I've been studying the code and schematics of the repatcher http://www.openmusiclabs.com/projects/repatcher/ trying to understand how it functions. I've more or less grasped the whole thing and what I actually wanna do is expand it, cause six pins are a bit too few for a modular synthesizer... I have a small idea of expanding pins on the Arduino, either with shift registers or multiplexers (I've managed a couple of things), but I'm really not sure in the first place if this (the repatcher) is really expandable, and secondly, how to go about it. My first though is shift registers, as the whole processing is being done with the digital pins, but I can't really think of a way. First of all, I think that the more pins you use the larger the numbers you need to manipulate, meaning that quite fast you could reach Arduino's limits. Then, the pins that are responsible for the processing are being switched from input to output inside a for loop. Could that be done with shift registers? Any ideas, hints or directions are welcome.
P.S. the repatcher is an Arduino shield that functions as a modular synth interface, controlling Pure Data or Max/MSP.