Chapter 2. API Reference
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if( xQueue1 != 0 )
{
// Send an uint32_t. Wait for 10 ticks for space to become
// available if necessary.
if( xQueueGenericSend( xQueue1, ( void * ) &ulVar, ( TickType_t ) 10,␣
,→queueSEND_TO_BACK ) != pdPASS )
{
// Failed to post the message, even after 10 ticks.
}
}
if( xQueue2 != 0 )
{
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage;
xQueueGenericSend( xQueue2, ( void * ) &pxMessage, ( TickType_t ) 0,␣
,→queueSEND_TO_BACK );
}
// ... Rest of task code.
}
Return pdTRUE if the item was successfully posted, 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.
• xTicksToWait: The maximum amount of time the task should block waiting for space to become
available on the queue, should it already be full. The call will return immediately if this is set to 0
and the queue is full. The time is defined in tick periods so the constant portTICK_PERIOD_MS
should be used to convert to real time if this is required.
• 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 xQueuePeek(QueueHandle_t xQueue, void *const pvBuffer, TickType_t xTicksToWait)
Receive an item from a queue without removing the item from the queue. The item is received by copy so a
buffer of adequate size must be provided. The number of bytes copied into the buffer was defined when the
queue was created.
Successfully received items remain on the queue so will be returned again by the next call, or a call to
xQueueReceive().
This macro must not be used in an interrupt service routine. See xQueuePeekFromISR() for an alternative that
can be called from an interrupt service routine.
Example usage:
struct AMessage
{
char ucMessageID;
char ucData[ 20 ];
} xMessage;
QueueHandle_t xQueue;
// Task to create a queue and post a value.
void vATask( void *pvParameters )
{
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