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?

[Sarra.S]

Hello @AlfRomeo, 

Is the RTC correctly configured to use the 24-hour format? 

[waclawek.jan]

As @Sarra.S said above, you probably have set the RTC inadvertently to 12 hour format, probably because of uninitialized struct when calling Cube/HAL functions setting time.

JW

[AlfRomeo]

The format of the hour is still 24 hours, and I haven't changed it

[Uwe Bonnes]

Does the RTC continue with 24:01 ? Otherwise, where is the problem?

[Andrew Neil]

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@Uwe Bonnes wrote:

Otherwise, where is the problem?

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24:00 is never a valid time - it should go from 23:59:59.999 to 00:00

[Andrew Neil]

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@AlfRomeo wrote:

The format of the hour is still 24 hours, and I haven't changed it

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Did you follow @waclawek.jan's link - to details about the issues with uninitialised or incompletely-initialised config structures?

[waclawek.jan]

> The format of the hour is still 24 hours, and I haven't changed it

Read out and check/post the RTC registers content.

JW

[AlfRomeo]

At the time of debugging, the time continued to run after 24:00:00 seconds and changed to 00:00:00 after 39:59:59 seconds, but the week did not increase

[AlfRomeo · Accepted solution]

I don't know why, but after resetting after a power outage, it improved again. The code did not make any changes, except for performing modulo operations after hour, minute, and second when obtaining the clock. Nothing else has changed. At first, after changing this setting, the problem still persisted and there was no power outage. However, after the power outage, the problem disappeared and I felt very confused