"use strict"; var Cylon = require("cylon"); Cylon .robot() .connection("tessel", { adaptor: "tessel", port: "GPIO" }) .device("led", { driver: "led", pin: "G4" }) .on("ready", function(bot) { var brightness = 0, fade = 5; setInterval(function() { brightness += fade; bot.led.brightness(brightness); if ((brightness === 0) || (brightness === 255)) { fade = -fade; } }, 50); }); Cylon.start();