import processing.serial.*;

String buff = “”;
int val = 0;
int NEWLINE = 10;
Serial port;
void setup(){
  port = new Serial(this, Serial.list()[0], 9600); // Use the first available port
}
void draw(){
  while (port.available() > 0)
    serialEvent(port.read()); //look for data
  background(val); //change background clr based on input data
}
void serialEvent(int serial) {
  if(serial != NEWLINE) {
    buff += char(serial); //add on bytes until a newline is found
  } 
  else {
    buff = buff.substring(0, buff.length()-1);
    val = Integer.parseInt(buff)/4; // Parse the String to int
    println(val);
    buff = “”; // Clear the value of “buff”
  }
}