive
FIFO still contains data after a timeout period.
For Freescale SPI and MICROWIRE frame formats, the serial frame (SSIFss ) pin is active Low,
and is asserted (pulled down) during the entire transmission of the frame.
For Texas Instruments synchronous serial frame format, the SSIFss pin is pulsed for one serial
clock period starting at its rising edge, prior to the transmission of each frame. For this frame format,
both the SSI and the off-chip slave device drive their output data on the rising edge of SSIClk, and
latch data from the other device on the falling edge.
Unlike the full-duplex transmission of the other two frame formats, the MICROWIRE format uses a
special master-slave messaging technique, which operates at half-duplex. In this mode, when a
frame begins, an 8-bit control message is transmitted to the off-chip slave. During this transmit, no
incoming data is received by the SSI. After the message has been sent, the off-chip slave decodes
it and, after waiting one serial clock after the last bit of the 8-bit control message has been sent,
responds with the requested data. The returned data can be 4 to 16 bits in length, making the total
frame length anywhere from 13 to 25 bits.
12.2.4.1 Texas Instruments Synchronous Serial Frame Format
Figure 12-2 on page 257 shows the Texas Instruments synchronous serial frame format for a single
transmitted frame.
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Figure 12-2. TI Synchronous Serial Frame Format (Single Transfer)
SSIClk
SSIFss
MSB
LSB
SSITx/SSIRx
4 to 16 bits
In this mode, SSIClk and SSIFss are forced Low, and the transmit data line SSITx is tristated
whenever the SSI is idle. Once the bottom entry of the transmit FIFO contains data, SSIFss is
pulsed High for one SSIClk period. The value to be transmitted is also transferred from the transmit
FIFO to the serial shift register of the transmit logic. On the next rising edge of SSIClk, the MSB
of the 4 to 16-bit data frame is shifted out on the SSITx pin. Likewise, the MSB of the received data
is shifted onto the SSIRx pin by the off-chip serial slave device.
Both the SSI and the off-chip serial slave device then clock each data bit into their serial shifter on
the falling edge of each SSIClk. The received data is transferred from the serial shifter to the receive
FIFO on the first rising edge of SSIClk after the LSB has been latched.
Figure 12-3 on page 257 shows the Texas Instruments synchronous serial frame format when
back-to-back frames are transmitted.
Figure 12-3. TI Synchronous Serial Frame Format (Continuous Transfer)
SSIClk
SSIFss
MSB
LSB
SSITx/SSIRx
4 to 16 bits
12.2.4.2 Freescale SPI Frame Format
The Freescale SPI interface is a four-wire interface where the SSIFss signal behaves as a slave
select. The main feature of the Freescale SPI format is that the inactive state and phase of the
SSIClk signal are programmable through the SPO and SPH bits within the SSISCR0 control register.
SPO Clock Polarity Bit
When the SPO clock polarity control bit is Low, it produces a steady state Low value on the SSIClk
pin. If the SPO bit is High, a steady state High value is placed on the SSIClk pin when data is not
being transferred.
SPH Phase Control Bit
The SPH phase control bit selects the clock edge that captures data and allows it to change state.
It has the most impact on the first bit transmitted by either allowing or not allowing a clock transition
before the first data capture edge. When the SPH phase control bit is Low, data is captured on the
first clock edge transition. If the SPH bit is High, data is captured on the second clock edge transition.
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12.2.4.3 Freescale SPI Frame Format with SPO=0 and SPH=0
Single and continuous transmission signal sequences for Freescale SPI format with SPO=0 and
SPH=0 are shown in Figure 12-4 on page 258 and Figure 12-5 on page 258.
Figure 12-4. Freescale SPI Format (Single Transfer) with SPO=0 and SPH=0
SSIClk
SSIFss
SSIRx
SSITx
MSB
LSB
LSB
Q
4 to 16 bits
MSB
Note: Q is undefined.
Figure 12-5. Freescale SPI Format (Continuous Transfer) with SPO=0 and SPH=0
SSIClk
SSIFss
SSIRx
LSB
LSB
MSB
LSB
LSB
MSB
4 to 16 bits
SSITx
MSB
MSB
In this configuration, during idle periods:
■ SSIClk is forced Low
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
■ When the SSI is configured as a master, it enables the SSIClk pad
■ When the SSI is configured as a slave, it disables the SSIClk pad
If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is
signified by the SSIFss master signal being driven Low. This causes slave data to be enabled onto
the SSIRx input line of the master. The master SSITx output pad is enabled.
One half SSIClk period later, valid master data is transferred to the SSITx pin. Now that both the
master and slave data have been set, the SSIClk master clock pin goes High after one further half
SSIClk period.
The data is now captured on the rising and propagated on the falling edges of the SSIClk signal.
In the case of a single word transmission, after all bits of the data word have been transferred, the
SSIFss line is returned to its idle High state one SSIClk period after the last bit has been captured.
However, in the case of continuous back-to-back transmissions, the SSIFss signal must be pulsed
High between each data word transfer. This is because the slave select pin freezes the data in its
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serial peripheral register and does not allow it to be altered if the SPH bit is logic zero. Therefore,
the master device must raise the SSIFss pin of the slave device between each data transfer to
enable the serial peripheral data write. On completion of the continuous transfer, the SSIFss pin
is returned to its idle state one SSIClk period after the last bit has been captured.
12.2.4.4 Freescale SPI Frame Format with SPO=0 and SPH=1
The transfer signal sequence for Freescale SPI format with SPO=0 and SPH=1 is shown in Figure
12-6 on page 259, which covers both single and continuous transfers.
Figure 12-6. Freescale SPI Frame Format with SPO=0 and SPH=1
SSIClk
SSIFss
SSIRx
SSITx
Q
LSB
LSB
Q
MSB
MSB
4 to 16 bits
Note: Q is undefined.
In this configuration, during idle periods:
■ SSIClk is forced Low
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
■ When the SSI is configured as a master, it enables the SSIClk pad
■ When the SSI is configured as a slave, it disables the SSIClk pad
If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is
signified by the SSIFss master signal being driven Low. The master SSITx output is enabled. After
a further one half SSIClk period, both master and slave valid data is enabled onto their respective
transmission lines. At the same time, the SSIClk is enabled with a rising edge transition.
Data is then captured on the falling edges and propagated on the rising edges of the SSIClk signal.
In the case of a single word transfer, after all bits have been transferred, the SSIFss line is returned
to its idle High state one SSIClk period after the last bit has been captured.
For continuous back-to-back transfers, the SSIFss pin is held Low between successive data words
and termination is the same as that of the single word transfer.
12.2.4.5 Freescale SPI Frame Format with SPO=1 and SPH=0
Single and continuous transmission signal sequences for Freescale SPI format with SPO=1 and
SPH=0 are shown in Figure 12-7 on page 260 and Figure 12-8 on page 260.
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Figure 12-7. Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0
SSIClk
SSIFss
SSIRx
MSB
LSB
LSB
Q
4 to 16 bits
MSB
SSITx
Note: Q is undefined.
Figure 12-8. Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0
SSIClk
SSIFss
LSB
SSITx/SSIRx
MSB
LSB
MSB
4 to 16 bits
In this configuration, during idle periods:
■ SSIClk is forced High
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
■ When the SSI is configured as a master, it enables the SSIClk pad
■ When the SSI is configured as a slave, it disables the SSIClk pad
If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is
signified by the SSIFss master signal being driven Low, which causes slave data to be immediately
transferred onto the SSIRx line of the master. The master SSITx output pad is enabled.
One half period later, valid master data is transferred to the SSITx line. Now that both the master
and slave data have been set, the SSIClk master clock pin becomes Low after one further half
SSIClk period. This means that data is captured on the falling edges and propagated on the rising
edges of the SSIClk signal.
In the case of a single word transmission, after all bits of the data word are transferred, the SSIFss
line is returned to its idle High state one SSIClk period after the last bit has been captured.
However, in the case of continuous back-to-back transmissions, the SSIFss signal must be pulsed
High between each data word transfer. This is because the slave select pin freezes the data in its
serial peripheral register and does not allow it to be altered if the SPH bit is logic zero. Therefore,
the master device must raise the SSIFss pin of the slave device between each data transfer to
enable the serial peripheral data write. On completion of the continuous transfer, the SSIFss pin
is returned to its idle state one SSIClk period after the last bit has been captured.
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12.2.4.6 Freescale SPI Frame Format with SPO=1 and SPH=1
The transfer signal sequence for Freescale SPI format with SPO=1 and SPH=1 is shown in Figure
12-9 on page 261, which covers both single and continuous transfers.
Figure 12-9. Freescale SPI Frame Format with SPO=1 and SPH=1
SSIClk
SSIFss
SSIRx
SSITx
Q
LSB
LSB
Q
MSB
MSB
4 to 16 bits
Note: Q is undefined.
In this configuration, during idle periods:
■ SSIClk is forced High
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
■ When the SSI is configured as a master, it enables the SSIClk pad
■ When the SSI is configured as a slave, it disables the SSIClk pad
If the SSI is enabled and there is valid data within the transmit FIFO, the start of transmission is
signified by the SSIFss master signal being driven Low. The master SSITx output pad is enabled.
After a further one-half SSIClk period, both master and slave data are enabled onto their respective
transmission lines. At the same time, SSIClk is enabled with a falling edge transition. Data is then
captured on the rising edges and propagated on the falling edges of the SSIClk signal.
After all bits have been transferred, in the case of a single word transmission, the SSIFss line is
returned to its idle high state one SSIClk period after the last bit has been captured.
For continuous back-to-back transmissions, the SSIFss pin remains in its active Low state, until
the final bit of the last word has been captured, and then returns to its idle state as described above.
For continuous back-to-back transfers, the SSIFss pin is held Low between successive data words
and termination is the same as that of the single word transfer.
12.2.4.7 MICROWIRE Frame Format
Figure 12-10 on page 262 shows the MICROWIRE frame format, again for a single frame. Figure
12-11 on page 263 shows the same format when back-to-back frames are transmitted.
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Figure 12-10. MICROWIRE Frame Format (Single Frame)
SSIClk
SSIFss
MSB
LSB
SSITx
SSIRx
8-bit control
MSB
LSB
0
4 to 16 bits
output data
MICROWIRE format is very similar to SPI format, except that transmission is half-duplex instead of
full-duplex, using a master-slave message passing technique. Each serial transmission begins with
an 8-bit control word that is transmitted from the SSI to the off-chip slave device. During this
transmission, no incoming data is received by the SSI. After the message has been sent, the off-chip
slave decodes it and, after waiting one serial clock after the last bit of the 8-bit control message has
been sent, responds with the required data. The returned data is 4 to 16 bits in length, making the
total frame length anywhere from 13 to 25 bits.
In this configuration, during idle periods:
■ SSIClk is forced Low
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
A transmission is triggered by writing a control byte to the transmit FIFO. The falling edge of SSIFss
causes the value contained in the bottom entry of the transmit FIFO to be transferred to the serial
shift register of the transmit logic, and the MSB of the 8-bit control frame to be shifted out onto the
SSITx pin. SSIFss remains Low for the duration of the frame transmission. The SSIRx pin remains
tristated during this transmission.
The off-chip serial slave device latches each control bit into its serial shifter on the rising edge of
each SSIClk. After the last bit is latched by the slave device, the control byte is decoded during a
one clock wait-state, and the slave responds by transmitting data back to the SSI. Each bit is driven
onto the SSIRx line on the falling edge of SSIClk. The SSI in turn latches each bit on the rising
edge of SSIClk. At the end of the frame, for single transfers, the SSIFss signal is pulled High one
clock period after the last bit has been latched in the receive serial shifter, which causes the data
to be transferred to the receive FIFO.
Note: The off-chip slave device can tristate the receive line either on the falling edge of SSIClk
after the LSB has been latched by the receive shifter, or when the SSIFss pin goes High.
For continuous transfers, data transmission begins and ends in the same manner as a single transfer.
However, the SSIFss line is continuously asserted (held Low) and transmission of data occurs
back-to-back. The control byte of the next frame follows directly after the LSB of the received data
from the current frame. Each of the received values is transferred from the receive shifter on the
falling edge of SSIClk, after the LSB of the frame has been latched into the SSI.
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Figure 12-11. MICROWIRE Frame Format (Continuous Transfer)
SSIClk
SSIFss
LSB
MSB
LSB
SSITx
8-bit control
SSIRx
MSB
LSB
MSB
0
4 to 16 bits
output data
In the MICROWIRE mode, the SSI slave samples the first bit of receive data on the rising edge of
SSIClk after SSIFss has gone Low. Masters that drive a free-running SSIClk must ensure that
the SSIFss signal has sufficient setup and hold margins with respect to the rising edge of SSIClk.
Figure 12-12 on page 263 illustrates these setup and hold time requirements. With respect to the
SSIClk rising edge on which the first bit of receive data is to be sampled by the SSI slave, SSIFss
must have a setup of at least two times the period of SSIClk on which the SSI operates. With
respect to the SSIClk rising edge previous to this edge, SSIFss must have a hold of at least one
SSIClk period.
Figure 12-12. MICROWIRE Frame Format, SSIFss Input Setup and Hold Requirements
tSetup=(2*tSSIClk
)
tHold=tSSIClk
SSIClk
SSIFss
SSIRx
First RX data to be
sampled by SSI slave
12.3
Initialization and Configuration
To use the SSI, its peripheral clock must be enabled by setting the SSI bit in the RCGC1 register.
For each of the frame formats, the SSI is configured using the following steps:
1. Ensure that the SSE bit in the SSICR1 register is disabled before making any configuration
changes.
2. Select whether the SSI is a master or slave:
a. For master operations, set the SSICR1 register to 0x0000.0000.
b. For slave mode (output enabled), set the SSICR1 register to 0x0000.0004.
c. For slave mode (output disabled), set the SSICR1 register to 0x0000.000C.
3. Configure the clock prescale divisor by writing the SSICPSR register.
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4. Write the SSICR0 register with the following configuration:
■ Serial clock rate (SCR)
■ Desired clock phase/polarity, if using Freescale SPI mode (SPH and SPO)
■ The protocol mode: Freescale SPI, TI SSF, MICROWIRE (FRF)
■ The data size (DSS)
5. Enable the SSI by setting the SSE bit in the SSICR1 register.
As an example, assume the SSI must be configured to operate with the following parameters:
■ Master operation
■ Freescale SPI mode (SPO=1, SPH=1)
■ 1 Mbps bit rate
■ 8 data bits
Assuming the system clock is 20 MHz, the bit rate calculation would be:
FSSIClk = FSysClk / (CPSDVSR * (1 + SCR))
1x106 = 20x106 / (CPSDVSR * (1 + SCR))
In this case, if CPSDVSR=2, SCR must be 9.
The configuration sequence would be as follows:
1. Ensure that the SSE bit in the SSICR1 register is disabled.
2. Write the SSICR1 register with a value of 0x0000.0000.
3. Write the SSICPSR register with a value of 0x0000.0002.
4. Write the SSICR0 register with a value of 0x0000.09C7.
5. The SSI is then enabled by setting the SSE bit in the SSICR1 register to 1.
12.4
Register Map
Table 12-1 on page 264 lists the SSI registers. The offset listed is a hexadecimal increment to the
register’s address, relative to that SSI module’s base address:
■ SSI0: 0x4000.8000
Note: The SSI must be disabled (see the SSE bit in the SSICR1 register) before any of the control
registers are reprogrammed.
Table 12-1. SSI Register Map
See
page
Offset
Name
Type
Reset
Description
0x000
SSICR0
R/W
0x0000.0000
SSI Control 0
266
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See
page
Offset
Name
Type
Reset
Description
0x004
0x008
0x00C
0x010
0x014
0x018
0x01C
0x020
0xFD0
0xFD4
0xFD8
0xFDC
0xFE0
0xFE4
0xFE8
0xFEC
0xFF0
0xFF4
0xFF8
0xFFC
SSICR1
R/W
R/W
RO
R/W
R/W
RO
RO
W1C
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
0x0000.0000
0x0000.0000
0x0000.0003
0x0000.0000
0x0000.0000
0x0000.0008
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0022
0x0000.0000
0x0000.0018
0x0000.0001
0x0000.000D
0x0000.00F0
0x0000.0005
0x0000.00B1
SSI Control 1
268
270
271
273
274
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
SSIDR
SSI Data
SSISR
SSI Status
SSICPSR
SSI Clock Prescale
SSIIM
SSI Interrupt Mask
SSIRIS
SSI Raw Interrupt Status
SSI Masked Interrupt Status
SSI Interrupt Clear
SSIMIS
SSIICR
SSIPeriphID4
SSIPeriphID5
SSIPeriphID6
SSIPeriphID7
SSIPeriphID0
SSIPeriphID1
SSIPeriphID2
SSIPeriphID3
SSIPCellID0
SSIPCellID1
SSIPCellID2
SSIPCellID3
SSI Peripheral Identification 4
SSI Peripheral Identification 5
SSI Peripheral Identification 6
SSI Peripheral Identification 7
SSI Peripheral Identification 0
SSI Peripheral Identification 1
SSI Peripheral Identification 2
SSI Peripheral Identification 3
SSI PrimeCell Identification 0
SSI PrimeCell Identification 1
SSI PrimeCell Identification 2
SSI PrimeCell Identification 3
12.5
Register Descriptions
The remainder of this section lists and describes the SSI registers, in numerical order by address
offset.
October 01, 2007
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Synchronous Serial Interface (SSI)
Register 1: SSI Control 0 (SSICR0), offset 0x000
SSICR0 is control register 0 and contains bit fields that control various functions within the SSI
module. Functionality such as protocol mode, clock rate, and data size are configured in this register.
SSI Control 0 (SSICR0)
SSI0 base: 0x4000.8000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
SCR
SPH
SPO
FRF
DSS
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
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
31:16
Name
Type
RO
Reset
0x00
Description
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.
15:8
SCR
R/W
0x0000
SSI Serial Clock Rate
The value SCR is used to generate the transmit and receive bit rate of
the SSI. The bit rate is:
BR=FSSIClk/(CPSDVSR * (1 + SCR))
where CPSDVSR is an even value from 2-254 programmed in the
SSICPSR register, and SCR is a value from 0-255.
7
SPH
R/W
0
SSI Serial Clock Phase
This bit is only applicable to the Freescale SPI Format.
The SPH control bit selects the clock edge that captures data and allows
it to change state. It has the most impact on the first bit transmitted by
either allowing or not allowing a clock transition before the first data
capture edge.
When the SPH bit is 0, data is captured on the first clock edge transition.
If SPH is 1, data is captured on the second clock edge transition.
6
SPO
R/W
0
SSI Serial Clock Polarity
This bit is only applicable to the Freescale SPI Format.
When the SPO bit is 0, it produces a steady state Low value on the
SSIClk pin. If SPO is 1, a steady state High value is placed on the
SSIClk pin when data is not being transferred.
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LM3S300 Microcontroller
Bit/Field
5:4
Name
FRF
Type
R/W
Reset
0x0
Description
SSI Frame Format Select
The FRF values are defined as follows:
Value Frame Format
0x0 Freescale SPI Frame Format
0x1 Texas Intruments Synchronous Serial Frame Format
0x2 MICROWIRE Frame Format
0x3 Reserved
3:0
DSS
R/W
0x00
SSI Data Size Select
The DSS values are defined as follows:
Value
Data Size
0x0-0x2 Reserved
0x3
0x4
0x5
0x6
0x7
0x8
4-bit data
5-bit data
6-bit data
7-bit data
8-bit data
9-bit data
0x9 10-bit data
0xA 11-bit data
0xB 12-bit data
0xC 13-bit data
0xD 14-bit data
0xE 15-bit data
0xF 16-bit data
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Synchronous Serial Interface (SSI)
Register 2: SSI Control 1 (SSICR1), offset 0x004
SSICR1 is control register 1 and contains bit fields that control various functions within the SSI
module. Master and slave mode functionality is controlled by this register.
SSI Control 1 (SSICR1)
SSI0 base: 0x4000.8000
Offset 0x004
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
SOD
MS
SSE
LBM
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:4
Name
Type
RO
Reset
0x00
Description
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.
3
SOD
R/W
0
SSI Slave Mode Output Disable
This bit is relevant only in the Slave mode (MS=1). In multiple-slave
systems, it is possible for the SSI master to broadcast a message to all
slaves in the system while ensuring that only one slave drives data onto
the serial output line. In such systems, the TXD lines from multiple slaves
could be tied together. To operate in such a system, the SOD bit can be
configured so that the SSI slave does not drive the SSITx pin.
The SOD values are defined as follows:
Value Description
0
1
SSI can drive SSITx output in Slave Output mode.
SSI must not drive the SSITx output in Slave mode.
2
MS
R/W
0
SSI Master/Slave Select
This bit selects Master or Slave mode and can be modified only when
SSI is disabled (SSE=0).
The MS values are defined as follows:
Value Description
0
1
Device configured as a master.
Device configured as a slave.
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LM3S300 Microcontroller
Bit/Field
1
Name
SSE
Type
R/W
Reset
0
Description
SSI Synchronous Serial Port Enable
Setting this bit enables SSI operation.
The SSE values are defined as follows:
Value Description
0
1
SSI operation disabled.
SSI operation enabled.
Note:
This bit must be set to 0 before any control registers
are reprogrammed.
0
LBM
R/W
0
SSI Loopback Mode
Setting this bit enables Loopback Test mode.
The LBM values are defined as follows:
Value Description
0
1
Normal serial port operation enabled.
Output of the transmit serial shift register is connected internally
to the input of the receive serial shift register.
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Synchronous Serial Interface (SSI)
Register 3: SSI Data (SSIDR), offset 0x008
SSIDR is the data register and is 16-bits wide. When SSIDR is read, the entry in the receive FIFO
(pointed to by the current FIFO read pointer) is accessed. As data values are removed by the SSI
receive logic from the incoming data frame, they are placed into the entry in the receive FIFO (pointed
to by the current FIFO write pointer).
When SSIDR is written to, the entry in the transmit FIFO (pointed to by the write pointer) is written
to. Data values are removed from the transmit FIFO one value at a time by the transmit logic. It is
loaded into the transmit serial shifter, then serially shifted out onto the SSITx pin at the programmed
bit rate.
When a data size of less than 16 bits is selected, the user must right-justify data written to the
transmit FIFO. The transmit logic ignores the unused bits. Received data less than 16 bits is
automatically right-justified in the receive buffer.
When the SSI is programmed for MICROWIRE frame format, the default size for transmit data is
eight bits (the most significant byte is ignored). The receive data size is controlled by the programmer.
The transmit FIFO and the receive FIFO are not cleared even when the SSE bit in the SSICR1
register is set to zero. This allows the software to fill the transmit FIFO before enabling the SSI.
SSI Data (SSIDR)
SSI0 base: 0x4000.8000
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
DATA
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
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
31:16
Name
Type
RO
Reset
Description
reserved
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
DATA
R/W
0x0000
SSI Receive/Transmit Data
A read operation reads the receive FIFO. A write operation writes the
transmit FIFO.
Software must right-justify data when the SSI is programmed for a data
size that is less than 16 bits. Unused bits at the top are ignored by the
transmit logic. The receive logic automatically right-justifies the data.
270
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LM3S300 Microcontroller
Register 4: SSI Status (SSISR), offset 0x00C
SSISR is a status register that contains bits that indicate the FIFO fill status and the SSI busy status.
SSI Status (SSISR)
SSI0 base: 0x4000.8000
Offset 0x00C
Type RO, reset 0x0000.0003
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
BSY
RFF
RNE
TNF
TFE
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
1
R0
1
Bit/Field
31:5
Name
Type
RO
Reset
0x00
Description
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.
4
BSY
RO
0
SSI Busy Bit
The BSY values are defined as follows:
Value Description
0
1
SSI is idle.
SSI is currently transmitting and/or receiving a frame, or the
transmit FIFO is not empty.
3
2
1
RFF
RNE
TNF
RO
RO
RO
0
0
1
SSI Receive FIFO Full
The RFF values are defined as follows:
Value Description
0
1
Receive FIFO is not full.
Receive FIFO is full.
SSI Receive FIFO Not Empty
The RNE values are defined as follows:
Value Description
0
1
Receive FIFO is empty.
Receive FIFO is not empty.
SSI Transmit FIFO Not Full
The TNF values are defined as follows:
Value Description
0
1
Transmit FIFO is full.
Transmit FIFO is not full.
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Synchronous Serial Interface (SSI)
Bit/Field
0
Name
TFE
Type
R0
Reset
1
Description
SSI Transmit FIFO Empty
The TFE values are defined as follows:
Value Description
0
1
Transmit FIFO is not empty.
Transmit FIFO is empty.
272
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LM3S300 Microcontroller
Register 5: SSI Clock Prescale (SSICPSR), offset 0x010
SSICPSR is the clock prescale register and specifies the division factor by which the system clock
must be internally divided before further use.
The value programmed into this register must be an even number between 2 and 254. The
least-significant bit of the programmed number is hard-coded to zero. If an odd number is written
to this register, data read back from this register has the least-significant bit as zero.
SSI Clock Prescale (SSICPSR)
SSI0 base: 0x4000.8000
Offset 0x010
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CPSDVSR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CPSDVSR
R/W
0x00
SSI Clock Prescale Divisor
This value must be an even number from 2 to 254, depending on the
frequency of SSIClk. The LSB always returns 0 on reads.
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Synchronous Serial Interface (SSI)
Register 6: SSI Interrupt Mask (SSIIM), offset 0x014
The SSIIM register is the interrupt mask set or clear register. It is a read/write register and all bits
are cleared to 0 on reset.
On a read, this register gives the current value of the mask on the relevant interrupt. A write of 1 to
the particular bit sets the mask, enabling the interrupt to be read. A write of 0 clears the corresponding
mask.
SSI Interrupt Mask (SSIIM)
SSI0 base: 0x4000.8000
Offset 0x014
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TXIM
RXIM
RTIM
RORIM
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:4
Name
Type
RO
Reset
0x00
Description
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.
3
2
1
TXIM
RXIM
RTIM
R/W
R/W
R/W
0
0
0
SSI Transmit FIFO Interrupt Mask
The TXIM values are defined as follows:
Value Description
0
1
TX FIFO half-full or less condition interrupt is masked.
TX FIFO half-full or less condition interrupt is not masked.
SSI Receive FIFO Interrupt Mask
The TFE values are defined as follows:
Value Description
0
1
RX FIFO half-full or more condition interrupt is masked.
RX FIFO half-full or more condition interrupt is not masked.
SSI Receive Time-Out Interrupt Mask
The RTIM values are defined as follows:
Value Description
0
1
RX FIFO time-out interrupt is masked.
RX FIFO time-out interrupt is not masked.
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October 01, 2007
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LM3S300 Microcontroller
Bit/Field
0
Name
Type
R/W
Reset
0
Description
RORIM
SSI Receive Overrun Interrupt Mask
The RORIM values are defined as follows:
Value Description
0
1
RX FIFO overrun interrupt is masked.
RX FIFO overrun interrupt is not masked.
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Synchronous Serial Interface (SSI)
Register 7: SSI Raw Interrupt Status (SSIRIS), offset 0x018
The SSIRIS register is the raw interrupt status register. On a read, this register gives the current
raw status value of the corresponding interrupt prior to masking. A write has no effect.
SSI Raw Interrupt Status (SSIRIS)
SSI0 base: 0x4000.8000
Offset 0x018
Type RO, reset 0x0000.0008
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TXRIS
RXRIS
RTRIS RORRIS
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
1
RO
0
RO
0
RO
0
Bit/Field
31:4
Name
Type
RO
Reset
0x00
Description
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.
3
2
1
0
TXRIS
RXRIS
RTRIS
RO
RO
RO
RO
1
0
0
0
SSI Transmit FIFO Raw Interrupt Status
Indicates that the transmit FIFO is half full or less, when set.
SSI Receive FIFO Raw Interrupt Status
Indicates that the receive FIFO is half full or more, when set.
SSI Receive Time-Out Raw Interrupt Status
Indicates that the receive time-out has occurred, when set.
RORRIS
SSI Receive Overrun Raw Interrupt Status
Indicates that the receive FIFO has overflowed, when set.
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October 01, 2007
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LM3S300 Microcontroller
Register 8: SSI Masked Interrupt Status (SSIMIS), offset 0x01C
The SSIMIS register is the masked interrupt status register. On a read, this register gives the current
masked status value of the corresponding interrupt. A write has no effect.
SSI Masked Interrupt Status (SSIMIS)
SSI0 base: 0x4000.8000
Offset 0x01C
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TXMIS
RXMIS
RTMIS RORMIS
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
Bit/Field
31:4
Name
Type
RO
Reset
0
Description
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.
3
2
1
0
TXMIS
RXMIS
RTMIS
RO
RO
RO
RO
0
0
0
0
SSI Transmit FIFO Masked Interrupt Status
Indicates that the transmit FIFO is half full or less, when set.
SSI Receive FIFO Masked Interrupt Status
Indicates that the receive FIFO is half full or more, when set.
SSI Receive Time-Out Masked Interrupt Status
Indicates that the receive time-out has occurred, when set.
RORMIS
SSI Receive Overrun Masked Interrupt Status
Indicates that the receive FIFO has overflowed, when set.
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Synchronous Serial Interface (SSI)
Register 9: SSI Interrupt Clear (SSIICR), offset 0x020
The SSIICR register is the interrupt clear register. On a write of 1, the corresponding interrupt is
cleared. A write of 0 has no effect.
SSI Interrupt Clear (SSIICR)
SSI0 base: 0x4000.8000
Offset 0x020
Type W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RTIC
RORIC
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
W1C
0
W1C
0
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
RTIC
W1C
0
SSI Receive Time-Out Interrupt Clear
The RTIC values are defined as follows:
Value Description
0
1
No effect on interrupt.
Clears interrupt.
0
RORIC
W1C
0
SSI Receive Overrun Interrupt Clear
The RORIC values are defined as follows:
Value Description
0
1
No effect on interrupt.
Clears interrupt.
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October 01, 2007
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LM3S300 Microcontroller
Register 10: SSI Peripheral Identification 4 (SSIPeriphID4), offset 0xFD0
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 4 (SSIPeriphID4)
SSI0 base: 0x4000.8000
Offset 0xFD0
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID4
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID4
RO
0x00
SSI Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
279
Preliminary
Synchronous Serial Interface (SSI)
Register 11: SSI Peripheral Identification 5 (SSIPeriphID5), offset 0xFD4
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 5 (SSIPeriphID5)
SSI0 base: 0x4000.8000
Offset 0xFD4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID5
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID5
RO
0x00
SSI Peripheral ID Register[15:8]
Can be used by software to identify the presence of this peripheral.
280
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 12: SSI Peripheral Identification 6 (SSIPeriphID6), offset 0xFD8
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 6 (SSIPeriphID6)
SSI0 base: 0x4000.8000
Offset 0xFD8
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID6
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID6
RO
0x00
SSI Peripheral ID Register[23:16]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
281
Preliminary
Synchronous Serial Interface (SSI)
Register 13: SSI Peripheral Identification 7 (SSIPeriphID7), offset 0xFDC
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 7 (SSIPeriphID7)
SSI0 base: 0x4000.8000
Offset 0xFDC
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID7
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID7
RO
0x00
SSI Peripheral ID Register[31:24]
Can be used by software to identify the presence of this peripheral.
282
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 14: SSI Peripheral Identification 0 (SSIPeriphID0), offset 0xFE0
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 0 (SSIPeriphID0)
SSI0 base: 0x4000.8000
Offset 0xFE0
Type RO, reset 0x0000.0022
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID0
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
0
RO
0
RO
1
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0
Description
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.
7:0
PID0
RO
0x22
SSI Peripheral ID Register[7:0]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
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Preliminary
Synchronous Serial Interface (SSI)
Register 15: SSI Peripheral Identification 1 (SSIPeriphID1), offset 0xFE4
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 1 (SSIPeriphID1)
SSI0 base: 0x4000.8000
Offset 0xFE4
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID1
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID1
RO
0x00
SSI Peripheral ID Register [15:8]
Can be used by software to identify the presence of this peripheral.
284
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 16: SSI Peripheral Identification 2 (SSIPeriphID2), offset 0xFE8
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 2 (SSIPeriphID2)
SSI0 base: 0x4000.8000
Offset 0xFE8
Type RO, reset 0x0000.0018
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID2
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
1
RO
1
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID2
RO
0x18
SSI Peripheral ID Register [23:16]
Can be used by software to identify the presence of this peripheral.
October 01, 2007
285
Preliminary
Synchronous Serial Interface (SSI)
Register 17: SSI Peripheral Identification 3 (SSIPeriphID3), offset 0xFEC
The SSIPeriphIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI Peripheral Identification 3 (SSIPeriphID3)
SSI0 base: 0x4000.8000
Offset 0xFEC
Type RO, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
PID3
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
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
PID3
RO
0x01
SSI Peripheral ID Register [31:24]
Can be used by software to identify the presence of this peripheral.
286
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 18: SSI PrimeCell Identification 0 (SSIPCellID0), offset 0xFF0
The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI PrimeCell Identification 0 (SSIPCellID0)
SSI0 base: 0x4000.8000
Offset 0xFF0
Type RO, reset 0x0000.000D
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID0
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
1
RO
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID0
RO
0x0D
SSI PrimeCell ID Register [7:0]
Provides software a standard cross-peripheral identification system.
October 01, 2007
287
Preliminary
Synchronous Serial Interface (SSI)
Register 19: SSI PrimeCell Identification 1 (SSIPCellID1), offset 0xFF4
The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI PrimeCell Identification 1 (SSIPCellID1)
SSI0 base: 0x4000.8000
Offset 0xFF4
Type RO, reset 0x0000.00F0
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID1
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
1
RO
1
RO
1
RO
0
RO
0
RO
0
RO
0
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID1
RO
0xF0
SSI PrimeCell ID Register [15:8]
Provides software a standard cross-peripheral identification system.
288
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 20: SSI PrimeCell Identification 2 (SSIPCellID2), offset 0xFF8
The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI PrimeCell Identification 2 (SSIPCellID2)
SSI0 base: 0x4000.8000
Offset 0xFF8
Type RO, reset 0x0000.0005
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID2
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
1
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID2
RO
0x05
SSI PrimeCell ID Register [23:16]
Provides software a standard cross-peripheral identification system.
October 01, 2007
289
Preliminary
Synchronous Serial Interface (SSI)
Register 21: SSI PrimeCell Identification 3 (SSIPCellID3), offset 0xFFC
The SSIPCellIDn registers are hard-coded and the fields within the register determine the reset
value.
SSI PrimeCell Identification 3 (SSIPCellID3)
SSI0 base: 0x4000.8000
Offset 0xFFC
Type RO, reset 0x0000.00B1
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
CID3
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
1
RO
0
RO
1
RO
1
RO
0
RO
0
RO
0
RO
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
CID3
RO
0xB1
SSI PrimeCell ID Register [31:24]
Provides software a standard cross-peripheral identification system.
290
October 01, 2007
Preliminary
LM3S300 Microcontroller
13
Inter-Integrated Circuit (I2C) Interface
The Inter-Integrated Circuit (I2C) bus provides bi-directional data transfer through a two-wire design
(a serial data line SDA and a serial clock line SCL), and interfaces to external I2C devices such as
serial memory (RAMs and ROMs), networking devices, LCDs, tone generators, and so on. The I2C
bus may also be used for system testing and diagnostic purposes in product development and
manufacture. The LM3S300 microcontroller includes one I2C module, providing the ability to interact
(both send and receive) with other I2C devices on the bus.
Devices on the I2C bus can be designated as either a master or a slave. The Stellaris® I2C module
supports both sending and receiving data as either a master or a slave, and also supports the
simultaneous operation as both a master and a slave. There are a total of four I2C modes: Master
Transmit, Master Receive, Slave Transmit, and Slave Receive. The Stellaris® I2C module can
operate at two speeds: Standard (100 Kbps) and Fast (400 Kbps).
Both the I2C master and slave can generate interrupts; the I2C master generates interrupts when
a transmit or receive operation completes (or aborts due to an error) and the I2C slave generates
interrupts when data has been sent or requested by a master.
13.1
Block Diagram
Figure 13-1. I2C Block Diagram
I2CSCL
I2C Control
I2C Master Core
I2CMSA
I2CMCS
I2CMDR
I2CMTPR
I2CMIMR
I2CMRIS
I2CMMIS
I2CMICR
I2CMCR
I2CSOAR
I2CSCSR
I2CSDR
I2CSIM
I2CSDA
I2CSCL
I2CSDA
Interrupt
I2C I/O Select
I2CSRIS
I2CSMIS
I2CSICR
I2CSCL
I2CSDA
I2C Slave Core
13.2
Functional Description
I2C module is comprised of both master and slave functions which are implemented as separate
peripherals. For proper operation, the SDA and SCL pins must be connected to bi-directional
open-drain pads. A typical I2C bus configuration is shown in Figure 13-2 on page 292.
See “I2C” on page 351 for I2C timing diagrams.
October 01, 2007
291
Preliminary
Inter-Integrated Circuit (I2C) Interface
Figure 13-2. I2C Bus Configuration
R
R
PUP
PUP
SCL
SDA
2
I C Bus
I2CSCL I2CSDA
SCL
SDA
SCL
SDA
3rd Party Device
with I C Interface
3rd Party Device
with I C Interface
TM
2
2
Stellaris
13.2.1
I2C Bus Functional Overview
The I2C bus uses only two signals: SDA and SCL, named I2CSDA and I2CSCL on Stellaris®
microcontrollers. SDA is the bi-directional serial data line and SCL is the bi-directional serial clock
line. The bus is considered idle when both lines are high.
Every transaction on the I2C bus is nine bits long, consisting of eight data bits and a single
acknowledge bit. The number of bytes per transfer (defined as the time between a valid START
and STOP condition, described in “START and STOP Conditions” on page 292) is unrestricted, but
each byte has to be followed by an acknowledge bit, and data must be transferred MSB first. When
a receiver cannot receive another complete byte, it can hold the clock line SCL Low and force the
transmitter into a wait state. The data transfer continues when the receiver releases the clock SCL.
13.2.1.1 START and STOP Conditions
The protocol of the I2C bus defines two states to begin and end a transaction: START and STOP.
A high-to-low transition on the SDA line while the SCL is high is defined as a START condition, and
a low-to-high transition on the SDA line while SCL is high is defined as a STOP condition. The bus
is considered busy after a START condition and free after a STOP condition. See Figure
13-3 on page 292.
Figure 13-3. START and STOP Conditions
SDA
SCL
SDA
SCL
START
STOP
condition
condition
13.2.1.2 Data Format with 7-Bit Address
Data transfers follow the format shown in Figure 13-4 on page 293. After the START condition, a
slave address is sent. This address is 7-bits long followed by an eighth bit, which is a data direction
bit (R/S bit in the I2CMSA register). A zero indicates a transmit operation (send), and a one indicates
a request for data (receive). A data transfer is always terminated by a STOP condition generated
by the master, however, a master can initiate communications with another device on the bus by
generating a repeated START condition and addressing another slave without first generating a
STOP condition. Various combinations of receive/send formats are then possible within a single
transfer.
292
October 01, 2007
Preliminary
LM3S300 Microcontroller
Figure 13-4. Complete Data Transfer with a 7-Bit Address
SDA
MSB
LSB
R/S
ACK
MSB
LSB
ACK
SCL
1
2
7
8
9
1
2
7
8
9
Slave address
Data
The first seven bits of the first byte make up the slave address (see Figure 13-5 on page 293). The
eighth bit determines the direction of the message. A zero in the R/S position of the first byte means
that the master will write (send) data to the selected slave, and a one in this position means that
the master will receive data from the slave.
Figure 13-5. R/S Bit in First Byte
MSB
LSB
R/S
Slave address
13.2.1.3 Data Validity
The data on the SDA line must be stable during the high period of the clock, and the data line can
only change when SCL is low (see Figure 13-6 on page 293).
Figure 13-6. Data Validity During Bit Transfer on the I2C Bus
SDA
SCL
Change
of data
allowed
Dataline
stable
13.2.1.4 Acknowledge
All bus transactions have a required acknowledge clock cycle that is generated by the master. During
the acknowledge cycle, the transmitter (which can be the master or slave) releases the SDA line.
To acknowledge the transaction, the receiver must pull down SDA during the acknowledge clock
cycle. The data sent out by the receiver during the acknowledge cycle must comply with the data
validity requirements described in “Data Validity” on page 293.
When a slave receiver does not acknowledge the slave address, SDA must be left high by the slave
so that the master can generate a STOP condition and abort the current transfer. If the master
device is acting as a receiver during a transfer, it is responsible for acknowledging each transfer
made by the slave. Since the master controls the number of bytes in the transfer, it signals the end
of data to the slave transmitter by not generating an acknowledge on the last data byte. The slave
transmitter must then release SDA to allow the master to generate the STOP or a repeated START
condition.
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13.2.1.5 Arbitration
A master may start a transfer only if the bus is idle. It's possible for two or more masters to generate
a START condition within minimum hold time of the START condition. In these situations, an
arbitration scheme takes place on the SDA line, while SCL is high. During arbitration, the first of the
competing master devices to place a '1' (high) on SDA while another master transmits a '0' (low)
will switch off its data output stage and retire until the bus is idle again.
Arbitration can take place over several bits. Its first stage is a comparison of address bits, and if
both masters are trying to address the same device, arbitration continues on to the comparison of
data bits.
13.2.2
Available Speed Modes
The I2C clock rate is determined by the parameters: CLK_PRD, TIMER_PRD, SCL_LP, and SCL_HP.
where:
CLK_PRD is the system clock period
SCL_LP is the low phase of SCL (fixed at 6)
SCL_HP is the high phase of SCL (fixed at 4)
TIMER_PRD is the programmed value in the I2C Master Timer Period (I2CMTPR) register (see
page 311).
The I2C clock period is calculated as follows:
SCL_PERIOD = 2*(1 + TIMER_PRD)*(SCL_LP + SCL_HP)*CLK_PRD
For example:
CLK_PRD = 50 ns
TIMER_PRD = 2
SCL_LP=6
SCL_HP=4
yields a SCL frequency of:
1/T = 333 Khz
Table 13-1 on page 294 gives examples of timer period, system clock, and speed mode (Standard
or Fast).
Table 13-1. Examples of I2C Master Timer Period versus Speed Mode
System Clock Timer Period Standard Mode Timer Period Fast Mode
4 Mhz
6 Mhz
0x01
0x02
0x06
0x08
0x09
0x0C
100 Kbps
100 Kbps
89 Kbps
-
-
-
-
12.5 Mhz
16.7 Mhz
20 Mhz
25 Mhz
0x01
0x02
0x02
0x03
312 Kbps
278 Kbps
333 Kbps
312 Kbps
93 Kbps
100 Kbps
96.2 Kbps
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13.2.3
Interrupts
The I2C can generate interrupts when the following conditions are observed:
■ Master transaction completed
■ Master transaction error
■ Slave transaction received
■ Slave transaction requested
There is a separate interrupt signal for the I2C master and I2C modules. While both modules can
generate interrupts for multiple conditions, only a single interrupt signal is sent to the interrupt
controller.
13.2.3.1 I2C Master Interrupts
The I2C master module generates an interrupt when a transaction completes (either transmit or
receive), or when an error occurs during a transaction. To enable the I2C master interrupt, software
must write a '1' to the I2C Master Interrupt Mask (I2CMIMR) register. When an interrupt condition
is met, software must check the ERROR bit in the I2C Master Control/Status (I2CMCS) register to
verify that an error didn't occur during the last transaction. An error condition is asserted if the last
transaction wasn't acknowledge by the slave or if the master was forced to give up ownership of
the bus due to a lost arbitration round with another master. If an error is not detected, the application
can proceed with the transfer. The interrupt is cleared by writing a '1' to the I2C Master Interrupt
Clear (I2CMICR) register.
If the application doesn't require the use of interrupts, the raw interrupt status is always visible via
the I2C Master Raw Interrupt Status (I2CMRIS) register.
13.2.3.2 I2C Slave Interrupts
The slave module generates interrupts as it receives requests from an I2C master. To enable the
I2C slave interrupt, write a '1' to the I2C Slave Interrupt Mask (I2CSIMR) register. Software
determines whether the module should write (transmit) or read (receive) data from the I2C Slave
Data (I2CSDR) register, by checking the RREQ and TREQ bits of the I2C Slave Control/Status
(I2CSCSR) register. If the slave module is in receive mode and the first byte of a transfer is received,
the FBR bit is set along with the RREQ bit. The interrupt is cleared by writing a '1' to the I2C Slave
Interrupt Clear (I2CSICR) register.
If the application doesn't require the use of interrupts, the raw interrupt status is always visible via
the I2C Slave Raw Interrupt Status (I2CSRIS) register.
13.2.4
13.2.5
Loopback Operation
The I2C modules can be placed into an internal loopback mode for diagnostic or debug work. This
is accomplished by setting the LPBK bit in the I2C Master Configuration (I2CMCR) register. In
loopback mode, the SDA and SCL signals from the master and slave modules are tied together.
Command Sequence Flow Charts
This section details the steps required to perform the various I2C transfer types in both master and
slave mode.
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13.2.5.1 I2C Master Command Sequences
The figures that follow show the command sequences available for the I2C master.
Figure 13-7. Master Single SEND
Idle
Write Slave
Address to
I2CMSA
Sequence
may be
omitted in a
Single Master
system
Write data to
I2CMDR
Read I2CMCS
NO
BUSBSY bit=0?
YES
Write ---0-111 to
I2CMCS
Read I2CMCS
NO
BUSY bit=0?
YES
NO
Error Service
ERROR bit=0?
YES
Idle
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Figure 13-8. Master Single RECEIVE
Idle
Sequence may be
omitted in a Single
Master system
Write Slave
Address to
I2CMSA
Read I2CMCS
NO
BUSBSY bit=0?
YES
Write ---00111 to
I2CMCS
Read I2CMCS
NO
BUSY bit=0?
YES
NO
Error Service
ERROR bit=0?
YES
Read data from
I2CMDR
Idle
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Figure 13-9. Master Burst SEND
Idle
Write Slave
Address to
I2CMSA
Sequence
may be
omitted in a
Single Master
system
Read I2CMCS
Write data to
I2CMDR
NO
BUSY bit=0?
YES
Read I2CMCS
NO
ERROR bit=0?
YES
NO
BUSBSY bit=0?
YES
NO
Write data to
I2CMDR
ARBLST bit=1?
YES
Write ---0-011 to
I2CMCS
Write ---0-100 to
I2CMCS
NO
Write ---0-001 to
I2CMCS
Index=n?
YES
Error Service
Write ---0-101 to
I2CMCS
Idle
Read I2CMCS
NO
BUSY bit=0?
YES
NO
Error Service
ERROR bit=0?
YES
Idle
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Figure 13-10. Master Burst RECEIVE
Idle
Sequence
may be
Write Slave
Address to
I2CMSA
omitted in a
Single Master
system
Read I2CMCS
BUSY bit=0?
YES
Read I2CMCS
NO
NO
BUSBSY bit=0?
YES
NO
ERROR bit=0?
NO
ARBLST bit=1?
YES
Write ---01011 to
I2CMCS
Read data from
I2CMDR
Write ---0-100 to
I2CMCS
NO
Write ---01001 to
I2CMCS
Index=m-1?
YES
Error Service
Idle
Write ---00101 to
I2CMCS
Read I2CMCS
NO
BUSY bit=0?
YES
NO
ERROR bit=0?
YES
Read data from
I2CMDR
Error Service
Idle
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Figure 13-11. Master Burst RECEIVE after Burst SEND
Idle
Master operates in
Master Transmit mode
STOP condition is not
generated
Write Slave
Address to
I2CMSA
Write ---01011 to
I2CMCS
Repeated START
condition is generated
with changing data
direction
Master operates in
Master Receive mode
Idle
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Figure 13-12. Master Burst SEND after Burst RECEIVE
Idle
Master operates in
Master Receive mode
STOP condition is not
generated
Write Slave
Address to
I2CMSA
Write ---0-011 to
I2CMCS
Repeated START
condition is generated
with changing data
direction
Master operates in
Master Transmit mode
Idle
13.2.5.2 I2C Slave Command Sequences
Figure 13-13 on page 302 presents the command sequence available for the I2C slave.
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Figure 13-13. Slave Command Sequence
Idle
Write OWN Slave
Address to
I2CSOAR
Write -------1 to
I2CSCSR
Read I2CSCSR
NO
NO
TREQ bit=1?
RREQ bit=1?
FBR is
also valid
YES
YES
Write data to
I2CSDR
Read data from
I2CSDR
13.3
Initialization and Configuration
The following example shows how to configure the I2C module to send a single byte as a master.
This assumes the system clock is 20 MHz.
1. Enable the I2C clock by writing a value of 0x0000.1000 to the RCGC1 register in the System
Control module.
2. Enable the clock to the appropriate GPIO module via the RCGC2 register in the System Control
module.
3. In the GPIO module, enable the appropriate pins for their alternate function using the
GPIOAFSEL register. Also, be sure to enable the same pins for Open Drain operation.
4. Initialize the I2C Master by writing the I2CMCR register with a value of 0x0000.0020.
5. Set the desired SCL clock speed of 100 Kbps by writing the I2CMTPR register with the correct
value. The value written to the I2CMTPR register represents the number of system clock periods
in one SCL clock period. The TPR value is determined by the following equation:
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TPR = (System Clock / (2 * (SCL_LP + SCL_HP) * SCL_CLK)) - 1;
TPR = (20MHz / (2 * (6 + 4) * 100000)) - 1;
TPR = 9
Write the I2CMTPR register with the value of 0x0000.0009.
6. Specify the slave address of the master and that the next operation will be a Send by writing
the I2CMSA register with a value of 0x0000.0076. This sets the slave address to 0x3B.
7. Place data (byte) to be sent in the data register by writing the I2CMDR register with the desired
data.
8. Initiate a single byte send of the data from Master to Slave by writing the I2CMCS register with
a value of 0x0000.0007 (STOP, START, RUN).
9. Wait until the transmission completes by polling the I2CMCS register’s BUSBSY bit until it has
been cleared.
13.4
I2C Register Map
Table 13-2 on page 303 lists the I2C registers. All addresses given are relative to the I2C base
addresses for the master and slave:
■ I2C Master 0: 0x4002.0000
■ I2C Slave 0: 0x4002.0800
Table 13-2. Inter-Integrated Circuit (I2C) Interface Register Map
See
page
Offset
Name
Type
Reset
Description
I2C Master
0x000
I2CMSA
I2CMCS
I2CMDR
I2CMTPR
I2CMIMR
I2CMRIS
I2CMMIS
I2CMICR
I2CMCR
R/W
R/W
R/W
R/W
R/W
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0001
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
I2C Master Slave Address
I2C Master Control/Status
I2C Master Data
305
306
310
311
312
313
314
315
316
0x004
0x008
0x00C
0x010
I2C Master Timer Period
I2C Master Interrupt Mask
I2C Master Raw Interrupt Status
I2C Master Masked Interrupt Status
I2C Master Interrupt Clear
I2C Master Configuration
0x014
0x018
RO
0x01C
0x020
WO
R/W
I2C Slave
0x000
I2CSOAR
I2CSCSR
I2CSDR
R/W
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
I2C Slave Own Address
I2C Slave Control/Status
I2C Slave Data
318
319
321
322
0x004
0x008
R/W
R/W
0x00C
I2CSIMR
I2C Slave Interrupt Mask
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See
page
Offset
Name
Type
Reset
Description
0x010
0x014
0x018
I2CSRIS
I2CSMIS
I2CSICR
RO
RO
WO
0x0000.0000
0x0000.0000
0x0000.0000
I2C Slave Raw Interrupt Status
I2C Slave Masked Interrupt Status
I2C Slave Interrupt Clear
323
324
325
13.5
Register Descriptions (I2C Master)
The remainder of this section lists and describes the I2C master registers, in numerical order by
address offset. See also “Register Descriptions (I2C Slave)” on page 317.
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Register 1: I2C Master Slave Address (I2CMSA), offset 0x000
This register consists of eight bits: seven address bits (A6-A0), and a Receive/Send bit, which
determines if the next operation is a Receive (High), or Send (Low).
I2C Master Slave Address (I2CMSA)
I2C Master 0 base: 0x4002.0000
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
SA
R/S
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:1
0
SA
R/W
R/W
0
0
I2C Slave Address
This field specifies bits A6 through A0 of the slave address.
R/S
Receive/Send
The R/S bit specifies if the next operation is a Receive (High) or Send
(Low).
0: Send
1: Receive
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Register 2: I2C Master Control/Status (I2CMCS), offset 0x004
This register accesses four control bits when written, and accesses seven status bits when read.
The status register consists of seven bits, which when read determine the state of the I2C bus
controller.
The control register consists of four bits: the RUN, START, STOP, and ACK bits. The START bit causes
the generation of the START, or REPEATED START condition.
The STOP bit determines if the cycle stops at the end of the data cycle, or continues on to a burst.
To generate a single send cycle, the I2C Master Slave Address (I2CMSA) register is written with
the desired address, the R/S bit is set to 0, and the Control register is written with ACK=X (0 or 1),
STOP=1, START=1, and RUN=1 to perform the operation and stop. When the operation is completed
(or aborted due an error), the interrupt pin becomes active and the data may be read from the
I2CMDR register. When the I2C module operates in Master receiver mode, the ACK bit must be set
normally to logic 1. This causes the I2C bus controller to send an acknowledge automatically after
each byte. This bit must be reset when the I2C bus controller requires no further data to be sent
from the slave transmitter.
Read-Only Status Register
I2C Master Control/Status (I2CMCS)
I2C Master 0 base: 0x4002.0000
Offset 0x004
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
BUSBSY
IDLE
ARBLST DATACK ADRACK ERROR
BUSY
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
Bit/Field
31:7
Name
Type
RO
Reset
0x00
Description
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.
6
BUSBSY
RO
0
Bus Busy
This bit specifies the state of the I2C bus. If set, the bus is busy;
otherwise, the bus is idle. The bit changes based on the START and
STOP conditions.
5
4
IDLE
RO
RO
0
0
I2C Idle
This bit specifies the I2C controller state. If set, the controller is idle;
otherwise the controller is not idle.
ARBLST
Arbitration Lost
This bit specifies the result of bus arbitration. If set, the controller lost
arbitration; otherwise, the controller won arbitration.
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Bit/Field
3
Name
Type
RO
Reset
0
Description
DATACK
Acknowledge Data
This bit specifies the result of the last data operation. If set, the
transmitted data was not acknowledged; otherwise, the data was
acknowledged.
2
1
ADRACK
ERROR
RO
RO
0
0
Acknowledge Address
This bit specifies the result of the last address operation. If set, the
transmitted address was not acknowledged; otherwise, the address was
acknowledged.
Error
This bit specifies the result of the last bus operation. If set, an error
occurred on the last operation; otherwise, no error was detected. The
error can be from the slave address not being acknowledged, the
transmit data not being acknowledged, or because the controller lost
arbitration.
0
BUSY
RO
0
I2C Busy
This bit specifies the state of the controller. If set, the controller is busy;
otherwise, the controller is idle. When the BUSY bit is set, the other status
bits are not valid.
Write-Only Control Register
I2C Master Control/Status (I2CMCS)
I2C Master 0 base: 0x4002.0000
Offset 0x004
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
Reset
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
reserved
ACK
STOP
START
RUN
Type
Reset
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
Bit/Field
31:4
Name
Type
WO
Reset
0x00
Description
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.
3
2
ACK
WO
WO
0
0
Data Acknowledge Enable
When set, causes received data byte to be acknowledged automatically
by the master. See field decoding in Table 13-3 on page 308.
STOP
Generate STOP
When set, causes the generation of the STOP condition. See field
decoding in Table 13-3 on page 308.
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Bit/Field
1
Name
Type
WO
Reset
0
Description
START
Generate START
When set, causes the generation of a START or repeated START
condition. See field decoding in Table 13-3 on page 308.
0
RUN
WO
0
I2C Master Enable
When set, allows the master to send or receive data. See field decoding
in Table 13-3 on page 308.
Table 13-3. Write Field Decoding for I2CMCS[3:0] Field (Sheet 1 of 3)
Current I2CMSA[0]
I2CMCS[3:0]
STOP START
Description
State
R/S
ACK
RUN
Idle
0
0
1
1
1
1
Xa
0
1
1
START condition followed by SEND (master goes to the
Master Transmit state).
X
0
0
1
1
1
0
1
0
1
1
1
1
1
1
1
1
1
1
1
START condition followed by a SEND and STOP
condition (master remains in Idle state).
START condition followed by RECEIVE operation with
negative ACK (master goes to the Master Receive state).
START condition followed by RECEIVE and STOP
condition (master remains in Idle state).
START condition followed by RECEIVE (master goes to
the Master Receive state).
Illegal.
All other combinations not listed are non-operations. NOP.
Master
Transmit
X
X
0
0
1
SEND operation (master remains in Master Transmit
state).
X
X
X
X
1
1
0
0
0
1
STOP condition (master goes to Idle state).
SEND followed by STOP condition (master goes to Idle
state).
0
0
1
X
X
0
0
1
0
1
1
1
1
1
1
Repeated START condition followed by a SEND (master
remains in Master Transmit state).
Repeated START condition followed by SEND and STOP
condition (master goes to Idle state).
Repeated START condition followed by a RECEIVE
operation with a negative ACK (master goes to Master
Receive state).
1
1
1
0
1
1
1
0
1
1
1
1
1
1
1
Repeated START condition followed by a SEND and
STOP condition (master goes to Idle state).
Repeated START condition followed by RECEIVE (master
goes to Master Receive state).
Illegal.
All other combinations not listed are non-operations. NOP.
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Current I2CMSA[0]
I2CMCS[3:0]
STOP START
Description
State
R/S
ACK
RUN
Master
Receive
X
0
0
0
1
RECEIVE operation with negative ACK (master remains
in Master Receive state).
X
X
X
0
1
1
0
0
0
1
STOP condition (master goes to Idle state).b
RECEIVE followed by STOP condition (master goes to
Idle state).
X
1
0
0
1
RECEIVE operation (master remains in Master Receive
state).
X
1
1
0
1
0
0
1
1
1
Illegal.
Repeated START condition followed by RECEIVE
operation with a negative ACK (master remains in Master
Receive state).
1
1
0
0
0
1
1
0
0
1
1
1
1
1
1
1
1
1
Repeated START condition followed by RECEIVE and
STOP condition (master goes to Idle state).
Repeated START condition followed by RECEIVE (master
remains in Master Receive state).
X
X
Repeated START condition followed by SEND (master
goes to Master Transmit state).
Repeated START condition followed by SEND and STOP
condition (master goes to Idle state).
All other combinations not listed are non-operations. NOP.
a. An X in a table cell indicates the bit can be 0 or 1.
b. In Master Receive mode, a STOP condition should be generated only after a Data Negative Acknowledge executed by
the master or an Address Negative Acknowledge executed by the slave.
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Register 3: I2C Master Data (I2CMDR), offset 0x008
This register contains the data to be transmitted when in the Master Transmit state, and the data
received when in the Master Receive state.
I2C Master Data (I2CMDR)
I2C Master 0 base: 0x4002.0000
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DATA
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
DATA
R/W
0x00
Data Transferred
Data transferred during transaction.
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October 01, 2007
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LM3S300 Microcontroller
Register 4: I2C Master Timer Period (I2CMTPR), offset 0x00C
This register specifies the period of the SCL clock.
I2C Master Timer Period (I2CMTPR)
I2C Master 0 base: 0x4002.0000
Offset 0x00C
Type R/W, reset 0x0000.0001
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
TPR
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
1
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
TPR
R/W
0x1
SCL Clock Period
This field specifies the period of the SCL clock.
SCL_PRD = 2*(1 + TPR)*(SCL_LP + SCL_HP)*CLK_PRD
where:
SCL_PRD is the SCL line period (I2C clock).
TPR is the Timer Period register value (range of 1 to 255).
SCL_LP is the SCL Low period (fixed at 6).
SCL_HP is the SCL High period (fixed at 4).
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Inter-Integrated Circuit (I2C) Interface
Register 5: I2C Master Interrupt Mask (I2CMIMR), offset 0x010
This register controls whether a raw interrupt is promoted to a controller interrupt.
I2C Master Interrupt Mask (I2CMIMR)
I2C Master 0 base: 0x4002.0000
Offset 0x010
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IM
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
R/W
0
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
IM
R/W
0
Interrupt Mask
This bit controls whether a raw interrupt is promoted to a controller
interrupt. If set, the interrupt is not masked and the interrupt is promoted;
otherwise, the interrupt is masked.
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October 01, 2007
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LM3S300 Microcontroller
Register 6: I2C Master Raw Interrupt Status (I2CMRIS), offset 0x014
This register specifies whether an interrupt is pending.
I2C Master Raw Interrupt Status (I2CMRIS)
I2C Master 0 base: 0x4002.0000
Offset 0x014
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
RIS
RO
0
Raw Interrupt Status
This bit specifies the raw interrupt state (prior to masking) of the I2C
master block. If set, an interrupt is pending; otherwise, an interrupt is
not pending.
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Inter-Integrated Circuit (I2C) Interface
Register 7: I2C Master Masked Interrupt Status (I2CMMIS), offset 0x018
This register specifies whether an interrupt was signaled.
I2C Master Masked Interrupt Status (I2CMMIS)
I2C Master 0 base: 0x4002.0000
Offset 0x018
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
MIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
MIS
RO
0
Masked Interrupt Status
This bit specifies the raw interrupt state (after masking) of the I2C master
block. If set, an interrupt was signaled; otherwise, an interrupt has not
been generated since the bit was last cleared.
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 8: I2C Master Interrupt Clear (I2CMICR), offset 0x01C
This register clears the raw interrupt.
I2C Master Interrupt Clear (I2CMICR)
I2C Master 0 base: 0x4002.0000
Offset 0x01C
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IC
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
WO
0
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
IC
WO
0
Interrupt Clear
This bit controls the clearing of the raw interrupt. A write of 1 clears the
interrupt; otherwise, a write of 0 has no affect on the interrupt state. A
read of this register returns no meaningful data.
October 01, 2007
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Inter-Integrated Circuit (I2C) Interface
Register 9: I2C Master Configuration (I2CMCR), offset 0x020
This register configures the mode (Master or Slave) and sets the interface for test mode loopback.
I2C Master Configuration (I2CMCR)
I2C Master 0 base: 0x4002.0000
Offset 0x020
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
SFE
MFE
reserved
LPBK
Type
Reset
RO
0
RO
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
R/W
0
Bit/Field
31:6
Name
Type
RO
Reset
0x00
Description
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.
5
4
SFE
MFE
R/W
R/W
0
0
I2C Slave Function Enable
This bit specifies whether the interface may operate in Slave mode. If
set, Slave mode is enabled; otherwise, Slave mode is disabled.
I2C Master Function Enable
This bit specifies whether the interface may operate in Master mode. If
set, Master mode is enabled; otherwise, Master mode is disabled and
the interface clock is disabled.
3:1
0
reserved
LPBK
RO
0x00
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.
R/W
I2C Loopback
This bit specifies whether the interface is operating normally or in
Loopback mode. If set, the device is put in a test mode loopback
configuration; otherwise, the device operates normally.
316
October 01, 2007
Preliminary
LM3S300 Microcontroller
13.6
Register Descriptions (I2C Slave)
The remainder of this section lists and describes the I2C slave registers, in numerical order by
address offset. See also “Register Descriptions (I2C Master)” on page 304.
October 01, 2007
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Preliminary
Inter-Integrated Circuit (I2C) Interface
Register 10: I2C Slave Own Address (I2CSOAR), offset 0x000
This register consists of seven address bits that identify the Stellaris® I2C device on the I2C bus.
I2C Slave Own Address (I2CSOAR)
I2C Slave 0 base: 0x4002.0800
Offset 0x000
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OAR
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:7
Name
Type
RO
Reset
0x00
Description
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.
6:0
OAR
R/W
0x00
I2C Slave Own Address
This field specifies bits A6 through A0 of the slave address.
318
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 11: I2C Slave Control/Status (I2CSCSR), offset 0x004
This register accesses one control bit when written, and three status bits when read.
The read-only Status register consists of three bits: the FBR, RREQ, and TREQ bits. The First
Byte Received (FBR) bit is set only after the Stellaris® device detects its own slave address
and receives the first data byte from the I2C master. The Receive Request (RREQ) bit indicates
that the Stellaris® I2C device has received a data byte from an I2C master. Read one data byte from
the I2C Slave Data (I2CSDR) register to clear the RREQ bit. The Transmit Request (TREQ) bit
indicates that the Stellaris® I2C device is addressed as a Slave Transmitter. Write one data byte
into the I2C Slave Data (I2CSDR) register to clear the TREQ bit.
The write-only Control register consists of one bit: the DA bit. The DA bit enables and disables the
Stellaris® I2C slave operation.
Read-Only Status Register
I2C Slave Control/Status (I2CSCSR)
I2C Slave 0 base: 0x4002.0800
Offset 0x004
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
FBR
TREQ
RREQ
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
Bit/Field
31:3
Name
Type
RO
Reset
Description
reserved
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
FBR
RO
0
First Byte Received
Indicates that the first byte following the slave’s own address is received.
This bit is only valid when the RREQ bit is set, and is automatically cleared
when data has been read from the I2CSDR register.
Note:
This bit is not used for slave transmit operations.
1
TREQ
RO
0
0
Transmit Request
This bit specifies the state of the I2C slave with regards to outstanding
transmit requests. If set, the I2C unit has been addressed as a slave
transmitter and uses clock stretching to delay the master until data has
been written to the I2CSDR register. Otherwise, there is no outstanding
transmit request.
0
RREQ
RO
Receive Request
This bit specifies the status of the I2C slave with regards to outstanding
receive requests. If set, the I2C unit has outstanding receive data from
the I2C master and uses clock stretching to delay the master until the
data has been read from the I2CSDR register. Otherwise, no receive
data is outstanding.
October 01, 2007
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Preliminary
Inter-Integrated Circuit (I2C) Interface
Write-Only Control Register
I2C Slave Control/Status (I2CSCSR)
I2C Slave 0 base: 0x4002.0800
Offset 0x004
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DA
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
WO
0
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
DA
WO
0
Device Active
1=Enables the I2C slave operation.
0=Disables the I2C slave operation.
320
October 01, 2007
Preliminary
LM3S300 Microcontroller
Register 12: I2C Slave Data (I2CSDR), offset 0x008
This register contains the data to be transmitted when in the Slave Transmit state, and the data
received when in the Slave Receive state.
I2C Slave Data (I2CSDR)
I2C Slave 0 base: 0x4002.0800
Offset 0x008
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
DATA
Type
Reset
RO
0
RO
0
RO
0
RO
0
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
Bit/Field
31:8
Name
Type
RO
Reset
0x00
Description
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.
7:0
DATA
R/W
0x0
Data for Transfer
This field contains the data for transfer during a slave receive or transmit
operation.
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Preliminary
Inter-Integrated Circuit (I2C) Interface
Register 13: I2C Slave Interrupt Mask (I2CSIMR), offset 0x00C
This register controls whether a raw interrupt is promoted to a controller interrupt.
I2C Slave Interrupt Mask (I2CSIMR)
I2C Slave 0 base: 0x4002.0800
Offset 0x00C
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IM
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
R/W
0
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
IM
R/W
0
Interrupt Mask
This bit controls whether a raw interrupt is promoted to a controller
interrupt. If set, the interrupt is not masked and the interrupt is promoted;
otherwise, the interrupt is masked.
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October 01, 2007
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LM3S300 Microcontroller
Register 14: I2C Slave Raw Interrupt Status (I2CSRIS), offset 0x010
This register specifies whether an interrupt is pending.
I2C Slave Raw Interrupt Status (I2CSRIS)
I2C Slave 0 base: 0x4002.0800
Offset 0x010
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
RIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
RIS
RO
0
Raw Interrupt Status
This bit specifies the raw interrupt state (prior to masking) of the I2C
slave block. If set, an interrupt is pending; otherwise, an interrupt is not
pending.
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Inter-Integrated Circuit (I2C) Interface
Register 15: I2C Slave Masked Interrupt Status (I2CSMIS), offset 0x014
This register specifies whether an interrupt was signaled.
I2C Slave Masked Interrupt Status (I2CSMIS)
I2C Slave 0 base: 0x4002.0800
Offset 0x014
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
MIS
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
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
MIS
RO
0
Masked Interrupt Status
This bit specifies the raw interrupt state (after masking) of the I2C slave
block. If set, an interrupt was signaled; otherwise, an interrupt has not
been generated since the bit was last cleared.
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Register 16: I2C Slave Interrupt Clear (I2CSICR), offset 0x018
This register clears the raw interrupt.
I2C Slave Interrupt Clear (I2CSICR)
I2C Slave 0 base: 0x4002.0800
Offset 0x018
Type WO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IC
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
WO
0
Bit/Field
31:1
Name
Type
RO
Reset
0x00
Description
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.
0
IC
WO
0
Clear Interrupt
This bit controls the clearing of the raw interrupt. A write of 1 clears the
interrupt; otherwise a write of 0 has no affect on the interrupt state. A
read of this register returns no meaningful data.
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Analog Comparators
14
Analog Comparators
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S300 controller provides three independent integrated analog comparators that can be
configured to drive an output or generate an interrupt.
Note: Not all comparators have the option to drive an output pin. See the Comparator Operating
Mode tables for more information.
A comparator can compare a test voltage against any one of these voltages:
■ An individual external reference voltage
■ A shared single external reference voltage
■ A shared internal reference voltage
The comparator can provide its output to a device pin, acting as a replacement for an analog
comparator on the board, or it can be used to signal the application via interrupts to cause it to start
capturing a sample sequence.
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14.1
Block Diagram
Figure 14-1. Analog Comparator Module Block Diagram
C2-
-ve input
+ve input
Comparator 2
output
C2+
C2o
+ve input (alternate)
ACCTL2
ACSTAT2
interrupt
interrupt
reference input
C1-
-ve input
Comparator 1
output
+ve input
C1+
C1o
+ve input (alternate)
ACCTL1
ACSTAT1
interrupt
interrupt
reference input
C0-
-ve input
Comparator 0
output
C0+
+ve input
C0o
+ve input (alternate)
ACCTL0
ACSTAT0
interrupt
interrupt
reference input
Voltage
Ref
internal
bus
ACREFCTL
14.2
Functional Description
Important: It is recommended that the Digital-Input enable (the GPIODEN bit in the GPIO module)
for the analog input pin be disabled to prevent excessive current draw from the I/O
pads.
The comparator compares the VIN- and VIN+ inputs to produce an output, VOUT.
VIN- < VIN+, VOUT = 1
VIN- > VIN+, VOUT = 0
As shown in Figure 14-2 on page 328, the input source for VIN- is an external input. In addition to
an external input, input sources for VIN+ can be the +ve input of comparator 0 or an internal reference.
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Analog Comparators
Figure 14-2. Structure of Comparator Unit
-ve input
+ve input
0
1
2
output
CINV
+ve input (alternate)
reference input
IntGen
ACCTL
ACSTAT
A comparator is configured through two status/control registers (ACCTL and ACSTAT ). The internal
reference is configured through one control register (ACREFCTL). Interrupt status and control is
configured through three registers (ACMIS, ACRIS, and ACINTEN). The operating modes of the
comparators are shown in the Comparator Operating Mode tables.
Typically, the comparator output is used internally to generate controller interrupts. It may also be
used to drive an external pin.
Important: Certain register bit values must be set before using the analog comparators. The proper
pad configuration for the comparator input and output pins are described in the
Comparator Operating Mode tables.
Table 14-1. Comparator 0 Operating Modes
ACCNTL0 Comparator 0
ASRCP
00
VIN- VIN+
Output Interrupt
C0-
C0-
C0-
C0+
C0o
C0o
C0o
yes
yes
yes
yes
01
C0+
Vref
10
11
C0- reserved C0o
Table 14-2. Comparator 1 Operating Modes
ACCNTL1 Comparator 1
ASRCP
00
VIN- VIN+
C1- C1o/C1+a C1o/C1+
Output Interrupt
yes
yes
yes
yes
01
C1-
C1-
C0+
Vref
C1o/C1+
C1o/C1+
10
11
C1- reserved C1o/C1+
a. C1o and C1+ signals share a single pin and may only be used as one or the other.
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Table 14-3. Comparator 2 Operating Modes
ACCNTL2 Comparator 2
ASRCP
00
VIN- VIN+
C2- C2o/C2+a C2o/C2+
Output Interrupt
yes
yes
yes
yes
01
C2-
C2-
C0+
Vref
C2o/C2+
C2o/C2+
10
11
C2- reserved C2o/C2+
a. C2o and C2+ signals share a single pin and may only be used as one or the other.
14.2.1
Internal Reference Programming
The structure of the internal reference is shown in Figure 14-3 on page 329. This is controlled by a
single configuration register (ACREFCTL). Table 14-4 on page 329 shows the programming options
to develop specific internal reference values, to compare an external voltage against a particular
voltage generated internally.
Figure 14-3. Comparator Internal Reference Structure
8R
AVDD
8R
R
R
R
R
•••
EN
15
14
1
0
•••
Decoder
internal
reference
VREF
RNG
Table 14-4. Internal Reference Voltage and ACREFCTL Field Values
ACREFCTL Register
Output Reference Voltage Based on VREF Field Value
EN Bit Value RNG Bit Value
EN=0
RNG=X
0 V (GND) for any value of VREF; however, it is recommended that RNG=1 and VREF=0
for the least noisy ground reference.
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Analog Comparators
ACREFCTL Register
EN Bit Value RNG Bit Value
EN=1 RNG=0
Output Reference Voltage Based on VREF Field Value
Total resistance in ladder is 32 R.
RVREF
RT
VREF = AVDD ----------------
×
VREF + 8
(
)
VREF = AVDD ------------------------------
×
32
VR EF = 0.825 + 0.103 VREF
The range of internal reference in this mode is 0.825-2.37 V.
Total resistance in ladder is 24 R.
RNG=1
RVREF
RT
VREF = AVDD ----------------
×
VREF
24
(
)
VREF = AVDD --------------------
×
VREF = 0.1375 x VREF
The range of internal reference for this mode is 0.0-2.0625 V.
14.3
Initialization and Configuration
The following example shows how to configure an analog comparator to read back its output value
from an internal register.
1. Enable the analog comparator 0 clock by writing a value of 0x0010.0000 to the RCGC1 register
in the System Control module.
2. In the GPIO module, enable the GPIO port/pin associated with C0- as a GPIO input.
3. Configure the internal voltage reference to 1.65 V by writing the ACREFCTL register with the
value 0x0000.030C.
4. Configure comparator 0 to use the internal voltage reference and to not invert the output on the
C0o pin by writing the ACCTL0 register with the value of 0x0000.040C.
5. Delay for some time.
6. Read the comparator output value by reading the ACSTAT0 register’s OVAL value.
Change the level of the signal input on C0- to see the OVAL value change.
14.4
Register Map
Table 14-5 on page 331 lists the comparator registers. The offset listed is a hexadecimal increment
to the register’s address, relative to the Analog Comparator base address of 0x4003.C000.
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Table 14-5. Analog Comparators Register Map
See
page
Offset
Name
Type
Reset
Description
0x00
0x04
0x08
0x10
0x20
0x24
0x40
0x44
0x60
0x64
ACMIS
R/W1C
RO
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
0x0000.0000
Analog Comparator Masked Interrupt Status
Analog Comparator Raw Interrupt Status
Analog Comparator Interrupt Enable
Analog Comparator Reference Voltage Control
Analog Comparator Status 0
332
333
334
335
336
337
336
337
336
337
ACRIS
ACINTEN
ACREFCTL
ACSTAT0
ACCTL0
ACSTAT1
ACCTL1
ACSTAT2
ACCTL2
R/W
R/W
RO
R/W
RO
Analog Comparator Control 0
Analog Comparator Status 1
R/W
RO
Analog Comparator Control 1
Analog Comparator Status 2
R/W
Analog Comparator Control 2
14.5
Register Descriptions
The remainder of this section lists and describes the Analog Comparator registers, in numerical
order by address offset.
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Register 1: Analog Comparator Masked Interrupt Status (ACMIS), offset 0x00
This register provides a summary of the interrupt status (masked) of the comparator.
Analog Comparator Masked Interrupt Status (ACMIS)
Base 0x4003.C000
Offset 0x00
Type R/W1C, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IN2
IN1
IN0
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
R/W1C
0
R/W1C
0
R/W1C
0
Bit/Field
31:3
Name
Type
RO
Reset
Description
reserved
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
1
0
IN2
IN1
IN0
R/W1C
R/W1C
R/W1C
0
Comparator 2 Masked Interrupt Status
Gives the masked interrupt state of this interrupt. Write 1 to this bit to
clear the pending interrupt.
0
0
Comparator 1 Masked Interrupt Status
Gives the masked interrupt state of this interrupt. Write 1 to this bit to
clear the pending interrupt.
Comparator 0 Masked Interrupt Status
Gives the masked interrupt state of this interrupt. Write 1 to this bit to
clear the pending interrupt.
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Register 2: Analog Comparator Raw Interrupt Status (ACRIS), offset 0x04
This register provides a summary of the interrupt status (raw) of the comparator.
Analog Comparator Raw Interrupt Status (ACRIS)
Base 0x4003.C000
Offset 0x04
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IN2
IN1
IN0
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
Bit/Field
31:3
Name
Type
RO
Reset
Description
reserved
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
1
0
IN2
IN1
IN0
RO
RO
RO
0
Comparator 2 Interrupt Status
When set, indicates that an interrupt has been generated by comparator
2.
0
0
Comparator 1 Interrupt Status
When set, indicates that an interrupt has been generated by comparator
1.
Comparator 0 Interrupt Status
When set, indicates that an interrupt has been generated by comparator
0.
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Register 3: Analog Comparator Interrupt Enable (ACINTEN), offset 0x08
This register provides the interrupt enable for the comparator.
Analog Comparator Interrupt Enable (ACINTEN)
Base 0x4003.C000
Offset 0x08
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
IN2
IN1
IN0
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
R/W
0
R/W
0
R/W
0
Bit/Field
31:3
Name
Type
RO
Reset
Description
reserved
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
1
0
IN2
IN1
IN0
R/W
R/W
R/W
0
0
0
Comparator 2 Interrupt Enable
When set, enables the controller interrupt from the comparator 2 output
Comparator 1 Interrupt Enable
When set, enables the controller interrupt from the comparator 1 output.
Comparator 0 Interrupt Enable
When set, enables the controller interrupt from the comparator 0 output.
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Register 4: Analog Comparator Reference Voltage Control (ACREFCTL), offset
0x10
This register specifies whether the resistor ladder is powered on as well as the range and tap.
Analog Comparator Reference Voltage Control (ACREFCTL)
Base 0x4003.C000
Offset 0x10
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
EN
RNG
reserved
VREF
Type
Reset
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
R/W
0
R/W
0
R/W
0
R/W
0
Bit/Field
31:10
Name
Type
RO
Reset
0x00
Description
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.
9
EN
R/W
0
Resistor Ladder Enable
The EN bit specifies whether the resistor ladder is powered on. If 0, the
resistor ladder is unpowered. If 1, the resistor ladder is connected to
the analog VDD
.
This bit is reset to 0 so that the internal reference consumes the least
amount of power if not used and programmed.
8
RNG
R/W
0
Resistor Ladder Range
The RNG bit specifies the range of the resistor ladder. If 0, the resistor
ladder has a total resistance of 32 R. If 1, the resistor ladder has a total
resistance of 24 R.
7:4
3:0
reserved
VREF
RO
0x00
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.
R/W
Resistor Ladder Voltage Ref
The VREF bit field specifies the resistor ladder tap that is passed through
an analog multiplexer. The voltage corresponding to the tap position is
the internal reference voltage available for comparison. See Table
14-4 on page 329 for some output reference voltage examples.
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Analog Comparators
Register 5: Analog Comparator Status 0 (ACSTAT0), offset 0x20
Register 6: Analog Comparator Status 1 (ACSTAT1), offset 0x40
Register 7: Analog Comparator Status 2 (ACSTAT2), offset 0x60
These registers specify the current output value of the comparator.
Analog Comparator Status 0 (ACSTAT0)
Base 0x4003.C000
Offset 0x20
Type RO, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
OVAL
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
Bit/Field
31:2
Name
Type
RO
Reset
0x00
Description
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.
1
0
OVAL
RO
RO
0
0
Comparator Output Value
The OVAL bit specifies the current output value of the comparator.
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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Register 8: Analog Comparator Control 0 (ACCTL0), offset 0x24
Register 9: Analog Comparator Control 1 (ACCTL1), offset 0x44
Register 10: Analog Comparator Control 2 (ACCTL2), offset 0x64
These registers configure the comparator’s input and output.
Analog Comparator Control 0 (ACCTL0)
Base 0x4003.C000
Offset 0x24
Type R/W, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
reserved
Type
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
reserved
ASRCP
reserved
ISLVAL
ISEN
CINV
reserved
Type
Reset
RO
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
RO
0
RO
0
RO
0
RO
0
R/W
0
R/W
0
R/W
0
R/W
0
RO
0
Bit/Field
31:11
Name
Type
RO
Reset
0x00
Description
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.
10:9
ASRCP
R/W
0x00
Analog Source Positive
The ASRCP field specifies the source of input voltage to the VIN+ terminal
of the comparator. The encodings for this field are as follows:
Value Function
0x0 Pin value
0x1 Pin value of C0+
0x2 Internal voltage reference
0x3 Reserved
8:5
4
reserved
ISLVAL
RO
0
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.
R/W
Interrupt Sense Level Value
The ISLVAL bit specifies the sense value of the input that generates
an interrupt if in Level Sense mode. If 0, an interrupt is generated if the
comparator output is Low. Otherwise, an interrupt is generated if the
comparator output is High.
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Analog Comparators
Bit/Field
3:2
Name
ISEN
Type
R/W
Reset
0x0
Description
Interrupt Sense
The ISEN field specifies the sense of the comparator output that
generates an interrupt. The sense conditioning is as follows:
Value Function
0x0 Level sense, see ISLVAL
0x1 Falling edge
0x2 Rising edge
0x3 Either edge
1
CINV
R/W
RO
0
0
Comparator Output Invert
The CINV bit conditionally inverts the output of the comparator. If 0, the
output of the comparator is unchanged. If 1, the output of the comparator
is inverted prior to being processed by hardware.
0
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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October 01, 2007
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15
Pin Diagram
Figure 15-1 on page 339 shows the pin diagram and pin-to-signal-name mapping.
Figure 15-1. Pin Connection Diagram
36
35
34
33
32
31
30
29
28
27
26
25
1
PE1
PE5/CCP5
PE4/CCP3
PE3/CCP1
PE2/CCP4
RST
2
PE0
3
PB3/I2CSDA
PB2/I2CSCL
VDD
4
5
6
GND
LDO
7
PB1
VDD
8
PB0
GND
9
PD3/U1Tx
PD2/U1Rx
PD1
OSC0
10
11
12
OSC1
PC7/C2-
PC6/C2+/C2o
PD0
LM3S300
October 01, 2007
339
Preliminary
Signal Tables
16
Signal Tables
The following tables list the signals available for each pin. Functionality is enabled by software with
the GPIOAFSEL register.
Important: All multiplexed pins are GPIOs by default, with the exception of the five JTAG pins (PB7
and PC[3:0]) which default to the JTAG functionality.
Table 16-1 on page 340 shows the pin-to-signal-name mapping, including functional characteristics
of the signals. Table 16-2 on page 342 lists the signals in alphabetical order by signal name.
Table 16-3 on page 344 groups the signals by functionality, except for GPIOs. Table 16-4 on page
345 lists the GPIO pins and their alternate functionality.
Table 16-1. Signals by Pin Number
Pin Number
Pin Name
PE5
Pin Type
Buffer Type Description
1
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
Power
GPIO port E bit 5
CCP5
PE4
Capture/Compare/PWM 5
GPIO port E bit 4
2
3
4
CCP3
PE3
Capture/Compare/PWM 3
GPIO port E bit 3
CCP1
PE2
Capture/Compare/PWM 1
GPIO port E bit 2
CCP4
RST
Capture/Compare/PWM 4
System reset input.
5
6
LDO
-
Low drop-out regulator output voltage. This
pin requires an external capacitor between
the pin and GND of 1 µF or greater.
7
8
9
VDD
GND
-
-
I
Power
Power
Analog
Positive supply for I/O and some logic.
Ground reference for logic and I/O pins.
OSC0
Main oscillator crystal input or an external
clock reference input.
10
11
OSC1
PC7
C2-
PC6
C2+
C2o
PC5
C1+
C1o
PC4
VDD
GND
PA0
U0Rx
O
I/O
I
Analog
TTL
Main oscillator crystal output.
GPIO port C bit 7
Analog
TTL
Analog comparator 2 negative input
GPIO port C bit 6
12
13
I/O
I
Analog
TTL
Analog comparator positive input
Analog comparator 2 output
GPIO port C bit 5
O
I/O
I
TTL
Analog
TTL
Analog comparator positive input
Analog comparator 1 output
GPIO port C bit 4
O
I/O
-
14
15
16
17
TTL
Power
Power
TTL
Positive supply for I/O and some logic.
Ground reference for logic and I/O pins.
GPIO port A bit 0
-
I/O
I
TTL
UART module 0 receive
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Pin Number
Pin Name
PA1
Pin Type
Buffer Type Description
GPIO port A bit 1
UART module 0 transmit
18
I/O
O
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
Power
Power
TTL
TTL
TTL
TTL
U0Tx
PA2
19
20
21
22
I/O
I/O
I/O
I/O
I/O
I
GPIO port A bit 2
SSIClk
PA3
SSI clock
GPIO port A bit 3
SSIFss
PA4
SSI frame
GPIO port A bit 4
SSIRx
PA5
SSI module 0 receive
GPIO port A bit 5
I/O
O
SSITx
VDD
SSI module 0 transmit
Positive supply for I/O and some logic.
Ground reference for logic and I/O pins.
GPIO port D bit 0
23
24
25
26
27
-
GND
-
PD0
I/O
I/O
I/O
I
PD1
GPIO port D bit 1
PD2
GPIO port D bit 2
U1Rx
UART module 1 receive. When in IrDA mode,
this signal has IrDA modulation.
28
PD3
I/O
O
TTL
TTL
GPIO port D bit 3
U1Tx
UART module 1 transmit. When in IrDA mode,
this signal has IrDA modulation.
29
30
31
32
33
PB0
PB1
I/O
I/O
-
TTL
TTL
Power
Power
TTL
OD
GPIO port B bit 0
GPIO port B bit 1
GND
Ground reference for logic and I/O pins.
Positive supply for I/O and some logic.
GPIO port B bit 2
VDD
-
PB2
I/O
I/O
I/O
I/O
I/O
I/O
I/O
O
I2CSCL
PB3
I2C module 0 clock
GPIO port B bit 3
34
TTL
OD
I2CSDA
PE0
I2C module 0 data
GPIO port E bit 0
35
36
37
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
PE1
GPIO port E bit 1
PC3
GPIO port C bit 3
TDO
JTAG TDO and SWO
JTAG TDO and SWO
GPIO port C bit 2
SWO
O
38
39
PC2
I/O
I
TDI
JTAG TDI
PC1
I/O
I/O
I/O
I/O
I
GPIO port C bit 1
TMS
JTAG TMS and SWDIO
JTAG TMS and SWDIO
GPIO port C bit 0
SWDIO
PC0
40
41
TCK
JTAG/SWD CLK
SWCLK
PB7
I
JTAG/SWD CLK
I/O
I
GPIO port B bit 7
TRST
JTAG TRSTn
October 01, 2007
341
Preliminary
Signal Tables
Pin Number
Pin Name
PB6
Pin Type
Buffer Type Description
42
I/O
I
TTL
Analog
TTL
GPIO port B bit 6
C0+
Analog comparator 0 positive input
GPIO port B bit 5
43
44
45
46
PB5
I/O
I
C1-
Analog
TTL
Analog comparator 1 negative input
GPIO port B bit 4
PB4
I/O
I
C0-
Analog
TTL
Analog comparator 0 negative input
GPIO port D bit 4
PD4
I/O
I/O
I/O
I/O
I/O
I/O
O
CCP0
PD5
TTL
Capture/Compare/PWM 0
GPIO port D bit 5
TTL
CCP2
PD6
TTL
Capture/Compare/PWM 2
GPIO port D bit 6
47
48
TTL
PD7
TTL
GPIO port D bit 7
C0o
TTL
Analog comparator 0 output
Table 16-2. Signals by Signal Name
Pin Name
C0+
Pin Number
Pin Type
Buffer Type Description
42
44
48
13
43
13
12
11
12
45
3
I
I
Analog
Analog
TTL
Analog comparator 0 positive input
C0-
Analog comparator 0 negative input
Analog comparator 0 output
Analog comparator positive input
Analog comparator 1 negative input
Analog comparator 1 output
Analog comparator positive input
Analog comparator 2 negative input
Analog comparator 2 output
Capture/Compare/PWM 0
C0o
O
I
C1+
Analog
Analog
TTL
C1-
I
C1o
O
I
C2+
Analog
Analog
TTL
C2-
I
C2o
O
I/O
I/O
I/O
I/O
I/O
I/O
-
CCP0
CCP1
CCP2
CCP3
CCP4
CCP5
GND
TTL
TTL
Capture/Compare/PWM 1
46
2
TTL
Capture/Compare/PWM 2
TTL
Capture/Compare/PWM 3
4
TTL
Capture/Compare/PWM 4
1
TTL
Capture/Compare/PWM 5
8
Power
Power
Power
Power
OD
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
I2C module 0 clock
GND
16
24
31
33
34
6
-
GND
-
GND
-
I2CSCL
I2CSDA
LDO
I/O
I/O
-
OD
I2C module 0 data
Power
Low drop-out regulator output voltage. This
pin requires an external capacitor between
the pin and GND of 1 µF or greater.
OSC0
OSC1
9
I
Analog
Analog
Main oscillator crystal input or an external
clock reference input.
10
O
Main oscillator crystal output.
342
October 01, 2007
Preliminary
LM3S300 Microcontroller
Pin Name
PA0
Pin Number
17
18
19
20
21
22
29
30
33
34
44
43
42
41
40
39
38
37
14
13
12
11
Pin Type
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
Buffer Type Description
GPIO port A bit 0
GPIO port A bit 1
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
PA1
PA2
GPIO port A bit 2
GPIO port A bit 3
GPIO port A bit 4
GPIO port A bit 5
GPIO port B bit 0
GPIO port B bit 1
GPIO port B bit 2
GPIO port B bit 3
GPIO port B bit 4
GPIO port B bit 5
GPIO port B bit 6
GPIO port B bit 7
GPIO port C bit 0
GPIO port C bit 1
GPIO port C bit 2
GPIO port C bit 3
GPIO port C bit 4
GPIO port C bit 5
GPIO port C bit 6
GPIO port C bit 7
GPIO port D bit 0
GPIO port D bit 1
GPIO port D bit 2
GPIO port D bit 3
GPIO port D bit 4
GPIO port D bit 5
GPIO port D bit 6
GPIO port D bit 7
GPIO port E bit 0
GPIO port E bit 1
GPIO port E bit 2
GPIO port E bit 3
GPIO port E bit 4
GPIO port E bit 5
System reset input.
SSI clock
PA3
PA4
PA5
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PC0
PC1
PC2
PC3
PC4
PC5
PC6
PC7
PD0
25
26
27
28
45
46
47
48
35
36
4
PD1
PD2
PD3
PD4
PD5
PD6
PD7
PE0
PE1
PE2
PE3
3
PE4
2
PE5
1
RST
5
SSIClk
SSIFss
SSIRx
SSITx
SWCLK
19
20
21
22
40
I/O
I/O
I
SSI frame
SSI module 0 receive
SSI module 0 transmit
JTAG/SWD CLK
O
I
October 01, 2007
343
Preliminary
Signal Tables
Pin Name
SWDIO
SWO
Pin Number
Pin Type
Buffer Type Description
39
37
40
38
37
39
41
17
18
27
I/O
O
I
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
TTL
JTAG TMS and SWDIO
JTAG TDO and SWO
JTAG/SWD CLK
TCK
TDI
I
JTAG TDI
TDO
O
I/O
I
JTAG TDO and SWO
JTAG TMS and SWDIO
JTAG TRSTn
TMS
TRST
U0Rx
U0Tx
U1Rx
I
UART module 0 receive
UART module 0 transmit
O
I
UART module 1 receive. When in IrDA mode,
this signal has IrDA modulation.
U1Tx
28
O
TTL
UART module 1 transmit. When in IrDA mode,
this signal has IrDA modulation.
VDD
VDD
VDD
VDD
7
-
-
-
-
Power
Power
Power
Power
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
15
23
32
Table 16-3. Signals by Function, Except for GPIO
Function
Pin Name
Pin
Pin Type
Buffer
Description
Number
Type
Analog
Analog
TTL
Analog
Comparators
C0+
C0-
C0o
C1+
C1-
C1o
C2+
C2-
C2o
42
44
48
13
43
13
12
11
12
45
3
I
Analog comparator 0 positive input
Analog comparator 0 negative input
Analog comparator 0 output
Analog comparator positive input
Analog comparator 1 negative input
Analog comparator 1 output
Analog comparator positive input
Analog comparator 2 negative input
Analog comparator 2 output
Capture/Compare/PWM 0
Capture/Compare/PWM 1
Capture/Compare/PWM 2
Capture/Compare/PWM 3
Capture/Compare/PWM 4
Capture/Compare/PWM 5
I2C module 0 clock
I
O
I
Analog
Analog
TTL
I
O
I
Analog
Analog
TTL
I
O
General-Purpose CCP0
Timers
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
TTL
CCP1
TTL
CCP2
CCP3
CCP4
CCP5
46
2
TTL
TTL
4
TTL
1
TTL
I2C
I2CSCL
I2CSDA
33
34
OD
OD
I2C module 0 data
344
October 01, 2007
Preliminary
LM3S300 Microcontroller
Function
Pin Name
Pin
Number
Pin Type
Buffer
Type
Description
JTAG/SWD/SWO SWCLK
40
39
37
40
38
37
39
8
I
I/O
O
I
TTL
TTL
JTAG/SWD CLK
SWDIO
SWO
JTAG TMS and SWDIO
TTL
JTAG TDO and SWO
TCK
TTL
JTAG/SWD CLK
TDI
I
TTL
JTAG TDI
TDO
O
I/O
-
TTL
JTAG TDO and SWO
TMS
TTL
JTAG TMS and SWDIO
Power
GND
GND
GND
GND
LDO
Power
Power
Power
Power
Power
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
Ground reference for logic and I/O pins.
16
24
31
6
-
-
-
-
Low drop-out regulator output voltage. This pin
requires an external capacitor between the pin and
GND of 1 µF or greater.
VDD
7
-
-
Power
Power
Power
Power
TTL
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
Positive supply for I/O and some logic.
SSI clock
VDD
15
23
32
19
20
21
22
9
VDD
-
VDD
-
SSI
SSIClk
SSIFss
SSIRx
SSITx
I/O
I/O
I
TTL
SSI frame
TTL
SSI module 0 receive
O
I
TTL
SSI module 0 transmit
System Control & OSC0
Analog
Main oscillator crystal input or an external clock
reference input.
Clocks
OSC1
RST
10
5
O
I
Analog
TTL
Main oscillator crystal output.
System reset input.
TRST
41
17
18
27
I
TTL
JTAG TRSTn
UART
U0Rx
U0Tx
U1Rx
I
TTL
UART module 0 receive
UART module 0 transmit
O
I
TTL
TTL
UART module 1 receive. When in IrDA mode, this
signal has IrDA modulation.
U1Tx
28
O
TTL
UART module 1 transmit. When in IrDA mode, this
signal has IrDA modulation.
Table 16-4. GPIO Pins and Alternate Functions
GPIO Pin
PA0
Pin Number
Multiplexed Function
Multiplexed Function
17
18
19
20
21
22
29
U0Rx
U0Tx
PA1
PA2
SSIClk
SSIFss
SSIRx
SSITx
PA3
PA4
PA5
PB0
October 01, 2007
345
Preliminary
Signal Tables
GPIO Pin
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PC0
PC1
PC2
PC3
PC4
PC5
PC6
PC7
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
PE0
PE1
PE2
PE3
PE4
PE5
Pin Number
Multiplexed Function
Multiplexed Function
30
33
34
44
43
42
41
40
39
38
37
14
13
12
11
25
26
27
28
45
46
47
48
35
36
4
I2CSCL
I2CSDA
C0-
C1-
C0+
TRST
TCK
SWCLK
SWDIO
TMS
TDI
TDO
SWO
C1+
C2+
C2-
C1o
C2o
U1Rx
U1Tx
CCP0
CCP2
C0o
CCP4
CCP1
CCP3
CCP5
3
2
1
346
October 01, 2007
Preliminary
LM3S300 Microcontroller
17
Operating Characteristics
Table 17-1. Temperature Characteristics
Characteristic
Symbol Value
Unit
Operating temperature rangea TA
-40 to +85 °C
a. Maximum storage temperature is 150°C.
Table 17-2. Thermal Characteristics
Characteristic
Thermal resistance (junction to ambient)a ΘJA
Average junction temperatureb
Symbol Value
Unit
°C/W
°C
76
TJ
TA + (PAVG • ΘJA)
Maximum junction temperature
TJMAX
115
°C
c
a. Junction to ambient thermal resistance θJA numbers are determined by a package simulator.
b. Power dissipation is a function of temperature.
c. TJMAX calculation is based on power consumption values and conditions as specified in “Power Specifications” on page
383 of the data sheet.
October 01, 2007
347
Preliminary
Electrical Characteristics
18
Electrical Characteristics
18.1
DC Characteristics
18.1.1
Maximum Ratings
The maximum ratings are the limits to which the device can be subjected without permanently
damaging the device.
Note: The device is not guaranteed to operate properly at the maximum ratings.
Table 18-1. Maximum Ratings
Characteristica
Symbol
Value
Unit
V
Supply voltage range (VDD
)
VDD 0.0 to +3.6
Input voltage
VIN
-0.3 to 5.5
100
V
Maximum current for pins, excluding pins operating as GPIOs
Maximum current for GPIO pins
I
I
mA
mA
100
a. Voltages are measured with respect to GND.
Important: This device contains circuitry to protect the inputs against damage due to high-static
voltages or electric fields; however, it is advised that normal precautions be taken to
avoid application of any voltage higher than maximum-rated voltages to this
high-impedance circuit. Reliability of operation is enhanced if unused inputs are
connected to an appropriate logic voltage level (for example, either GND or VDD).
18.1.2
Recommended DC Operating Conditions
Table 18-2. Recommended DC Operating Conditions
Parameter Parameter Name
Min
3.0
Nom
Max
3.6
Unit
V
VDD
VIH
Supply voltage
3.3
High-level input voltage
Low-level input voltage
2.0
-
-
-
-
-
-
5.0
V
VIL
-0.3
1.3
V
VSIH
VSIL
VOH
VOL
IOH
High-level input voltage for Schmitt trigger inputs 0.8 * VDD
VDD
0.2 * VDD
-
V
Low-level input voltage for Schmitt trigger inputs
High-level output voltage
Low-level output voltage
High-level source current, VOH=2.4 V
2-mA Drive
0
2.4
-
V
V
0.4
V
2.0
4.0
8.0
-
-
-
-
-
-
mA
4-mA Drive
mA
mA
8-mA Drive
IOL
Low-level sink current, VOL=0.4 V
2-mA Drive
2.0
4.0
8.0
-
-
-
-
-
-
mA
mA
mA
4-mA Drive
8-mA Drive
348
October 01, 2007
Preliminary
LM3S300 Microcontroller
18.1.3
On-Chip Low Drop-Out (LDO) Regulator Characteristics
Table 18-3. LDO Regulator Characteristics
Parameter Parameter Name
Min Nom Max Unit
VLDOOUT Programmable internal (logic) power supply output value 2.25
2.75
-
V
Output voltage accuracy
-
2%
%
tPON
tON
Power-on time
-
-
-
100 µs
200 µs
100 µs
Time on
-
-
tOFF
Time off
-
VSTEP
CLDO
Step programming incremental voltage
External filter capacitor size for internal power supply
-
50
-
-
mV
1.0
3.0 µF
18.1.4
Power Specifications
The power measurements specified in the tables that follow are run on the core processor using
SRAM with the following specifications (except as noted):
■ VDD = 3.3 V
■ Temperature = 25°C
Table 18-4. Detailed Power Specifications
Parameter Parameter Name
Conditions
Run mode 1 (Flash loop) LDO = 2.50 V
Code = while(1){} executed in Flash
Nom Max Unit
IDD_RUN
60
40
50
30
18
65 mA
45 mA
55 mA
35 mA
21 mA
Peripherals = All clock-gated ON
System Clock = 25 MHz (with PLL)
Run mode 2 (Flash loop) LDO = 2.50 V
Code = while(1){} executed in Flash
Peripherals = All clock-gated OFF
System Clock = 25 MHz (with PLL)
Run mode 1 (SRAM loop) LDO = 2.50 V
Code = while(1){} executed in SRAM
Peripherals = All clock-gated ON
System Clock = 25 MHz (with PLL)
Run mode 2 (SRAM loop) LDO = 2.50 V
Code = while(1){} executed in SRAM
Peripherals = All clock-gated OFF
System Clock = 25 MHz (with PLL)
LDO = 2.50 V
IDD_SLEEP
Sleep mode
Peripherals = All clock-gated OFF
System Clock = 25 MHz (with PLL)
October 01, 2007
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Preliminary
Electrical Characteristics
Parameter Parameter Name
IDD_DEEPSLEEP Deep-Sleep mode
Conditions
Nom Max Unit
LDO = 2.25 V
950 1150 μA
Peripherals = All OFF
System Clock = MOSC/16
18.1.5
Flash Memory Characteristics
Table 18-5. Flash Memory Characteristics
Parameter Parameter Name
Min Nom Max Unit
PECYC
TRET
Number of guaranteed program/erase cycles before failurea 1000
-
-
-
-
-
-
-
-
-
-
cycles
years
µs
Data retention at average operating temperature of 85˚C
Word program time
10
20
TPROG
TERASE Page erase time
TME Mass erase time
20
ms
200
ms
a. A program/erase cycle is defined as switching the bits from 1-> 0 -> 1.
18.2
AC Characteristics
18.2.1
Load Conditions
Unless otherwise specified, the following conditions are true for all timing measurements. Timing
measurements are for 4-mA drive strength.
Figure 18-1. Load Conditions
pin
CL = 50 pF
GND
18.2.2
Clocks
Table 18-6. Phase Locked Loop (PLL) Characteristics
Parameter Parameter Name
Min
Nom Max Unit
fref_crystal
fref_ext
fpll
Crystal referencea
3.579545
-
8.192 MHz
8.192 MHz
External clock referencea 3.579545
PLL frequencyb
-
200
-
-
-
-
MHz
TREADY
PLL lock time
0.5 ms
a. The exact value is determined by the crystal value programmed into the XTAL field of the Run-Mode Clock Configuration
(RCC) register.
b. PLL frequency is automatically calculated by the hardware based on the XTAL field of the RCC register.
Table 18-7. Clock Characteristics
Parameter Parameter Name
fIOSC Internal oscillator frequency
Min Nom Max Unit
12 22 MHz
7
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Parameter Parameter Name
fMOSC Main oscillator frequency
tMOSC_per Main oscillator period
fref_crystal_bypass Crystal reference using the main oscillator (PLL in BYPASS mode)
Min Nom Max Unit
1
125
1
-
-
-
-
-
8
MHz
1000 ns
MHz
8
fref_ext_bypass
fsystem_clock
External clock reference (PLL in BYPASS mode)
System clock
0
25 MHz
25 MHz
0
18.2.3
Analog Comparator
Table 18-8. Analog Comparator Characteristics
Parameter Parameter Name
Min Nom Max Unit
VOS
VCM
CMRR
TRT
Input offset voltage
-
0
50
-
±10
±25
mV
V
Input common mode voltage range
Common mode rejection ratio
Response time
-
-
-
-
VDD-1.5
-
dB
µs
µs
1
TMC
Comparator mode change to Output Valid
-
10
Table 18-9. Analog Comparator Voltage Reference Characteristics
Parameter Parameter Name
Min Nom Max Unit
RHR
RLR
AHR
ALR
Resolution high range
-
-
-
-
VDD/32
-
-
LSB
LSB
Resolution low range
VDD/24
Absolute accuracy high range
Absolute accuracy low range
-
-
±1/2 LSB
±1/4 LSB
18.2.4
I2C
Table 18-10. I2C Characteristics
Parameter No. Parameter Parameter Name
Min Nom
Max
Unit
I1a
I2a
I3b
I4a
I5c
I6a
I7a
I8a
tSCH
tLP
tSRT
tDH
tSFT
tHT
Start condition hold time
Clock Low period
36
36
-
-
-
-
system clocks
system clocks
ns
-
I2CSCL/I2CSDA rise time (VIL =0.5 V to V IH =2.4 V)
Data hold time
-
(see note b)
2
-
-
10
-
system clocks
ns
I2CSCL/I2CSDA fall time (VIH =2.4 V to V IL =0.5 V)
Clock High time
-
9
-
24
18
system clocks
system clocks
system clocks
tDS
Data setup time
-
-
tSCSR
Start condition setup time (for repeated start condition 36
only)
-
-
I9a
tSCS
Stop condition setup time
24
-
-
system clocks
a. Values depend on the value programmed into the TPR bit in the I2C Master Timer Period (I2CMTPR) register; a TPR
programmed for the maximum I2CSCL frequency (TPR=0x2) results in a minimum output timing as shown in the table
above. The I 2C interface is designed to scale the actual data transition time to move it to the middle of the I2CSCL Low
period. The actual position is affected by the value programmed into the TPR; however, the numbers given in the above
values are minimum values.
b. Because I2CSCL and I2CSDA are open-drain-type outputs, which the controller can only actively drive Low, the time
I2CSCL or I2CSDA takes to reach a high level depends on external signal capacitance and pull-up resistor values.
c. Specified at a nominal 50 pF load.
October 01, 2007
351
Preliminary
Electrical Characteristics
Figure 18-2. I2C Timing
I2
I6
I5
I2CSCL
I1
I4
I7
I8
I3
I9
I2CSDA
18.2.5
Synchronous Serial Interface (SSI)
Table 18-11. SSI Characteristics
Parameter No. Parameter Parameter Name
Min Nom Max
Unit
S1
S2
S3
S4
S5
S6
S7
S8
S9
tclk_per
SSIClk cycle time
2
-
-
65024 system clocks
tclk_high SSIClk high time
1/2
-
-
t clk_per
tclk_low
tclkrf
SSIClk low time
-
1/2
t clk_per
SSIClk rise/fall time
-
7.4
26
20
-
ns
ns
ns
ns
ns
ns
tDMd
tDMs
tDMh
tDSs
Data from master valid delay time
Data from master setup time
Data from master hold time
Data from slave setup time
Data from slave hold time
0
-
-
-
-
-
20
40
20
40
-
-
tDSh
-
Figure 18-3. SSI Timing for TI Frame Format (FRF=01), Single Transfer Timing Measurement
S1
S2
S4
SSIClk
SSIFss
S3
SSITx
SSIRx
MSB
LSB
4 to 16 bits
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Figure 18-4. SSI Timing for MICROWIRE Frame Format (FRF=10), Single Transfer
S2
S1
SSIClk
SSIFss
SSITx
SSIRx
S3
MSB
LSB
8-bit control
0
MSB
LSB
4 to 16 bits output data
Figure 18-5. SSI Timing for SPI Frame Format (FRF=00), with SPH=1
S1
S2
S4
SSIClk
(SPO=0)
S3
SSIClk
(SPO=1)
S6
S7
S9
SSITx
(master)
MSB
LSB
LSB
S5
S8
SSIRx
(slave)
MSB
SSIFss
18.2.6
JTAG and Boundary Scan
Table 18-12. JTAG Characteristics
Parameter No.
Parameter
fTCK
Parameter Name
Min Nom Max Unit
J1
J2
J3
TCK operational clock frequency
TCK operational clock period
TCK clock Low time
0
100
-
-
-
10 MHz
tTCK
-
-
ns
ns
tTCK_LOW
tTCK
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Preliminary
Electrical Characteristics
Parameter No.
Parameter
Parameter Name
TCK clock High time
TCK rise time
Min Nom Max Unit
J4
J5
tTCK_HIGH
-
tTCK
-
-
ns
tTCK_R
0
10 ns
10 ns
J6
tTCK_F
TCK fall time
0
-
J7
tTMS_SU
TMS setup time to TCK rise
TMS hold time from TCK rise
TDI setup time to TCK rise
TDI hold time from TCK rise
2-mA drive
20
20
25
25
-
-
-
-
-
-
ns
ns
ns
ns
J8
tTMS_HLD
tTDI_SU
-
J9
-
J10
J11
tTDI_HLD
-
TCK fall to Data Valid from High-Z
23
15
14
18
21
14
13
18
9
35 ns
26 ns
25 ns
29 ns
35 ns
25 ns
24 ns
28 ns
11 ns
4-mA drive
t TDO_ZDV
8-mA drive
8-mA drive with slew rate control
2-mA drive
J12
TCK fall to Data Valid from Data Valid
TCK fall to High-Z from Data Valid
-
-
4-mA drive
t TDO_DV
8-mA drive
8-mA drive with slew rate control
2-mA drive
J13
4-mA drive
7
9
8
9
-
ns
ns
ns
ns
ns
t TDO_DVZ
8-mA drive
6
8-mA drive with slew rate control
TRST assertion time
TRST setup time to TCK rise
7
J14
J15
tTRST
100
10
-
tTRST_SU
-
-
Figure 18-6. JTAG Test Clock Input Timing
J2
J3
J4
TCK
J6
J5
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Figure 18-7. JTAG Test Access Port (TAP) Timing
TCK
J7
TMS Input Valid
J9 J10
TDI Input Valid
J8
J7
TMS Input Valid
J9 J10
TDI Input Valid
J8
TMS
TDI
J11
J12
J13
TDO Output Valid
TDO Output Valid
TDO
Figure 18-8. JTAG TRST Timing
TCK
J14
J15
TRST
18.2.7
General-Purpose I/O
Note: All GPIOs are 5 V-tolerant.
Table 18-13. GPIO Characteristics
Parameter Parameter Name
Condition
Min Nom Max Unit
tGPIOR
GPIO Rise Time (from 20% to 80% of VDD
)
2-mA drive
4-mA drive
8-mA drive
-
17
9
26 ns
13 ns
6
9
ns
8-mA drive with slew rate control
GPIO Fall Time (from 80% to 20% of VDD) 2-mA drive
10
17
8
12 ns
25 ns
12 ns
10 ns
13 ns
tGPIOF
-
4-mA drive
8-mA drive
6
8-mA drive with slew rate control
11
18.2.8
Reset
Table 18-14. Reset Characteristics
Parameter No. Parameter Parameter Name
Min Nom Max Unit
2.0
R1
VTH
Reset threshold
-
-
V
October 01, 2007
355
Preliminary
Electrical Characteristics
Parameter No. Parameter Parameter Name
Min Nom Max Unit
R2
VBTH
TPOR
TBOR
Brown-Out threshold
Power-On Reset timeout
Brown-Out timeout
2.85 2.9 2.95
V
R3
-
10
-
-
ms
µs
R4
-
500
R5
TIRPOR Internal reset timeout after POR
TIRBOR Internal reset timeout after BORa
15
2.5
15
-
-
-
-
-
-
-
30 ms
20 µs
30 ms
20 µs
20 µs
20 µs
100 ms
R6
R7
TIRHWR Internal reset timeout after hardware reset (RST pin)
R8
TIRSWR Internal reset timeout after software-initiated system reset a 2.5
R9
R10
TIRWDR Internal reset timeout after watchdog reseta
TIRLDOR Internal reset timeout after LDO reseta
TVDDRISE Supply voltage (VDD) rise time (0 V-3.3 V)
2.5
2.5
-
R11
a. 20 * t MOSC_per
Figure 18-9. External Reset Timing (RST)
RST
R7
/Reset
(Internal)
Figure 18-10. Power-On Reset Timing
R1
VDD
R3
/POR
(Internal)
R5
/Reset
(Internal)
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October 01, 2007
Preliminary
LM3S300 Microcontroller
Figure 18-11. Brown-Out Reset Timing
R2
VDD
R4
/BOR
(Internal)
R6
/Reset
(Internal)
Figure 18-12. Software Reset Timing
SW Reset
R8
/Reset
(Internal)
Figure 18-13. Watchdog Reset Timing
WDOG
Reset
(Internal)
R9
/Reset
(Internal)
Figure 18-14. LDO Reset Timing
LDO Reset
(Internal)
R10
/Reset
(Internal)
October 01, 2007
357
Preliminary
Package Information
19
Package Information
Figure 19-1. 48-Pin LQFP Package
aaa
bbb
ccc
Note: The following notes apply to the package drawing.
1. All dimensions are in mm. All dimensioning and tolerancing conform to ANSI Y14.5M-1982.
2. The top package body size may be smaller than the bottom package body size by as much as
0.20.
3. Datums A-B and -D- to be determined at datum plane -H-.
4. To be determined at seating plane -C-.
5. Dimensions D1 and E1 do not include mold protrusion. Allowable protrusion is 0.25 per side.
D1 and E1 are maximum plastic body size dimensions including mold mismatch.
6. Surface finish of the package is #24-27 Charmille (1.6-2.3μmR0) Pin 1 and ejector pin may be
less than 0.1μmR0.
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October 01, 2007
Preliminary
LM3S300 Microcontroller
7. Dambar removal protrusion does not exceed 0.08. Intrusion does not exceed 0.03.
8. Burr does not exceed 0.08 in any direction.
9. Dimension b does not include Dambar protrusion. Allowable Dambar protrusion shall not cause
the lead width to exceed the maximum b dimension by more than 0.08. Dambar cannot be
located on the lower radius or the foot. Minimum space between protrusion and adjacent lead
is 0.07 for 0.40 and 0.50 pitch package.
10. Corner radius of plastic body does not exceed 0.20.
11. These dimensions apply to the flat section of the lead between 0.10 and 0.25 from the lead tip.
12. A1 is defined as the distance from the seating plane to the lowest point of the package body.
13. Finish of leads is tin plated.
14. All specifications and dimensions are subjected to IPAC’S manufacturing process flow and
materials.
15. M5-026A. Where discrepancies between the JEDEC and IPAC documents exist, this drawing
will take the precedence.
Symbol
Package Type
48LD LQFP
NOM
Note
MIN
===
0.05
1.35
MAX
1.60
0.15
1.45
A
A1
A2
D
===
===
1.40
9.00 BSC
7.00 BSC
9.00 BSC
7.00 BSC
0.80
D1
E
E1
L
0.45
0.75
e
0.50 BSC
0.22
b
0.17
0.17
0.09
0.09
0.27
0.23
0.20
0.16
b1
c
0.20
===
c1
===
Tolerances of form and position
aaa
bbb
ccc
ddd
0.20
0.20
0.08
0.08
October 01, 2007
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Preliminary
Serial Flash Loader
A
Serial Flash Loader
A.1
Serial Flash Loader
The Stellaris® serial flash loader is a preprogrammed flash-resident utility used to download code
to the flash memory of a device without the use of a debug interface. The serial flash loader uses
a simple packet interface to provide synchronous communication with the device. The flash loader
runs off the crystal and does not enable the PLL, so its speed is determined by the crystal used.
The two serial interfaces that can be used are the UART0 and SSI0 interfaces. For simplicity, both
the data format and communication protocol are identical for both serial interfaces.
A.2
Interfaces
Once communication with the flash loader is established via one of the serial interfaces, that interface
is used until the flash loader is reset or new code takes over. For example, once you start
communicating using the SSI port, communications with the flash loader via the UART are disabled
until the device is reset.
A.2.1
UART
The Universal Asynchronous Receivers/Transmitters (UART) communication uses a fixed serial
format of 8 bits of data, no parity, and 1 stop bit. The baud rate used for communication is
automatically detected by the flash loader and can be any valid baud rate supported by the host
and the device. The auto detection sequence requires that the baud rate should be no more than
1/32 the crystal frequency of the board that is running the serial flash loader. This is actually the
same as the hardware limitation for the maximum baud rate for any UART on a Stellaris® device
which is calculated as follows:
Max Baud Rate = System Clock Frequency / 16
In order to determine the baud rate, the serial flash loader needs to determine the relationship
between its own crystal frequency and the baud rate. This is enough information for the flash loader
to configure its UART to the same baud rate as the host. This automatic baud-rate detection allows
the host to use any valid baud rate that it wants to communicate with the device.
The method used to perform this automatic synchronization relies on the host sending the flash
loader two bytes that are both 0x55. This generates a series of pulses to the flash loader that it can
use to calculate the ratios needed to program the UART to match the host’s baud rate. After the
host sends the pattern, it attempts to read back one byte of data from the UART. The flash loader
returns the value of 0xCC to indicate successful detection of the baud rate. If this byte is not received
after at least twice the time required to transfer the two bytes, the host can resend another pattern
of 0x55, 0x55, and wait for the 0xCC byte again until the flash loader acknowledges that it has
received a synchronization pattern correctly. For example, the time to wait for data back from the
flash loader should be calculated as at least 2*(20(bits/sync)/baud rate (bits/sec)). For a baud rate
of 115200, this time is 2*(20/115200) or 0.35 ms.
A.2.2
SSI
The Synchronous Serial Interface (SSI) port also uses a fixed serial format for communications,
with the framing defined as Motorola format with SPH set to 1 and SPO set to 1. See “Frame
Formats” on page 256 in the SSI chapter for more information on formats for this transfer protocol.
Like the UART, this interface has hardware requirements that limit the maximum speed that the SSI
clock can run. This allows the SSI clock to be at most 1/12 the crystal frequency of the board running
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October 01, 2007
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LM3S300 Microcontroller
the flash loader. Since the host device is the master, the SSI on the flash loader device does not
need to determine the clock as it is provided directly by the host.
A.3
Packet Handling
All communications, with the exception of the UART auto-baud, are done via defined packets that
are acknowledged (ACK) or not acknowledged (NAK) by the devices. The packets use the same
format for receiving and sending packets, including the method used to acknowledge successful or
unsuccessful reception of a packet.
A.3.1
Packet Format
All packets sent and received from the device use the following byte-packed format.
struct
{
unsigned char ucSize;
unsigned char ucCheckSum;
unsigned char Data[];
};
ucSize
The first byte received holds the total size of the transfer including
the size and checksum bytes.
ucChecksum
Data
This holds a simple checksum of the bytes in the data buffer only.
The algorithm is Data[0]+Data[1]+…+ Data[ucSize-3].
This is the raw data intended for the device, which is formatted in
some form of command interface. There should be ucSize–2
bytes of data provided in this buffer to or from the device.
A.3.2
Sending Packets
The actual bytes of the packet can be sent individually or all at once; the only limitation is that
commands that cause flash memory access should limit the download sizes to prevent losing bytes
during flash programming. This limitation is discussed further in the section that describes the serial
flash loader command, COMMAND_SEND_DATA (see “COMMAND_SEND_DATA
(0x24)” on page 363).
Once the packet has been formatted correctly by the host, it should be sent out over the UART or
SSI interface. Then the host should poll the UART or SSI interface for the first non-zero data returned
from the device. The first non-zero byte will either be an ACK (0xCC) or a NAK (0x33) byte from
the device indicating the packet was received successfully (ACK) or unsuccessfully (NAK). This
does not indicate that the actual contents of the command issued in the data portion of the packet
were valid, just that the packet was received correctly.
A.3.3
Receiving Packets
The flash loader sends a packet of data in the same format that it receives a packet. The flash loader
may transfer leading zero data before the first actual byte of data is sent out. The first non-zero byte
is the size of the packet followed by a checksum byte, and finally followed by the data itself. There
is no break in the data after the first non-zero byte is sent from the flash loader. Once the device
communicating with the flash loader receives all the bytes, it must either ACK or NAK the packet to
indicate that the transmission was successful. The appropriate response after sending a NAK to
the flash loader is to resend the command that failed and request the data again. If needed, the
host may send leading zeros before sending down the ACK/NAK signal to the flash loader, as the
October 01, 2007
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Preliminary
Serial Flash Loader
flash loader only accepts the first non-zero data as a valid response. This zero padding is needed
by the SSI interface in order to receive data to or from the flash loader.
A.4
Commands
The next section defines the list of commands that can be sent to the flash loader. The first byte of
the data should always be one of the defined commands, followed by data or parameters as
determined by the command that is sent.
A.4.1
COMMAND_PING (0X20)
This command simply accepts the command and sets the global status to success. The format of
the packet is as follows:
Byte[0] = 0x03;
Byte[1] = checksum(Byte[2]);
Byte[2] = COMMAND_PING;
The ping command has 3 bytes and the value for COMMAND_PING is 0x20 and the checksum of one
byte is that same byte, making Byte[1] also 0x20. Since the ping command has no real return status,
the receipt of an ACK can be interpreted as a successful ping to the flash loader.
A.4.2
COMMAND_GET_STATUS (0x23)
This command returns the status of the last command that was issued. Typically, this command
should be sent after every command to ensure that the previous command was successful or to
properly respond to a failure. The command requires one byte in the data of the packet and should
be followed by reading a packet with one byte of data that contains a status code. The last step is
to ACK or NAK the received data so the flash loader knows that the data has been read.
Byte[0] = 0x03
Byte[1] = checksum(Byte[2])
Byte[2] = COMMAND_GET_STATUS
A.4.3
COMMAND_DOWNLOAD (0x21)
This command is sent to the flash loader to indicate where to store data and how many bytes will
be sent by the COMMAND_SEND_DATA commands that follow. The command consists of two 32-bit
values that are both transferred MSB first. The first 32-bit value is the address to start programming
data into, while the second is the 32-bit size of the data that will be sent. This command also triggers
an erase of the full area to be programmed so this command takes longer than other commands.
This results in a longer time to receive the ACK/NAK back from the board. This command should
be followed by a COMMAND_GET_STATUS to ensure that the Program Address and Program size
are valid for the device running the flash loader.
The format of the packet to send this command is a follows:
Byte[0] = 11
Byte[1] = checksum(Bytes[2:10])
Byte[2] = COMMAND_DOWNLOAD
Byte[3] = Program Address [31:24]
Byte[4] = Program Address [23:16]
Byte[5] = Program Address [15:8]
Byte[6] = Program Address [7:0]
Byte[7] = Program Size [31:24]
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October 01, 2007
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LM3S300 Microcontroller
Byte[8] = Program Size [23:16]
Byte[9] = Program Size [15:8]
Byte[10] = Program Size [7:0]
A.4.4
COMMAND_SEND_DATA (0x24)
This command should only follow a COMMAND_DOWNLOAD command or another
COMMAND_SEND_DATA command if more data is needed. Consecutive send data commands
automatically increment address and continue programming from the previous location. The caller
should limit transfers of data to a maximum 8 bytes of packet data to allow the flash to program
successfully and not overflow input buffers of the serial interfaces. The command terminates
programming once the number of bytes indicated by the COMMAND_DOWNLOAD command has been
received. Each time this function is called it should be followed by a COMMAND_GET_STATUS to
ensure that the data was successfully programmed into the flash. If the flash loader sends a NAK
to this command, the flash loader does not increment the current address to allow retransmission
of the previous data.
Byte[0] = 11
Byte[1] = checksum(Bytes[2:10])
Byte[2] = COMMAND_SEND_DATA
Byte[3] = Data[0]
Byte[4] = Data[1]
Byte[5] = Data[2]
Byte[6] = Data[3]
Byte[7] = Data[4]
Byte[8] = Data[5]
Byte[9] = Data[6]
Byte[10] = Data[7]
A.4.5
COMMAND_RUN (0x22)
This command is used to tell the flash loader to execute from the address passed as the parameter
in this command. This command consists of a single 32-bit value that is interpreted as the address
to execute. The 32-bit value is transmitted MSB first and the flash loader responds with an ACK
signal back to the host device before actually executing the code at the given address. This allows
the host to know that the command was received successfully and the code is now running.
Byte[0] = 7
Byte[1] = checksum(Bytes[2:6])
Byte[2] = COMMAND_RUN
Byte[3] = Execute Address[31:24]
Byte[4] = Execute Address[23:16]
Byte[5] = Execute Address[15:8]
Byte[6] = Execute Address[7:0]
A.4.6
COMMAND_RESET (0x25)
This command is used to tell the flash loader device to reset. This is useful when downloading a
new image that overwrote the flash loader and wants to start from a full reset. Unlike the
COMMAND_RUN command, this allows the initial stack pointer to be read by the hardware and set
up for the new code. It can also be used to reset the flash loader if a critical error occurs and the
host device wants to restart communication with the flash loader.
October 01, 2007
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Preliminary
Serial Flash Loader
Byte[0] = 3
Byte[1] = checksum(Byte[2])
Byte[2] = COMMAND_RESET
The flash loader responds with an ACK signal back to the host device before actually executing the
software reset to the device running the flash loader. This allows the host to know that the command
was received successfully and the part will be reset.
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October 01, 2007
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LM3S300 Microcontroller
B
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
System Control
Base 0x400F.E000
DID0, type RO, offset 0x000, reset -
VER
MAJOR
MINOR
PBORCTL, type R/W, offset 0x030, reset 0x0000.7FFD
LDOPCTL, type R/W, offset 0x034, reset 0x0000.0000
RIS, type RO, offset 0x050, reset 0x0000.0000
IMC, type R/W, offset 0x054, reset 0x0000.0000
MISC, type R/W1C, offset 0x058, reset 0x0000.0000
RESC, type R/W, offset 0x05C, reset -
BORTIM
BORIOR BORWT
VADJ
PLLLRIS
PLLLIM
CLRIS
CLIM
IOFRIS MOFRIS LDORIS BORRIS PLLFRIS
IOFIM
MOFIM
LDOIM
BORIM
PLLFIM
PLLLMIS CLMIS
IOFMIS MOFMIS LDOMIS BORMIS
LDO
SW
WDT
BOR
POR
EXT
RCC, type R/W, offset 0x060, reset 0x07A0.3AD1
USESYSDIV
ACG
SYSDIV
PWRDN
OEN
BYPASS PLLVER
XTAL
OSCSRC
IOSCVER MOSCVER IOSCDIS MOSCDIS
PLLCFG, type RO, offset 0x064, reset -
OD
F
R
DSLPCLKCFG, type R/W, offset 0x144, reset 0x0780.0000
CLKVCLR, type R/W, offset 0x150, reset 0x0000.0000
LDOARST, type R/W, offset 0x160, reset 0x0000.0000
IOSC
VERCLR
LDOARST
DID1, type RO, offset 0x004, reset -
VER
FAM
PARTNO
PKG
TEMP
ROHS
QUAL
DC0, type RO, offset 0x008, reset 0x000F.0007
DC1, type RO, offset 0x010, reset 0x0000.709F
SRAMSZ
FLASHSZ
MINSYSDIV
MPU
PLL
WDT
SWO
SWD
JTAG
DC2, type RO, offset 0x014, reset 0x0707.1013
COMP2
COMP1 COMP0
TIMER2 TIMER1 TIMER0
UART1 UART0
I2C0
SSI0
October 01, 2007
365
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
DC3, type RO, offset 0x018, reset 0x3F00.7FC0
CCP5
CCP4
CCP3
C1O
CCP2
CCP1
CCP0
C0O
C2O
C2PLUS C2MINUS
C1PLUS C1MINUS
C0PLUS C0MINUS
DC4, type RO, offset 0x01C, reset 0x0000.001F
RCGC0, type R/W, offset 0x100, reset 0x00000040
SCGC0, type R/W, offset 0x110, reset 0x00000040
DCGC0, type R/W, offset 0x120, reset 0x00000040
RCGC1, type R/W, offset 0x104, reset 0x00000000
GPIOE
GPIOD
WDT
GPIOC
GPIOB
GPIOA
WDT
WDT
COMP2
COMP2
COMP2
COMP1 COMP0
COMP1 COMP0
COMP1 COMP0
TIMER2 TIMER1 TIMER0
UART1 UART0
I2C0
SSI0
SSI0
SCGC1, type R/W, offset 0x114, reset 0x00000000
TIMER2 TIMER1 TIMER0
UART1 UART0
I2C0
DCGC1, type R/W, offset 0x124, reset 0x00000000
TIMER2 TIMER1 TIMER0
I2C0
SSI0
UART1
GPIOB
GPIOB
GPIOB
UART0
GPIOA
GPIOA
GPIOA
RCGC2, type R/W, offset 0x108, reset 0x00000000
GPIOE
GPIOE
GPIOE
GPIOD
GPIOD
GPIOD
WDT
GPIOC
GPIOC
GPIOC
SCGC2, type R/W, offset 0x118, reset 0x00000000
DCGC2, type R/W, offset 0x128, reset 0x00000000
SRCR0, type R/W, offset 0x040, reset 0x00000000
SRCR1, type R/W, offset 0x044, reset 0x00000000
COMP2
COMP1 COMP0
TIMER2 TIMER1 TIMER0
I2C0
SSI0
UART1
UART0
SRCR2, type R/W, offset 0x048, reset 0x00000000
GPIOE
GPIOD
GPIOC
GPIOB
GPIOA
Internal Memory
Flash Control Offset
Base 0x400F.D000
FMA, type R/W, offset 0x000, reset 0x0000.0000
OFFSET
FMD, type R/W, offset 0x004, reset 0x0000.0000
DATA
DATA
366
October 01, 2007
Preliminary
LM3S300 Microcontroller
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
FMC, type R/W, offset 0x008, reset 0x0000.0000
FCRIS, type RO, offset 0x00C, reset 0x0000.0000
FCIM, type R/W, offset 0x010, reset 0x0000.0000
FCMISC, type R/W1C, offset 0x014, reset 0x0000.0000
WRKEY
COMT MERASE ERASE
WRITE
ARIS
PRIS
PMASK
PMISC
AMASK
AMISC
Internal Memory
System Control Offset
Base 0x400F.E000
USECRL, type R/W, offset 0x140, reset 0x16
FMPRE, type R/W, offset 0x130, reset 0x8000.00FF
FMPPE, type R/W, offset 0x134, reset 0x0000.00FF
USEC
READ_ENABLE
READ_ENABLE
PROG_ENABLE
PROG_ENABLE
General-Purpose Input/Outputs (GPIOs)
GPIO Port A base: 0x4000.4000
GPIO Port B base: 0x4000.5000
GPIO Port C base: 0x4000.6000
GPIO Port D base: 0x4000.7000
GPIO Port E base: 0x4002.4000
GPIODATA, type R/W, offset 0x000, reset 0x0000.0000
GPIODIR, type R/W, offset 0x400, reset 0x0000.0000
GPIOIS, type R/W, offset 0x404, reset 0x0000.0000
GPIOIBE, type R/W, offset 0x408, reset 0x0000.0000
GPIOIEV, type R/W, offset 0x40C, reset 0x0000.0000
GPIOIM, type R/W, offset 0x410, reset 0x0000.0000
GPIORIS, type RO, offset 0x414, reset 0x0000.0000
GPIOMIS, type RO, offset 0x418, reset 0x0000.0000
DATA
DIR
IS
IBE
IEV
IME
RIS
MIS
October 01, 2007
367
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
GPIOICR, type W1C, offset 0x41C, reset 0x0000.0000
IC
GPIOAFSEL, type R/W, offset 0x420, reset -
AFSEL
DRV2
DRV4
DRV8
ODE
PUE
GPIODR2R, type R/W, offset 0x500, reset 0x0000.00FF
GPIODR4R, type R/W, offset 0x504, reset 0x0000.0000
GPIODR8R, type R/W, offset 0x508, reset 0x0000.0000
GPIOODR, type R/W, offset 0x50C, reset 0x0000.0000
GPIOPUR, type R/W, offset 0x510, reset 0x0000.00FF
GPIOPDR, type R/W, offset 0x514, reset 0x0000.0000
GPIOSLR, type R/W, offset 0x518, reset 0x0000.0000
GPIODEN, type R/W, offset 0x51C, reset 0x0000.00FF
PDE
SRL
DEN
PID4
PID5
PID6
PID7
PID0
PID1
PID2
GPIOPeriphID4, type RO, offset 0xFD0, reset 0x0000.0000
GPIOPeriphID5, type RO, offset 0xFD4, reset 0x0000.0000
GPIOPeriphID6, type RO, offset 0xFD8, reset 0x0000.0000
GPIOPeriphID7, type RO, offset 0xFDC, reset 0x0000.0000
GPIOPeriphID0, type RO, offset 0xFE0, reset 0x0000.0061
GPIOPeriphID1, type RO, offset 0xFE4, reset 0x0000.0000
GPIOPeriphID2, type RO, offset 0xFE8, reset 0x0000.0018
368
October 01, 2007
Preliminary
LM3S300 Microcontroller
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
GPIOPeriphID3, type RO, offset 0xFEC, reset 0x0000.0001
GPIOPCellID0, type RO, offset 0xFF0, reset 0x0000.000D
GPIOPCellID1, type RO, offset 0xFF4, reset 0x0000.00F0
GPIOPCellID2, type RO, offset 0xFF8, reset 0x0000.0005
GPIOPCellID3, type RO, offset 0xFFC, reset 0x0000.00B1
PID3
CID0
CID1
CID2
CID3
General-Purpose Timers
Timer0 base: 0x4003.0000
Timer1 base: 0x4003.1000
Timer2 base: 0x4003.2000
GPTMCFG, type R/W, offset 0x000, reset 0x0000.0000
GPTMTAMR, type R/W, offset 0x004, reset 0x0000.0000
GPTMTBMR, type R/W, offset 0x008, reset 0x0000.0000
GPTMCTL, type R/W, offset 0x00C, reset 0x0000.0000
GPTMCFG
TAAMS
TBAMS
TACMR
TBCMR
TAMR
TBMR
TBPWML TBOTE
TBEVENT
TBSTALL
CBMIM
TBEN
TAPWML TAOTE
RTCEN
TAEVENT
TASTALL
CAMIM
TAEN
GPTMIMR, type R/W, offset 0x018, reset 0x0000.0000
GPTMRIS, type RO, offset 0x01C, reset 0x0000.0000
GPTMMIS, type RO, offset 0x020, reset 0x0000.0000
GPTMICR, type W1C, offset 0x024, reset 0x0000.0000
CBEIM
TBTOIM
RTCIM
CAEIM
TATOIM
CBERIS CBMRIS TBTORIS
CBEMIS CBMMIS TBTOMIS
CBECINT CBMCINT TBTOCINT
RTCRIS CAERIS CAMRIS TATORIS
RTCMIS CAEMIS CAMMIS TATOMIS
RTCCINT CAECINT CAMCINT TATOCINT
GPTMTAILR, type R/W, offset 0x028, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
TAILRH
TAILRL
GPTMTBILR, type R/W, offset 0x02C, reset 0x0000.FFFF
TBILRL
GPTMTAMATCHR, type R/W, offset 0x030, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
TAMRH
TAMRL
October 01, 2007
369
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
GPTMTBMATCHR, type R/W, offset 0x034, reset 0x0000.FFFF
GPTMTAPR, type R/W, offset 0x038, reset 0x0000.0000
GPTMTBPR, type R/W, offset 0x03C, reset 0x0000.0000
GPTMTAPMR, type R/W, offset 0x040, reset 0x0000.0000
GPTMTBPMR, type R/W, offset 0x044, reset 0x0000.0000
TBMRL
TAPSR
TBPSR
TAPSMR
TBPSMR
GPTMTAR, type RO, offset 0x048, reset 0x0000.FFFF (16-bit mode) and 0xFFFF.FFFF (32-bit mode)
TARH
TARL
GPTMTBR, type RO, offset 0x04C, reset 0x0000.FFFF
TBRL
Watchdog Timer
Base 0x4000.0000
WDTLOAD, type R/W, offset 0x000, reset 0xFFFF.FFFF
WDTLoad
WDTLoad
WDTVALUE, type RO, offset 0x004, reset 0xFFFF.FFFF
WDTValue
WDTValue
WDTCTL, type R/W, offset 0x008, reset 0x0000.0000
RESEN
INTEN
WDTICR, type WO, offset 0x00C, reset -
WDTIntClr
WDTIntClr
WDTRIS, type RO, offset 0x010, reset 0x0000.0000
WDTRIS
WDTMIS
WDTMIS, type RO, offset 0x014, reset 0x0000.0000
WDTTEST, type R/W, offset 0x418, reset 0x0000.0000
STALL
WDTLOCK, type R/W, offset 0xC00, reset 0x0000.0000
WDTLock
WDTLock
WDTPeriphID4, type RO, offset 0xFD0, reset 0x0000.0000
PID4
PID5
WDTPeriphID5, type RO, offset 0xFD4, reset 0x0000.0000
370
October 01, 2007
Preliminary
LM3S300 Microcontroller
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
WDTPeriphID6, type RO, offset 0xFD8, reset 0x0000.0000
PID6
PID7
PID0
PID1
PID2
PID3
CID0
CID1
CID2
CID3
WDTPeriphID7, type RO, offset 0xFDC, reset 0x0000.0000
WDTPeriphID0, type RO, offset 0xFE0, reset 0x0000.0005
WDTPeriphID1, type RO, offset 0xFE4, reset 0x0000.0018
WDTPeriphID2, type RO, offset 0xFE8, reset 0x0000.0018
WDTPeriphID3, type RO, offset 0xFEC, reset 0x0000.0001
WDTPCellID0, type RO, offset 0xFF0, reset 0x0000.000D
WDTPCellID1, type RO, offset 0xFF4, reset 0x0000.00F0
WDTPCellID2, type RO, offset 0xFF8, reset 0x0000.0005
WDTPCellID3, type RO, offset 0xFFC, reset 0x0000.00B1
Universal Asynchronous Receivers/Transmitters (UARTs)
UART0 base: 0x4000.C000
UART1 base: 0x4000.D000
UARTDR, type R/W, offset 0x000, reset 0x0000.0000
OE
BE
PE
FE
DATA
UARTRSR/UARTECR, type RO, offset 0x004, reset 0x0000.0000
UARTRSR/UARTECR, type WO, offset 0x004, reset 0x0000.0000
UARTFR, type RO, offset 0x018, reset 0x0000.0090
OE
BE
PE
FE
DATA
TXFE
RXFF
TXFF
RXFE
BUSY
UARTIBRD, type R/W, offset 0x024, reset 0x0000.0000
UARTFBRD, type R/W, offset 0x028, reset 0x0000.0000
DIVINT
DIVFRAC
October 01, 2007
371
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
UARTLCRH, type R/W, offset 0x02C, reset 0x0000.0000
UARTCTL, type R/W, offset 0x030, reset 0x0000.0300
UARTIFLS, type R/W, offset 0x034, reset 0x0000.0012
UARTIM, type R/W, offset 0x038, reset 0x0000.0000
UARTRIS, type RO, offset 0x03C, reset 0x0000.000F
UARTMIS, type RO, offset 0x040, reset 0x0000.0000
UARTICR, type W1C, offset 0x044, reset 0x0000.0000
SPS
LBE
WLEN
FEN
STP2
EPS
PEN
BRK
RXE
TXE
UARTEN
RXIFLSEL
RXIM
TXIFLSEL
OEIM
OERIS
OEMIS
OEIC
BEIM
BERIS
BEMIS
BEIC
PEIM
PERIS
PEMIS
PEIC
FEIM
FERIS
FEMIS
FEIC
RTIM
RTRIS
RTMIS
RTIC
TXIM
TXRIS
TXMIS
TXIC
RXRIS
RXMIS
RXIC
UARTPeriphID4, type RO, offset 0xFD0, reset 0x0000.0000
UARTPeriphID5, type RO, offset 0xFD4, reset 0x0000.0000
UARTPeriphID6, type RO, offset 0xFD8, reset 0x0000.0000
UARTPeriphID7, type RO, offset 0xFDC, reset 0x0000.0000
UARTPeriphID0, type RO, offset 0xFE0, reset 0x0000.0011
UARTPeriphID1, type RO, offset 0xFE4, reset 0x0000.0000
UARTPeriphID2, type RO, offset 0xFE8, reset 0x0000.0018
UARTPeriphID3, type RO, offset 0xFEC, reset 0x0000.0001
UARTPCellID0, type RO, offset 0xFF0, reset 0x0000.000D
UARTPCellID1, type RO, offset 0xFF4, reset 0x0000.00F0
PID4
PID5
PID6
PID7
PID0
PID1
PID2
PID3
CID0
CID1
372
October 01, 2007
Preliminary
LM3S300 Microcontroller
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
UARTPCellID2, type RO, offset 0xFF8, reset 0x0000.0005
CID2
CID3
UARTPCellID3, type RO, offset 0xFFC, reset 0x0000.00B1
Synchronous Serial Interface (SSI)
SSI0 base: 0x4000.8000
SSICR0, type R/W, offset 0x000, reset 0x0000.0000
SCR
SPH
SPO
FRF
DSS
SSICR1, type R/W, offset 0x004, reset 0x0000.0000
SOD
MS
SSE
LBM
SSIDR, type R/W, offset 0x008, reset 0x0000.0000
SSISR, type RO, offset 0x00C, reset 0x0000.0003
SSICPSR, type R/W, offset 0x010, reset 0x0000.0000
SSIIM, type R/W, offset 0x014, reset 0x0000.0000
SSIRIS, type RO, offset 0x018, reset 0x0000.0008
SSIMIS, type RO, offset 0x01C, reset 0x0000.0000
SSIICR, type W1C, offset 0x020, reset 0x0000.0000
SSIPeriphID4, type RO, offset 0xFD0, reset 0x0000.0000
SSIPeriphID5, type RO, offset 0xFD4, reset 0x0000.0000
SSIPeriphID6, type RO, offset 0xFD8, reset 0x0000.0000
SSIPeriphID7, type RO, offset 0xFDC, reset 0x0000.0000
SSIPeriphID0, type RO, offset 0xFE0, reset 0x0000.0022
SSIPeriphID1, type RO, offset 0xFE4, reset 0x0000.0000
DATA
BSY
RFF
RNE
TNF
TFE
CPSDVSR
TXIM
RXIM
RXRIS
RXMIS
RTIM
RTRIS
RTMIS
RTIC
RORIM
RORRIS
RORMIS
RORIC
TXRIS
TXMIS
PID4
PID5
PID6
PID7
PID0
PID1
October 01, 2007
373
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
SSIPeriphID2, type RO, offset 0xFE8, reset 0x0000.0018
SSIPeriphID3, type RO, offset 0xFEC, reset 0x0000.0001
SSIPCellID0, type RO, offset 0xFF0, reset 0x0000.000D
SSIPCellID1, type RO, offset 0xFF4, reset 0x0000.00F0
SSIPCellID2, type RO, offset 0xFF8, reset 0x0000.0005
SSIPCellID3, type RO, offset 0xFFC, reset 0x0000.00B1
PID2
PID3
CID0
CID1
CID2
CID3
Inter-Integrated Circuit (I2C) Interface
I2C Master
I2C Master 0 base: 0x4002.0000
I2CMSA, type R/W, offset 0x000, reset 0x0000.0000
I2CMCS, type RO, offset 0x004, reset 0x0000.0000
I2CMCS, type WO, offset 0x004, reset 0x0000.0000
I2CMDR, type R/W, offset 0x008, reset 0x0000.0000
I2CMTPR, type R/W, offset 0x00C, reset 0x0000.0001
I2CMIMR, type R/W, offset 0x010, reset 0x0000.0000
I2CMRIS, type RO, offset 0x014, reset 0x0000.0000
I2CMMIS, type RO, offset 0x018, reset 0x0000.0000
I2CMICR, type WO, offset 0x01C, reset 0x0000.0000
I2CMCR, type R/W, offset 0x020, reset 0x0000.0000
SA
R/S
BUSY
RUN
BUSBSY
IDLE
ARBLST DATACK ADRACK ERROR
ACK
STOP
START
DATA
TPR
IM
RIS
MIS
IC
SFE
MFE
LPBK
Inter-Integrated Circuit (I2C) Interface
374
October 01, 2007
Preliminary
LM3S300 Microcontroller
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
I2C Slave
I2C Slave 0 base: 0x4002.0800
I2CSOAR, type R/W, offset 0x000, reset 0x0000.0000
I2CSCSR, type RO, offset 0x004, reset 0x0000.0000
I2CSCSR, type WO, offset 0x004, reset 0x0000.0000
I2CSDR, type R/W, offset 0x008, reset 0x0000.0000
I2CSIMR, type R/W, offset 0x00C, reset 0x0000.0000
I2CSRIS, type RO, offset 0x010, reset 0x0000.0000
I2CSMIS, type RO, offset 0x014, reset 0x0000.0000
I2CSICR, type WO, offset 0x018, reset 0x0000.0000
OAR
FBR
TREQ
RREQ
DA
DATA
IM
RIS
MIS
IC
Analog Comparators
Base 0x4003.C000
ACMIS, type R/W1C, offset 0x00, reset 0x0000.0000
ACRIS, type RO, offset 0x04, reset 0x0000.0000
ACINTEN, type R/W, offset 0x08, reset 0x0000.0000
ACREFCTL, type R/W, offset 0x10, reset 0x0000.0000
ACSTAT0, type RO, offset 0x20, reset 0x0000.0000
ACSTAT1, type RO, offset 0x40, reset 0x0000.0000
ACSTAT2, type RO, offset 0x60, reset 0x0000.0000
ACCTL0, type R/W, offset 0x24, reset 0x0000.0000
IN2
IN2
IN2
IN1
IN1
IN1
IN0
IN0
IN0
EN
RNG
VREF
OVAL
OVAL
OVAL
CINV
ASRCP
ISLVAL
ISEN
October 01, 2007
375
Preliminary
Register Quick Reference
31
15
30
14
29
13
28
12
27
11
26
10
25
9
24
8
23
7
22
6
21
5
20
4
19
3
18
2
17
1
16
0
ACCTL1, type R/W, offset 0x44, reset 0x0000.0000
ASRCP
ASRCP
ISLVAL
ISLVAL
ISEN
ISEN
CINV
CINV
ACCTL2, type R/W, offset 0x64, reset 0x0000.0000
376
October 01, 2007
Preliminary
LM3S300 Microcontroller
C
Ordering and Contact Information
C.1
Ordering Information
L M 3 S n n n n – g p p s s – r r m
Part Number
Shipping Medium
T = Tape-and-reel
Omitted = Default shipping (tray or tube)
Temperature
I = -40 C to 85 C
Revision
Package
Omitted = Default to current shipping
revision
A0 = First all-layer mask
A1 = Metal layers update to A0
A2 = Metal layers update to A1
B0 = Second all-layer mask revision
RN = 28-pin SOIC
QN = 48-pin LQFP
QC = 100-pin LQFP
Speed
20 = 20 MHz
25 = 25 MHz
50 = 50 MHz
Table C-1. Part Ordering Information
Orderable Part Number Description
LM3S300-IQN25
Stellaris® LM3S300 Microcontroller
Stellaris® LM3S300 Microcontroller
LM3S300-IQN25(T)
C.2
Kits
The Luminary Micro Stellaris® Family provides the hardware and software tools that engineers need
to begin development quickly.
■ Reference Design Kits accelerate product development by providing ready-to-run hardware, and
comprehensive documentation including hardware design files:
http://www.luminarymicro.com/products/reference_design_kits/
■ Evaluation Kits provide a low-cost and effective means of evaluating Stellaris® microcontrollers
before purchase:
http://www.luminarymicro.com/products/evaluation_kits/
■ Development Kits provide you with all the tools you need to develop and prototype embedded
applications right out of the box:
http://www.luminarymicro.com/products/boards.html
See the Luminary Micro website for the latest tools available or ask your Luminary Micro distributor.
C.3
Company Information
Luminary Micro, Inc. designs, markets, and sells ARM Cortex-M3-based microcontrollers (MCUs).
Austin, Texas-based Luminary Micro is the lead partner for the Cortex-M3 processor, delivering the
world's first silicon implementation of the Cortex-M3 processor. Luminary Micro's introduction of the
October 01, 2007
377
Preliminary
Ordering and Contact Information
Stellaris® family of products provides 32-bit performance for the same price as current 8- and 16-bit
microcontroller designs. With entry-level pricing at $1.00 for an ARM technology-based MCU,
Luminary Micro's Stellaris product line allows for standardization that eliminates future architectural
upgrades or software tool changes.
Luminary Micro, Inc.
108 Wild Basin, Suite 350
Austin, TX 78746
Main: +1-512-279-8800
Fax: +1-512-279-8879
http://www.luminarymicro.com
sales@luminarymicro.com
C.4
Support Information
For support on Luminary Micro products, contact:
support@luminarymicro.com +1-512-279-8800, ext. 3
378
October 01, 2007
Preliminary
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