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( “Timer”, xTimerPeriod, pdFALSE, ( void * ) &xStruct, / <<<<<< */ prvCallback ); /* Start the timer. */ xTimerStart( xTimer, 0 ); vTaskStartScheduler(); for( ;; ); } void prvCallback( TimerHandlet xTimer ) { MyStructt *pxStructAddress; /* Obtain the address of the struct from the timer’s ID. */ pxStructAddress = ( 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!