STM32H523CE RTC wakeup

[thansen]

I want to use the on-board RTC while all power (except VBAT which will be connected to a battery) is turned off to retain the clock.

Is it possible to power the on-board RTC from VBAT and turn off ALL other supplies?

What will happen after the other supplies are turned on again together with a POR?

Can one of the VBAT GPIOs be used to signal an RTC event with only VBAT powered (want to use this to wakeup)?

[waclawek.jan]

> Is it possible to power the on-board RTC from VBAT and turn off ALL other supplies?

Yes. That's the purpose of VBAT.

> What will happen after the other supplies are turned on again together with a POR?

What would you expect to "happen"?

> Can one of the VBAT GPIOs be used to signal an RTC event with only VBAT powered (want to use this to wakeup)?

I don't know what do you mean by "RTC event", but reading the Power, RTC and TAMP chapters in RM will answer your question.

JW

[PGump.1 · Accepted solution]

Hi,

Yes you can. Use the RTC_OUT pin to control VCC.

Kind regards
Pedro

[thansen]

I want to wake up at a specific time.

[thansen]

Thank you Pedro I think that answers my question.

[thansen]

Thanks Pedro for the precise answer.