trev/nodejs/ar-com/arduino.js

var events = require('events'),
    child  = require('child_process'),
    util   = require('util'),
    serial = require("serialport");

var Arduino = function (debug, baudrate) {
  this.baudrate = baudrate && baudrate || 9600;
  this.debug = debug && debug || false;
  this.writeBuffer = [];
}

util.inherits(Arduino, events.EventEmitter);

Arduino.prototype.HIGH = '255';
Arduino.prototype.LOW = '000';

Arduino.prototype.setup = function () {
  var self = this;
  child.exec('cd ../arduino && ino build && ino upload', function(err, stdout, stderr){
    
    if(err){
      console.log('Please install the ino utility and connect arduino!\nIf there are other open programs that communicate with the arduino, close them!');
      if(self.debug) {console.log(err.message);}
      return;
    }

    var buff = stdout.slice(stdout.indexOf('Guessing serial port ... ')+25);
    buff = buff.slice(0, buff.indexOf('\n'));
    console.log('Guessing serial port ... ' + buff);

    self.serial = new serial.SerialPort(buff, {
      baudrate: self.baudrate,
      parser: serial.parsers.readline('\n')
    }, false);
    
    self.serial.open(function (error) {
      if ( error ) {
        console.log('Please check arduino!');
        return;
      }
    });

    self.serial.on('open', function () { setTimeout(function () {
      self.serial.write(new Buffer('00000000'));
      self.serial.write(new Buffer('Zn000000', 'ascii'));
      if(self.debug) { self.serial.write(new Buffer('P0000000', 'ascii')); }
      self.emit('success');
      
      self.serial.on('data', function(data){
        if(self.debug) { console.log(data) };
        self.emit('data', data);
      });
      
      self.processWriteBuffer();
    }, 5000);});

  });
}

Arduino.prototype.write = function (message) {
  if (this.serial) {
    console.log('sending '+message);
    this.serial.write(message);
  } else {
    this.writeBuffer.push(message);
    console.log('Board isn\'t available (yet?).')
  }
}

Arduino.prototype.processWriteBuffer = function () {
  while (this.writeBuffer.length > 0) {
    this.write(this.writeBuffer.shift());
  }
}

// Helpers

Arduino.prototype.valueToLastFour = function(val) {
  var encodedVal = ""; 

  for (var i = 3; i > 0; i--) {
    
    encodedVal += String.fromCharCode(val/(Math.pow(2,8*i)));
    val = val%Math.pow(2,8*i);

  }

  return encodedVal;
};

Arduino.prototype.valueToFirstTwo = function(val) {
  var encodedVal  = ""; 

  for (var i = 1; i > 0; i--) {
    
    encodedVal += String.fromCharCode(val/(Math.pow(2,8*i)));
    val = val%Math.pow(2,8*i);

  }

  return encodedVal;
};

module.exports = Arduino;