How to debug lwm2m_client sample on Thingy91 development kit?

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Wed, 18 Jun 2025 07:28:27 GMT

Could you please eleborate a little bit more what it dies and why it fixes the issue in this case on the Thingy91?

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Wed, 18 Jun 2025 06:35:50 GMT

Hi,

[quote user="cellular_iot"]Debugging is working:[/quote]

This is great to hear. Thank you for the update.

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 17 Jun 2025 12:42:31 GMT

Hi Dejan,

Thanks for that - CONFIG_TFM_CMAKE_BUILD_TYPE_MINSIZEREL=y seemingly is fixing the issue with blinky in Thingy91:

Debugging is not working:

Debugging is working:

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Tue, 17 Jun 2025 08:20:23 GMT

Hi,

Can you try to set CONFIG_TFM_CMAKE_BUILD_TYPE_MINSIZEREL=y in your project configuration?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Mon, 16 Jun 2025 08:23:12 GMT

Like this?

Outcome is the same - stuck in

NRFX_ASSERT(!(p_reg->FLASHREGION[region_id].PERM & SPU_FLASHREGION_PERM_LOCK_Msk)); in nrf_spu_flashregion_set()

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Mon, 16 Jun 2025 08:06:04 GMT

Hi,

Can you try to add debug optimizations also for the application using
-Dblinky_CONFIG_DEBUG_OPTIMIZATIONS=y?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Wed, 11 Jun 2025 07:41:29 GMT

Hi,

[quote user="cellular_iot"]I now had a similiar issue when I tried to debug lwm2m_client sample on nRF9151DK. replacing -Og with -Os did fix it for now, I could debug main() of the app. [/quote]

Thank you for letting me know. I have reported this internally as well.

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 10 Jun 2025 09:49:02 GMT

Thanks and looking forward!

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 10 Jun 2025 09:47:39 GMT

BTW: I now had a similiar issue when I tried to debug lwm2m_client sample on nRF9151DK. replacing -Og with -Os did fix it for now, I could debug main() of the app.

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Tue, 10 Jun 2025 09:45:54 GMT

Hi,

I have tried to replicate debugging issue that you reported.

[quote user="cellular_iot"]And what helps reliably is to disable "optimize for debug (-Og), use -Os and manually add cmake argument -DCONFIG_DEBUG_THREAD_INFO=y[/quote]

There seems to be a problem when debug optimization is included in the project build configuration in VS Code. I have reported this internally. I expect to get back to you with status update by the end of the week.

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Thu, 05 Jun 2025 15:01:36 GMT

when I try to debug the sample lwm2m_client, it works as expected on the nRF9151DK and not on the thing91, mostly the CPU spins endless in the "flash is not locked" assertion like here:

So it looks like the larger the app the higher the chance the debug setup is breaking

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Thu, 05 Jun 2025 14:56:36 GMT

Now lets create and build a thingy91 debug version:

And lunch the debugger:

Now the CPU doesnt hit the apps main():

single stepping is not working:

Oh wow, after several atempts to F10/F5 this time I get a blinking board and a UART output:

- but the call stack is not showing app threads and I cannot single step

After stopping the debugger, reflashing, attach debugger it looks like this - that the exception/assertion I see most often when I try to debug the lwm2m_client sample on the thingy91:

And what helps reliably is to disable "optimize for debug (-Og), use -Os and manually add cmake argument -DCONFIG_DEBUG_THREAD_INFO=y

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Thu, 05 Jun 2025 14:28:43 GMT

Now the good version using Thingy91.

Lets create a non debug in build_60:

flash it:

It blinks and UART output is working:

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Thu, 05 Jun 2025 14:16:54 GMT

Ok, lets first show the good version using the nRF9151DK:
New VSCode Window:

create new app, copy sample from "nrf/samples.../blinky"

created in c:\blinky

nrf connect/application/blinky/add build configuration:
- sdk & toolchain v3.0.1
- board: nrF9151dk/nRF9151/ns
- prj.conf
- optimize for debugging (-Og)
- Build directory name: build_51_dbg

- click: generate and build, wait several minutes on my 16 Core i7-1360p
- build OK:

Click on actions/debug
- some west magic, flashing, debugg view loads

I can single step using F10:

Serial terminal is showing blinky Uart output:

LED1 is blinking

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Thu, 05 Jun 2025 13:53:59 GMT

Hi,

I suggest that we start from very beginning, looking at what does not work as expected. For example, you mentioned

[quote user="cellular_iot"]Blinky on nrf9151DK_nrf9151ns: all versions work including debugging[/quote]

Can you provide detailed steps and screenshots to reproduce this (starting from build command you used)?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Wed, 04 Jun 2025 12:07:04 GMT

I installed SDK prepackaged version v3.0.1 via VSCode as descibed in the same tutorial: docs.nordicsemi.com/.../quick_setup.html

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Wed, 04 Jun 2025 10:33:21 GMT

Hi,

Which NCS version do you use?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 03 Jun 2025 09:33:42 GMT

Maybe later, for now I need to the lwm2m_client sample fully working on the thingy91 we own - sensors are not working so I need to debug this urgently.

For debugging I followed this tutorial: docs.nordicsemi.com/.../quick_debug.html

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Tue, 03 Jun 2025 09:25:20 GMT

Hi,

[quote user="cellular_iot"]I use VSCode like described in the tutorials and getting started and I use the blinky example for reproduction. I gave the console a short try but lots of issues for now[/quote]

Can you show which tutorial you followed?
Which issues did you encounter when you used console? Can you share your build log?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 03 Jun 2025 09:09:39 GMT

BTW - when I configure blinky for a debug build and launch the debug config, the debugger doens't halt in main but just runs. When I pause, the CPU mostly hangs in this assert:

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Tue, 03 Jun 2025 08:47:16 GMT

Thanks for reaching out!

I use VSCode like described in the tutorials and getting started and I use the blinky example for reproduction. I gave the console a short try but lots of issues for now, have to try later when I have time.

* Blinky on nrf9151DK_nrf9151ns: all versions work including debugging
* Blinky on thingy91_nrf9160: all versions work including debugging
* Blinky on thingy91_nrf9160ns:
- standard build works
- standard build with "optimize for debugging (-Og)" doesn't work
- standard build with "optimize for speed (-O2)" and Extra CMake arguments "-DCONFIG_DEBUG_THREAD_INFO=y" works, I can debug in VSCode.

When I don't choose "Optimize for debugging (-Og)" but set -DCONFIG_DEBUG_THREAD_INFO=y and -DCONFIG_DEBUG_OPTIMIZATIONS=y as extra CMake arguments, blinky is not working. When I re-open the build settings with "Edit build configuration" my manual set Cmake arguments are gone and "Optimize for debugging (-Og)" is selected - so the gui just manages the translation to "-DCONFIG_DEBUG_OPTIMIZATIONS=y" - which seems to be the bad guy here.

So how to proceed with that?

RE: How to debug lwm2m_client sample on Thingy91 development kit?

dejans — Mon, 02 Jun 2025 16:15:53 GMT

Hi,

Do you use VS Code for building and flashing? Do you see the same behavior if you do not use VS Code?

Do you see the same problem if you do not use "Optimize for debugging (-Og)" but instead add both
-DCONFIG_DEBUG_THREAD_INFO=y and -DCONFIG_DEBUG_OPTIMIZATIONS=y
to your build command manually?

Do you see the same result when using only -DCONFIG_DEBUG_THREAD_INFO=y (without optimization)?

Best regards,
Dejan

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Mon, 02 Jun 2025 07:20:12 GMT

Any idee how a thingy:91 with LTE modem active can be debugged in 2025?

RE: How to debug lwm2m_client sample on Thingy91 development kit?

cellular_iot — Wed, 28 May 2025 15:05:58 GMT

Another data point:

When I flash the merged.hex of a non-debug blinky build to the Thingy:91 via SWD, everything works fine — UART output appears and the LED blinks. Then I press the button, power-cycle the board, and end up in MCUboot. From there, I use the nRF Connect Programmer to flash zephyr.signed.hex from the debug build. After that, nothing works — no UART output, no LED activity.

I press the button again, power-cycle once more, and this time flash the zephyr.signed.hex from the non-debug build — and the LED starts blinking again.