Page 176 - Hacking Roomba

Chapter 8 — Making Roomba Sing 157

Listing 8-2: RoombaComm playNote()

public void playNote(int note, int duration) {
byte cmd[] = {(byte)SONG, 15, 1,
(byte)note, (byte)duration, // define “song”
(byte)PLAY, 15 }; // play it back
send(cmd);
}

Playing Roomba as a Live Instrument

Now that you can play single musical notes on Roomba, it should be easy to turn it into a
musical instrument that can be played live. Although Java offers some amount of MIDI sup-
port, it doesn’t offer the feature needed to turn the Roomba into a MIDI instrument: the
creation of virtual MIDI destinations. Also, not everyone has a MIDI keyboard and a MIDI
interface, but everyone should definitely be allowed to use their robotic vacuum cleaners to jam
along with their favorite MIDI tunes.
The computer keyboard offers a workable replacement to a musical keyboard and because of
the Roomba’s limitations, using it doesn’t affect the articulation of the Roomba as an instru-
ment. The computer keyboard’s simplicity of input mirrors the Roomba’s simplicity of output.
Figure 8-4 shows the computer keyboard to musical keyboard mapping to be used in a
Processing sketch called RoombaTune, shown in Listing 8-3. The a key becomes a C note,
the w key becomes a C# note, the s key becomes a D note, and so on. The mapping allows
only a little more than an octave, so the z and x keys are used to move the keyboard up and
down an octave.

` 1 2 3 4 5 6 7 8 9 0 - = Del

Tab q w e r t y u i o p [ ] \

Caps a s d f g h j k l ; ‘ Return

Shift z x c v b n m , . / Shift

– +
Octave
FIGURE 8-4: The RoombaTune computer keyboard mapping of musical keyboard