johnny-five/eg/photoresistor-servo.js

The JavaScript Arduino Programming Framework.

var five = require("../lib/johnny-five.js"),
  board, photoresistor, servo, range;

board = new five.Board();

board.on("ready", function() {

  //range for the servo (degrees)
  //CAUTION: don't set the numbers past what you servo can handle
  //         it could potentially damage the servo
  range = [0, 159];

  // Create a new `photoresistor` hardware instance.
  photoresistor = new five.Sensor({
    //pin to listen to
    pin: "A0",
    //how often to check for a change in miliseconds (default value is 25 milliseconds)
    freq: 250
  });

  // Create a new `servo` hardware instance.
  servo = new five.Servo({
    //what pin to control server
    pin: 9,

    //how far the servo turns
    range: range
  });

  // Inject the `photoresistor` hardware into
  // the Repl instance's context;
  // allows direct command line access
  board.repl.inject({
    pot: photoresistor,
    servo: servo
  });

  //equate the photoresistor values to the servo scale
  //do something when the a value is read from the photoresistor
  photoresistor.scale(range).on("data", function() {
    //outputs to screen the values being used from the photoresistor
    //console.log( "Normalized value: " + this.normalized + "  Scaled Value: " + this.scaled );

    //tell the servo arm to move the scaled value.
    servo.to(Math.floor(this.scaled));
  });

});