let serial;          // variable to hold an instance of the serialport library

let portName = 'dev/tty.usbmodem14101';  // fill in your serial port name here

​

let circleSize = 10;

function setup() {

  createCanvas(windowWidth,windowHeight);

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

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

  serial.on('connected', serverConnected); // callback for connecting to the server

  serial.on('open', portOpen);        // callback for the port opening

  serial.on('data', serialEvent);     // callback for when new data arrives

  serial.on('error', serialError);    // callback for errors

  serial.on('close', portClose);      // callback for the port closing

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

  serial.open(portName);              // open a serial port

}

//

function draw() {

  background("orange");

  fill(255);

  noStroke();

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

} 

​

// get the list of ports:

function printList(portList) {

  // portList is an array of serial port names

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

    // Display the list the console:

    console.log(i + portList[i]);

  }

}

​

function serverConnected() {

  console.log('connected to server.');

}

function portOpen() {

  console.log('the serial port opened.')

}

function serialEvent() {

  let data = serial.read();

  console.log(data);

  circleSize = data;

}

function serialError(err) {

  console.log('Something went wrong with the serial port. ' + err);

}

function portClose() {

  console.log('The serial port closed.');

}