STM32WB RTC LSI RTC Init Timeout

[ASiva.1]

I programmed the RTC to work on LSI for this application. When I use LSI for the RTC the RTC init goes into timeout, but RTC works fine with LSE. I am using P-Nucleo-WB55 board to test this. Can anyone explain the reason behind this?

[Mecanix]

Sorry for the intrusion, wish I'd be able to help but got the same problem as you have. Unable to use the LSI as part of my BLE application.

Just wanted to drop by to ask if you've had any success and what is it that you did to resolve it, if you did.

Thanks

[ASiva.1]

LSI can be used with HSE as a part of BLE application. when using LSI I added HAL_PWR_EnableBkUpAccess(); after SystemClock_Config(); and it worked. I also still have not found out the exact reason yet.

[Mecanix]

Appreciate the response. Although your solution didn't worked for my application it does gives me pointers as to where to start looking for, thanks! I've neglected looking into power modes so I'll have a look at this and let you know if I come across anything relevant to what you are looking for.

In a meantime I've started a thread on the subject of HSE & LSI config "workflow". Although un-popular to this day I hope it may clear-out why this HSE & LSI hardware set-up works for some and doesn't for both the custom and Nucleo WB55 boards I'm using here. *Note everything works perfectly fine with a NX2012SA part (NDK's 32.768KHZ) so I might just stick to this solution if no answer is provided.

All the best of luck to you and thanks again.

[RMiot.1]

Thank you ! Got the same problem with STM32WB35CC, noticed that RTC fails to init when debug probe is connected (I use SWD) but works normally when SWD is unplugged.

[Amogh]

THANKS!!!! I am developing BLE app as well, and adding HAL_PWR_EnableBkUpAccess() in HAL_RTC_MspInit() function at the end worked for me!

[Vyacheslav]

And the most interesting thing is that STM employees have not yet answered this question.

Guys, thank you very much for solving the problem.