RTC Low Power Wakeup in STM32U385xx

[alxm]

Update:

I found out that HAL_PWR_EnableWakeUpLine() must be enabled to wake up the system.

The system now wakes up correctly from Stop3 mode. With the SMPS enabled and all pins configured as analog, the current draw is approximately 5 µA, which matches the values given in the datasheet.

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Hello everyone,

I am working with NUCLEO-U385RG-Q board and using the RTC wake-up timer as the wake source for low-power modes. I noticed consistent differences between STOP2 and STOP3:

Issue

• The RTC wake-up interrupt works reliably in STOP2.

• The exact same configuration does not wake the system from STOP3.

Configuration

• LSE is running (32.768 kHz crystal).

• RTC is clocked from LSE.

• RTC wake-up timer is configured via HAL_RTCEx_SetWakeUpTimer_IT().

• No other wake sources are enabled.

Questions

1. Are there additional registers or power settings required for STOP3 to allow RTC wake-up events?

2. Does STOP3 disable any internal domains used by the wake-up timer?

3. Are there known limitations or errata regarding STOP3 + RTC WUT on STM32U-series devices that i may have overlooked?

Any hints or confirmations would be very helpful.
Thank you!

[Gyessine]

hello @alxm 
So do you confirm that you resolved your issue?
BR
Gyessine