RTC precision on H573I-DK board

emd64 · ‎2025-11-21

Hi,

I'm running test on the Discovery board H573I-DK.

On a 24 hours period, I measure a 340 ppm precision that is far from the 20 ppm of the LSE Quartz.

Is it normal ?

Uwe Bonnes · ‎2025-11-21

Did the board run to slow? If yes, was the board running continious or did resets happen as caused by loading a new programm. It is quit easy to stop the RTC for some short period during programm startup while the startup code checks the status of the RTC.

mƎALLEm · ‎2025-11-21

Hello @emd64 and welcome to the community,

Refer also to this knowledge base: How to calibrate the STM32's real-time clock (RTC)

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

waclawek.jan · ‎2025-11-21

> I'm running test

What test?

> I measure a 340 ppm precision

How do you measure that?

Read out and check/post content of RCC_BDCR and RTC registers.

Also, as @Uwe Bonnes said above, Cube/HAL used to (and may still do?) cause RTC to be delayed upon each reset.

JW