Chapter 2. API Reference
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taskYIELD_YIELD_FROM_ISR();
}
}
Return pdTRUE if the data was successfully sent to the queue, otherwise errQUEUE_FULL.
Parameters
• xQueue: The handle to the queue on which the item is to be posted.
• pvItemToQueue: A pointer to the item that is to be placed on the queue. The size of the items
the queue will hold was defined when the queue was created, so this many bytes will be copied from
pvItemToQueue into the queue storage area.
• [out] pxHigherPriorityTaskWoken: xQueueGenericSendFromISR() will set *pxHigh-
erPriorityTaskWoken to pdTRUE if sending to the queue caused a task to unblock, and the un-
blocked task has a priority higher than the currently running task. If xQueueGenericSendFromISR()
sets this value to pdTRUE then a context switch should be requested before the interrupt is exited.
• xCopyPosition: Can take the value queueSEND_TO_BACK to place the item at the back of
the queue, or queueSEND_TO_FRONT to place the item at the front of the queue (for high priority
messages).
BaseType_t xQueueGiveFromISR(QueueHandle_t xQueue, BaseType_t *const pxHigherPriority-
TaskWoken)
BaseType_t xQueueReceiveFromISR(QueueHandle_t xQueue, void *const pvBuffer, BaseType_t
*const pxHigherPriorityTaskWoken)
Receive an item from a queue. It is safe to use this function from within an interrupt service routine.
Example usage:
QueueHandle_t xQueue;
// Function to create a queue and post some values.
void vAFunction( void *pvParameters )
{
char cValueToPost;
const TickType_t xTicksToWait = ( TickType_t )0xff;
// Create a queue capable of containing 10 characters.
xQueue = xQueueCreate( 10, sizeof( char ) );
if( xQueue == 0 )
{
// Failed to create the queue.
}
// ...
// Post some characters that will be used within an ISR. If the queue
// is full then this task will block for xTicksToWait ticks.
cValueToPost = 'a';
xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
cValueToPost = 'b';
xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
// ... keep posting characters ... this task may block when the queue
// becomes full.
cValueToPost = 'c';
xQueueSend( xQueue, ( void * ) &cValueToPost, xTicksToWait );
}
// ISR that outputs all the characters received on the queue.
void vISR_Routine( void )
{
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