ePBB Development Guide.pdf

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Microtime Computer Inc.List-5. Single-Task project execution starts at main() (OS_uCOS-II : app.c)List-5-(1) :Start main() by calling BSP_IntDisAll() that disable all interrupts. On most processors,though interrupt are disabled at startup time, it's more safer to turn off all peripheralinterrupts at this moment.List-5-(2) :Call OSInit() to initialize uCOS-II framework, such as :● Internal variables and data structures● Creates internal use tasks (idle, tick, timer, ...)It's important to note that OSInit() must be called before any other uCOS-II functions.List-5-(3) :OSTaskCreateExt() creates a task to be managed by uC/OS-II. Tasks can be createdeither prior to the start of multitasking or by a running task.List-5-(4) :It's a pointer which points to the task’s codeList-5-(5) :It's a pointer which points to the top of task’s stackList-5-(6) :It's the task priority. A unique priority number must be assigned to each task: the lower thenumber, the higher the priority (i.e., the importance) of the task.List-5-(7) :It's task's ID. You should set id to the same value as the task’s priority.List-5-(8) :It's a pointer which points to the bottom of task’s stack.ePPB Development Guide 3-10
Microtime Computer Inc.List-5-(9) :It specifies the size of the task’s stack in number of elements. The size of element could bebyte(8-bit), word(16-bit) or long-word(32-bit).List-5-(10) :It contains task-specific options such as :● OS_TASK_OPT_STK_CHK● OS_TASK_OPT_STK_CLR● ...List-5-(11) :OSTaskNameSet() allows you to assign a name to a task. This function is typically used bydebugger to associate a task name to task. Here we assign "Start Task" to taskApp_TaskStart().List-5-(12) :The final step in main() is to call OSStart(), which starts the multitasking process. OSStart()is never returned after calling.List-6. The first application task : App_TaskStart() (OS_uCOS-II : app.c)List-6-(1) :Task looks like any other C function, the argument p_arg is passed to App_TaskStart() byOSTaskCreateExt().List-6-(2) :It's a BSP function that is responsible for initializing the hardware on target board. It'slocated in file bsp.cList-6-(3) :CPU_Init() initialize the uC/CPU services.List-6-(4) :BSP_CPU_ClkFreq() determines the system tick reference frequency of the board.3-11 ePPB Development Guide
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