How to Reliably Disable BOR_EN in Production for STM32G0B1RET6

[Anagha_Sasindran]

Hello,

We are currently facing an issue related to the BOR_EN (Brown-Out Reset Enable) option byte during production on the STM32G0B1RET6 .

In our firmware, we do not modify the option byte registers. On some boards, we observed that the BOR_EN bit is enabled by default. When this is the case and the supply voltage is below the BOR threshold (e.g., 2.2V), the MCU enters a continuous reset loop and the application never starts.

This raises a few important questions:

1. What is the recommended approach to ensure BOR_EN is disabled during production flashing?

2. Should this configuration be explicitly included in the production flashing script?

3. Is disabling BOR_EN from firmware a viable solution?

   • Our understanding is that the value of this bit is applied very early during the boot process—before the application code begins execution. If the application cannot start due to a BOR-induced reset, then any firmware attempt to modify the option bytes would never take effect.

4. Is there any configuration mechanism available (e.g., via CubeProgrammer or similar tools) to reliably ensure BOR_EN is disabled before flashing the firmware?

We are looking for a robust and consistent method to ensure that all production units behave as expected at startup, particularly in cases where supply voltage may momentarily dip below the BOR threshold.

Any guidance on this would be greatly appreciated.

[Andrei Chichak]

Also, beware, I've been working with G0 processors this week, setting/clearing BOR_EN and messing with BORF and BORR, with CubeProg and in code, and I've managed to brick 3 processors so far. (for more info and code, see my post that has been moved to software development tools cubeprogrammer.