Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

rwl — Fri, 31 Aug 2018 18:47:06 GMT

I was not able to fix the issue but in my case it is only debugger related. Since it happens only occasionally I learned to just live with it and restart the debugger when it occurs.

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

bale11 — Fri, 31 Aug 2018 14:49:24 GMT

I'm facing the same issue. Just a little different in my case. I'm using freertos so first it gets stuck at "0x000008C8" and when I resume it again , it points to "prvIdleTask();" which is an idle hook task in freertos.

Are you able to fix this problem ? I tried using the serial monitor for debugging but the nrf52832 stops responding after an hour.

I'm using sdk 15

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

rwl — Thu, 19 Apr 2018 13:09:31 GMT

Thank you Jakub, I suspected that. I will try what you suggested.

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

Jakub Rzeszutko — Thu, 19 Apr 2018 13:05:08 GMT

Hi rluc,

I think that problem you are facing with is related to your debugger. Please take a closer look to function: task_manager_start in the task_manager.c file. It is significantly messing up stack and I guess it confuses your debugger.

Please start debugging after calling the function task_manager_start to see if you are still observing the isse.

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

rwl — Mon, 16 Apr 2018 12:54:27 GMT

Yes I understand about debugging while the soft device is enabled. Do you see any issue with using both the Task Manager with the app_scheduler? I'm using the app_scheduler to handle my timer events asynchronously. I found that I had to use the Task Manager to make the CLI work in conjunction with my app. Without the Task Manager, things would fail miserably if I simply called nrf_cli_process() in my idle loops ( I also have a lot of log messages going out the UART).

As a side note, I am not calling sd_app_evt_wait() in my app, it is always fully running. I do recognize that systick clock stops when the processor sleeps.

RE: Starting idle task using Task Manager library frequently throws error "Unknown function at 0x000008C8" when running with the debugger (often takes several restarts until it runs).

Sigurd — Mon, 16 Apr 2018 08:57:52 GMT

Hi,

You could get the «Unknown function at 0x000008C8” when you try to step through the code after the SoftDevice have been enabled. When stepping through the code, or when setting breakpoints, the CPU will be halted. This will cause a hard-fault due to BLE timing being violated. This will result in a disconnected BLE link and the code will end up in the error-handler. Alternative debugging approaches with the SoftDevice enabled includes using RTT or UART for debug messages and/or toggling GPIOs to indicate software states.

Also note that the systick is sourced by the same clock as the CPU, which is turned off when going to WFE/WFI (sd_app_evt_wait()). It is therefore not recommended to use systick. I would recommend using the RTCx peripheral (via app_timer for instance), or the TIMER peripheral instead.