/**************************************************************************
trafic light without instruction in the loop
**************************************************************************/

#define led1 	11 
#define led2 	 8 
#define led3   4

volatile int state;
 
void setup() {
  
  pinMode(led1,OUTPUT);
  pinMode(led2,OUTPUT);
  pinMode(led3,OUTPUT);
    
  cli(); // Nointerrupt
  TCCR1A = 0;
  TCCR1B = 0;

  // fattore di divisione del prescaler
  TCCR1B |= (1 << CS12) |(1 << CS10) ; //(1 << CS12)|(1 << CS11)|(1 << CS10);

  /*
   WGM  Waveform Generation Mode
   con WGM 10 11 12 13 puoi impostare una delle seguenti modalità
   - PWM, phase correct 8-10bit
   - CTC
   - Fast PWM 8-10bit
   - PWM, phase and Frequency Correct
  */
  TCCR1B |= (1 << WGM10); 

  
  //      frequenza con prescaler

  //      con le soglie definisco il duty cycle  
  //      lento   medio    veloce
  OCR1A = 43000; //37000; // 58000  // soglia alta max 64k
  OCR1B = 21600; //26000; // 52000  // soglia bassa
  TCNT1 =  1000; //15000; // 46000   // valore di inizio conteggio stesso numero in ISR_OVR
  
  TIMSK1 |= (1 << OCIE1B);
  TIMSK1 |= (1 << OCIE1A);
  TIMSK1 |= (1 << TOIE1);
    
  sei(); // ok interrupt

  // START
  digitalWrite(led1, HIGH);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, HIGH);
  delay(300);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
}

ISR(TIMER1_COMPB_vect) {
    digitalWrite(led1,HIGH); 
    digitalWrite(led2,HIGH); 
    digitalWrite(led3,LOW); 
}

ISR(TIMER1_COMPA_vect) {
    digitalWrite(led1,LOW); 
    digitalWrite(led2,LOW);
    digitalWrite(led3,HIGH);   
}

ISR(TIMER1_OVF_vect) {
    digitalWrite(led1,HIGH); 
    digitalWrite(led2,LOW);
    digitalWrite(led3,LOW);
    TCNT1=1000;
  }

void loop() {

  /*
  your code
  */ 
}