Sugarcube - a tactile music controller

This project has the potential to be expanded upon quite a bit. Unfortunately, I just don't have the time to invest in exploring all the possibilities, but here's some ideas I had for things to look into:

More apps: The current implementation of this device allows you to boot into 16 different applications, but I've only written seven so far. There's a ton of great ideas over on the monome website for grid based controllers, it'd be great to see some of that translated into Arduino.

Gyro Control: As I mentioned earlier, I threw an x/y gyroscope in the controller, but I've yet to write an app that actually uses it. I'd love to hear if someone has an idea for how this could work with MIDI.

Wireless: When I started this project, my major design objectives were portability and plug and play ease of use. I wanted to try to break away from the model of the electronic controller that necessitates a computer to run, in an effort to bring electronic music out of the traditional studio environment. In keeping with that idea, I'd like to eventually get this controller to wirelessly send MIDI to my phone to make it totally portable. I have one of these bluetooth boards from Red Bear Labs, and I think there might be some way to send the data to my phone, translate it into CoreMIDI and run it though a MIDI synth, but I just haven't explored the idea enough yet. If anyone has any insight, I'd love to hear your thoughts.

For the final firmware, I've extracted all the code that controls the buttons and leds into a library to make it more tidy, all of this is in a class called SugarCube. I was inspired by the work I've been doing on the Instructables iOS app, and wrote the event handling pieces of the code so that they work in a similar way that an iPhone deals with touch and other gestural events. Basically I created a set of methods that each app can subscribe to, things like "deviceWasShaken" or "buttonPressed". When the SugarCube class detects one of these events, it tells the current app to execute the corresponding method. If you're interested in seeing an example of this structure in action, check out SimpleMIDIKeyboard.cpp, it shows how few lines of code are needed to wire up all the button and analog controls to MIDI outputs. I hope to eventually write out a little more complete documentation for how to write your own apps based on this framework, please let me know if there is interest. This is by far my biggest piece of C++ code, and I am by no means an expert in C++, I'd love to hear an expert's thoughts on how I did!

https://github.com/amandaghassaei/Sugarcube-Arduino-Library

I borrowed an idea from my friend Mads Hobye for my enclosure. Mads founds these sleek boxes at the container store and used them to make project enclosures for the various musical instruments he's built. These boxes are particularly convenient because they have a bevel around the top that allows you to easily mount a 5mm acrylic front panel.

I used a laser cutter to cut out two USB ports (one for the Arduino and one for MIDI out) in the bottom of the enclosure. Then I used a drill to make holes for two pots, a power switch, and a charging jack.

I laser cut a front panel from translucent white 5mm acrylic so that it would snap fit into the wood box.  This has stayed fairly secure so far, but I think it might be made better with some kind of magnetic snap.

Two 74HC595s (wired in parallel) will be driving all the LEDs in the project as well as providing power to all of the buttons. The 74HC595 is an 8 bit serial in parallel out shift register. I've written a detailed tutorial about multiplexing with the 74HC595, and you can find more info about this chip on its datasheet.

Each 74HC595 can only source 70mA at a time for all its pins. With the 100ohm current limiting resistors, if all 4 LEDs in a row are on at the same time (with multiplexing this is the max number of LEDs that can possibly be on at the same time), they will each draw about 18mA which puts the current requirements slightly above the 70mA maximum rating. I'll be drawing additional current from pins Q0-Q7 to multiplex the buttons (in later steps). An easy solution to this problem is to add another 74HC595 to the circuit, it will be wired parallel to the current 74HC595 (see schematic). This will give me additional 70mA to draw from on all 8 pins.

The 74HC595 can only do parallel output, so I used a 74HC165 to measure the state of the buttons via 4 current limiting resistors and send this information to the Arduino. More info about the chip can be found on its datasheet.

More info about wiring and schematics can be found in the instructions section.