Semaphore times out

jstoezel wrote on Sunday, March 22, 2009:


I have added a tick hook that counts ticks and give a semaphore periodically using xSemaphoreGiveFromISR.

A task waits on this semaphore using xSemaphoreTake and the maximum delay (portMAX_DELAY).
I have an LED that shows when the semaphore is given and an LED showing when the semaphore is taken.
The semaphore is given consistently from the ISR (the ISR LED blinks). You would expect the task LED to blink too… However the semaphore is only taken once from the task. All other tentatives to take the semaphore pend forever, or timeout if I use a timeout value other than portMAX_DELAY.

This issues occurs whenever I use binary or counting semaphores.

Any idea what is going wrong?


jstoezel wrote on Sunday, March 22, 2009:

I thought I would also say that I tried to add the following code and it still fails:

xSemaphoreGiveFromISR(mySemaphore, &dummy);
if(pdTRUE == dummy)

davedoors wrote on Sunday, March 22, 2009:

Which port are you using (CPU and compiler). Which version of FreeRTOS are you using? Can you post your code?