Im using an Arduino nano, and am only using one audio channel. Also I am using a preamp buffer and lm386 to boost the audio signal going into the arduino analogue in.
Its working well apart from a couple of things which I was wondering if anyone might have any input on:
Firstly one of the analogue inputs on the nano has stopped working altogether, pin 3, being used for the voltage divider pot to control effect parameters. The other two pots are wired identically and work well, so Im not sure what went wrong, Im currently just using other analogue inputs and leaving the seemingly dead one, which is fine for now.
Secondly, the control pots are quite jittery. The values received jump around a bit which sounds quite glitchy (kind of cool but would be nice to know how to stabilise it somewhat). I tried putting 1uf capacitors between the ground and analogue in legs of the potentiometer which does seem to make the input smoother.
Would be great to hear any ideas or advice on this!
Unless you're using exactly the same hardware that the article author used, you should make double-sure you understand what he's doing, and why.
My first thought on the dead pin is that it was simply burned out from being overloaded at some point. Still, you can check to make sure you've got continuity (zero resistance) between the board pin and the chip pin.
The noise on the control ports is almost certainly due to "dirty" pots - that is, pots that aren't making good contact between the wiper and the resistive element. You can try spraying some canned air or contact cleaner in them to see if that helps. If they're basically DC voltages going into the board, try adding smaller cap values (.1 or .01 u) from the pin to ground to filter the noise; there is a relationship between cap values and the AC component they can handle -- the smaller the cap value, the higher the frequency. If the noise is more "treble" than "bass", use lower value caps.
For the audio input, I'd suggest getting a non-polarized electrolytic cap (maybe 100u) and put it in SERIES with the input -- that'll block the DC component of the signal, but let the AC through; it should convert that -1 to +1 signal to 0-2V.