code: function Barcode(board, rxPin, txPin) {
      Module.call(this);
      this._board = board;
      this._rx = !isNaN(rxPin) ? board.getDigitalPin(rxPin) : rxPin;
      this._tx = !isNaN(txPin) ? board.getDigitalPin(txPin) : txPin;
  
      this._init = false;
      this._scanData = '';
      this._callback = function () {};
      this._messageHandler = onMessage.bind(this);
      this._board.send([0xf0, 0x04, 0x16, 0x00,
        this._rx._number, this._tx._number, 0xf7
      ]);
    }
docs: The Barcode class.
  
  @namespace webduino.module
  @class Barcode
  @constructor
  @param {webduino.Board} board The board the barcode scanner is attached to.
  @param {webduino.Pin | Number} rxPin Receivin pin (number) the barcode scanner is connected to.
  @param {webduino.Pin | Number} txPin Transmitting pin (number) the barcode scanner is connected to.
  @extends webduino.Module