Chapter 2. API Reference
(continued from previous page)
*
* // Query the hardware to determine which interface needs processing.
* xInterfaceToService = prvCheckInterfaces();
*
* // The actual processing is to be deferred to a task. Request the
* // vProcessInterface() callback function is executed, passing in the
* // number of the interface that needs processing. The interface to
* // service is passed in the second parameter. The first parameter is
* // not used in this case.
* xHigherPriorityTaskWoken = pdFALSE;
* xTimerPendFunctionCallFromISR( vProcessInterface, NULL, ( uint32_t )␣
,→xInterfaceToService, &xHigherPriorityTaskWoken );
*
* // If xHigherPriorityTaskWoken is now set to pdTRUE then a context
* // switch should be requested. The macro used is port specific and will
* // be either portYIELD_FROM_ISR() or portEND_SWITCHING_ISR() - refer to
* // the documentation page for the port being used.
* portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
*
* }
*
Return pdPASS is returned if the message was successfully sent to the timer daemon task, otherwise
pdFALSE is returned.
Parameters
• xFunctionToPend: The function to execute from the timer service/ daemon task. The function
must conform to the PendedFunction_t prototype.
• pvParameter1: The value of the callback function’s first parameter. The parameter has a void
* type to allow it to be used to pass any type. For example, unsigned longs can be cast to a void *,
or the void * can be used to point to a structure.
• ulParameter2: The value of the callback function’s second parameter.
• pxHigherPriorityTaskWoken: As mentioned above, calling this function will result in a
message being sent to the timer daemon task. If the priority of the timer daemon task (which is
set using configTIMER_TASK_PRIORITY in FreeRTOSConfig.h) is higher than the priority of
the currently running task (the task the interrupt interrupted) then *pxHigherPriorityTaskWoken
will be set to pdTRUE within xTimerPendFunctionCallFromISR(), indicating that a context switch
should be requested before the interrupt exits. For that reason *pxHigherPriorityTaskWoken must
be initialised to pdFALSE. See the example code below.
BaseType_t xTimerPendFunctionCall(PendedFunction_t xFunctionToPend, void *pvParameter1,
uint32_t ulParameter2, TickType_t xTicksToWait)
BaseType_t xTimerPendFunctionCall( PendedFunction_t xFunctionToPend, void *pvParameter1, uint32_t
ulParameter2, TickType_t xTicksToWait );
Used to defer the execution of a function to the RTOS daemon task (the timer service task, hence this function
is implemented in timers.c and is prefixed with ‘Timer’).
Return pdPASS is returned if the message was successfully sent to the timer daemon task, otherwise
pdFALSE is returned.
Parameters
• xFunctionToPend: The function to execute from the timer service/ daemon task. The function
must conform to the PendedFunction_t prototype.
• pvParameter1: The value of the callback function’s first parameter. The parameter has a void
* type to allow it to be used to pass any type. For example, unsigned longs can be cast to a void *,
or the void * can be used to point to a structure.
• ulParameter2: The value of the callback function’s second parameter.
• xTicksToWait: Calling this function will result in a message being sent to the timer daemon task
on a queue. xTicksToWait is the amount of time the calling task should remain in the Blocked state
(so not using any processing time) for space to become available on the timer queue if the queue is
found to be full.
Espressif Systems 920
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