This is for MIDI over Bluetooth. There's also a module for Wired MIDI.
Bluetooth Espruino devices like Puck.js can be programmed to appear as any type of Bluetooth LE device, and this includes a Bluetooth LE MIDI controller.
Joe Bowbeer and George Mandis did the original work on this. However it's now been converted into the ble_midi (About Modules) module to make it easier to use.
You can simply use the module as follows:
var midi = require("ble_midi");
midi.init();
setWatch(function() {
// When a button is pressed...
digitalPulse(LED,1,10);
// midi.send(channel, controller, value);
midi.send(0, 60, 100);
}, BTN, { repeat:true, edge:"rising", debounce:10 });
Then when you next connect to your Puck.js device it will be treated
as a MIDI instrument. When you press the button, a MIDI command will be sent
using the send
function.
You can then even use the Web MIDI APIs to receive the MIDI data inside a web page!
Note: Because of the way advertising data is modified to allow the long
BLE UUID to be transmitted, this will change the name of the Puck.js device to PuckCC
.
Note: You may require a Mac for this work automatically.
midi.send
sends a 'control change' command. Often you'll want
to send a midi.noteOn(0,note,velocity)
or midi.noteOff(0,note,0)
command instead.
When notes are sent to the midi device, the raw MIDI message is output
in midi
event which you can handle with midi.on('midi', ...)
.
The example below echoes received MIDI events back one 5th higher, as well as lighting LED3 if the note sent has any velocity value.
var midi = require("ble_midi");
midi.init();
midi.on('midi', function(data) {
var cmd = data[2] & 0xF0; // command
var chn = data[2] & 0x0F; // channel
switch(cmd) {
case 0x80: // noteOff
case 0x90: // noteOn
var num = data[3]; // note number
var val = data[4]; // note velocity
if (val) LED3.set(); else LED3.reset();
midi.cmd(cmd+chn, num+7, val);
break;
}
});
Channels sent to these functions are zero-based, so channel
0
in a function call actually represents channel 1
.
// Turns the device into a MIDI controller
exports.init = function () { ... }
// Sends a raw MIDI command
exports.cmd = function (cmd, d1, d2) { ... }
// Send a 'control change' (0xB0) MIDI command
exports.send = function (channel, controller, value) { ... }
// Send a 'note on' (0x90) MIDI command
exports.noteOn = function (channel, note, velocity) { ... }
// Send a 'note off' (0x80) MIDI command
exports.noteOff = function (channel, note, velocity) { ... }
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