RTC time greater than 24 hours

[AlfRomeo]

Hello everyone, I am using an internal RTC on STM32L431. After running for 23:59:59 seconds, the time changes to 24:00:00 instead of 00:00:00, and the week day has not been incremented. Why is this?

[AlfRomeo]

Because the phenomenon disappears after power off reset, no difference can be seen when reading the register

[waclawek.jan]

This is an English language forum. 

JW

[Andrew Neil]

@AlfRomeo wrote:
the time continued to run after 24:00:00 seconds and changed to 00:00:00 after 39:59:59 seconds, 

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Which is exactly the symptom described in @waclawek.jan's link

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@AlfRomeo wrote:

I don't know why, but after resetting after a power outage, it improved again. 

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That could suggest uninitialised data.

Or perhaps data corruption.