Make Roland Juno sysex messages from sensible MIDI CC messages.
Arduino JavaScript
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Control Roland Alpha Juno 1, 2, 106 & MKS-50 with MIDI CC, instead of SysEx

All decent MIDI sequencers speak CC, but being able to speak SysEx particular to these synths is harder to come by. This code, when placed on an ATMEGA8/168/328 will do the conversion for you, and allow your computer/ipad/sequencer to get romantic with your Juno.

There are 2 versions. One is a software implementation, and one is an Arduino-based version. I made several options for putting it together in either form.

Software Version

I made a CLI-version, and a GUI version.


To install the CLI dependencies, run this, in the software directory:

npm install

You can get help with:

./junosex --help


I only tested this on Mac, so that is the only platform I included, but the process should be fairly similar. For Mac, just extract software/, and run. For other platforms, you can run npm install to build MIDI, put the contents of junosex.nw (make package.json be in root) into a zip file and change the extension to .nw, which should make it run if you have the node-webkit runtime installed. They also have some info on building a stand-alone app on their site.

The build process is the same as CLI, using the software/junosex.nw directory and the node-webkit runtime for your system. I had to use nw-gyp to make it build the MIDI library for 32bit (a current limitation of node-webkit: Mac requires 32bit versions of everything.) but Mac-peeps should be covered with premade zipfile.

Hardware Version

The hardware version can be made with an Arduino and a MIDI shield or MIDI breakout, or you can make it on a custom PCB with an ATMEGA chip, or a cheap-o USB-to-MIDI adapter and an ATMEGA/Arduino.

The Arduino MIDI Library is required. I compiled the code in the Arduino IDE.


The arduino/shield route just requires that you put them together, and run the Arduino code (junosex.ino.) This should take about 5 minutes to complete.


Follow the schematic to put it together. I will provide better instructions, later. I used ArduinoISP running on a teensy to program an ATMEGA8. I used a resonator to be cheap and lazy (rather than a crystal and 2 capacitors.)

If you want it to run on batteries, use a 9V battery and a 7805 regulator.

I made a full parts list, for mouser, to build what is listed in the schematic. I just picked parts that are cheap and available. Feel free to choose replacements.

cheap-o USB-to-MIDI adapter

If you are using a cheap-o USB-to-MIDI adapter, you can open it up, and solder the wires direct to TX/RX, and use the power/ground from USB (inside adapter) to make it all simpler/cheaper.


Feel free to modify. This thing is super-simple.

Some ideas:

  • put RGB LEDs on PWM pins, for cool light-effects when different control messages are sent
  • add knobs to change how CCs are interpreted, or set values directly
  • Attach wireless to it for cheap, so you can hide your computer/sequencer.