STM32H755 Nucleo M4 core debugging problem.

[shubham_patayane]

Hello, STM32 community,

I am currently working on a project using the STM32H755ZI-Q Nucleo board, and I've encountered a perplexing issue with the M4 core during debugging. I have written a basic code to toggle two onboard LEDs, and while the code seems to work as expected, the M4 core gets stuck at "Waiting for Debugger Connection" during debugging. Strangely, I can still add breakpoints in the M4 code and pause the LED toggling successfully. The project files are attached. Please can someone help me with resolving the debugging issue for M4? If you find this post irrelevant feel free to delete it.

Solutions I tried:

https://community.st.com/t5/stm32cubeide-mcus/stm32h755-dual-core-debugging-problem/m-p/608795#M22058

https://community.st.com/t5/stm32cubeide-mcus/how-can-i-remove-error-like-waiting-for-debugger-connection/td-p/250559/page/2 

Snaps from my Cube IDE:

[shubham_patayane]

Any Help?

[Imen.D]

Hello @shubham_patayane and welcome to the Community 🙂

Did you used the debugger pins for other purpose? Make sure that your debug pins are Free. 

I advise you check this article: How to solve debugger connection issues?

Check also this AN4989 (in sections: 9 Dual-Core microcontrollers debugging, 3. Low-power case) and the AN5361 which contains a checklist helping to avoid the most debug problems.

[shubham_patayane]

@Imen.D Tried it all today. But getting the same prob! Left the M7 core running and tried to open the debugger for M4 but it's showing the same error. Is there any other thing I should try? And it sometimes comes and pops up this page (screenshot 2).

[shubham_patayane]

@Imen.D  Any help regarding this new error? M7 core works fine but I am not getting any response from M4.

[SofLit · Accepted solution]

Hello,

Not easy to determine the source of the error but from the project you've already posted at the beginning:

I see two issues:

1- You need to set "Download" in CM4 debug configuration as following: 

2- You need to set the reset behavior at least with: Connect under reset:

PS:

1- debugging Dual core is a bit tricky mainly when CM4 is using low power mode:

HAL_PWREx_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFE, PWR_D2_DOMAIN);

So if you need to debug CM4 side without issue, comment this line.

2- You can use this example for your reference: https://github.com/STMicroelectronics/STM32CubeH7/tree/master/Projects/NUCLEO-H745ZI-Q/Examples/GPIO/GPIO_EXTI

[shubham_patayane]

Thanks this works. @SofLit