FreeRTOS Task Priority VS Interrupt Priority nRF52840

[Dave_couling]

Hi guys,

I have a 4 thread freeRTOS setup.

1. BLE - priority 4
2. TWI - priority 3
3. LED - priority 2
4. Logging - priority 1

After running for some time my code always gets caught in an infinite loop inside the vListInsert function of freeRTOS, or hardfaults @ PC:0x20003188 PSR: 0x4000000e (PendSV). It occurs like a random race-condition. Typically this indicates an issue with interrupt priorities. Looking thru my Stack trace, On the BLE thread (4), I get a SAADC IRQ (IRQ priority 6 in sdk_config.h) which triggers a callback function to write the value to the Log Thread (1). Here I try and grab a Semaphore which calls the following sequence, xSemaphoreTake() -> xQueueGenericReceive() -> vTaskPlaceOnEventList() -> vListInsert().

As an FYI I'm trying to Port FreeRTOS to the nRF52840 which i realize doesn't have an official support from Nordic yet.  Just want to double check there is nothing unique about the any vector implementation that might propagate to different behaviour in upper levels of an RTOS.  Thanks for your help.

[Dave_couling]

I read somewhere there was some issues with RTT Logging to in a freeRTOS setup. I couldn't find the post though sorry. I just starting testing this project again and got another hardfault, so I guess I only minimized the issue, but didn't squash the bug. Back to the drawing board, but I'll keep this post updated with any progress I make.