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Visitor II
November 14, 2025
Question

STM32U585: RTC Wakeup interrupt not waking MCU from STOP2 mode

  • November 14, 2025
  • 3 replies
  • 139 views

I am using STM32WB55 and entering STOP2 mode for low-power operation.
RTC Wakeup timer is configured, and the interrupt works correctly in RUN mode,
but the MCU does not wake up from STOP2 mode when the RTC wakeup interrupt is expected.

Configuration:
- RTC enabled using LSE
- Wakeup timer configured with WUT
- MX generated code + custom low power entry
- NVIC enabled for RTC Wakeup

Tried:
- Ensured RTC interrupt flag is cleared before entering STOP2
- Enabled DBG and checked if STOP2 entry works
- Checked PWR->WUPEN / PWR_SCR flags

Still, the MCU does not wake when RTC WUT expires.

Any suggestions or known STM32WB55 issues related to STOP2 + RTC Wakeup?

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    3 replies

    Super User
    November 14, 2025

    Please provide the full part number of your chip.

    You've indicated STM32U5xx twice and STM32WB55xx twice.

    Technical Moderator
    November 17, 2025

    hello @swapnilnerkar585 
    Could you please specify which product you are using? You mentioned two products.
    In case you are using an STM32WB55

    Here is an example that provides a wake-up from Stop 2 mode using the RTC.
    You can base your project on this example to identify any differences to solve your problem 
    BR
    Gyessine

    Technical Moderator
    December 15, 2025

    hello @swapnilnerkar585 
    just asking about any feedback, Does the problem still persist, or has it been resolved?
    Gyessine