Associate II

Question

Detect origin of a wake-up from standby mode

Hello !

I have a problem : I'm looking for a way to know the origin of a wake-up from standby mode.

I'm using STM32U083C Discovery Kit.

In my application, MCU can wake-up in two different manners : an external wake-up pin and an RTC periodic wake-up.

The question is : how to distinguish the two after MCU reset ?

I tried :

if (__HAL_RTC_WAKEUPTIMER_GET_FLAG(&hrtc, RTC_FLAG_WUTF) == SET)
{...}

But the flag is never SET...

Thank you in advance for your feedback !

Xavier

Associate II

Any clue, anybody ?

Chief III

Have you interrupt enabled ???

Associate II

Well yes, interrupts are enabled...but not executed as mcu is stopped in standby mode !

My board has no problem to wake up from the two sources : RTC and EXTI button.

After leaving standby, mcu performs a complete reset. Only VBAT domain (RTC and backup registers) is saved).

Chief III

I mean RTC WU interrupt, i mean his flag is set only when WUIE is set. And EXTI not wakeup from standby, only wake pins work.

Associate II

if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUFI) == SET) won't work either...

Maybe no solution ?

Associate II

Thank you MM..1 but that won't help me...

You're right my button is connected to an wake-up pin.

Apparently there is no flag indicating a wake-up from RTC after mcu's reset.

Chief III

HAL have some issue on init , that can reset clear RTC . Try use noinit memory and store flag in asm init part. Standby is hard to debug.How to avoid reset RTC after wake up from standby ... - STMicroelectronics Community

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