That is interesting, unexpected, and more than I would expect as 'breadboard effect'.The interesting point is: when I move the brown wire , ADC1 from the right resistor column 47 to the left resistor column 44, then I expect the same voltage. But the voltage on the ADC changes by almost 200mV (!).
I am wondering what happens if you turn the resistors into a Y configuration, their bottom ends into the same breadboard column ?
Unfortunately I don't have any Pico configured for breadboard use so can't do my own experiments at the moment.
One explanation for varying analogue readings when they should be the same is possible mains pick-up inducing ripple, by fluke of timing taking readings for one during peaks the other in troughs. A bit of a long shot though, and one would expect to see variations when repeatedly testing the same position.
Applying a multi-meter, or even better a scope, to each position may help reveal what the issue is.
Statistics: Posted by hippy — Fri May 03, 2024 12:01 pm
