Processing code:

                    

                     
import processing.serial.*;
                     
Serial myPort;
                     


                     
int numChannels = 16;
                     


                     
void setup() {
                     
 size(1280,800);
                     
//  println(Serial.list());
                     
  myPort = new Serial(this, Serial.list()[0], 9600);
                     
 background(0);
                     
}
                     


                     
void draw() {
                     
}
                     


                     
void mouseMoved() {
                     
 int ID = int(map(mouseX,0,width,0,numChannels));
                     
 myPort.write(ID);
                     
}
                    

1. Arduino code:
2. // 16 channels
3. int r0 = 0;
4. int r1 = 0;
5. int r2 = 0;
6. int r3 = 0;
7. int row = 0;
8. int ID = 0;
9. int bin [] = {0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111};
10. 
    
11. void setup(){
12.   pinMode(2, OUTPUT);
13.   pinMode(3, OUTPUT);
14.   pinMode(4, OUTPUT);
15.   pinMode(5, OUTPUT);
16.   Serial.begin(115200);
17. }
18. 
    
19. void loop () {
20.   if (Serial.available()) {
21.     ID = Serial.read();
22.     Serial.print(ID);
23.   }
24.   row = bin[ID];
25.   r0 = row & 0x01;
26.   r1 = (row>>1) & 0x01;
27.   r2 = (row>>2) & 0x01;
28.   r3 = (ID>7)? 1:0;
29.   digitalWrite(2, r0);
30.   digitalWrite(3, r1);
31.   digitalWrite(4, r2);
32.   digitalWrite(5, r3);
33. }