[sdiy] Reading two buttons with a single IO pin

[Tom Wiltshire]

On 20 Feb 2015, at 23:33, John Speth <jspeth at avnera.com> wrote:

> 
> Word to the wise: Make a very in depth study of tolerance to voltage
> divider ref voltage variations and resistor variations.  Then add a fudge
> factor for unforeseen variations.

Yes, this is important.
Using only two bits of the ADC, I've got simple ranges of 0-0.25, 0.25-0.5, 0.5-0.75, 0.75-1 and I set the inputs up to give 1/8th, 3/8ths, 5/8ths, and 7/8ths - e.g. right in the middle of each range. With 5V, each range is 1.25V, so I've got over 0.5V tolerance in each direction. That should be enough fudge factor.

Tom