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Enabled the RTC_CLOCK_SOURCE_LSE in RTC_TimeStamp example application

Nagaraj1
Associate II

Hi,

I am trying to use the RTC_TimeStamp example application provided with the STM32H743I-EVAL board, I've enabled the RTC_CLOCK_SOURCE_LSE in main.h to use the Low-speed external oscillator as a clock source for the RTC.

The problem is that even though i enabled the LSE, when i power cycle the board, RTC doesn't keep up the latest time, it resets to the old time only. When i refer to the user manual of the eval board, to provide OSC32_IN, the R18 to be removed and SB1 shall be closed. Can you please confirm, without making these HW changes, the LSE cannot be configured?

Thanks

Nagaraj

1 REPLY 1
Peter BENSCH
ST Employee

You misunderstood: the definition of RTC_CLOCK_SOURCE_LSE means using the 32768Hz crystal X2 on the EVAL board. SB1 (if set) is there to feed OSC32_IN when using an EXTERNAL clock of 32768Hz, i.e. from a clock source existing outside the EVAL board.
So you should leave R18 populated (or restore it with a solder bridge) and leave SB1 open.

Hope that helps?

Regards
/Peter

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