RTC shifting in stm32L431

Hi,

I am using stm32L431 and (32.768KHz ±20ppm 12.5pF 70kΩ) as LSE.

Every day the time is update by internet, but in some cases, the clock shifting about 5 minutes.

It occur aroung 2 times to week.

what is probably happening?

Binary data format and Alarm A is used.

Any help I would appreciate.

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Super User

Isn't this still the infamous Cube RTC "initialization" which causes loss of subseconds?

and many other places.

JW

Associate III

Thank for you answer.

But my board sleep and wake up only once a day, after wake up by Alarm it update the time.

But it is wake up about 5 minutes later in some cases, in other cases is working fine.

Super User

OK, then I don't have an instant answer, just some random remarks:

> But it is wake up about 5 minutes later

How do you know?

Can you check, if the time is correct, just before going to sleep, e.g. outputting it to UART->PC or some other suitable way?

If the device does not go to sleep, is there any time shift?

Is there any power outage during sleep? Is there a battery on VBAT?

Can you try the code - or main parts of it - on a "known good" board such as Disco or Nucleo?

JW

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