The competition rules stated that the bend had to cost less than $70 dollars, run off 9V batteries, and be repeatable. Source code and schematics will be available via GitHub in the coming weeks (once I clean it all up)
I bent a Yamaha DD6 to mash up drum samples using an iPad.
I used an Atmel XmegaA3BU Xplain board as the brain along with an Intersil crosspoint switching matrix IC. The Xmega communicates with an iPad via USB by functioning as a class compliant USB MIDI device. There are 3 buttons on the board; an up, down, and enter button. When the device first powers up, it is in the "HOME" screen. The "HOME" screen also acts as a way of clearing a preset so the DD6 can go back to stock when using the device, by pressing enter when "HOME". Any of the 10 presets can be recalled by scrolling to them and pressing enter. The last position in the menu is a "RANDOM" setting which creates a random preset.
The app on the iPad allows you to make connections on an 8X16 grid, which creates 3.4e38(!!!) possibilities. Using the iPad, you can save your preset to one of the 10 available preset locations on the device. With the iPad, you can also clear all the connections or make them all.
I also added a sync out from the DD6. This sync allows me to clock an external sequencer or even a Korg Volca.
Here are some of the videos:
This video is actually the last video, but it includes a discussion of the overall project and sound demos at the end.
Going over the hardware.
The iPad app and it's code
XMega firmware code