> > Using the F877, I have PortA configured for analog inputs, and had 10K
> pots.
> > Seemed to work ok, I had a watch window set up, and a breakpoint right
> after
> > the read sequences (for 4 pots).
> >
> > I've changed the pots to 50K now, and upped the aquisition time, but the
> > values seem to be way off now, and are affected by each other.
>
> Microchip specifies the A/D source should be 10Kohm or less.  Yours could
be
> 2.5 times higher, so you should either use 20Kohm pots max, or buffer the
> voltages.

As someone else pointed out, this is off by a factor of two.  The highest
impedence from a 50Kohm pot tied to ground and supply at the fixed ends is
12.5Kohms, not 25Kohms.  You should not use anything higher than a 40Kohm
pot, assuming the fixed ends are driven with 0 impedence.


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