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Topic: Due Integrated RTC time drift (Read 1 time) previous topic - next topic

mantoui

#10
Dec 05, 2013, 12:02 pm Last Edit: Dec 05, 2013, 02:44 pm by mantoui Reason: 1
here are some data on drift of MCU crystals and RTC's including DUE
https://github.com/manitou48/crystals

crystals.txt has the drift data.  drift is affected by voltage, temperature, age, and capacitance.
your mileage may vary.

Here are specs for MCU crystal and RTC from the DUE schematic/bom
  Y1,12MHz KX-7 20pF     CRYSTAL-3.2-2.5           CRYSTAL-3.2-2.5  probably 30ppm
  Y2,32.768Khz,RESONATOR_EPSON_FC_145,RESONATOR_EPSON_FC_145   20ppm 12.5pf

garygid

OK, with about 4000 seconds per hour (really 3600), and
about 25 hours a day, there are about 100,000 seconds per day.

A 10 ppm (parts per million) error, would be about 1 second per day.
One course, then 20 ppm would be about 2 seconds per day.

I will need to check against a better "reference", but I thought
that I got 30 seconds or a minute error in 12 hours, and
sometimes plus and sometimes minus... I will re-test.
Cheers, Gary
Due for controlling Electric car charging.
Nissan LEAF - Mini Quick Charge (mQC)

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