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! 

[STackPointer64]

Hello @suresh kumar1,

Yes, that is possible by unchecking the IWDG_STOP option byte in STM32CubeProgrammer after connecting to the board.

As for example code demonstrating IWDG operating in stop mode, there isn’t any for this specific use case. However, you can check the following examples and draw inspiration from how IWDG is implemented in them.

• STM32CubeU0 IWDG examples 

Best regards,