Contents
Preface............................................................................................................ xv
Acknowledgements.......................................................................................... xvii
About the Author ...........................................................................................xviii
Chapter 1 What Is Embedded Programming?.................................................. 1
1.1 What’s Special About Embedded Systems?.......................................................... 1
1.1.1 Embedded Design Constraints................................................................... 3
1.1.2 The Embedded Tool Chain ........................................................................ 4
1.1.3 OS, RTOS, or Bareback?........................................................................... 5
1.1.4 Embedded Middleware .............................................................................. 6
1.1.5 Codevelopment with Hardware ................................................................. 7
1.1.6 Debugging and Testing .............................................................................. 8
1.2 OO or Structured – It’s Your Choice..................................................................... 9
1.2.1 Classes...................................................................................................... 10
1.2.2 Objects ..................................................................................................... 13
1.2.3 Polymorphism and Virtual Functions ...................................................... 14
1.2.4 Subclassing............................................................................................... 15
1.2.5 Finite State Machines............................................................................... 25
1.3 What Did We Learn? ........................................................................................... 33
Chapter 2 Embedded Programming with The HarmonyTM for Embedded
RealTime Process........................................................................................ 35
2.1 Basic Elements of the Harmony Process............................................................. 36
2.1.1 A Quick Overview of the Development Workflow................................. 36
2.1.2 What Is a Design Pattern? ....................................................................... 44
2.1.3 Basic Structure of Design Patterns .......................................................... 45
2.1.4 How to Read Design Patterns in This Book ........................................... 46
2.1.5 Using Design Patterns in Development................................................... 47
2.1.6 Observer Pattern....................................................................................... 66
2.2 The Approach ...................................................................................................... 77
2.3 What’s Coming Up .............................................................................................. 78
Chapter 3 Design Patterns for Accessing Hardware....................................... 79
3.1 Basic Hardware Access Concepts........................................................................ 81
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3.2 Hardware Proxy Pattern....................................................................................... 85
3.2.1 Abstract .................................................................................................... 85
3.2.2 Problem .................................................................................................... 86
3.2.3 Pattern Structure....................................................................................... 86
3.2.4 Collaboration Roles ................................................................................. 87
3.2.5 Consequences........................................................................................... 88
3.2.6 Implementation Strategies........................................................................ 89
3.2.7 Related Patterns........................................................................................ 89
3.2.8 Example ................................................................................................... 89
3.3 Hardware Adapter Pattern.................................................................................... 96
3.3.1 Abstract .................................................................................................... 96
3.3.2 Problem .................................................................................................... 96
3.3.3 Pattern Structure....................................................................................... 96
3.3.4 Collaboration Roles ................................................................................. 96
3.3.5 Consequences........................................................................................... 97
3.3.6 Implementation Strategies........................................................................ 98
3.3.7 Related Patterns........................................................................................ 98
3.3.8 Example ................................................................................................... 98
3.4 Mediator Pattern................................................................................................. 100
3.4.1 Abstract .................................................................................................. 100
3.4.2 Problem .................................................................................................. 100
3.4.3 Pattern Structure..................................................................................... 101
3.4.4 Collaboration Roles ............................................................................... 101
3.4.5 Consequences......................................................................................... 102
3.4.6 Implementation Strategies...................................................................... 102
3.4.7 Related Patterns...................................................................................... 102
3.4.8 Example ................................................................................................. 103
3.5 Observer Pattern..................................................................................................111
3.5.1 Abstract ...................................................................................................111
3.5.2 Problem ...................................................................................................112
3.5.3 Pattern Structure......................................................................................112
3.5.4 Collaboration Roles ................................................................................112
3.5.5 Consequences..........................................................................................114
3.5.6 Implementation Strategies.......................................................................114
3.5.7 Related Patterns.......................................................................................115
3.5.8 Example ..................................................................................................115
3.6 Debouncing Pattern............................................................................................ 122
3.6.1 Abstract .................................................................................................. 123
3.6.2 Problem .................................................................................................. 123
3.6.3 Pattern Structure..................................................................................... 123
3.6.4 Collaboration Roles ............................................................................... 123
3.6.5 Consequences......................................................................................... 125
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3.6.6 Implementation Strategies...................................................................... 125
3.6.7 Related Patterns...................................................................................... 126
3.6.8 Example ................................................................................................. 126
3.7 Interrupt Pattern ................................................................................................. 130
3.7.1 Abstract .................................................................................................. 130
3.7.2 Problem .................................................................................................. 130
3.7.3 Pattern Structure..................................................................................... 131
3.7.4 Collaboration Roles ............................................................................... 131
3.7.5 Consequences......................................................................................... 132
3.7.6 Implementation Strategies...................................................................... 134
3.7.7 Related Patterns...................................................................................... 135
3.7.8 Example ................................................................................................. 135
3.8 Polling Pattern.................................................................................................... 138
3.8.1 Abstract .................................................................................................. 138
3.8.2 Problem .................................................................................................. 138
3.8.3 Pattern Structure..................................................................................... 138
3.8.4 Collaboration Roles ............................................................................... 138
3.8.5 Consequences......................................................................................... 141
3.8.6 Implementation Strategies...................................................................... 141
3.8.7 Related Patterns...................................................................................... 142
3.8.8 Example ................................................................................................. 142
3.9 So, What Did We Learn?................................................................................... 147
Chapter 4 Design Patterns for Embedding Concurrency and Resource
Management ............................................................................................ 149
4.1 Basic Concurrency Concepts ............................................................................. 152
4.1.1 Identifying Tasks.................................................................................... 160
4.1.2 Concurrency in the UML....................................................................... 161
4.1.3 Real-Time Operating Systems ............................................................... 163
Scheduling Patterns............................................................................................... 164
4.2 Cyclic Executive Pattern.................................................................................... 164
4.2.1 Abstract .................................................................................................. 165
4.2.2 Problem .................................................................................................. 165
4.2.3 Pattern Structure..................................................................................... 165
4.2.4 Collaboration Roles ............................................................................... 165
4.2.5 ConcreteCEThread................................................................................. 166
4.2.6 Consequences......................................................................................... 167
4.2.7 Implementation Strategies...................................................................... 167
4.2.8 Related Patterns...................................................................................... 167
4.2.9 Example ................................................................................................. 167
4.3 Static Priority Pattern......................................................................................... 170
4.3.1 Abstract .................................................................................................. 170
4.3.2 Problem .................................................................................................. 171
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4.3.3 Pattern Structure..................................................................................... 171
4.3.4 Collaboration Roles ............................................................................... 172
4.3.5 Consequences......................................................................................... 173
4.3.6 Implementation Strategies...................................................................... 173
4.3.7 Related Patterns...................................................................................... 174
4.3.8 Example ................................................................................................. 175
Task Coordination Patterns ................................................................................... 182
4.4 Critical Region Pattern....................................................................................... 182
4.4.1 Abstract .................................................................................................. 182
4.4.2 Problem .................................................................................................. 182
4.4.3 Pattern Structure..................................................................................... 182
4.4.4 Collaboration Roles ............................................................................... 183
4.4.5 Consequences......................................................................................... 184
4.4.6 Implementation Strategies...................................................................... 184
4.4.7 Related Patterns...................................................................................... 184
4.4.8 Example ................................................................................................. 184
4.5 Guarded Call Pattern.......................................................................................... 190
4.5.1 Abstract .................................................................................................. 190
4.5.2 Problem .................................................................................................. 190
4.5.3 Pattern Structure..................................................................................... 190
4.5.4 Collaboration Roles ............................................................................... 191
4.5.5 Consequences......................................................................................... 192
4.5.6 Implementation Strategies...................................................................... 192
4.5.7 Related Patterns...................................................................................... 193
4.5.8 Example ................................................................................................. 194
4.6 Queuing Pattern ................................................................................................. 207
4.6.1 Abstract .................................................................................................. 207
4.6.2 Problem .................................................................................................. 207
4.6.3 Pattern Structure..................................................................................... 208
4.6.4 Collaboration Roles ............................................................................... 208
4.6.5 Consequences......................................................................................... 209
4.6.6 Implementation Strategies...................................................................... 210
4.6.7 Related Patterns...................................................................................... 210
4.6.8 Example ................................................................................................. 210
4.7 Rendezvous Pattern............................................................................................ 224
4.7.1 Abstract .................................................................................................. 225
4.7.2 Problem .................................................................................................. 226
4.7.3 Pattern Structure..................................................................................... 226
4.7.4 Collaboration Roles ............................................................................... 226
4.7.5 Consequences......................................................................................... 227
4.7.6 Implementation Strategies...................................................................... 228
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4.7.7 Related Patterns...................................................................................... 228
4.7.8 Example ................................................................................................. 228
Deadlock Avoidance Patterns ............................................................................... 231
4.8 Simultaneous Locking Pattern ........................................................................... 232
4.8.1 Abstract .................................................................................................. 232
4.8.2 Problem .................................................................................................. 233
4.8.3 Pattern Structure..................................................................................... 233
4.8.4 Collaboration Roles ............................................................................... 234
4.8.5 Consequences......................................................................................... 236
4.8.6 Implementation Strategies...................................................................... 236
4.8.7 Related Patterns...................................................................................... 236
4.8.8 Example ................................................................................................. 236
4.9 Ordered Locking ................................................................................................ 242
4.9.1 Abstract .................................................................................................. 242
4.9.2 Problem .................................................................................................. 243
4.9.3 Pattern Structure..................................................................................... 243
4.9.4 Collaboration Roles ............................................................................... 244
4.9.5 Consequences......................................................................................... 247
4.9.6 Implementation Strategies...................................................................... 248
4.9.7 Related Patterns...................................................................................... 248
4.9.8 Example ................................................................................................. 248
4.10 So, What Have We Learned?........................................................................... 255
Chapter 5 Design Patterns for State Machines............................................ 257
5.1 Oh Behave! ........................................................................................................ 259
5.2 Basic State Machine Concepts........................................................................... 261
5.2.1 OR-States ............................................................................................... 263
5.2.2 AND-States ............................................................................................ 265
5.2.3 Special Stuff: Timeouts, Conditionals, and More.................................. 267
5.2.4 Synchronous versus Asynchronous? ..................................................... 270
5.3 Single Event Receptor Pattern ........................................................................... 274
5.3.1 Abstract .................................................................................................. 274
5.3.2 Problem .................................................................................................. 274
5.3.3 Pattern Structure..................................................................................... 274
5.3.4 Collaboration Roles ............................................................................... 275
5.3.5 Consequences......................................................................................... 278
5.3.6 Implementation Strategies...................................................................... 278
5.3.7 Related Patterns...................................................................................... 278
5.3.8 Example ................................................................................................. 278
5.4 Multiple Event Receptor Pattern........................................................................ 287
5.4.1 Abstract .................................................................................................. 287
5.4.2 Problem .................................................................................................. 287
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5.4.3 Pattern Structure..................................................................................... 288
5.4.4 Collaboration Roles ............................................................................... 288
5.4.5 Consequences......................................................................................... 290
5.4.6 Implementation Strategies...................................................................... 290
5.4.7 Related Patterns...................................................................................... 290
5.4.8 Example ................................................................................................. 290
5.5 State Table Pattern ............................................................................................. 296
5.5.1 Abstract .................................................................................................. 296
5.5.2 Problem .................................................................................................. 296
5.5.3 Pattern Structure..................................................................................... 296
5.5.4 Collaboration Roles ............................................................................... 297
5.5.5 Consequences......................................................................................... 299
5.5.6 Implementation Strategies...................................................................... 299
5.5.7 Related Patterns...................................................................................... 299
5.5.8 Example ................................................................................................. 300
5.6 State Pattern ....................................................................................................... 308
5.6.1 Abstract .................................................................................................. 308
5.6.2 Problem .................................................................................................. 308
5.6.3 Pattern Structure..................................................................................... 308
5.6.4 Collaboration Roles ............................................................................... 310
5.6.5 Consequences......................................................................................... 312
5.6.6 Implementation Strategies...................................................................... 313
5.6.7 Related Patterns...................................................................................... 313
5.6.8 Example ................................................................................................. 314
5.7 AND-States ........................................................................................................ 327
5.8 Decomposed AND-State Pattern ....................................................................... 330
5.8.1 Abstract .................................................................................................. 331
5.8.2 Problem .................................................................................................. 331
5.8.3 Pattern Structure..................................................................................... 331
5.8.4 Collaboration Roles ............................................................................... 331
5.8.5 Consequences......................................................................................... 333
5.8.6 Implementation Strategies...................................................................... 333
5.8.7 Related Patterns...................................................................................... 334
5.8.8 Example ................................................................................................. 334
5.9 OK, What Have We Learned? ........................................................................... 356
Chapter 6 Safety and Reliability Patterns ................................................... 357
6.1 A Little Bit About Safety and Reliability.......................................................... 359
6.1.1 Safety and Reliability Related Faults .................................................... 360
6.1.2 Achieving Safety and Reliability........................................................... 361
6.2 One’s Complement Pattern ................................................................................ 362
6.2.1 Abstract .................................................................................................. 362
6.2.2 Problem .................................................................................................. 362
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6.2.3 Pattern Structure..................................................................................... 362
6.2.4 Collaboration Roles ............................................................................... 362
6.2.5 Consequences......................................................................................... 363
6.2.6 Implementation Strategies...................................................................... 363
6.2.7 Related Patterns...................................................................................... 363
6.2.8 Example ................................................................................................. 363
6.3 CRC Pattern ....................................................................................................... 367
6.3.1 Abstract .................................................................................................. 367
6.3.2 Problem .................................................................................................. 367
6.3.3 Pattern Structure..................................................................................... 368
6.3.4 Collaboration Roles ............................................................................... 368
6.3.5 Consequences......................................................................................... 369
6.3.6 Implementation Strategies...................................................................... 369
6.3.7 Related Patterns...................................................................................... 369
6.3.8 Example ................................................................................................. 369
6.4 Smart Data Pattern ............................................................................................. 380
6.4.1 Abstract .................................................................................................. 380
6.4.2 Problem .................................................................................................. 381
6.4.3 Pattern Structure..................................................................................... 381
6.4.4 Collaboration Roles ............................................................................... 382
6.4.5 Consequences......................................................................................... 382
6.4.6 Implementation Strategies...................................................................... 383
6.4.7 Related Patterns...................................................................................... 383
6.4.8 Example ................................................................................................. 383
6.5 Channel Pattern.................................................................................................. 395
6.5.1 Abstract .................................................................................................. 395
6.5.2 Problem .................................................................................................. 395
6.5.3 Pattern Structure..................................................................................... 395
6.5.4 Collaboration Roles ............................................................................... 395
6.5.5 Consequences......................................................................................... 396
6.5.6 Implementation Strategies...................................................................... 397
6.5.7 Related Patterns...................................................................................... 397
6.5.8 Example ................................................................................................. 397
6.6 Protected Single Channel Pattern ...................................................................... 402
6.6.1 Abstract .................................................................................................. 402
6.6.2 Problem .................................................................................................. 402
6.6.3 Pattern Structure..................................................................................... 403
6.6.4 Collaboration Roles ............................................................................... 404
6.6.5 Implementation Strategies...................................................................... 405
6.6.6 Related Patterns...................................................................................... 405
6.6.7 Example ................................................................................................. 405
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6.7 Dual Channel Pattern......................................................................................... 413
6.7.1 Abstract .................................................................................................. 413
6.7.2 Problem .................................................................................................. 414
6.7.3 Pattern Structure..................................................................................... 414
6.7.4 Collaboration Roles ............................................................................... 414
6.7.5 Consequences......................................................................................... 417
6.7.6 Implementation Strategies...................................................................... 417
6.7.7 Related Patterns...................................................................................... 417
6.7.8 Example ................................................................................................. 421
6.8 Summary ............................................................................................................ 422
Appendix A UML Notation........................................................................ 425
1.1 Class Diagram.................................................................................................... 425
1.1.1 Semantic Elements................................................................................. 425
1.2 Sequence Diagram ............................................................................................. 429
1.2.1 Semantic Elements................................................................................. 429
1.3 State Diagram..................................................................................................... 430
1.3.1 Semantic Elements................................................................................. 430
Index ....................................................................................................... 437