Setting/getting brownout reset (BOR) level.

[bobemoe]

I am trying to set and get the brownout reset level on my stm32f4. I think I have successfully got it with:

(FLASH->OPTCR & FLASH_OPTCR_BOR_LEV_Msk) >> FLASH_OPTCR_BOR_LEV_Pos)

But I cant figure out how to change/set it. This compiles but seems not to change anything:

    HAL_FLASH_Unlock();
    HAL_FLASH_OB_Unlock();
    uint8_t New_BOR_Value = 1;
    MODIFY_REG(FLASH->OPTCR, FLASH_OPTCR_BOR_LEV_Msk, New_BOR_Value << FLASH_OPTCR_BOR_LEV_Pos);
    HAL_FLASH_OB_Lock();
    HAL_FLASH_Lock();

Any clues? Thanks

[bobemoe]

I think I figured it out:

uint8_t Get_BOR_Level(void)
{
    FLASH_OBProgramInitTypeDef OBInit;
    HAL_FLASHEx_OBGetConfig(&OBInit);
    return OBInit.BORLevel;
}

void Set_BOR_Level(uint8_t BOR_Level) {
    FLASH_OBProgramInitTypeDef OBInit;

    // Unlock the Flash to enable the flash control register access
    HAL_FLASH_Unlock();

    // Clear any existing option bytes error flags
    __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_OPERR);

    // Unlock the Options Bytes
    HAL_FLASH_OB_Unlock();

    // Get the current option bytes configuration including other settings
    HAL_FLASHEx_OBGetConfig(&OBInit);

    // Modify only the BOR Level
    OBInit.OptionType = OPTIONBYTE_BOR;
    OBInit.BORLevel = BOR_Level;

    // Change the BOR level while preserving other settings
    HAL_FLASHEx_OBProgram(&OBInit);

    // Launch the Option Bytes programming process
    HAL_FLASH_OB_Launch();

    // Lock the Options Bytes
    HAL_FLASH_OB_Lock();

    // Lock the Flash to disable the flash control register access
    HAL_FLASH_Lock();
}