xQueueReceive FreeRTOS hardfault NRF52840

[AntonLev]

Hello,

It is my first time running FreeRTOS on NRF52 and I would really appreciate any help to figure out the root cause for the hard fault. 

I run a  simple FreeRTOS application with 2 tasks. The application receives UART data and loops it back. The system starts fine and runs fine for 1 - 2 mins and then the hard fault happens. In xQueueReceive function. The call stack screen shot is attached:

As the stack shows the hard fault happens in the  DSB instruction inside the  portYIELD()  macro.  I'll appreciate any ideas about the root cause of the issue.

Best Regards,
Anton

[Susheel Nuguru]

Hi Antony, 

Sorry for the late response,

did you find out the reason? if not then i could do a quick test run if you give me the code for your tasks and see what causing the hardfault

[AntonLev]

Hi Susheel,

Yes, it took me some time but found the root cause. The configMAX_SYSCALL_INTERRUPT_PRIORITY and configKERNEL_INTERRUPT_PRIORITY values were incorrect in the FreeRTOS configuration file. 

Best Regards,
Anton

[Susheel Nuguru]

were they wrong in the example file, or they did not suit your application? What values did you change them to? 

Just trying to understand the need for change.

[AntonLev]

We have used the configuration file from the previous project that used another ARM processor. The mentioned configMAX_SYSCALL_INTERRUPT_PRIORITY and configKERNEL_INTERRUPT_PRIORITY values were correct for the other processor but wrong for NRF52840. 

I followed the description from here https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v11.0.0%2Ffreertos.html. The configMAX_SYSCALL_INTERRUPT_PRIORITY and configKERNEL_INTERRUPT_PRIORITY  values were changed to NRF_APP_PRIORITY_LOW that  is 6 in our case.