“What really makes an instrument musical is that a musician decides to make use of it.” ~ Allen Strange, Electronic Music: Systems, Techniques, and Controls (2nd Edition, 1983, p. 2).
This post documents two circuits connecting an Arduino to electronic controls on a breadboard and the programs necessary to generate basic MIDI note commands. These circuits can be used to make music, conduct experiments, or both. For an introduction to Arduino and MIDI, please see Arduino and Midi for Beginners. Or, you can skip all this backstory and just watch the videos: Boogie Bass or Mathematical Midi.