When the arduino is not powered up but the wires connected, the heat pump controller results from the thermistor are all wrong. I guess this is normal but can someone explain ?
When is use my multimeter on the wires' end, the reading are OK (volt). Using the multimeter on the cable connected to the arduino pins, I can see the voltage is lower.
how can I stabilize the arduino analor readings ? When using the multimeter on the wires' end, the reading I get is stable. But in the arduino, it varies a lot. Not in a significants matter but still. I know that the ethernet shield can introduce variance but I'm not getting stable reading from the Uno analog pin as well even with the shield disconnected.
But why is it that when I connect the wires directly to a multimeter, I don't see any variance in the readings ? Question could be : why aren't the arduino reading on the analog pin as stable as the ones I can get on a multimeter ? Is some filtering already built in the multimeter ?