About configMAX_SYSCALL_INTERRUPT_PRIORITY and xQueueSendFromISR

joe_her wrote on Tuesday, January 26, 2016:

I have a STM32F4 UART interrupt which sends a queue msg as soon as data is ready.
When UART interrupt priority was 0, I had assertion fail.
The text describes the failure (thanks for the comment near the assertion, very helpful) , and changing the priority to 15 ( was 0) solves the problem.
However I am not sure I fully understand what I did.
The configMAX_SYSCALL_INTERRUPT_PRIORITY equals 0x50 ( which I don’t get as the interrupt priority can be 0 - 15).
Why when the UART priority is 0 (highest) it does not work?
What should be the correct value of the UART interrupt priority for safe operation?

Thanks
Johanan

davedoors wrote on Tuesday, January 26, 2016:

did you see this page already http://www.freertos.org/RTOS-Cortex-M3-M4.html ?

joe_her wrote on Tuesday, January 26, 2016:

Now I did :slight_smile:
Thanks