I am trying to output a somewhat precise, has to be +- 250ppm, 32.768Khz clock on PA22 (GCLK6 output) but I am having a little problem. The chip outputs a clock that is around 32.90 KHz (I've seen it drop to 32.65.) The datasheet doesn't say anything about tolerance or accuracy of the internal clock system. (I am using the external crystal as the input to GCLK6.) I have attached some scope captures and below is the measurement data I captured with my oscilloscope.
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Vpp 5.52V Vmax 3.44V Vmin -160mV Vavg 1.63V Vamp 3.23V Vtop 3.26V Vbase -3.24mV Vrms 2.31V Vover 4.61% Vpre 2.21% Frequency 32.90kHz Rise Time 0.000s Fall Time 0.000s Period 30.40us Pulse Width+ 15.20us Pulse Width- 15.20us Duty+ 50.0% Duty- 49.8%