一、消息隊列（queue）

隊列是一種用于實現任務與任務之間，任務與中斷之間消息交流的機制。

注意：1.數據的操作是FIFO模式。

2.隊列需要明確數據的大小和隊列的長度。

3.寫和讀都會出現堵塞。

實驗：創建一個消息隊列，兩個發送任務，一個接收任務。

其中任務一任務三的等待時間為0，任務二的等待時間為portMAX_DELAY（死等）。

實現：在前一個項目的基礎上進行更改【STM32】利用CubeMX對FreeRTOS用按鍵控制任務

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("當前%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 */
}

現象：隊列滿了以后，任務一無法發送，任務二會死等，隊列空閑以后完成發送。

二、信號量

消息隊列用于傳輸多個數據，占用時間也相對較長，但有時只需要傳輸狀態，因此引入信號量。信號量也是隊列的一種。信號量有兩種，如果它的量只有0（被拿走的狀態）和1（被填入的狀態）兩種狀態，就稱為二進制的信號量；當量的狀態大于兩種，就稱為計數型信號量。

1.二值信號量

實驗：任務一：按鍵采集數據；任務二：拿走以后串口發送信息

實現：

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 */
}

?現象：當按鍵釋放了信號量，串口才能成功發送信息。

2.記數型信號量

實驗：任務一 ：按鍵一記錄人進來；按鍵二記錄人出去；（最多有10個人）

任務二：串口每隔3S打印人數。

實現：

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 */
}

?因為用了函數

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

默認當前計數值為滿值。如果設置為0，使用下面的函數：

myCountingSem01Handle=xSemaphoreCreateCounting(10,0);

現象：通過按鍵一和二實現記錄人數，并串口打印了當前人數。