Watchdog functionality in Sleep mode for STM32U535CET microcontroller

[shwetapal02]

Hello,

I am facing reset problem when I am waking up from Sleep mode. I am using WWDG in Software mode.

APB1 Frequency as 40MHz. COnfiguration of WWDG:

hwwdg.Instance = WWDG;

hwwdg.Init.Prescaler = WWDG_PRESCALER_128;

hwwdg.Init.Window = 127;

hwwdg.Init.Counter = 127;

hwwdg.Init.EWIMode = WWDG_EWI_DISABLE;

 

I am calling MX_WWDG_Init function after initialization of peripherals and functionality needed.

Then I am refreshing it in while loop of main function.

1st Tested Scenario:

While entering sleep mode I just refresh the WWDG. Then by waking up

from sleep mode by push button, I am getting reset and it's started from main function again instead of Re-init function.

2nd Tested Scenario:

While entering in sleep mode, I am refreshing WWDG first, then disabling APB1 clock and after that

when I wake up from push button I am enabling the APB1 clock. In this scenario I assumed that WWDG

clock should be stop in sleep mode and it should resume after wakeup.

When controller wakes up by pressing button, I am getting reset.

Please suggest me the setting if I am missing anything.

 

[Sarra.S]

Hello @shwetapal02, Welcome to ST Community, 

Please check this bit in the RCC_APB1SMENR1 register

 

[shwetapal02]

Hello @Sarra.S, 

Thanks for reply. I am setting and resetting the suggested bit by calling below function.

I am calling __HAL_RCC_WWDG_CLK_SLEEP_ENABLE(); after waking up and calling __HAL_RCC_WWDG_CLK_SLEEP_DISABLE(); function during going in sleep mode. But Once it woke up from sleep mode (by pressing button) it is giving me reset. 

I am not able to understand why?

I tried this scenario with WWDG_SW 0 and 1 in both case. But it's not working.

Please help me ASAP.

[shwetapal02]

Hello,

I need support for the above issue on urgent basis. Please help for the same.

Thanks, your understanding and kind support!!

[Sarra.S]

so, just before entering stop mode, refresh the WWDG counter: 

void SleepControlTask(void)
{
 delayStop(&SleepWakeUpDelay);
 SleepACK = false;
 HAL_WWDG_Refresh(&hwwdg); // Refresh WWDG before entering sleep mode
 SleepWakeUpMode();
}
void SleepWakeUpMode(void)
{
 GPIO_deInit();
 __HAL_RCC_RTC_DISABLE();
 HAL_PWR_EnableBkUpAccess();
 HAL_SuspendTick();
 HAL_PWR_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFI);
 __HAL_RCC_RTC_ENABLE();
 HAL_ResumeTick();
 SystemClock_Config();
 HAL_WWDG_Refresh(&hwwdg); // Refresh WWDG immediately after waking up
}

and when exiting stop mode, re-enable the WWDG clock and re-initialize it  

// After waking up from sleep mode
__HAL_RCC_WWDG_CLK_SLEEP_ENABLE(); // Re-enable the WWDG clock after waking up
MX_WWDG_Init(); // Re-initialize the WWDG
HAL_WWDG_Refresh(&hwwdg); // Refresh the WWDG counter

 

[shwetapal02]

Thank you so much for your quick reply. It was really helpful. Now my code is working.

Thanks a lot!!