Disabling IWDG In Standby

[TWood.4]

I'm using a WB55 with IWDG enabled. 

I want to disable The IWDG when the device is in Standby mode. 

I have cleared the IWDGSTDBY bit using STM32CubeProgrammer, but I still get resets from the IWDG.

What am I doing wrong?

[gzj]

2025-04-15 1108

中文：

感谢 ASimo.3 ，我尝试了你的代码，在 STM32U575RI56 上工作正常 ！

实际上，我想用的是 Shutdown 模式，但是发现 IWDG 在低功耗期间仍然工作，通过查看参考手册，我怀疑进入的是 Standby 模式，所以需要办法来 “冻结” IWDG。我检查了进入 Shutdown 的各项条件，都正常，不明白为什么还会进入 Standby，如果有人知道原因，请及时联系我，谢谢！

English:

Thank ASimo.3! I tried your code, and it works properly on STM32U575RI56!

Actually, what I intended to use was the Shutdown mode. However, I found that the IWDG (Independent Watchdog) still operates during low-power consumption. After checking the reference manual, I suspected that the device entered Standby mode instead. Therefore, I need a way to "freeze" the IWDG. I have checked all the conditions for entering Shutdown mode, and they are all normal. I don't understand why it still enters Standby mode. If anyone knows the reason, please contact me. Thank you!

I add one condition and some log:

HAL_StatusTypeDef power_iwdg_frozen(void)
{
    FLASH_OBProgramInitTypeDef OB;

    HAL_FLASHEx_OBGetConfig(&OB);  // get current config

    if((OB.USERConfig & FLASH_OPTR_IWDG_STDBY) ||
       (OB.USERConfig & FLASH_OPTR_IWDG_STOP))
    {
        HAL_FLASH_Unlock();
        HAL_FLASH_OB_Unlock();

        OB.OptionType = OPTIONBYTE_USER;
        OB.USERType   = (OB_USER_IWDG_STOP | OB_USER_IWDG_STDBY);
        OB.USERConfig = (OB_IWDG_STOP_FREEZE | OB_IWDG_STDBY_FREEZE);

        if(HAL_FLASHEx_OBProgram(&OB) != HAL_OK)
        {
            HAL_FLASH_OB_Lock();
            HAL_FLASH_Lock();

            log_warning("HAL_FLASHEx_OBProgram failed\r\n");

            return HAL_ERROR;
        }

        HAL_FLASH_OB_Launch();  // REBOOTS THE MCU

        /* We should not make it past the Launch, so lock
         * flash memory and return an error from function
         */
        HAL_FLASH_OB_Lock();
        HAL_FLASH_Lock();

        log_warning("HAL_FLASH_OB_Launch failed\r\n");

        return HAL_ERROR;
    }

    log_debug("IWDG Frozen in Standby & Stop\r\n");

    return HAL_OK;
}