[PD] Arduino, any feedback to help me choose the model?

Martin Peach martin.peach at sympatico.ca
Sun Apr 10 17:28:21 CEST 2011

Probably the thing will read quieter if the pots are lower resistance. 
The data sheet for the atmega microcontroller used in the arduino says 
hat the impedance of the analog source should be less than 10kOhm. Also 
putting a .1uF capacitor from the analog pin to ground will smooth out 
glitchy noise. (And averaging a few values in software helps too.)

The arduino can send its data as MIDI by using two 220 Ohm resistors 
(one from 5V to MIDI pin 4, the other from TX to MIDI pin 5, ground to 
pin 3) and a baud rate of 31250. That can eliminate noise caused by the 
USB connection, but you have to program the MIDI messages yourself 
instead of using pduino, as well as powering the arduino from a battery 
(quiet) or AC adapter (noisy).

I have built a MIDI pedal that uses an optical sensor to detect the 
pedal position. It is much quieter than a potentiometer.


On 2011-04-10 10:56, Pedro Lopes wrote:
> You can filter out some noise if that happens. I have done several
> arduino projects (namely public installations or sculptures with
> sensors), one thing I learned is that you can always filter the (some)
> noise, by ignoring some values and so forth.
> Another fun aspect is that in public installations whenever I connected
> the arduino to the AC power outlets (instead of battery) the noise was
> much higher. (which makes sense, since AC powers of houses, steet, etc..
> are actually noisy (have you ever noticed that AC induces noise on most
> laptop on-board sound-cards - due to ground loop and so forth) )
>  >use i wanted to use a pot to control a delay length (you can hear
> gliches if the delay length jumps from one value to another rapidly).
> But don't panic about it, its workable. You can defined thresholds, and
> if it varies withing a certain range you will not consider as the pot
> has moved, if you do not have noise: even better. But electricity is not
> perfect, components are definitely not perfect either :)
> Best,
> Pedro
> On Sun, Apr 10, 2011 at 3:50 PM, Pierre Massat <pimassat at gmail.com
> <mailto:pimassat at gmail.com>> wrote:
>     uctuate a little"? This could be anoying if they fluctuate too much,
>     because i wanted to use a pot to control a delay length (you can
>     hear gliches if the delay length jumps from one value to another
>     rapidly).
> --
> Pedro Lopes (MSc)
> contact: pedro.lopes at ist.utl.pt <mailto:pedro.lopes at ist.utl.pt>
> website: http://web.ist.utl.pt/Pedro.Lopes /
> http://pedrolopesresearch.wordpress.com/ | http://twitter.com/plopesresearch
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