On Tuesday 17 July 2007 08:03, Alan B. Pearce wrote:
> OK, using the 2.5V reference is straight forward - but I do seem to
> remember that this could be pushing the limits of minimum reference
> voltage.

Actually 2.0V range is the min required on these PIC's.


> But I take it you are looking to use the full A/D range (no of bits) on the
> Vdd/2 input. If using a Vdd of 5V I would be tempted to have an analogue
> input on a Vdd/2 divider, measure that each cycle using 2.5V reference, and
> then measure the desired input again against the 2.5V reference. The ratio
> between the two is then surely what you are looking for?

Ahhh... I just posted about that too.  Would work beautifully (with some math 
in software), if only I had an extra analog input available.  Moving around 
some pins is very difficult as a lot of code files that would need to be 
changed, and I'll need to maintain the old code still for upgrades.  I'm 
sitll evaluating/considering this still as it is a workable option.

Cheers,
-Neil.
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