+ Collaboration diagram for xSemaphoreGiveFromISR:

semphr. h

                         SemaphoreHandle_t xSemaphore,
                         BaseType_t *pxHigherPriorityTaskWoken

Macro to release a semaphore. The semaphore must have previously been created with a call to xSemaphoreCreateBinary() or xSemaphoreCreateCounting().

Mutex type semaphores (those created using a call to xSemaphoreCreateMutex()) must not be used with this macro.

This macro can be used from an ISR.

xSemaphoreA handle to the semaphore being released. This is the handle returned when the semaphore was created.
pxHigherPriorityTaskWokenxSemaphoreGiveFromISR() will set *pxHigherPriorityTaskWoken to pdTRUE if giving the semaphore caused a task to unblock, and the unblocked task has a priority higher than the currently running task. If xSemaphoreGiveFromISR() sets this value to pdTRUE then a context switch should be requested before the interrupt is exited.
pdTRUE if the semaphore was successfully given, otherwise errQUEUE_FULL.

Example usage:

#define LONG_TIME 0xffff
#define TICKS_TO_WAIT  10
SemaphoreHandle_t xSemaphore = NULL;
// Repetitive task.
void vATask( void * pvParameters )
   for( ;; )
       // We want this task to run every 10 ticks of a timer.  The semaphore
       // was created before this task was started.
       // Block waiting for the semaphore to become available.
       if( xSemaphoreTake( xSemaphore, LONG_TIME ) == pdTRUE )
           // It is time to execute.
           // ...
           // We have finished our task.  Return to the top of the loop where
           // we will block on the semaphore until it is time to execute
           // again.  Note when using the semaphore for synchronisation with an
        // ISR in this manner there is no need to 'give' the semaphore back.
// Timer ISR
void vTimerISR( void * pvParameters )
static uint8_t ucLocalTickCount = 0;
static BaseType_t xHigherPriorityTaskWoken;
   // A timer tick has occurred.
   // ... Do other time functions.
   // Is it time for vATask () to run?
   xHigherPriorityTaskWoken = pdFALSE;
   if( ucLocalTickCount >= TICKS_TO_WAIT )
       // Unblock the task by releasing the semaphore.
       xSemaphoreGiveFromISR( xSemaphore, &xHigherPriorityTaskWoken );
       // Reset the count so we release the semaphore again in 10 ticks time.
       ucLocalTickCount = 0;
   if( xHigherPriorityTaskWoken != pdFALSE )
       // We can force a context switch here.  Context switching from an
       // ISR uses port specific syntax.  Check the demo task for your port
       // to find the syntax required.

This documentation file has been automatically generated on Wed May 6 2020 20:45:23 by doxygen 1.8.8