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Contents
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List of Figures vi
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List of Code Listings viii
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List of Tables xi
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List of Notation xii
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Preface FreeRTOS and the Cortex-M3 1
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Multitasking on a Cortex-M3 Microcontroller 2
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An Introduction to Multitasking in Small Embedded Systems 2
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A Note About Terminology 2
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Why Use a Real-time Kernel? 3
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The Cortex-M3 Port of FreeRTOS 4
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Resources Used By FreeRTOS 5
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The FreeRTOS, OpenRTOS, and SafeRTOS Family 6
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Using the Examples that Accompany this Book 8
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Required Tools and Hardware 8
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Chapter 1 Task Management 9
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1.1 Chapter Introduction and Scope 10
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Scope 10
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1.2 Task Functions 11
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1.3 Top Level Task States 12
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1.4 Creating Tasks 13
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The xTaskCreate() API Function 13
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Example 1. Creating tasks 16
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Example 2. Using the task parameter 19
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1.5 Task Priorities 22
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Example 3. Experimenting with priorities 23
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1.6 Expanding the ‘Not Running’ State 26
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The Blocked State 26
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The Suspended State 27
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The Ready State 27
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Completing the State Transition Diagram 27
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Example 4. Using the Blocked state to create a delay 28
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The vTaskDelayUntil() API Function 31
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Example 5. Converting the example tasks to use vTaskDelayUntil() 33
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Example 6. Combining blocking and non-blocking tasks 34
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1.7 The Idle Task and the Idle Task Hook 37
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Idle Task Hook Functions 37
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Limitations on the Implementation of Idle Task Hook Functions 38
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