// Pointers to hardware registers
volatile char *dird, *eicra, *eimsk, *sreg, *dirf, *outf, *ind;

void interruptSetup();
void timerSetup();

void setup() {
   volatile char *outf = (volatile char*)0x31;
   *outf = 0x00;
  Serial.begin(9600);
  interruptSetup();
  
}

void interruptSetup() {
  // Set Port D direction
  dird = 0x2A; 
  *dird = 0x00; // Set all to input
   ind = 0x29;
  // Set Port F direction
  dirf = 0x30; 
  *dirf = 0xFF; // Set all pins to output
  
  // Set up output register
  outf = 0x31;
  
  // Configure EICRA for INT0
  eicra = 0x69;
  *eicra = (1<<ISC00); // for any edge

  // Enable INT0 interrupt
  eimsk = 0x3D;
  *eimsk = (1<<INT0);
  
  // Enable global interrupts
  sreg = 0x5F;
  *sreg |= 1<<7; // Set global interrupt flag
}

void timerSetup() {
   
   volatile short *timer_TCCR1A =  0x80;
   volatile short *timer_TCCR1B =  0x81;
   volatile short *timer_TCNT1 =  0x84;
   volatile short *timer_OCR1A =  0x88;
   volatile short *timer_TIMSK1 =  0x6F;
   
   // Set Port F direction to output
   dirf =  0x30; 
   *dirf = 0xFF; // Set all pins to output
  
   // Set up output register
   outf =  0x31;
   //*outf =0x00; // Initially turn off LED connected to Port F pin 0

   // Configure Timer1
   *timer_TCCR1A = 0;    
   *timer_TCCR1B = 0;        
   *timer_TCCR1B =  (1<<CS12)|(1<<CS10)|(1<<WGM12);  //  PRESCALER 1024  AND CTC MODE   
   *timer_TCNT1 = 0;       
   *timer_OCR1A = 46000;  // count 3seconds
   *timer_TIMSK1 = (1<<OCIE1A);          

   // Enable global interrupts
   sreg =  0x5F;
   *sreg |= 1 << 7; // Set global interrupt flag
   
}

ISR(INT0_vect) {
  dird = 0x2A; 
  *dird = 0x00; // Set all to input
   ind = 0x29;
   *outf = 0x00;
if((*ind &0x01)==0x01){
*outf = 0x01;
 timerSetup();
}
else{
  *outf = 0x00;
}

  
}

ISR(TIMER1_COMPA_vect){
  volatile short *timer_TCNT1 = (volatile short*) 0x84;
  volatile char *dirf = (volatile char*)0x30;
  volatile char *outf = (volatile char*)0x31;
   *dirf = 0xFF;
   *outf = 0x00; 
 
}


void loop() {

  

}