For xTimerCreate function, we can assign a unique TimerID for each timer (as shown follows). But, can we use pvTimerID pointer to point to a struct so that we can pass more parameters to timer callback function?
TimerHandlet xTimerCreate( const char * const pcTimerName,
* TickTypet xTimerPeriodInTicks,
* UBaseTypet uxAutoReload,
* void * pvTimerID,
* TimerCallbackFunctiont pxCallbackFunction );
yes - it is a void pointer to allow you to use it for whatever you want.
Just set a pointer to point to the structure, then pass THE ADDRESS OF
THE POINTER as the ID parameter. Inside the callback function declare a
pointer to a structure, and receive the ID into that pointer.
Thanks so much for your reply!!
But I am still a little confused about how to "receive the ID into that pointer" inside callback function.
For example, is the following expression correct?
void vTimerCallbacktr(TimerHandlet pxTimer)
pointer * ptr=(pointer * )pxTimer;
See the following example:
void main( void )
const TickTypet xTimerPeriod = pdMSTO_TICKS( 100 );
/* Create the timer with the ID set to the address
of the struct. /
xTimer = xTimerCreate(
( void * ) &xStruct, / <<<<<< */
/* Start the timer. */
xTimerStart( xTimer, 0 );
for( ;; );
void prvCallback( TimerHandlet xTimer )
/* Obtain the address of the struct from the
timer's ID. */
( MyStruct_t * ) pvTimerGetTimerID( xTimer );
/* Check the structure members are as expected. */
configASSERT( pxStructAddress->x == 1 );
configASSERT( pxStructAddress->y == 2 );
That works well! Thanks so much!