STM32H743 runs in debug mode only

[DGall]

Hi, I have several boards with same issue. After weeks of tests when flashing boards using STLink suddenly the micro is not running except in SWD debug mode. Flash is properly programmed but the micro is not running. A complete flash erase (all sectors) is not able to recover the board. Even If I program microcontroller with same fw of a running board it doesn't work. once "stoned" the micro runs in debug mode only. I use internal HSI as clock source.

Hany suggestion to solve the matter? Thanks Denis

[TDK]

Is boot0 pulled low?

What happens if you run the board, then start a debug session without resetting it? Where is the code execution?

How do you know it’s not running?

[DGall]

Hi, I fixed the issue!

I don't know why but during fw update using UART the "BOOT ADDRESS OPTION BYTE" area has been changed, I put the original configuration (see picture) and board started working.

2 questions:

A) How is it possible to change this area? Can it be corrupted during option byte writing operation or flash writing operation? I want to understand how it could have happened in order to fix the issue and avoid problems on the field.

B) Why a a "flash erase" (using ST-Link) is not able to solve the problem?

Thanks a lot Denis

[TDK]

Option bytes and flash are separate. Erasing or programming flash doesnt change option bytes.
You can change option bytes in stm32cubeprogrammer among other options.