nRF52840 - How to debug Zephyr code when the radio is running. HardFault

[naps]

Hi, I found that after migration from Zigbee Thread SDK to Zephyr GDB debugging functionality is broken.
I have read a lot about PRIMASK register, GDB hooks, and so on, but those didn't fix all of my problems.
I want to use Eclipse + GDB for stepping through the code and dynamic breakpoint placement.
I found a solution, that is somehow satisfying my needs - I mean Monitor mode debugging using Jtrace probe.
```
https://www.segger.com/products/debug-probes/j-link/technology/monitor-mode-debugging/
```
+ custom settings passed to JLINK cmd.

This isn't an ideal solution, as MMD works only in Jlink PRO / Jtrace programmers - so no way to get it working on your dev boards.

Can you provide some universal way to step through the code without HardFaults and resets?

[Jørgen Holmefjord]

Hi,

Are you using Zephyr directly, or nRF Connect SDK? Which protocol are you using (Zigbee/Thread/BLE)?

Monitor Mode Debugging can be run on our nRF52 DKs in evaluation mode, see this tutorial. For commercial use, you will have to get a license from Segger.

Best regards,
Jørgen

[naps]

Hi, thanks for your fast reply.
We are using nRF Connect SDK for the Zigbee application and building it with west + makefiles.
According to www.segger.com/.../

Do all J-Links support Monitor Mode Debugging?

A: No, Monitor Mode Debugging is only supported by J-Link PLUS, PRO, ULTRA+, and J-Trace. J-Link BASE and on-board J-Links cannot be used for Monitor Mode Debugging

I'm wondering if it is really possible.

I'm using opensource toolchains and IDE, and I was able to run MMD by compiling some parts of the sample project from Segger. Next, I've added some gdb commands for init 

mon reset 0
mon exec SetMonModeDebug=1
mon exec SetMonModeVTableAddr=0x1f000

And It just works, but only using our external JTrace probe.
You mention some additional licenses; is it possible to upgrade onboard nrf52 devkit JLlink? Or should it work out of the box in your opinion, if our second (JTrace) configuration is working? 

[Jørgen Holmefjord]

I have only tested MMD with nRF5 SDK, and the instructions in the GitHub tutorial I linked, not together with NCS or Zigbee, but I did only run it on a standard nRF52 DK. No modifications were made to the DK or J-Link FW.

If you have the required files and commands in place, I believe you should be able to run it with the DK as well. 

You may get some better answers regarding exactly why it does not work in the Segger Forums.

[naps]

I will dig into this topic and will try to provide some universal open-source solution and post it here in this thread.
Thanks for your help.