cancel
Showing results for 
Search instead for 
Did you mean: 

Wake STM32L4xx from SHUTDOWN using RTC Alarm?

David.Sorber
Associate II

I'm currently using the STM32L4R9I-EVAL board and trying to prototype an application where the microcontroller will need to be in lowest power (i.e. SHUTDOWN) mode for several days or weeks and then wake up to perform an action. I can get the the microcontroller to enter shutdown mode but I can't seem to get it to wake up using the RTC alarm (which works fine otherwise).

The datasheet suggests this is possible: "The device exits Shutdown mode when an external reset (NRST pin), a WKUP pin event (configurable rising or falling edge), or an RTC event occurs (alarm, periodic wakeup, timestamp, tamper)." But I can't find any examples.

Can someone confirm this is possible and if possible point me in the right direction?

There don't seem to be any SHUTDOWN mode examples in STM32Cube_FW_L4 for the STM32L4R9I-EVAL board, the closest example I can find is for the NUCLEO-L4R5ZI board, but that example uses a wakeup pin rather than an RTC alarm. Any help is appreciated.

1 REPLY 1
JGarc.5
Associate III

Hi David,

Here:

https://community.st.com/s/question/0D53W000008kePvSAI/rtc-alarm-not-working-more-than-once

You can find a simple code that wakes up with alarm from Shutdown mode. Anyway I still have a problem with waking up more than once, because it only works the first time I program it with the debugger. The next time the systems is powered it does not wake up from shutdown.

Maybe you can see something different...

Regards,

Jose Luis