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In this instructable I will show you how to make a basic MIDI instrument using an Arduino Uno. This instrument plays three notes (a triad) in a row. Using the different potentiometers, you can move up and down the notes as well as up and down a scale. You can also control the delay between each note. I feel like I learned a some interesting things about MIDI controllers from this project and I hope you will too.

This instrument is a really basic version of an arpeggiator. Here is a video of a fancy one in action. Arpeggiators exploit the natural musicality of chords to make a lot of nice sounding noise for not that much effort. They often come as part of synths where you just hold down the chords you want to be arpeggiated. In this example, we have only have one button that trigger the arpeggio and three buttons to control what the starting pitch is and its position on the scale.

For the arduino Uno, the easist way to use the MIDI protocol is over the Serial port. It takes some configuration for this to work on Windows, which I will go over. I used the Ardunio MIDI library by FortySevenEffects. I also followed these excellent youtube tutorials: MIDI for the Arduino, How to construct a MIDI controller with an Arduino. I based the code for controlling the buttons and the potentiometers from the code from the second video series. It is really well documented at part of an entire free course on making MIDI controllers.

In this project I used the Grove Starter Kit Plus for the RGB backlit LCD screen. This is not strictly necessary, but it is nice to see what notes you are playing.

4 potentiometers (I used whatever I had lying around)
1 Button
1 1k resistor for button
1 Arduino Uno
1 Grove Starter kit/ RGB backlight LCD (optional)
Wires for connecting pieces
For the computer

DAW (I am just using a trial version of Ableton right now. Cakewalk is free)
Hairless MIDI (A serial bridge— something that converts your serial output to MIDI input)
Loop MIDI (Creates virtual loopback ports for your computer. )
Arduino IDE

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