This iis video number one of a series I will make documenting the construction of a MIDI wind-controller in the form factor of a harmonica. The unit will operate via 7 bi-directional air pressure sensors. I'm using the MPXV7007GP, made by Freescale, which can sense +-1 PSI (about the range of pressure that a normal person can exude by breath force). The sensor data will be fed to a Teensy 3.1 microcontroller board, which is similar to an Arduino. I will write a sketch (C program) that will interpret the voltage changes across the sensors as they are blown or drawn, and translate that to MIDI note data, with velocity information for the "attack". The plan is to also use that data (polling the pressures over time) for overall volume control via MIDI cc messages. This should make for a very expressive instrument! I'll also attach an X/Y joystick to one end of the unit, which will control pitchbend, and possibly octave switching (although I may use some capacitive touch switches for that). There will be a rotary encoder which will let me cycle through keys (transposing), and, if held down, will cycle through different note layouts (richter, solo, natural minor, etc.). A final option could be to add a couple touch switches to make chords out of single notes (major, minor, seventh). THe unit will be capable of both usbMIDI and serial MIDI, so should be able to talk to software and hardware synths, just the same.
Obviously, this is a big project, and it will proceed in stages. Stage one will be to get the Teensy and the sensors talking to each other, and for MIDI data to be output. This will require a basic set of connections and software. Then, I will begin expanding and tweaking the software, adding the other peripherals as the code becomes available to take advantage of them. Finally, I may eventually spring for a custom 3D-printed case for the thing.
I'll document the project as best as I can during each phase, so stay tuned!!!