phi-launchpad

A Node.js interface for interacting with the Novation Launchpad.

phi-launchpad implements the Launchpad MIDI spec allowing you to catch button presses and manipulate LEDs.

Installation

Install via npm:

$ npm install phi-launchpad

Usage

Setup

Connect to MIDI:

var plaunchpad = require('phi-launchpad');

var lpadIn = new plaunchpad.input();
lpadIn.init();

var lpadOut = new plaunchpad.output();
lpadOut.init();

MIDI device is configurable; see below.

Listening for button presses

lpadIn.on('press', function(row, col) {
  console.log(util.format("press %d %d", row, col));
});

lpadIn.on('release', function(row, col) {
  console.log(util.format("release %d %d", row, col));
});

Setting LEDs

lpadOut.setLed(3, 4, [0, 3]);
lpadOut.setLed(4, 2, [2, 2]);
lpadOut.setLed(0, 0, [2, 0]);
lpadOut.setLed(8, 8, [3, 3]);

Set the LED in row 3, column 4, to be the color with red = 0 la(no red) and green = 3 (full green). Calls with arguments out of range either in position or color are ignored.

plaunchpad addresses the Launchpad as a 9x9 matrix with a "hole" in the upper rightmost element.

Colors are represented as red/green pairs: [0..3,0..3]

Buffered Updates

The Launchpad is double-buffered; it has one showing buffer, and another that is hidden. To reduce flicker while updating large portions of the Launchpad, you can send updates to the hidden buffer, then swap the two buffers to show all of the changes immediately.

Send a number of updates to the hidden buffer:

lpadOut.setLed(5, 6, [2, 2], 'update');
lpadOut.setLed(3, 4, [0, 2], 'update');
lpadOut.setLed(5, 7, [2, 0], 'update');

Show all changes at once:

lpadOut.swapBuffers();

Rapid Updates

You can update large parts of the Launchpad with fewer MIDI messages using the rapid update function. Pass in a list of up to 80 red/green pairs as a flat array:

lpadOut.rapidUpdate(2, 3, 4, 2, 0 ... 3, 2);
lpadOut.swapBuffers();

Note that swapBuffers() needs to be called for the update to show.

Autoflash

Set some LEDs with the 'flash' flag:

lpadOut.setLed(2, 5, [2, 2], 'flash');

Then turn on autoflash to see them blink at a set rate:

lpadOut.autoFlash(true);

Pass false to autoFlash to stop the blinking.

lpadOut.autoFlash(false);

Adjusting Brightness

Set brightness as a single value (0 - 255):

lpadOut.setBrightness(64);

Set brightness as duty cycle (numerator, denominator):

lpadOut.setDutyCycle(1, 8);

MIDI device name

To use a Launchpad with a MIDI device name other than "Launchpad" (the default if unspecified), you can do the following:

var midiInt = require('./node_midi_interface').midi;
var m = new midiInt(/Your Device Name/);

var lpadIn = new plaunchpad.input();
lpadIn.init(m);

lpadOut = new plaunchpad.output();
lpadOut.init(m);