How to use the firmata.Board function in firmata

var rpio = require('rpio');
var firmata = require('firmata');

// GPIO18 low -> Arduino reset off
rpio.setOutput(12);
rpio.write(12, rpio.LOW);

// start connection to Arduino
//  USB: /dev/ttyUSB0 or /dev/ttyACM0
//  UART: /dev/ttyAMA0
var board = new firmata.Board('/dev/ttyAMA0', function(err)
{
  if(err)
  {
    console.log(err);
    return;
  }
  console.log('connected');
  board.pinMode(13, board.MODES.OUTPUT);
  // switch on LED
  board.digitalWrite(13, board.HIGH);
  // switch off LED after 3s
  setTimeout(function()
  {
    board.digitalWrite(13, board.LOW);
    process.exit(0);
  }, 3000);

'experimental at best. Have fun! :)'
    );
    setupConnection('experimental-board', board);
    board.on('ready', (error) => {
      if (error) {
        callback(error);
      } else {
        updateConnection('experimental-board', board);
        callback(null, board);
      }
    });
    return;
  }

  console.info('Connecting to port "%s"', port);
  const board = new Board(port, (error) => {
    if (error) {
      console.info('Board setup error');
      callback(error);
    } else {
      updateConnection(port, board);
      callback(null, board);
    }
  });
  setupConnection(port, board);

  board.on('error', (error) => {
    // TODO: look up docs/source code for this
    console.info('Board error event!');
    console.log(error);
  });

var firmata = require("firmata");
var repl = require("repl");

var serialport = "/dev/ttyUSB0";

var red = 0, green = 0, blue = 0;

var board = new firmata.Board(serialport, function (error) {
    if (error) {
        console.log(error);
        return;
    }

    console.log('Connected to ' + serialport);
    console.log('Firmware: ' +
        board.firmware.name + '-' +
        board.firmware.version.major + '.' +
        board.firmware.version.minor
        );

    var context = repl.start("RGB>").context;
//    context.sses = sendSysExString;
    context.sendPixel = sendPixel;
    context.rainbow = rainbow;

// Board({ port: path String })
      //
      // Board()
      //    ie. auto-detected
      //
      path = portOrPath;
    }

    // Add the usb device path to the list of device paths that
    // are currently in use - this is used by the filter function
    // above to remove any device paths that we've already encountered
    // or used to avoid blindly attempting to reconnect on them.
    Serial.used.push(path);

    try {
      io = new IO(portOrPath, function(error) {
        if (error) {
          caught = error;
        }

        callback.call(this, caught, caught ? "error" : "ready", io);
      }.bind(this));

      // Extend io instance with special expandos used
      // by Johny-Five for the IO Plugin system.
      io.name = "Firmata";
      io.defaultLed = 13;
      io.port = path;

      // Made this far, safely connected
      isConnected = true;
    } catch (error) {

var mqtt = require('mqtt');
          VirtualSerialPort = require('mqtt-serial').SerialPort;

          client = mqtt.connect(n.mqttServer,
          {username: n.username, password: n.password});
          client.on('error', function(err){
            node.warn(err);
          });

          sp = new VirtualSerialPort({
            client: client,
            transmitTopic: n.pubTopic,
            receiveTopic: n.subTopic
          });

          node.io = new firmata.Board(sp, {samplingInterval: 300, reportVersionTimeout: 15000});
          start(node);
        }catch(exp){
          console.log('error initializing mqtt firmata', exp);
          process.nextTick(function() {
            node.emit('ioError', exp);
          });
        }
      }
      else if(n.connectionType === 'tcplisten'){ //mode listen network

        node.tcpServer = net.createServer(function(socket){
          node.io = new firmata.Board(socket);
          start(node);
            console.log('client ready', socket.remoteAddress + ":" + socket.remotePort );
             socket.emit('open', {});
            socket.on('error', function(err){

function connect(port) {
    console.info('Connecting to port "%s"', port);
    const board = new Board(port, function(err) {
      if (err) {
        console.error('Failed connecting to port %s', port);
        throw err;
      }

      callback(board, port);
    });
  }
}