Connecting yourself to ground/earth when using the Makey Makey keyboard takes a little bit of the fun away, as it often means you end up with a wire often clipped to your wrist or held in your hand. So, Divya came up with the excellent idea of placing the ground in your mouth, with some sort of mouth piece, and then using both hands to operate buttons on an instrument. This essentially means we get a Electronic Melodica, which does not need the blowing and is easily reprogrammable.
For the first version we used a Virtual MIDI Piano Keyboard program, because you can map certain keyboard keys (hence Makey Makey inputs) to certain notes on the computer. Version 2 will almost certainly be running with a scratch program, where we can assign custom mp3 music files to each button, and make it perform animations on the screen, reprogrammable by almost anyone (from kid to adult).
Step 1: Sizing the Veroboard
Using veroboard to break out the connectors on the back of the MakeyMakey allows us to gain access to additional pins, and makes it easy to make multiple instruments and simply migrate the MakeyMakey from one instrument to the next.
We marked out the veroboard to be the same size as the Makey Makey, and carefully cut the board out using a Tennon saw. The Tennon saw makes great straight lines, but is a little bit aggressive, so don't saw too quickly.
Step 2: Lining Up the Headers
Header normally is cheaper to buy in long lengths, but can easily be cut using side cutters. Be careful though, if you don't hold both ends of the header when cutting it can launch half way across the room.
To make sure all the header lines up, insert it into the MakeyMakey and place the board on top. Mark next to the pins with a Sharpie so that when you take it off to drill the holes you don't accidentally put it back in the wrong position.
Step 3: Preventing Pin Shorting
The connector on the top (next to where is says MakeyMakey) does not provide extra inputs (containing KEY OUT, MS OUT, RESET, 5V, GND, PGD and PGC) which are not going to be used in this task. Essentially the header on that side is just being used for structural reasons, to help keep the MakeyMakey in place.
On the bottom all the pins are connected to the same ground/earth pin, so it does not matter that the header is shorting itself out with the adjacent tracks on the veroboard.
To ensure the two ends of the board don't short, a line is cut through the middle of the board. This isolates the WASDFG and the up, down, left, right, click1 and click2 buttons.
An additional 4 mounting holes are drilled in the corner to allow for cable ties to be threaded through and to hold the final cables down.
Step 4: Cable Management
As with all Hackspaces, there seems to be an abundance of CAT5 cable, so we split that up and soldered it to the back of the board, with the wires coming out of the same side as the header. This way once the MakeyMakey is pushed on it sandwiches the cables between the MakeyMakey and the PCB. We pushed some heat shrink tubing over all the cables so that they are held together in a bunch and then used cable ties as strain relief should the cables get tugged.
All the cabled are soldered near the centre of the board, as it means they are all in a bunch, making tidying them up easier.
Step 5: Cutting Out the Instrument
We decided to go for a bit of a short clarinet look, so that the Makey Makey could be tucked away into the bottom fluted end of the instrument. We made a paper prototype, to gauge how it felt size wise, and decided on a length of about 45cm (spaced such that our fingers could easy reach each key).
Using a jigsaw and a router we cut out three pieces from plywood, cutting a gully in the centre piece to run all of the wires and a hole in the bottom piece to install the Makey Makey.
The top two layers (the complete one and the one with the gully) where glued together with wood glue and left overnight to set.
Step 6: Installing Buttons
The buttons are make of split pins which we had washer for. After drilling holes for them, we pushed them through and cut the legs short so that adjacent pins would not short out with each other.
The buttons were laid out such that the main notes (the white keys on the keyboard) are on one side of the instrument, and the black keys of the keyboard on the rear side. This is working on the theory that most music is written to use the white keys, which are operated with your fingers. The black keys which are used less would then be operated with your thumbs.
Step 7: Wiring Up the Buttons
We secured the veroboard down to the instrument with 4 mounting screws, such that the Makey Makey can now just be pushed on using it's in built headers.
All the wires are run through the gully, cut to the correct length and soldered onto the buttons. We had problems with some of the split pins where they were coated with some sort of lacquer or wax, making it difficult to solder to (though not impossible because you can scratch of the coating). To keep the wires in place whilst soldering it was wrapped around the split pin in a figure of 8, and then electrical tape was used to secure the wires down (mainly to keep it neat and make screwing the other side on easier.
Step 8: The Mouth Piece
The mouth piece located at the top of the instrument is critical for the working of the system, so we doubled up the number of wires goes up to it, just to be paranoid. It used the same split pins as everywhere else, but mounted end of with hot melt glue.
The last part was to simply screwed on the top, finishing off our Makey Makey Melodica. All you need to do to start making music is plug it into the computer using the stylish red USB lead, run the MIDI keyboard software, and get your groove on. As the Makey Makey acts just as a keyboard, there is no need for writing a custom API or performing strange hardware tweeks.