STM32L431 brown out.

[LeventF16]

Hello.

How can we enable brown out for this processor and the brown out voltage?

Thank you.

[Tesla DeLorean]

Perhaps it's covered in the Reference Manual, or there are examples in the code trees of CubeL4 ?

[Tesla DeLorean · Accepted solution]

Some mechanics along the lines of..

    // Read the option byte
    FLASH_OBProgramInitTypeDef OBInit;
    HAL_FLASHEx_OBGetConfig(&OBInit);

    // Check bitwise if the brownout level is not 3
    if ((OBInit.USERConfig & OB_BOR_LEVEL_3) != OB_BOR_LEVEL_3)
    {
        // Set the brownout level to 3
        OBInit.OptionType = OPTIONBYTE_USER;
        OBInit.USERType = OB_USER_BOR_LEV;
        OBInit.USERConfig |= OB_BOR_LEVEL_3;

        HAL_FLASH_Unlock();
        HAL_FLASH_OB_Unlock();
        HAL_FLASHEx_OBProgram(&OBInit);
        // This function needs to be called Unlocked Flash and OB state.
        HAL_FLASH_OB_Launch();
        HAL_FLASH_OB_Lock();
        HAL_FLASH_Lock();
        HAL_FLASH_OB_Launch();
    }

[TDK]

You can adjust it in STM32CubeProgrammer along with other option bytes.

[CGadg]

Is the option byte available in Cube IDE? I can't see it.

I've used the above code after initialisation and think it should be before initialisation, or better still in the option byte without a routine to change it.

[TDK]

No. Use STM32CubeProgrammer.

[CGadg]

I've moved the code posted above to immediately after HAL_Init() and it runs OK. I haven't seen any problems yet from slow powering up that I was seeing before. I'm very surprised ST didn't include that in the IOC section. I will use it from the Cube Programmer unless anyone finds it lurking in the IOC anywhere. Device is STM32L412