STM32U031 doesent wakup from STOP 0 mode after enabling the Window Watchdog.

[suresh kumar1]

Hi Everyone,

I am facing an issue with my MCU entering low-power mode.

My code works fine when tested separately. I can successfully put the MCU into STOP 0 mode and wake it up through an EXTI line interrupt, but only when the Window Watchdog (WWDG) is disabled.

However, when I enable the WWDG, the MCU seems to get stuck at the WFI instruction when trying to enter STOP mode. It doesn’t proceed further or wake up through the EXTI line Interrupt. The only recovery option is a power cycle.

Has anyone faced a similar issue, or know what might cause this behaviour when WWDG is active?

I am open to sharing the source code.

Any suggestions or pointers would be appreciated! 

[TDK]

> seems to get stuck at the WFI instruction

What makes you think this?

Could the WWDG be firing and resetting the chip?

[STackPointer64]

Hello @suresh kumar1,

The issue arises because the WWDG is not operational in STOP mode due to the absence of the APB clock. To resolve this, you can either disable the WWDG before entering STOP mode and re-enable it upon waking up, or use an alternative low-power mode like Sleep mode where the WWDG can function.

Best regards,