【STM32】FreeRTOS消息队列和信号量学习

一、消息队列（queue）

队列是一种用于实现任务与任务之间，任务与中断之间消息交流的机制。

注意：1.数据的操作是FIFO模式。

2.队列需要明确数据的大小和队列的长度。

3.写和读都会出现堵塞。

实验：创建一个消息队列，两个发送任务，一个接收任务。

其中任务一任务三的等待时间为0，任务二的等待时间为portMAX_DELAY（死等）。

实现：在前一个项目的基础上进行更改【STM32】利用CubeMX对FreeRTOS用按键控制任务

cpp 复制代码

void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* Create the semaphores(s) */

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* Create the queue(s) */
  /* definition and creation of myQueue01 */
  osMessageQDef(myQueue01, 2, uint32_t);
  myQueue01Handle = osMessageCreate(osMessageQ(myQueue01), NULL);

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of Task1 */
  osThreadDef(Task1, StartDefaultTask, osPriorityNormal, 0, 128);
  Task1Handle = osThreadCreate(osThread(Task1), NULL);

  /* definition and creation of Task2 */
  osThreadDef(Task2, StartTask02, osPriorityIdle, 0, 128);
  Task2Handle = osThreadCreate(osThread(Task2), NULL);

  /* definition and creation of Task3 */
  osThreadDef(Task3, StartTask03, osPriorityIdle, 0, 128);
  Task3Handle = osThreadCreate(osThread(Task3), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartDefaultTask */
/**
  * @brief  Function implementing the Task1 thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartDefaultTask */
void StartDefaultTask(void const * argument)
{
  /* USER CODE BEGIN StartDefaultTask */
  /* Infinite loop */
	BaseType_t xStatus;
	uint32_t Buf=10086;
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
			{
				xStatus=xQueueSendToBack(myQueue01Handle,&Buf,0);
				if(xStatus!=pdTRUE)
				{
					printf("NO1\r\n");osDelay(500);
				}
				else
				{
					printf("YES1%u\r\n",Buf);osDelay(500);
				}
			}
		}
    
  }
  /* USER CODE END StartDefaultTask */
}

/* USER CODE BEGIN Header_StartTask02 */
/**
* @brief Function implementing the Task2 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask02 */
void StartTask02(void const * argument)
{
  /* USER CODE BEGIN StartTask02 */
  /* Infinite loop */
	BaseType_t xStatus;
	uint32_t Buf=66666;
  for(;;)
  {		
    if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_4)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_4)==0)
			{
				xStatus=xQueueSendToBack(myQueue01Handle,&Buf,portMAX_DELAY);
				if(xStatus!=pdTRUE)
				{
					printf("NO2\r\n");osDelay(500);
				}
				else
				{
					printf("YES2%u\r\n",Buf);osDelay(500);
				}
			}
		}
  }
  /* USER CODE END StartTask02 */
}

/* USER CODE BEGIN Header_StartTask03 */
/**
* @brief Function implementing the Task3 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask03 */
void StartTask03(void const * argument)
{
  /* USER CODE BEGIN StartTask03 */
  /* Infinite loop */
	//BaseType_t xStatus;
	uint32_t Buf=0;
  for(;;)
  {
    if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_2)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_2)==0)
			{
				printf("当前%u\r\n",Buf);
				//xStatus=xQueueReceive(myQueue01Handle,&Buf,portMAX_DELAY);
				if(xQueueReceive(myQueue01Handle,&Buf,portMAX_DELAY)!=pdTRUE)
				{
					printf("NO3\r\n");
				}
				else
				{
					printf("YES3%u\r\n",Buf);
				}
			}
		}
  }
  /* USER CODE END StartTask03 */
}

现象：队列满了以后，任务一无法发送，任务二会死等，队列空闲以后完成发送。

二、信号量

消息队列用于传输多个数据，占用时间也相对较长，但有时只需要传输状态，因此引入信号量。信号量也是队列的一种。信号量有两种，如果它的量只有0（被拿走的状态）和1（被填入的状态）两种状态，就称为二进制的信号量；当量的状态大于两种，就称为计数型信号量。

1.二值信号量

实验：任务一：按键采集数据；任务二：拿走以后串口发送信息

实现：

cpp 复制代码

void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* Create the semaphores(s) */
  /* definition and creation of myBinarySem01 */
  osSemaphoreDef(myBinarySem01);
  myBinarySem01Handle = osSemaphoreCreate(osSemaphore(myBinarySem01), 1);

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* Create the queue(s) */
  /* definition and creation of myQueue01 */
  osMessageQDef(myQueue01, 2, uint32_t);
  myQueue01Handle = osMessageCreate(osMessageQ(myQueue01), NULL);

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of Task1 */
  osThreadDef(Task1, StartDefaultTask, osPriorityNormal, 0, 128);
  Task1Handle = osThreadCreate(osThread(Task1), NULL);

  /* definition and creation of Task2 */
  osThreadDef(Task2, StartTask02, osPriorityNormal, 0, 128);
  Task2Handle = osThreadCreate(osThread(Task2), NULL);

  /* definition and creation of Task3 */
  osThreadDef(Task3, StartTask03, osPriorityNormal, 0, 128);
  Task3Handle = osThreadCreate(osThread(Task3), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartDefaultTask */
/**
  * @brief  Function implementing the Task1 thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartDefaultTask */
void StartDefaultTask(void const * argument)
{
  /* USER CODE BEGIN StartDefaultTask */
  /* Infinite loop */
	BaseType_t xStatus;
	uint32_t Buf=10086;
  for(;;)
	{
//  {
		if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
			{
//				xStatus=xQueueSendToBack(myQueue01Handle,&Buf,0);
				if(xSemaphoreGive(myBinarySem01Handle)==pdTRUE)
				{
					printf("NO1\r\n");
				}
				else
				{
					printf("YES1%u\r\n",Buf);
				}
			}
		}
    
  }
  /* USER CODE END StartDefaultTask */
}

/* USER CODE BEGIN Header_StartTask03 */
/**
* @brief Function implementing the Task3 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask03 */
void StartTask03(void const * argument)
{
  /* USER CODE BEGIN StartTask03 */
  /* Infinite loop */	
	uint32_t Buf=0;
  for(;;)
  {
    if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_2)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_2)==0)
			{				
				if(xSemaphoreTake(myBinarySem01Handle,0)==pdTRUE)
				{
					printf("YES3\r\n");
				}
				else
				{
					printf("NO3%u\r\n",Buf);
				}
			}
		}
  }
  /* USER CODE END StartTask03 */
}

现象：当按键释放了信号量，串口才能成功发送信息。

2.记数型信号量

实验：任务一：按键一记录人进来；按键二记录人出去；（最多有10个人）

任务二：串口每隔3S打印人数。

实现：

cpp 复制代码

void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* Create the semaphores(s) */
  /* definition and creation of myBinarySem01 */
  osSemaphoreDef(myBinarySem01);
  myBinarySem01Handle = osSemaphoreCreate(osSemaphore(myBinarySem01), 1);

  /* definition and creation of myCountingSem01 */
  osSemaphoreDef(myCountingSem01);
  myCountingSem01Handle = osSemaphoreCreate(osSemaphore(myCountingSem01), 10);

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* Create the queue(s) */
  /* definition and creation of myQueue01 */
  osMessageQDef(myQueue01, 2, uint32_t);
  myQueue01Handle = osMessageCreate(osMessageQ(myQueue01), NULL);

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* definition and creation of Task1 */
  osThreadDef(Task1, StartDefaultTask, osPriorityNormal, 0, 128);
  Task1Handle = osThreadCreate(osThread(Task1), NULL);

  /* definition and creation of Task2 */
  osThreadDef(Task2, StartTask02, osPriorityNormal, 0, 128);
  Task2Handle = osThreadCreate(osThread(Task2), NULL);

  /* definition and creation of Task3 */
  osThreadDef(Task3, StartTask03, osPriorityNormal, 0, 128);
  Task3Handle = osThreadCreate(osThread(Task3), NULL);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

}

/* USER CODE BEGIN Header_StartDefaultTask */
/**
  * @brief  Function implementing the Task1 thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartDefaultTask */
void StartDefaultTask(void const * argument)
{
  /* USER CODE BEGIN StartDefaultTask */
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_3)==0)
			{
				
				if(xSemaphoreGive(myCountingSem01Handle)!=pdTRUE)
				{
					printf("NO1\r\n");
				}
				else
				{
					printf("YES1\r\n");
				}
			}
			
		}
		if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_4)==0)
		{
			osDelay(20);
			if(HAL_GPIO_ReadPin(GPIOE,GPIO_PIN_4)==0)
			{
				
				if(xSemaphoreTake(myCountingSem01Handle,0)!=pdTRUE)
				{
					printf("NO2\r\n");
				}
				else
				{
					printf("YES2\r\n");
				}
			}
			
		}
    
  }
  /* USER CODE END StartDefaultTask */
}

/* USER CODE BEGIN Header_StartTask02 */
/**
* @brief Function implementing the Task2 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask02 */
void StartTask02(void const * argument)
{
  /* USER CODE BEGIN StartTask02 */
  /* Infinite loop */
	
  for(;;)
  {
    
  }
  /* USER CODE END StartTask02 */
}

/* USER CODE BEGIN Header_StartTask03 */
/**
* @brief Function implementing the Task3 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask03 */
void StartTask03(void const * argument)
{
  /* USER CODE BEGIN StartTask03 */
  /* Infinite loop */

  for(;;)
  {
		printf("possess %d people\r\n",(uint16_t)uxSemaphoreGetCount(myCountingSem01Handle));
		osDelay(3000);
  }
  /* USER CODE END StartTask03 */
}

因为用了函数

cpp 复制代码

myCountingSem01Handle = osSemaphoreCreate(osSemaphore(myCountingSem01), 10);

默认当前计数值为满值。如果设置为0，使用下面的函数：

cpp 复制代码

myCountingSem01Handle=xSemaphoreCreateCounting(10,0);

现象：通过按键一和二实现记录人数，并串口打印了当前人数。