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Need RTC Configuration in wakeup counter mode with 1sec wake up time and LSE as Clock source.

User16669512935851271792
Associate II

‎2022-11-14 03:43 AM

Hi Team,

Need the RTC Code base with LSE as clock source in wake-up counter mode and needs to get the interrupt at every 1sec rate.

We have some queries regarding the LSI Clock source which is in example project.

  1. If we use the LSI as Clock, calibration is required continuously or at a certain frequency only it is required, if required at what frequency we need to calibrate.
  2. If we use the LSE as Clock source also calibration is required or not.
  3. Can we give the source code for the RTC in Wakeup counter mode with LSE as Clock source with all register settings and how to calculate the wake-up counter value with all clock pre scalar register settings values.
  4. Reason is as compared to LSI clock LSE is more accurate and calibration is not required in run time, please correct me my assumption is wrong.

Regards,

Srinivas.V

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2 REPLIES 2
Peter BENSCH
ST Employee

‎2022-11-14 04:38 AM

What do you think of the suggestions made by @KDJEM.1​  and @Community member​  in your previous, very similar question?

The need for calibration depends on your accuracy requirements. Calibration has often been discussed here in the community. You can use the LSE and either synchronise it with an external reference frequency (see reference manual), or use the so-called smooth calibration to correct the number of clock pulses entering the RTC, see e.g. here.

Regards

/Peter

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User16669512935851271792
Associate II
In response to Peter BENSCH

‎2022-11-14 10:03 AM

Hi Peter,

Thanks for your reply. I do Understatnd the @KDJEM_1 Reply. In that example used the LSI Clock source and doing the auto calibration by using the another timer, that's where we need the more clarity, it that calibration is continuously required or just based on some condition. In the example code doing the calibration based on user key press.

That is the reason we are asking about LSE Clock source for RTC. How more accuracy as compared to LSI Clock. Just comparing the LSI and LSE Clock sources with respect to calibration Accuracy.

Regards,

Srinivas.V

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