Hello! Currently I'm trying to handle the incoming messages from two CAN busses, with a handler for each bus. I have adapted some existing code to make those handlers run only once a semaphore is freed when a CAN interrupt is triggered. However the code guarded by the semaphores does unfortunatly not execute. Since I am very new to freertos i would appreciate your input on my code. I am using libopencm3. I have uploaded to relevant code here: https://github.com/dawg91/CanInterruptHandling with SystemStatus.c containing the handlers and interrupt routines and can_handling.c the initialization of the can busses. Thank you very much for your time!

First, are you sure the CAN drivers are working when you use them in a driver that is not using FreeRTOS. That would always be the first step. How you configure the CAN buses is outside the scope of the FreeRTOS forum though.

Second, there is nothing that immediately stands out as being wrong in the use of your semaphore, but it does appear that you have two tasks which are blocking on the same semaphore - is that the case? The semaphore will only unblock one of the tasks (the highest priority task if the tasks have different priorities, or the task that has been blocked the longest if both tasks have the same priority).