  
 int count = 0;
 int current_idx = -1;
-int lengths[3] = {20, 0, 15};   
+int lengths[4] = {20, 5, 10, 15};   
  
 void setup() 
 {

  }
   if( current_idx == 0) {
      digitalWrite( A0, 0 );      
      digitalWrite( 13, 1 );
   }
   if( current_idx == 1) {
      digitalWrite( 13, 0 );
      digitalWrite( A0, 1 );      
   }
   if( current_idx == 2) {
      digitalWrite( A0, 0 );      
      digitalWrite( 13, 0 );
   }
   count--;
   current_idx %= 3;
}

  // Pin 13 has an LED connected on most Arduino boards
  pinMode(13, OUTPUT);    
  pinMode(A0, OUTPUT);
  pinMode(A1, OUTPUT);
    
  digitalWrite( 13, 0 );
  digitalWrite( A0, 0 );      
  digitalWrite( A1, 0 );      
  
  Timer1.initialize(20000); // set a timer of length 20000 microseconds (or 0.02 sec - or 50Hz => frequency of electricity in europe)
  Timer1.attachInterrupt( timerIsr ); // attach the service routine here
}
 
