Bob:
> > Anybody have any idea how much OSCTUNE 'pulls' the internal oscillator
> > frequency in nanoWatt PICs? (like the PIC18F2320, for example). I
> > couldn't seem to find anything in the datasheets.

Olin:
> I don't think I've ever seen a spec for that.  I think the only thing you
> can rely on is that it can pull the internal oscillator enough so that one
> of the settings results in the specified frequency within the specified
> tolerance.

Bob:
I was afraid of that.

Actually, according the datasheet I was looking at (18F2320), they don't
even specify a tolerance. They say +/- 1 % typical, untuned, but give no
maximum error.

The OSCTUNE on these PICs is a little bit different than we've seen before.
When the factory 'tunes' up the PIC they must tweak some undocumented flash
location to define the zero point. Then OSCTUNE can vary -32..0..+31 from
that point. This has the significant advantage that you don't have to
remember the calibration value before overwriting a part.

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