Today we're building the 400 key MIDI controller using an Arduino and computer keyboards!

For the budget conscious music producers out there, this project is a great way to build an inexpensive control board for your digital audio workstation.

Or if you're just a musician with an odd taste for instruments, this geeky looking device will surely give you some strange looks.

Step 1: Watch the Video!

Check out this quick video to see how this mega MIDI device translates to an instrument and for a run-through of all the steps below from start to finish.

Click here to watch on YouTube

Step 2: What We'll Need...

We're going to build a box that translates signals from multiple keyboards into standard MIDI out signals.

To do so, we'll need:

An Arduino (I'll be using the UNO, but any other variants will work fine)
2 PS/2 ports (as many as you'd like, as long as there's enough digital pins on the Arduino for it)
MIDI female port
Cardboard
A 220Ω resistor
Perboard
Wires
Keyboards!

Where to buy

Soldering gear:

Weller WES51 Analog Soldering Station: http://amzn.to/2dq7Q4m
MG Chemicals Silver Solder: http://amzn.to/2dHj0nq
Helping hand: http://amzn.to/2dc553O

Testing gear:

Multimeter: http://amzn.to/2dc54N6
Breadboard & Jumpers: http://amzn.to/2dHknm2

Step 3: Prepare the PS/2 Ports

Push a piece of perfboard through the bottom pins of the PS/2 ports to make soldering easier.

Clamp the PS/2 ports in place and solder wires to the four pins of each of the PS/2 port that we need to access (they are the Vcc, Ground, Clock, and Data pins - see diagram).

Hot glue the PS/2 ports together.

Step 4: Prepare the MIDI Port

Push a piece of perfboard through the bottom pins of the MIDI port to make soldering easier.

Add a 220Ω resistor in series to the Vcc pin (see diagram).

Solder wires to the three pins we need to access (they are the Vcc, Ground and Serial pins - see diagram).

Step 5: Wire Up the Arduino

Wire the PS/2 and MIDI ports to the Arduino as follows:

For the PS/2 ports:

Vcc pins goes to 5V
Ground to GND
Clock and Data pins goes to digital pins 4 to 11

For the MIDI port:

Vcc pin goes to the 220Ω resistor, then to 5V
Ground to GND
Serial to TX

Step 6: Upload the Arduino Program

I've made the source code to this project open-source, so simply head over my GitHub to download the Arduino sketch:

https://github.com/evankale/ArduinoMidiPS2

Plug in the Arduino to the PC, open up the sketch in Arduino IDE, and upload the program to the Arduino.

Step 7: Make a Box

Cut out a cardboard box template that fits all the components.

I decided to expose the MIDI and PS/2 ports in the front of the box while the Arduino USB port through the back so that it can be USB powered or reprogrammed easily.

Hot glue the components into place.