STM32U0xx BOR_EN Factory Value

[TSN]

Hi!
In version 4 of the reference manual for STM32U0, it is suggested that BOR is enabled and on Level 3 from the factory.
Is that correct?
I'm currently working on an construction running @ 2V, so it would never start up, if so. And when I read out the Option Bytes on a new MCU, BOR is disabled?

https://www.st.com/resource/en/reference_manual/rm0503-stm32u0-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf

[Gyessine]

Hello @TSN and welcome to STcommunity!
Based on the product reference manual, level three corresponds to 2.8 V, so 2.0 V is not sufficient.
You can upgrade your power supply to a minimum of 2.8V, or modify the BOR_LEV bits in the FLASH option register to set the desired voltage.

Also, you can use STM32CubeProgrammer to verify and make sure of the current BOR value.

Hope that helps!
Gyessine

[TSN]

Hi!
And thanks for the reply.
However, I think my question was misunderstood.
My construction works fine and is is running fine @2V. But I never programmed the Option Bytes.

That is why I suspect that there is an error in the reference manual, as it looks like the BOR is disabled from the factory, which is the opposite of what is written in the manual.

Best regards!
/Tommie