>     The internal clock seens to be very stable even at high temperatures,
> but this 3% diference is very strange.

Why?  Microchip only promises the frequency will be from 3.65 to 4.28 MHz,
which is what you are getting.  See DS40300B page 139, parameter number 4.

Note that this accuracy range is unsuitable for RS-232.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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