stm32f103中freertos的tasks基本使用案例及备忘

基本实例

  freetos的在stm32中使用踩了一些坑，事情做完了，就 做个备忘，希望能给后面的人一些借鉴。

先给出一个实际的例子吧。

• 启动代码

void task_create(void)
{
    xTaskCreate(vButtonCheckTask,"Button",configMINIMAL_STACK_SIZE,NULL,configMAX_PRIORITIES-1,NULL);
    xTaskCreate(vButtonLEDsTask,"ButtonLeds",configMINIMAL_STACK_SIZE,NULL,configMAX_PRIORITIES-1,NULL);
}

• 回调函数

static void vButtonCheckTask( void *pvParameters )
{
  //for debounce
  static uint8_t count;
  portTickType xLastWakeTime;
  const portTickType xFrequency = 20;
  const portTickType yDelay = 20 / portTICK_RATE_MS;
  xLastWakeTime=xTaskGetTickCount();
  //create semaphores for each button
  vSemaphoreCreateBinary(xButtonWakeupSemaphore);
  vSemaphoreCreateBinary(xButtonUser1Semaphore);
  vSemaphoreCreateBinary(xButtonUser2Semaphore);
//check if semaphores were created successfully
  if((xButtonWakeupSemaphore!=NULL)&&(xButtonUser1Semaphore!=NULL)&&(xButtonUser2Semaphore!=NULL))
  {
    //successfully created
    //resets initial semaphores to 0
    xSemaphoreTake(xButtonWakeupSemaphore, (portTickType)0);
    xSemaphoreTake(xButtonUser1Semaphore, (portTickType)0);
    xSemaphoreTake(xButtonUser2Semaphore, (portTickType)0);
  }  else {
      //send error of failure
  }

  for (;;)
    {
      if (ButtonRead(BWAKEUPPORT, BWAKEUP)==pdTRUE)
        {
          vTaskDelay(yDelay);
          if(ButtonRead(BWAKEUPPORT, BWAKEUP)==pdTRUE)
          {
              while(ButtonRead(BWAKEUPPORT, BWAKEUP)==pdTRUE);
              xSemaphoreGive(xButtonWakeupSemaphore);
              //LEDToggle(1);
              usart1_puts(" key1 pressed \r\n");
              //printf(" led 1 on\r\n");
          }
        }
      if (ButtonRead(BUSER1PORT, BUSER1)==pdTRUE)
        {
          vTaskDelay(yDelay);
          if(ButtonRead(BUSER1PORT, BUSER1)==pdTRUE)
          {
              while(ButtonRead(BUSER1PORT, BUSER1)==pdTRUE);
              //LEDToggle(1);
              //printf(" use1 presssed\n\r");
              usart1_puts("key2 presssed\n\r");
              xSemaphoreGive(xButtonUser1Semaphore);
          }
        }
      if (ButtonRead(BUSER2PORT, BUSER2)==pdTRUE)
        {
          vTaskDelay(yDelay);
          if(ButtonRead(BUSER2PORT, BUSER2)==pdTRUE)
          {
              while(ButtonRead(BUSER2PORT, BUSER2)==pdTRUE);
              usart1_puts("key3 presssed \n\r");
              //xSemaphoreGive(xButtonUser2Semaphore);
          }
        }
    }
}

void vButtonLEDsTask( void *pvParameters )
{
  const portTickType xDelay = 50 / portTICK_RATE_MS;

  for( ;; )
  {
      if((xButtonWakeupSemaphore!=NULL)&&(xButtonUser1Semaphore!=NULL)&&(xButtonUser2Semaphore!=NULL))
      {
         if (xSemaphoreTake(xButtonWakeupSemaphore, (portTickType)10)==pdTRUE)
             {
               //LEDOn(1);
               usart1_puts("led1 on \n\r");
               LEDToggle(1);
               //give semaphore back
               //xSemaphoreGive(xButtonWakeupSemaphore);
             }
         if (xSemaphoreTake(xButtonUser1Semaphore, (portTickType)10)==pdTRUE)
             {
               usart1_puts("led2 on \n\r");
               LEDToggle(2);
               //LEDOn(2);
               //xSemaphoreGive(xButtonUser1Semaphore);
             }
         if (xSemaphoreTake(xButtonUser2Semaphore, (portTickType)10)==pdTRUE)
             {
               usart1_puts("led3 on \n\r");
               //LEDToggle(3);
               //LEDOn(2);
               //xSemaphoreGive(xButtonUser2Semaphore);
             }
      }

    //usart1_puts("task running \n\r");
    vTaskDelay(xDelay);
    //vTaskDelayUntil(&xLastWakeTime,xFrequency);
  }
}

重要备忘

  freetos的task和里面的函数尽量在一个文件中。

对于某些stm32 的平台，回调函数和task不在一个文件下，会出现一些异常。

  freetos的task的回调函数尽量使用静态函数：

  freetos的task中的循环中一定不能丢了

vTaskDelay(xDelay);不然会出现一直循环，被调度不到的情况，特别是你的task优先级比较高的时候。