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Message started by rux on 04/04/08 at 07:45:46

Title: hi! and sensor interferences
Post by rux on 04/04/08 at 07:45:46
hi all!

first of all i'd like to introduce myself to (and apologize for such a troubled start!).
my name is Rui, portuguese boy currently living and studying in ny, finishing my master at ITP.
I've started playing with the wiring board a couple of weeks ago though i've been playing around with arduino boards for some time now.

anyways i'm having some trouble with two analog sensors readings and hope anyone can help me:
i have an fsr and a touch linear pot (spectraSymbol's softpot) connected to two analog inputs. When i'm not pressing the softpot i get some noise but funny enough when i press the fsr the noise values from the softpot also increase, decreasing when i stop touching the fsr.
does anyone have an idea why this is happening, suggestions, directions?



Title: Re: hi! and sensor interferences
Post by Titus on 04/04/08 at 09:47:20
could you post some code and how you wired it?
What wiring version are you using?


Title: Re: hi! and sensor interferences
Post by rux on 04/07/08 at 04:52:55
hi Titus!

i/m using a wiring mini board running on 10.
i tried running it on an arduino board and the same thing happens..
i'm using simple message system to send to max-msp, even when running the example code gives me the same results.
i'v added a delay between readings and nothing changed either...
i believe i must be having some kind of interference on the circuit but can't find what going wrong.

here r some pics::



Title: Re: hi! and sensor interferences
Post by Vaccumdiode2 on 04/07/08 at 17:22:16
        If I understand you have two potentiometer hooked up and your trying to read them.  This may not be the answer both I have had problems with potentiometers.  If they are old, dirty or low quality.  You can check the with an ohm meter to make sure that they are in good work order.  Remember even new part can be bad.  

 It was the first thing I thought of when I read your post.

      The another thing is your power source could you some trouble.  If you are using a switch regulated power supply, you are not give the potentiometer an analog voltage.  youmay need to put a digial to analog converter circut, to turn the pulses in to an analog smooth analog signal.  I had to make a couple of these for my motor controls for my robot using the analog out(PWM) of my wiring board.  It is simplely a resistor and a capasistor.  The Cap charges to the voltage and the discharges it when the pulse ends.  That way you get the voltage your look for.

          Hey an another thing could be your delay in the program.  If it is too long in one statement it can do strange things.  I had to break it up into three delay statement once to get it to work.

Last one...  you could try using a newer version of the wiring solfware.  We are currently using ver 00015.

Good luck.


Title: Re: hi! and sensor interferences
Post by rux on 04/08/08 at 07:55:03
hey thanx for the suggestions!

i'm using wiring 15 too (messed version numbers with arduino..) and already smoothing with the capacitor.
i'm using the power from the usb adapter, should i go for an external power source?
i'd really like to keep on getting the power from the computer usb..
there's some wrong in my circuit definitely..
i've replaced the fsr with a potentiometer and increasing its values also increases the other sensor noise values.

thanx for your help!


Title: Re: hi! and sensor interferences
Post by rux on 04/12/08 at 19:27:48
grounding the spectrasymbol sensor's data channel solved it.


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