After a couple of requests for a tutorial I figured I’d provide ya’ll with some more information about my arduino midi mixer.
I’m not going to make a step by step tutorial because that’s impractical. If you want to do a similar thing you should customize it to your liking. I don’t need to walk you through drilling the holes and making slots.
The heart of the project is two 4051 multiplexers that expand the analog input capabilities of the arduino board. This link to the Arduino Playground has everything you need to learn how they work: http://www.arduino.cc/playground/Learning/4051
The way it works is each 4051 goes to it’s own analog input. You use the digital pins to select which pin on the 4051 you want to poll. My code switches this digital pins, polls the first multiplexer and then the second. Then it switches the digital pins and reads the next pin on each 4051.
That’s really all there is to it! You could simplify this by taking out the 4051 multiplexers and use the 6 analog pins on the arduino and have 6 controls that are polled and translated into midi signals.
For the USB to Serial communications is all handled by the Roland USB driver: http://www.roland.com/products/en/_support/dld.cfm?iCncd=724&ln=en&SearchBy=RcId&dst=P&iRcId=0000010777&dsp=1
Also check out some of this stuff. It will help explain midi, how it works with the Arduino and help you pick out the notes and controls you need to send: