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take & give semaphorePosted by Martin Velek on December 11, 2008 Hello, is there a simple way, how to achieve this functionality? void interrupt_handler_timer_A(void) { xSemaphoreGiveFromISROnlyIfSemaphoreWasTakenBefore(xSemaphore); } void TaskA(...) { startTimerA(); stopTimerA(); xSemaphoreTake(xSemaphore); exit(1); // we should never get here } I mean that the interrupt handler can give semaphore only if was taken before. In other cases it skips it. Thank you for help Martin RE: take & give semaphorePosted by Richard on December 12, 2008 You could do something like this: if( xQueueIsQueueEmptyFromISR( (xQueueHandle) xSemaphore ) { ____xSemaphoreGiveFromISR( xSemaphore ); } be careful of race conditions though. I don't understand the comment "// we should never get here" in your sample task code. It looks like you would get there as soon as the semaphore was available. Regards. RE: take & give semaphorePosted by Martin Velek on December 12, 2008 Hi Richard, thank you for answer. The comment "// we should never get here" means, that by function stopTimerA() disables generating Timer interrupt. Amazing function xQueueIsQueueEmptyFromISR. Exactly what I need. I didn't find it in documentation :( ... I would be glad if something like MicroC/OS-II was written about FRT. BR Martin
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