I have an FreeRTOS application and I am currently stuck on pxTimer being NULL. Please see below. The pxTimer after listGET_OWNER_OF_HEAD_ENTRY is actually NULL. Surprisingly, this function actually got through the end where it tried to make a call pxTimer->pxCallbackFunction. That was where I caught a Usage Fault.
What could be the possible causes for this issue ?
static void prvProcessExpiredTimer( const TickType_t xNextExpireTime, const TickType_t xTimeNow )
{
BaseType_t xResult;
Timer_t * const pxTimer = ( Timer_t * ) listGET_OWNER_OF_HEAD_ENTRY( pxCurrentTimerList ); /*lint !e9087 !e9079 void * is used as this macro is used with tasks and co-routines too. Alignment is known to be fine as the type of the pointer stored and retrieved is the same. */
/* Remove the timer from the list of active timers. A check has already
been performed to ensure the list is not empty. */
( void ) uxListRemove( &( pxTimer->xTimerListItem ) );
traceTIMER_EXPIRED( pxTimer );
/* If the timer is an auto reload timer then calculate the next
expiry time and re-insert the timer in the list of active timers. */
if( ( pxTimer->ucStatus & tmrSTATUS_IS_AUTORELOAD ) != 0 )
{
/* The timer is inserted into a list using a time relative to anything
other than the current time. It will therefore be inserted into the
correct list relative to the time this task thinks it is now. */
if( prvInsertTimerInActiveList( pxTimer, ( xNextExpireTime + pxTimer->xTimerPeriodInTicks ), xTimeNow, xNextExpireTime ) != pdFALSE )
{
/* The timer expired before it was added to the active timer
list. Reload it now. */
xResult = xTimerGenericCommand( pxTimer, tmrCOMMAND_START_DONT_TRACE, xNextExpireTime, NULL, tmrNO_DELAY );
configASSERT( xResult );
( void ) xResult;
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
pxTimer->ucStatus &= ~tmrSTATUS_IS_ACTIVE;
mtCOVERAGE_TEST_MARKER();
}
/* Call the timer callback. */
pxTimer->pxCallbackFunction( ( TimerHandle_t ) pxTimer );
}