To set the home position (no USB communication), change these lines :
if(idle) {
idleCounter++;
if(idleCounter > 10000) {
analogWrite(5, 50);
delay(250);
digitalWrite(5, LOW);
idleCounter = 0;
}
else{
digitalWrite(5, LOW);
}
xPosition = 110 ;
yPosition = 100 ;
fire = 0;
}