NUCLEO-H755ZIQ "Bricked" behavior after unplugging during debug session

[AraceliGuerrero]

Hi everyone,

I think I’ve messed up my NUCLEO-H755ZIQ board. A few days ago, I accidentally unplugged the board while an active debug session was running. Since then, the board "dies" every time I power it off.

To get it back to a working state, I have to follow this tedious process every single time:

1. Set Boot0 to VCC.

2. Connect via STM32CubeProgrammer (Power Down mode).

3. Perform a Full Mass Erase.

4. Disconnect and set Boot0 back to GND.

5. Connect again and flash a simple .elf file (a basic SPI project that toggles an LED) just to verify it's alive.

6. After this, I can debug normally in CubeIDE—until I power cycle the board again.

This was manageable until I started working on a Bootloader project. Today, it took me all morning to recover the board because the bootloader logic seems to interfere with my "recovery" steps.

I’ve already tried messing with Option Bytes and performing several mass erases, but the issue persists. It feels like the flash or the option bytes are stuck in a state that prevents a normal cold boot.

Has anyone experienced something similar? Any idea which specific Option Bytes or sector settings I should check to fix this permanently?

Thanks in advance!

[mƎALLEm]

Hello,

What power configuration you set for that NUCLEO-H755ZIQ? you need to set the power as Direct SMPS otherwise you break the MCU. The default power mode for that board is Direct SMPS.

As the following:

[AraceliGuerrero]

I don't have that option available. I can't remember which of the many features I enabled caused a conflict, but it has disappeared from my valid options. These are the only ones I have left, and LDO is currently selected.

 

[mƎALLEm]

Because most probably you have set the system clock > 400Mhz.

Direct SMPS is only available at System frequency <= 400MHz (VOS1) 

So set the system clock at 400MHz and Direct SMPS option will appear.