Grumpy_Mike:
Could it be that softpots are not homogeneous at all?
Yes that is right.
Oh noes, then I guess I'll have to correct it in the program. Any approach recommended? (if anyone has ever tried a similar thing)
I thought measuring carefully the readings with a ruler and finding the point where deviation is the biggest (e.g.: softpot 1 and 2 at 30cm reading 261 and 232), then calculate the proximity of any reading to that point and use it as a deviation ratio.
Grumpy_Mike:
I'm using 800k resistors as pull-downs
That is very high, it will cause problems when rapidly switching between channels.
You mean channels of a multiplexer? Like signal contamination?
I chose it so because of this article:
Apparently, the linearity improves for higher resistor values.
Anyway in between readings I switch to channel 15 which is connected directly to ground and do an useless analogRead there to clean the signal before the next reading, that seems to work well enough. Also a delay(1) works like charm.
Also there's pressure sensors below the softpots, so I know when they are pressed.
Thanks!