The simplest MIDI (Musical Instrument Digital Interface) input devices use good ol’ fashioned buttons: push a button and the device sends a MIDI message to trigger a specific note. But that control scheme doesn’t replicate the flexibility of a real instrument very well, because a standard button is a binary mechanism. To introduce more range, Xavier Dumont developed this breath-controlled MIDI device.
This looks like a cross between a flute, an ocarina, and an old cell phone. The front face has 35 buttons to trigger specific notes. But there are two ways for the player to gain almost analog control over the output: a mouthpiece with a breath sensor and a linear touch sensor. The breath sensor lets the player control the intensity of a note by blowing into the mouthpiece like a wind instrument. The linear touch sensor, mounted on the bottom of the device, lets the user bend the pitch of the notes with their thumb.
Inside the 3D-printed enclosure is a custom PCB. Almost every component mounts directly onto that board. The exception is the touch sensor, which connects to the PCB through a jumper cable. An Arduino Micro monitors the keypad matrix, the touch sensor, and the breath sensor. It outputs MIDI messages to a computer connected via USB. There is a TFT screen for the control interface, which lets the user change modes, switch octaves, and tweak settings