n6-dk hard fault with unresponsive debugger

[rfronteddu]

I have been playing with the n6-dk for a while and today something unexpected happened.

When I try to run the stock code provided in the model zoo services, the board flashes for a moment at startup and the debugger and the board become unresponsive (requiring power cycling).

Another weird thing is that if I flash the code and connect the board to a power source the code seems to be running correctly. I tried with another desktop experiencing the same issue. I also tried to do a mass erase and fresh flashing of fsbl, source, and network code.

This was not a problem before, for weeks I run the code with the board connected to my desktop, I have never seen the code crash like that (normally, if something in the code is wrong, I hit a fault and the board get stuck in a sig handler loop).

Has anyone experienced anything similar?

[FBL · Accepted solution]

Hello @rfronteddu 

Did you follow this article How to run AI models from model zoo on STM32N6

If so, to narrow it down, I suggest you to check basic debugging: Flash a simple example to blink led.

Then, try to debug this project:

• If it debugs correctly, the basic ST‑LINK and board are OK, and the problem is specific to the Model Zoo application or maybe memory layout.
• If this simple example also fails, you should focus on ST‑LINK firmware, cable, option bytes, or the board itself.

You need to reproduce the issue with minimum firmware.

[rfronteddu]

II have followed the article and successfully deployed the base and modified code. For my tests, I reverted back to the stock code doing a mass erase.

I am waiting for my other discovery kit to come back to validate if it's a problem with the board or with something else that changed. I noticed that at the same time this problem happened CUBE IDE updated the ST-LINK drivers.

It's very peculiar to me that I have never seen the board become unresponsive (i.e. disconnecting me from the debugger, normally if I did something wrong a fault would be triggered and the board would get stuck in one of the fault handlers of the code.