Hi, I am having strange problem (at least in my point of view). When I do this: __arm void vRPM_ISR ( void ) {         xNewRPM = xTaskGetTickCount(); whole freertos kernell freezes. When I chanege it to this: __arm void vRPM_ISR ( void ) {         xNewRPM = xTickCount; everything runs well. So the problem must be in xTaskGetTickCount function in here: taskENTER_CRITICAL(); and taskEXIT_CRITICAL(); any explanation appreciated Thanks Josef

You point out the answer yourself – do not call API functions from ISR’s unless they have FromISR at the end of the function name.  Critical sections inside an ISR is not good.

Hi, Thank you for your reply. I thought that I have missed something. thank you very much Josef