How to find the default level of BOR as well as set a custom level to STM32F103CB

[Shanmugapriya]

Hi everyone,

I'm working with an STM32F103CB in my project and would like to know the default Brown‑Out Reset (BOR) threshold set for this MCU. Additionally, I’m looking for guidance on how to configure the BOR threshold to a custom level.

Any help or pointers would be greatly appreciated!

Thanks in advance.

[mfgkw]

The F103 will be reset if voltage drops below a threshold. According to DS5792 (2.3.2 Power supply supervisor) the threshold value can be influenced by 3 bits PLS[2:0] according to Table 12 "Embedded reset and power control characteristics".

See RM0008 "5.4 Power control registers"

(F103 seems not to have more sophisticated brown out behaviour like F4xx and others.)

DS5792: https://www.st.com/resource/en/datasheet/cd00191185.pdf

RM0008: https://www.st.com/content/ccc/resource/technical/document/reference_manual/59/b9/ba/7f/11/af/43/d5/CD00171190.pdf/files/CD00171190.pdf/jcr:content/translations/en.CD00171190.pdf

[Gyessine]

Hello @Shanmugapriya 
Based on table 11 of the product datasheet, ensure that the voltage does not fall below 2.0 V to ensure functionality at extreme conditions.

and like @mfgkw said, you can modify the power mode by setting the PLS bits in the power control register.

Hope that helps!
Gyessine