RTC subseconds count down

KIbra.3 · ‎2023-07-21

I am using the RTC of the STM32L4 Discovery board and have noticed that the sub-seconds are counting down. Is there anyone with an idea on how to resolve this issue?

waclawek.jan · ‎2023-07-21

Why would that be an issue? It's a documented behaviour. Simply subtract the value read out from the subsecond register from the synchronous prescaler to obtain increasing value.

Note, that consistently reading out subseconds together with time/date may be challenging.

JW

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waclawek.jan · ‎2023-07-21

Why would that be an issue? It's a documented behaviour. Simply subtract the value read out from the subsecond register from the synchronous prescaler to obtain increasing value.

Note, that consistently reading out subseconds together with time/date may be challenging.

JW

Peter BENSCH · ‎2023-07-21

@KIbra.3 You could also take a look at this discussion on subseconds, where the (apparent) mystery is revealed a little.

Good luck
/Peter

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KIbra.3 · ‎2023-07-28

Thank you for providing this information. I'd like to know if there is any configuration that may force the RTC to count up instead of subtracting the value.

waclawek.jan · ‎2023-07-28

> I'd like to know if there is any configuration that may force the RTC to count up instead of subtracting the value.

No.

JW