2024-07-25 02:01 PM
Hi Everyone,
I have a project utilizing a STM32G030F6P6 with a 32.768kHz crystal and the LSE to source the RTC clock. It is exhibiting 2% clock error (which is huge!) over a 10 minute period despite using a 20ppm crystal. I am measuring this error by interrogating the RTC and communicating it to the rest of my system via i2c.
Now, I have read all of the crystal oscillator and load capacitor horror stories, but I have validated the actual crystal frequency by configuring the LSCO to output the LSE clock and it measures a stable 32.77 kHz (limited by the precision of my oscilloscope). In any case, much better than 2% error.
What gives? Can anyone confirm the expected duty cycle of the LSCO signal (I am measuring 40% and cannot find documentation as to what I should expect).
Solved! Go to Solution.
2024-07-26 06:28 AM
It's solved now anyway, but I'm not sure how that would help. If the LSCO is correct, then there should be nothing further to do with the crystal, no?
2024-07-26 06:53 AM
Correct ! I concur what you said . Prescaler is digital before RTC peripheral. Nothing to do in impacting LSCO and LSE