code: function gotData() {
    var currentString = serial.readLine();  // read the incoming data
    trim(currentString);                    // trim off trailing whitespace
    if (!currentString) return;             // if the incoming string is empty, do no more
    console.log(currentString);
    if (!isNaN(currentString)) {  // make sure the string is a number (i.e. NOT Not a Number (NaN))
      textXpos = currentString;   // save the currentString to use for the text position in draw()
    }
  }
docs: Called when there is data available from the serial port