STM32U385: Is there any way to save data autonomously in Stop mode without CPU wakeup?

[taebee00]

I'm working on a project using the STM32U385 and I'm trying to find a way to detect a specific condition and save data while the device stays in a low-power Stop mode — without waking up the CPU to do the saving.

Is there any peripheral combination or hardware feature on the STM32U385 that allows:
1. Detecting a condition (e.g., via Comparator, ADF, or LPTIM) while in Stop mode
2. Saving/writing data to memory autonomously — still in Stop mode, without waking up the CPU

If this is not possible natively, is there a recommended approach or workaround for this use case on the STM32U3 series?

Thanks in advance!

[TDK]

Yes, autonomous peripherals can be active in some stop modes without waking up the CPU. There are several to choose from. LPTIMx will work.

Per the reference manual:

[Ozone]

> ... I'm trying to find a way to detect a specific condition and save data ...

And what does "saving data" entail ?

[Gyessine]

Hello @taebee00 
Based on the product Datasheet , and if I understood your request correctly, it should be feasible.
You can use GPDMA1 because it can operate in stop mode and supports autonomous data transfers during low-power modes.
Consider using LPTIM or LPUART to detect your specific condition.
BR
Gyessine

[taebee00]

Thanks for the responses.

I'm trying to save pin state changes (LOW <-> HIGH) while the MCU is in low-power mode, not after waking up in Run mode.

Is there any feasible approach among the solutions mentioned here?

[TDK]

Timers can capture pin state changes. Look up input capture mode.