STM32C031C6T6 : wakeup from shutdown mode

[ouss_mans]

Hello,

I'm contacting you regarding a support request concerning the wakeup from shutdown mode of the STM32C031C6T6:

The issue we're facing is that __HAL_PWR_GET_FLAG(PWR_FLAG_WUF2) returns True when I power up my STM32, even though I haven't triggered the wakeup flag (which is tied to a button).

I solve this issue by adding a delay of at least 5 ms before calling this macro.

Does anyone know if this delay is always necessary?

Thank you.

Best regards.

[Sarra.S]

Hello @ouss_mans, 

Please note that the wake up from shutdown mode generates a system reset and all instructions after HAL_PWREx_EnterSHUTDOWNMode() function are not executed, to see if the flag is set or not you need to read it before entering shutdown mode.

And I propose to try this sequence( clearing the flag before entering shutdown mode):

__HAL_RCC_PWR_CLK_ENABLE();
HAL_PWR_EnableBkUpAccess(); 
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2);
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN2_HIGH);
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF2);
HAL_PWREx_EnterSHUTDOWNMode();

[ouss_mans]

hello @Sarra.S , 

Thank you for your response. My issue is that when I turn the power off and then turn it back on, the WKUP flag is set to true, even though I haven't triggered the wakeup pin.

Normally, the wakeup flag should only be true when I press the button (WKUP pin 2).

thank you 

[Sarra.S]

Hello again @ouss_mans, 

To investigate more, I need you to perform this sequence and share with us the value of PWR-> SR1 everytime 

monitor PWR-> SR1 in run mode-> enter shutdown-> trigger wkup pin2-> re-monitor (PWR-> SR1)-> power cycle-> RUN-> re-monitor (PWR-> SR1)-> Again Trigger wakeup pin 2-> re-monitor (PWR-> SR1)

Please let me know if that's clear! 

[ouss_mans]

Hello @Sarra.S ,

here is my code :

And this is what I get when I am in debug mode :

when i am not in debug mode : 

and this is my shutdown function : 

The first thing is that it seems like everything is working right in debug mode, but in non-debug mode, when I press the button (a short press), the device goes to shutdown and wakes up whith just one press.

However, when I do a very, very short press, the wakeup flag is false (PWR->SR1 = 0).

thank you in advance 

[ouss_mans]

So, we added a delay before going to shutdown to see what we get :

This is what we get:

- When I do a short press, the PWR_SR1 equals 0 and the device goes to shutdown.

- When I press the button and keep it pressed, the PWR_SR1 equals 0. After 1 second, it goes to shutdown, and after that, the device wakes up, and PWR_SR1 equals 258.

Thank you.

[MM..1]

Primary you cant activate WUpin when is LOW, then add chcek to release before ...

[ouss_mans]

hello @MM..1 ,

I changed my shutdown function to this: 

int8_t thsthal_shutdown()
{
	LL_PWR_SetPowerMode(LL_PWR_MODE_SHUTDOWN);
	__HAL_RCC_PWR_CLK_ENABLE();

	HAL_PWREx_EnableGPIOPullUp(PWR_GPIO_C, PWR_GPIO_BIT_13); // BTN wkup pin 2
	HAL_PWREx_EnableGPIOPullUp(PWR_GPIO_B, PWR_GPIO_BIT_5); // LED
	HAL_PWREx_EnableGPIOPullUp(PWR_GPIO_B, PWR_GPIO_BIT_8); // I2C_SCL
	HAL_PWREx_EnableGPIOPullUp(PWR_GPIO_B, PWR_GPIO_BIT_9); // I2C_SDA

	HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2);
	HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN2_HIGH);

	__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF2);

	HAL_SuspendTick();
	HAL_PWREx_EnterSHUTDOWNMode();

	return THSTHAL_ERROR;
}

and when I retrieve the value of `PWR->SR1`, it's always 0 when I press the button, although it should be 2.

thank you