node.js + johnny-five @ jsconf 2014

leds-cycle.js

var j5 = require('johnny-five');
var Leds = require('./leds').Leds;
var board = new j5.Board();
var delay = 20;

var leds;

board.on('ready', function() {
  leds = new Leds(4, 13);
  var button = new j5.Button(2);
  button.on('down', function() {
    autoCycle.off();
    nextMode();
  });
  button.on('hold', function() {
    autoCycle.on();
  });
  autoCycle.eventually();
  nextMode();
  (function loopy() { mode.loop(); setTimeout(loopy, mode.delay || delay); }());
});

var mode, modeidx;
var modes = [];
function nextMode() {
  var first = 0; //modes.length - 1;
  modeidx = modeidx == null ? first : (modeidx + 1) % modes.length;
  mode = modes[modeidx];
  console.log('mode %s (%d)', mode.name, modeidx);
  leds.off();
  if (mode.init) { mode.init(); }
}

var autoCycle = {
  id: null,
  eventuallyId: null,
  eventuallyDelay: 60000,
  delay: 15000,
  on: function() {
    this.eventuallyReset();
    if (!this.id) {
      console.log('auto-cycle: enabled');
      this.id = setInterval(nextMode, this.delay);
    }
  },
  off: function() {
    if (this.id) {
      console.log('auto-cycle: disabled');
      clearInterval(this.id);
      this.id = null;
    }
    this.eventually();
  },
  toggle: function() {
    this.eventuallyReset();
    if (this.id) {
      this.off();
    } else {
      this.on();
    }
  },
  eventually: function() {
    this.eventuallyReset();
    this.eventuallyId = setTimeout(this.on.bind(this), this.eventuallyDelay);
  },
  eventuallyReset: function() {
    clearTimeout(this.eventuallyId);
    this.eventuallyId = null;
  },
};

modes.push({
  name: 'Blink',
  init: function() {
    this.delay = 300;
  },
  loop: function() {
    leds.toggle();
  },
});

modes.push({
  name: 'Cycle',
  init: function() {
    this.delay = 50;
    this.dir = 1;
    this.current = -1;
  },
  loop: function() {
    this.current = (leds.length + this.current + this.dir) % leds.length;
    leds.on(this.current);
  },
});

modes.push({
  name: 'March',
  init: function() {
    this.delay = 300;
    this.remainder = 1;
  },
  loop: function() {
    this.remainder = 1 - this.remainder;
    leds.forEach(function(led, i) {
      led[i % 2 === this.remainder ? 'on' : 'off']();
    }.bind(this));
  },
});

modes.push({
  name: 'Ping-pong',
  init: function() {
    this.delay = 50;
    this.dir = 1;
    this.current = -1;
  },
  loop: function() {
    this.current += this.dir;
    if (this.current < 0 || this.current === leds.length) {
      this.dir = -this.dir;
      this.current += 2 * this.dir;
    }
    leds.on(this.current);
  },
});

modes.push({
  name: 'Cylon',
  init: function() {
    this.delay = 50;
    this.dir = 1;
    this.pad = 1;
    this.current = -1;
  },
  loop: function() {
    this.current += this.dir;
    if (this.current < 0 || this.current === leds.length) {
      this.dir = -this.dir;
      this.current += this.dir;
    }
    var arr = [];
    for (var i = 0; i < leds.length; i++) {
      if (i >= this.current - this.pad && i <= this.current + this.pad) {
        arr.push(i);
      }
    }
    leds.on(arr);
  },
});

modes.push({
  name: 'Starburst',
  init: function() {
    this.delay = 30;
    this.frames = [
      '          ',
      '    XX    ',
      '   XXXX   ',
      '  XX  XX  ',
      ' XX XX XX ',
      'XX XXXX XX',
      'X XX  XX X',
      ' XX XX XX ',
      'XX XXXX XX',
      'X XX  XX X',
      'XX      XX',
      'X        X',
      '          ',
      'XX      XX',
      'X X    X X',
      ' X X  X X ',
      'X X XX X X',
      ' X X  X X ',
      '  X XX X  ',
      '   X  X   ',
      '    XX    ',
      '          ',
      '          ',
    ];
    this.current = -1;
  },
  loop: function() {
    if (++this.current === this.frames.length) {
      this.current = 2;
    }
    var arr = [];
    this.frames[this.current].split('').forEach(function(n, i) {
      if (n === 'X') { arr.push(i); }
    });
    leds.on(arr);
  },
});

modes.push({
  name: 'Skippy',
  init: function() {
    this.delay = 30;
    this.frames = [
      '          ',
      'X         ',
      '  X       ',
      '    X     ',
      '      X   ',
      '        X ',
      '          ',
      '         X',
      '       X  ',
      '     X    ',
      '   X      ',
      ' X        ',
      '          ',
      'X         ',
      '  X       ',
      '    X     ',
      '      X   ',
      '        X ',
      '          ',
      '         X',
      '       X  ',
      '     X    ',
      '   X      ',
      ' X        ',
    ];
    this.current = -1;
  },
  loop: function() {
    this.current = (this.current + 1) % this.frames.length;
    var arr = [];
    this.frames[this.current].split('').forEach(function(n, i) {
      if (n === 'X') { arr.push(i); }
    });
    leds.on(arr);
  },
});

modes.push({
  name: 'Binary Counter',
  init: function() {
    this.delay = 200;
    this.num = 0;
  },
  loop: function() {
    var arr = [];
    (++this.num).toString(2).split('').forEach(function(n, i, a) {
      if (n === '1') {
        arr.push(leds.length - a.length + i + 1);
      }
    });
    if (this.delay > 10) {
      this.delay = Math.floor(this.delay * 0.99);
    }
    leds.on(arr);
  },
});

leds.js

var j5 = require('johnny-five');

function Leds(ledstartpin, ledendpin) {
  for (var i = 0; i <= ledendpin - ledstartpin; i++) {
    this[i] = new j5.Led(i + ledstartpin);
  }
  this.length = ledendpin - ledstartpin + 1;
}

exports.Leds = Leds;

Leds.prototype.forEach = function(fn) {
  for (var i = 0; i < this.length; i++) {
    if (typeof fn === 'function') {
      fn.call(this, this[i], i);
    } else if (typeof fn === 'string') {
      this[i][fn].apply(this[i], [].slice.call(arguments, 1));
    } else {
      throw new TypeError('Invalid argument.');
    }
  }
};

Leds.prototype.on = function(idxs) {
  if (arguments.length === 0) {
    this.forEach('on');
  } else {
    idxs = typeof idxs === 'number' ? [idxs] : idxs;
    this.forEach(function(led, i) {
      led[idxs.indexOf(i) !== -1 ? 'on' : 'off']();
    });
  }
};

Leds.prototype.off = function() {
  this.forEach('off');
};

Leds.prototype.toggle = function() {
  this.forEach('toggle');
};

In a shell

$ npm install johnny-five
$ node leds-cycle.js

What it looked like