let portName = '/dev/tty.usbserial-02898BB7';

let inData;

​

function setup() {

  createCanvas(displayWidth, displayHeight);

  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 serverConnected() {

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

}

function portOpen() {

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

}

function serialEvent() {

  inData = Number(serial.read());

   // inData = serial.readStringUntil('/n');

}

function serialError(err) {

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

}

function portClose() {

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

}

// get the list of ports:

function printList(portList) {

  // portList is an array of serial port names

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

    // Display the list the console:

    console.log(i + portList[i]);

  }

}

function draw() {

   background(0);

   fill(255);

  textSize(30);

   text("sensor value: " + inData, 30, 50);

  if (inData == 0) {

    circle(displayWidth/2, displayHeight/2, 60);

  } else {

    circle(displayWidth/2, displayHeight/2, 30);

  }

}