FreeRTOS二值信号量

API函数

#if( configSUPPORT_DYNAMIC_ALLOCATION == 1 )

    #define xSemaphoreCreateBinary() xQueueGenericCreate( ( UBaseType_t ) 1,

                                semSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_BINARY_SEMAPHORE )

    QueueHandle_t xQueueGenericCreate( const UBaseType_t uxQueueLength,

                                    const UBaseType_t uxItemSize, const uint8_t ucQueueType )

#endif

#define xSemaphoreGive( xSemaphore )

xQueueGenericSend( ( QueueHandle_t ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )

BaseType_t xQueueGenericSend( QueueHandle_t xQueue, const void * const pvItemToQueue,

                            TickType_t xTicksToWait, const BaseType_t xCopyPosition )

#define xSemaphoreGiveFromISR( xSemaphore, pxHigherPriorityTaskWoken )

xQueueGiveFromISR( ( QueueHandle_t ) ( xSemaphore ), ( pxHigherPriorityTaskWoken ) )

BaseType_t xQueueGiveFromISR( QueueHandle_t xQueue, BaseType_t * const pxHigherPriorityTaskWoken )

#define xSemaphoreTake( xSemaphore, xBlockTime )

xQueueGenericReceive( ( QueueHandle_t ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )

BaseType_t xQueueGenericReceive( QueueHandle_t xQueue, void * const pvBuffer,

                                TickType_t xTicksToWait, const BaseType_t xJustPeeking )

#define xSemaphoreTakeFromISR( xSemaphore, pxHigherPriorityTaskWoken )

xQueueReceiveFromISR( ( QueueHandle_t ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ) )

BaseType_t xQueueReceiveFromISR( QueueHandle_t xQueue, void * const pvBuffer,

                                BaseType_t * const pxHigherPriorityTaskWoken )

使用举例

u8 data;

void start_task(void *pvParameters)

{

    //创建二值信号量

    BinarySemaphore = xSemaphoreCreateBinary();

}

void USART1_IRQHandler(void)

{

    if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)

    {

        data = USART_ReceiveData(USART1);

        xSemaphoreGiveFromISR(BinarySemaphore, &xHigherPriorityTaskWoken);  //释放二值信号量

        portYIELD_FROM_ISR(xHigherPriorityTaskWoken);

    }

}

void data_task(void *pvParameters)

{

    BaseType_t ret;

    while(1)

    {

        ret = xSemaphoreTake(BinarySemaphore,portMAX_DELAY);

        if(ret == pdTRUE)

        {

            printf("data %c\r\n", data);

        }

        vTaskDelay(10);

    }

}

实验现象