Using VREF pins for pots that don't reach ADC=0 or 255

[Acetronics2]

It would be nice to see the electrical scheme of your test circuit ...

pics lead me to think it's a hardware / wiring problem ... as Richard nailed it

Alain

[Demon]

I'll try the batteries tomorrow.

Here's a view of the breadboard. I removed a 2nd pot with switch, and left just the essentials.




I still don't understand how 15mV at VREF- is not able/sufficient to deal with 1.5mV at the pot...?

[Demon]

ADC still only goes down to 12 even when battery-powered and other breadboard disconnected (3 new alcaline 1.5V).

Vref- of 15mV still connected.




I always thought battery-power was essentially noise-free (in a "clean" environment); either a straight line going up when charged, or slowly down when powering a circuit, or even much slower down over time when disconnected.

I don't get it.