µC/OS-III Users Manual - Analog Devices

654 Pages·2010·6.92 MB·English

by  Micrium Inc.

μC/ OS-III
TM
The Real-Time Kernel
User’s Manual
Weston, FL 33326
Micriμm Press
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Weston, FL 33326
USA
www.micrium.com
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The programs and code examples in this book are presented for instructional value. The
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ISBN: 978-0-9823375-9-2
600-uCOS-III-Users-Manual-002
Table of Contents
Preface..................................................................................................13
Chapter 1 Introduction ..........................................................................................15
1-1 Foreground/Background Systems ......................................................16
1-2 Real-Time Kernels ................................................................................17
1-3 RTOS (Real-Time Operating System) ..................................................19
1-4 μC/OS-III ...............................................................................................19
1-5 μC/OS, μC/OS-II and μC/OS-III Features Comparison ......................24
1-6 How the Book is Organized .................................................................26
1-7 μC/Probe ..............................................................................................26
1-8 Conventions .........................................................................................27
1-9 Chapter Contents .................................................................................28
1-10 Licensing ..............................................................................................32
1-11 Contacting Micrium ..............................................................................32
Chapter 2 Directories and Files ............................................................................33
2-1 Application Code .................................................................................36
2-2 CPU .......................................................................................................37
2-3 Board Support Package (BSP) ............................................................38
2-4 μC/OS-III, CPU Independent Source Code ........................................39
2-5 μC/OS-III, CPU Specific Source Code ................................................43
2-6 μC/CPU, CPU Specific Source Code ..................................................44
2-7 μC/LIB, Portable Library Functions .....................................................46
2-8 Summary ..............................................................................................47
Chapter 3 Getting Started with μC/OS-III ............................................................51
3-1 Single Task Application .......................................................................52
3-2 Multiple Tasks Application with Kernel Objects .................................60
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Table of Contents
Chapter 4 Critical Sections ...................................................................................69
4-1 Disabling Interrupts ..............................................................................70
4-1-1 Measuring Interrupt Disable Time .......................................................70
4-2 Locking the Scheduler .........................................................................71
4-2-1 Measuring Scheduler Lock Time .........................................................72
4-3 μC/OS-III Features with Longer Critical Sections ...............................73
4-4 Summary ..............................................................................................74
Chapter 5 Task Management ...............................................................................75
5-1 Assigning Task Priorities .....................................................................84
5-2 Determining the Size of a Stack ..........................................................86
5-3 Detecting Task Stack Overflows .........................................................87
5-4 Task Management Services ................................................................91
5-5 Task Management Internals ................................................................92
5-5-1 Task States ...........................................................................................92
5-5-2 Task Control Blocks (TCBs) .................................................................97
5-6 Internal Tasks .....................................................................................106
5-6-1 The Idle Task (OS_IdleTask()) ............................................................107
5-6-2 The Tick Task (OS_TickTask()) ..........................................................109
5-6-3 The Statistic Task (OS_StatTask()) ....................................................116
5-6-4 The Timer Task (OS_TmrTask()) ........................................................119
5-6-5 The ISR Handler Task (OS_IntQTask()) .............................................120
5-7 Summary ............................................................................................121
Chapter 6 The Ready List ...................................................................................123
6-1 Priority Levels .....................................................................................124
6-2 The Ready List ...................................................................................128
6-3 Adding Tasks to the Ready List ........................................................131
6-4 Summary ............................................................................................132
Chapter 7 Scheduling ..........................................................................................133
7-1 Preemptive Scheduling ......................................................................134
7-2 Scheduling Points ..............................................................................136
7-3 Round-Robin Scheduling ..................................................................138
7-4 Scheduling Internals ..........................................................................141
7-4-1 OSSched() ..........................................................................................142
7-4-2 OSIntExit() ...........................................................................................143
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7-4-3 OS_SchedRoundRobin() ....................................................................144
7-5 Summary ............................................................................................146
Chapter 8 Context Switching ..............................................................................147
8-1 OSCtxSw() ..........................................................................................150
8-2 OSIntCtxSw() ......................................................................................153
8-3 Summary ............................................................................................155
Chapter 9 Interrupt Management .......................................................................157
9-1 Handling CPU Interrupts ....................................................................158
9-2 Typical μC/OS-III Interrupt Service Routine (ISR) .............................159
9-3 Short Interrupt Service Routine (ISR) ................................................162
9-4 All Interrupts Vector to a Common Location ....................................163
9-5 Every Interrupt Vectors to a Unique Location ..................................165
9-6 Direct and Deferred Post Methods ...................................................166
9-6-1 Direct Post Method ............................................................................166
9-6-2 Deferred Post Method .......................................................................169
9-7 Direct vs. Deferred Post Method .......................................................172
9-8 The Clock Tick (or System Tick) ........................................................173
9-9 Summary ............................................................................................175
Chapter 10 Pend Lists (or Wait Lists) ...................................................................177
10-1 Summary ............................................................................................182
Chapter 11 Time Management .............................................................................183
11-1 OSTimeDly() ........................................................................................184
11-2 OSTimeDlyHMSM() ............................................................................189
11-3 OSTimeDlyResume() ..........................................................................191
11-4 OSTimeSet() and OSTimeGet() ..........................................................192
11-5 OSTimeTick() ......................................................................................192
11-6 Summary ............................................................................................192
Chapter 12 Timer Management ............................................................................193
12-1 One-Shot Timers ................................................................................195
12-2 Periodic (no initial delay) ....................................................................196
12-3 Periodic (with initial delay) .................................................................196
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Table of Contents
12-4 Timer Management Internals .............................................................197
12-4-1 Timer Management Internals - Timers States ..................................197
12-4-2 Timer Management Internals - OS_TMR ...........................................198
12-4-3 Timer Management Internals - Timer Task .......................................200
12-4-4 Timer Management Internals - Timer List .........................................203
12-5 Summary ............................................................................................208
Chapter 13 Resource Management ......................................................................209
13-1 Disable/Enable Interrupts ..................................................................212
13-2 Lock/Unlock .......................................................................................214
13-3 Semaphores .......................................................................................215
13-3-1 Binary Semaphores ............................................................................217
13-3-2 Counting Semaphores .......................................................................224
13-3-3 Notes on Semaphores .......................................................................226
13-3-4 Semaphore Internals (for resource sharing) .....................................227
13-3-5 Priority Inversions ..............................................................................232
13-4 Mutual Exclusion Semaphores (Mutex) ............................................234
13-4-1 Mutual Exclusion Semaphore Internals ............................................239
13-5 Should You Use a Semaphore Instead of a Mutex? ........................245
13-6 Deadlocks (or Deadly Embrace) ........................................................245
13-7 Summary ............................................................................................250
Chapter 14 Synchronization .................................................................................251
14-1 Semaphores .......................................................................................252
14-1-1 Unilateral Rendezvous .......................................................................254
14-1-2 Credit Tracking ...................................................................................257
14-1-3 Multiple Tasks Waiting on a Semaphore ..........................................259
14-1-4 Semaphore Internals (for synchronization) .......................................260
14-2 Task Semaphore ................................................................................267
14-2-1 Pending (i.e., Waiting) on a Task Semaphore ...................................268
14-2-2 Posting (i.e., Signaling) a Task Semaphore ......................................269
14-2-3 Bilateral Rendezvous .........................................................................271
14-3 Event Flags .........................................................................................273
14-3-1 Using Event Flags ..............................................................................275
14-3-2 Event Flags Internals .........................................................................279
14-4 Synchronizing Multiple Tasks ............................................................286
14-5 Summary ............................................................................................288
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Chapter 15 Message Passing ...............................................................................289
15-1 Messages ...........................................................................................290
15-2 Message Queues ...............................................................................290
15-3 Task Message Queue ........................................................................292
15-4 Bilateral Rendezvous .........................................................................293
15-5 Flow Control .......................................................................................294
15-6 Keeping the Data in Scope ................................................................296
15-7 Using Message Queues .....................................................................299
15-8 Clients and Servers ............................................................................307
15-9 Message Queues Internals ................................................................308
15-10 Summary ............................................................................................311
Chapter 16 Pending On Multiple Objects .............................................................313
16-1 Summary ............................................................................................321
Chapter 17 Memory Management ........................................................................323
17-1 Creating a Memory Partition .............................................................324
17-2 Getting a Memory Block from a Partition .........................................328
17-3 Returning a Memory Block to a Partition ..........................................329
17-4 Using Memory Partitions ...................................................................330
17-5 Summary ............................................................................................333
Chapter 18 Porting μC/OS-III ................................................................................335
18-1 μC/CPU ...............................................................................................338
18-2 μC/OS-III Port .....................................................................................341
18-3 Board Support Package (BSP) ..........................................................343
18-4 Summary ............................................................................................345
Chapter 19 Run-Time Statistics ............................................................................347
19-1 General Statistics – Run-Time ...........................................................348
19-2 Per-Task Statistics – Run-Time .........................................................352
19-3 Kernel Object – Run-Time ..................................................................355
19-4 OS_DBG.C – Static ............................................................................358
19-5 OS_CFG_APP.C – Static ....................................................................371
19-6 Summary ............................................................................................373
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Table of Contents
Appendix A μC/OS-III API Reference Manual .......................................................375
A-1 Task Management .............................................................................376
A-2 Time Management .............................................................................378
A-3 Mutual Exclusion Semaphores – Resource Management ...............379
A-4 Event Flags – Synchronization ..........................................................380
A-5 Semaphores – Synchronization .........................................................381
A-6 Task Semaphores – Synchronization ................................................382
A-7 Message Queues – Message Passing ..............................................383
A-8 Task Message Queues – Message Passing .....................................384
A-9 Pending on Multiple Objects .............................................................385
A-10 Timers .................................................................................................386
A-11 Fixed-Size Memory Partitions – Memory Management ...................387
OSCtxSw()...........................................................................................388
OSFlagCreate()....................................................................................390
OSFlagDel().........................................................................................392
OSFlagPend()......................................................................................394
OSFlagPendAbort().............................................................................398
OSFlagPendGetFlagsRdy().................................................................401
OSFlagPost().......................................................................................403
OSIdleTaskHook()...............................................................................405
OSInit().................................................................................................407
OSInitHook()........................................................................................409
OSIntCtxSw().......................................................................................410
OSIntEnter().........................................................................................412
OSIntExit()............................................................................................413
OSMemCreate()...................................................................................414
OSMemGet()........................................................................................417
OSMemPut()........................................................................................419
OSMutexCreate().................................................................................421
OSMutexDel()......................................................................................423
OSMutexPend()...................................................................................425
OSMutexPendAbort()..........................................................................428
OSMutexPost()....................................................................................430
OSPendMulti().....................................................................................432
OSQCreate()........................................................................................436
OSQDel()..............................................................................................438
OSQFlush()..........................................................................................440
OSQPend()...........................................................................................442
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