Update: Music MaKey

On Friday, July 5 I (Alex) spent the day with Eric Rosenbaum at the MIT Media Lab. We made some progress on the Music MaKey...

Eric's original prototype idea

 Above was Eric's first prototype idea, an idea similar to what we were also considering. The thinking was to provide more inputs and include a design that mirrored 2 octaves of a piano keyboard and a drum kit.

To get started, we simplified the keyboard layout to one octave and went to the FabLab to use the vinyl cutter to cut a copper foil template.

3rd times the charm (top) on the vinyl cutter

As you can see, we tried 3 times before we got a good cut. For the first try, the knife pressure (set to 50gf) was too light and it did not cut through the foil. The 2nd try with a setting of 130gf was too hard and tore the foil. We settled on a final cut pressure of 80gf and the top cut was the result.

Carefully transferring to side of MaKey box

Though masking tape was recommended as the transfer tape, we didn't have any nearby and instead used gaffers tape to transfer the foil cut out from the original tape to a cardboard side of a MaKey MaKey box.  This is a very careful process of finding a tape with an adhesive strong enough to lift the foil cutouts from foil, but weak enough to transfer the foil onto the prototype surface, in this case cardboard.

Successful test with Teensy2.0++ - Sending MIDI to GarageBand

Above is our first test clipping leads on the copper foil interface prototype onto Eric's Teensy2.0++ running custom MIDI code. Just like the MaKey MaKey a 22MOhm resistor is added between power (+5V from the USB cable) and the input pin. It worked! We were successfully able to trigger MIDI notes on and off in GarageBand, as well as send Control Change messages.

Once that worked, we tried creating a graphite potentiometer testing analog input to the Music MaKey prototype. 

Bottom right corner - graphite potentiometer prototype.

This test did not go so well. We tried mapping the resistance values to the MIDI pan control change message (10). There was simply too much "noise" on the ports and in the reading to be accurate. We'll have to think more about this, because we would like to also have analog inputs for the Music MaKey.

Possible alternative layout for a Music MIDI MaKey

After trying the above tests, we started discussing an alternative layout with the two octaves of the virtual keyboard's on Music MaKey mirrored. This would enable a more compact layout and possibly make it easier for users to connect two octaves worth of alligator clips. Alternative, it introduces the possibility to an embedded feature of splitting the keyboards onto different channels and sounds. That adds additional complexity to the design and user interface, so we may not keep that for the default firmware build.

We also moved ground connections to the sides and added 3 general purpose pin connections in the middle. By default, these might be initially mapped to sustain, octave + and octave -.

Next steps:

• Investigate ways of smoothing the analog input sensing for variable, homemade resistors.
• Mock up a design in Eagle and build an actual PCB prototype; begin first user tests.
• Decide on initial keyboard mode computer key mapping. Home row one octave mapping (GarageBand) vs. full two octave keyboard mapping (JamWithChrome.com).
• Design custom, cross-platform web audio API app for keyboard mode use?
• Prototype a custom remixing/visualization app based on remix.js from EchoNest.