var fromSerial = 0; //variable to hold the data

​

function setup() {

  createCanvas(320, 240);

  serial = new p5.SerialPort(); // make a new instance of  serialport library

  serial.on('list', printList); // callback function for serialport list event

  serial.on('data', serialEvent); // callback for new data coming in

  serial.list(); // list the serial ports

  serial.open("/dev/cu.usbmodem1411"); // open a port

}

​

function draw() {

  // do your drawing stuff here

    noFill();

    stroke (random(255),random(255), random(255));

    ellipse (width/2, height/2, fromSerial, fromSerial);

}

​

// get the list of ports:

function printList(portList) {

  for (var i = 0; i < portList.length; i++) {

    // Display the list the console:

    println(i + " " + portList[i]);

  }

}

​

function serialEvent() {

  // this is called when data is recieved, data will then live in fromSerial    

  asciiFromSerial = serial.readLine();

    if (asciiFromSerial.length>0){

        asciiFromSerial = trim (asciiFromSerial);

        fromSerial = Number (asciiFromSerial);

  println(fromSerial);

    }

}