[PD] arduino problem with analog sensors

[Andy Farnell]

At a guess, the two transducers are not adequately decoupled with
respect to the power supply and I'm guessing the potentiometer is
a fairly low resistance and the pressure sensor has a high resistance
so that their respective current flow changes are very different.

Solutions could be to either

1) Change the power supply to something that can source a higher
flow - is it a USB powered thing?

2) Put a big (33,000uF or 68,000uF) capacitors across each sensors
supply close to it.
 


On Thu, 12 Nov 2009 18:02:05 +0100
altern <altern2 at gmail.com> wrote:

> hi
> 
> not a PD question I guess...  i dont know much of electrical stuff. i am 
> connecting two analog sensors to the arduino. One is a pressure sensor 
> and the second a potentiometer, they are both from an old icube.
> 
> i noticed that when i raise the potentiometer (analog pin 5) the 
> pressure sensor (analog pin 2) reports values ranging 0 to ~0.16 
> increasing together as the potenciometer goes up. It is like some kind 
> of residual noise comming from pin 5 that goes into pin 0.
> 
> the power cables of both sensors go together to 5v inlet of the arduino 
> and the ground cables go to ground pin, each of the data cable goes to 
> its separate analog pin.
> 
> I am using arduino from Pure Data extended using latest Firmata, so i am 
> just filtering out any value smaller than 0.16 coming from analog pin 0.
> 
> is there anything I am doing wrong? or is this normal?
> 
> thanks
> 
> enrike
> 
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