I now see your other post with the computation of the voltage, and that should produce consistent results. So that got me to thinking that I have had problems with totally weird results when my sketch was fairly large and especially when I had many strings. I think that with the limited ram it is possible to run out heap and get some of the variables overwritten. This problem completely went away when I cut down on the number of string and I also try to do as much processing on the Linino side to make the sketch size sampler.So do you think that could be part of the problem?And you posted the last one while I was typing this
add 1M from A0 to GND..Salty water will give you a reading. As now the input is floating..
Quote from: knut_ny on Feb 03, 2014, 10:14 pmadd 1M from A0 to GND..Salty water will give you a reading. As now the input is floating..what do you mean by that first statement ?that i should put a large resistor between A0 and GND ? I had thought this too...my biggest resistor, on-hand, is 10K ohm... would that be large enough ?
It is not the sketch side itself that I had problem with, but rather (I think) the number of string that I used, which would used up variable space with being shown as global variables. For a test try to make your strings a shorter, or even get rid of some of them. I used to make changes in places totally unrelated to where my problem showed, and it went away.Do you have a URL or part number for the sensor or switch you have in the pan.You might not need a ground wire, but since you already have a 10k series resistor, the readings should have been cut in about half, did they? I am assuming they 10k resistor is in addition to the one you added for the test.
OK, I understood that you had a switch or sensor in the pan, now I see what you are doing, so you do need a resistor from A0 pin to ground on the Yun, but 10k will be too small. You need a large resistor like knut_ny is saying, like 1 Mohm.