let portName = '/dev/tty.usbserial-1410';  

let inDataY,outDataY;

function setup() {

  createCanvas(300,300);

  serial = new p5.SerialPort();       

  serial.on('data', serialEvent);     

  serial.on('error', serialError);    

  serial.open(portName);             

}

​

function draw(){

  background(200);

  outDataX=int(map(mouseX,0,width,0,255));

  outDataY=int(map(mouseY,0,height,0,255));

  serial.write(outDataX+","+outDataY+"\n");

  fill(255);

  textSize(20);

  text("outDataX: " + outDataX, 0, 30);

   text("outDataY: " + outDataY, 0, 60);

}

function serialEvent() {

  // inDataY=serial.read();

}

function serialError(err) {

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

}

​