ePBB Development Guide.pdf

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Microtime Computer Inc.Typically it's refer to the core clock frequency. The number of system tick per OS tick iscalculated by cnt = BSP_CPU_ClkFreq() / OS_TICKS_PER_SEC e.g. setOS_TICKS_PER_SEC to 1000 means the resolution of OS tick is 1/1000 seconds. For asystem like PTK-STM32F207, with MCU running at 120MHz core frequency the result ofcnt should be 120,000.List-6-(5) :Finally, pass the calculated cnt value to OS_CPU_SysTickInit() for OS tick setup. The OSsystem tick interrupt should be triggered once every 1/1000 seconds.List-6-(6) :OSStatInit() determines the maximum value that a 32-bit counter can reach when no othertask is executing.List-6-(7) :A typical RTOS task is implemented as an infinite loop. This is the first statement in theloop.BSP_LED_Toggle() is a BSP function which can be used for LED toggling.List-6-(8) :OSTimeDly() suspends task execution for a specified period. It's not only used for timekilling but releasing the CPU time for other tasks that are ready for execution.3.2.2. Example_2 : Multi-Task (LEDs Dancing)Scenario :According to , we've learned what is uCOS-II looks like and how to create task for applicationneed. In this section we'll try more about creating more task for our project and check if two taskswork as expected.When project executing, LEDs in target board should be set in blink state and the blinking rate ofeach LED should be different. You may found that the dancers, LED1 and LED2,are not evensynchronized in pace. Do you know why ?Project Browsing :ePBB\Applications\Projects\PTK-STM32F207\EWARM-V6\OS_uCOS-II\base_multi_task\demo.ewwePPB Development Guide 3-12
Microtime Computer Inc.Figure-8. Multi-Task project (OS_uCOS-II)Code Listing :The code of function main() is the same as main() function of "OS_uCOS-II Single-Task project"which is described in previous section. You may check List-6 and corresponding explanations forreference.3-13 ePPB Development Guide
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