> Am I barking up a tree of frustration, or can this work reliably?

Hi Josh,

Here's a simple practical keypad example -

https://www.flickr.com/photos/97814409@N04/29128519532/in/album-72157672972=
293475/

I've seen other resistor ratios. My voltages are perhaps a little closely
spaced but it's reliable. The minimum spacing is 0x11 between the '7'
and '4' buttons, which is easily discernable by the ADC, even when
using Vdd and Vss as Vref

I've done something similar with a 1P12W rotary switch and a "10-
position" pot (a springy metal strip on the pot shaft falls into detents
in the panel)

A 10-bit switch is getting quite fine though, particularly if the ADC is
10-bit. As Jean-Paul suggests, this would suit R-2R thinking, although
the precision of the resistors becomes more important as bit-width
increases

https://en.wikipedia.org/wiki/Resistor_ladder

"resistors of 1% accuracy would suffice for a 5-bit circuit .... For a 10-
bit converter, even using 0.1% precision resistors would not guarantee
monotonicity of output"

So 2 x 5-bit is going to be the least troublesome

Joe=20



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