> Talking about the internal osc, have anyone run any
> tests with the multiple-speed intosc in some of
> the newer PIC's ? Where you can select intosc speed
> of 31khz, 125khz, 250khz, 500khz, 1mhz, 2mhz, 4mhz
> or 8mhz "on-the-fly". With 125khz - 8mhz calibrated
> to 1%, according to the data sheet. And this without
> having to deal with some callibration variable/register.
> There *is* a OSCTUNE FSR, but that's only used if you want the
> speed to be different then the factory calibrated 8Mhz
> (within 1% over the full temp and volt range).

The 16F818/819 have this feature, but the datasheet says the 1% is
typical, with worst TBD. I am working together with a client on a system
where a lot of 16F819's will be connected to a PC (think ~ 2000). For
cost and pin count no crystal will be used. In a first try asynch
communication was unreliable, so he measured the freqency of 4 16F819's.
There were deviations of -1.5 %, +3%. I now work on pulse-duration
coding that is less sensitive to clock variations.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products

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