1. import processing.serial.*;
2.  
3. Serial myPort; // The serial port:
4. int backValue = 255; // Declare variable 'backValue' and assign it the value 255
5.  
6. void setup() { //  The setup() function is run once, when the program starts. It's used to define initial enviroment properties.
7.  size(640, 360);
8.  
9.  background(backValue);
10.  printArray(Serial.list()); // List all the available serial ports:
11.  myPort = new Serial(this, "COM5", 9600); // Open the port you are using at the rate you want:
12. }
13.  
14. void draw() { //  Called directly after setup(), the draw() function continuously executes the lines of code contained inside its block until the program is stopped or noLoop() is called.
15. }
16.  
17. void mousePressed() { //The mousePressed() function is called once after every time a mouse button is pressed.
18.  if (backValue == 255) { //If the test evaluates to true, the statements enclosed within the block are executed
19.    backValue = 10;
20.    myPort.write(0); //low
21.  } else { //It specifies a block of code to execute when the expression in if is false.
22.    backValue = 255;
23.    myPort.write(1); //high
24.  }
25.  background(backValue);
26. }
27.