Analog Clock runs slow on STM32H747I DISCO board

[Kenwang]

I executed "Clock Example" on stm32H747I DISCO. I found that after two minutes of execution, the analog clock was about 15 seconds slower. After 53 minutes of execution, it was about 5 minutes slower, and it will become slower and slower. I did not add any The program code is in the M7 core. The way I compare is to enable RTC and uart in the M4 core, use the HAL_RTC_GetTime() function to read out the rtc time every second, and print it out through the uart. My question is, If the analog clock really slows down, is there any way I can correct it without users noticing?

[Imen.D]

Hello @Kenwang ,

Did you test with smooth calibration ?

Check the calibration Settings (RTC_CALR register setting).

Are you using an external crystal or with an external clock?

Please check the section "Verifying the RTC calibration" in RM0399.

[Kenwang]

I have compared the time on the computer, it is really slow, and if you stare at the screen, its second hand will sometimes stop for a long time.