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。