Launchpad / Sequencer With MIDI Output




For a project we had to make an instrument, we came up with the idea to make a Sequencer capable of sending MIDI data to a MIDI player. We made this using Arduino and Processing. It took us about 5 days to design the instrument, collect all of the parts, construct it, make the software and put it all together. The costs for making it where quite low, about €30 (about $40).

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Step 1: Materials and Tools

Materials needed:

  • 64 3mm red LED's
  • 68 high pushbuttons
  • 64 220 Ohm resistors
  • 12 1K Ohm resistors
  • 4 10K Ohm linear potentiometers
  • 1 Arduino UNO
  • 1 USB cable
  • 1 16bit parallel I/O expander (MCP23016)
  • 1 3K Ohm resistor
  • 1 33pF capacitor
  • Perfboard (aproximately 70x70 holes)
  • Wires
  • 600x300mm triplex for lasercutter
  • 64 Doorstoppers
  • 1 latex glove

Tools needed:

  • Soldering iron
  • Wirestripper
  • Wirecutter
  • Sandpaper
  • Sharp knife
  • Woodglue
  • Lasercutter
  • Duct tape
  • Glue

Software needed:

  • Processing -
  • Arduino IDE -
  • optional a vecor file editor (illustrator, coreldraw)

To get the sequencer up and running you need some basic processing and arduino knowledge. Understanding how it works requires average knowledge of processing and arduino. But don't hesitate to take a look at the code and learn from it.

Step 2: Electronics

We used multiplexing to control the LED's and at the same time we read the state of the buttons.We used a separate piece of perfboard for the I/O expander to make it fit inside the box. To make sure that the multiplexing worked fine we changed the I2C speed to 4kHz, take a look over here on how to do that.

Step 3: Box

We used to make the box and edited it in Adobe Illustrator for the buttons. We made a pdf file of our design and cut the wood with the lasercutter.

Step 4: Code

The code is made and tested on a mac, windows does not have an internal MIDI input. It is possible to adapt the code to run on a Windows machine. We used the SoundCipher library to produce the MIDI.

Step 5: Buttons

We used a sharp knife to cut the ridges from the side of the door stoppers and made them smooth using sanding paper. For keeping the buttons in place we put a latex glove on the back with duct tape and glued the buttons on top of it.

Step 6: Putting It Together

Sandwich the electronics between the stand and the buttons, attach all of the wires to your arduino and connect it to your computer. Upload the firmware to the arduino and run the processing software. Then start a music program capable of playing MIDI, you should now be able to use the sequencer.

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    31 Discussions


    Question 1 year ago on Step 4

    Why the three codes for processing software have some problem?


    3 years ago

    Hey dude,how can i add RGB led and use it like real launchpad basically the led designs

    1 reply

    2 years ago

    i am making project with neopixels but can you show me where you bought doorstops or a list where you bought and also you should male a youtube video you would get ALOT OF VIEWS


    2 years ago

    What to do so it will work on Windows? Made everything now the program is just not working yet.


    2 years ago

    Is this working, did somebody try it?


    2 years ago

    any chance you could still show how you soldered the wires from under the board? Preferably diagrammatically. Thanks


    2 years ago

    Youtube or it didn´t happen XDD. Just kidding, but it would be great to see a youtube of this project working.


    3 years ago

    What is the program to run this, so the program to actually connect this to the computer.

    1 reply

    Reply 3 years ago

    We tested it on Ableton and FL studio, but any program that can handle MIDI over USB should work.


    3 years ago

    can you show me source code, i want make it work?


    3 years ago

    What price did all the components cost? (roughly if you do not know the exact cost)


    3 years ago

    do you have a better circuit diagram? if not I'll have to figure it out and make one myself. not complaining, just curious.

    3 replies

    Reply 3 years ago

    No, I'm sorry. I made this project a long time ago, and at the time I did not make a better diagram.


    Reply 3 years ago

    that's okay, in going to make a circuit diagram and PCB template for this. I'm also going to do a step by step. I'm going to post it on mine and reference you.

    Sergio Ulloa

    3 years ago

    This is a realy cool project, but, can i build it with neopixels?