RTC Calibration

Forum|Forum|1 year ago
May 5, 2025
2 replies
467 views

I have selected the RTC calibration as 512Hz. Will I be able to perform RTC smooth calibration if my frequency obtained on the RTC calib pin is beyond the range 511.75Hz - 512.25Hz.

How do I calibrate the RTC beyond this range ??

STM32G4 series

TDK

Super User

From the reference manual:

The RTC frequency can be digitally calibrated with a resolution of about 0.954 ppm with a
range from -487.1 ppm to +488.5 ppm.

If your crystal is outside of those limits, you will be unable to calibrate it with this method. Since crystals are typically accurate to well under 100 ppm, there is plenty of margin.

If your clock is outside of that range, choosing a more accurate clock source is probably the best option.

"If you feel a post has answered your question, please click ""Accept as Solution""."