#include <avr/io.h> 
#include <util/delay.h> 
//Interrupt Service Routine for INT0
volatile int state=LOW;
byte bit5;
ISR(INT0_vect){
  state ^= bit5;//exclusive OR
}
int main() { 
  init();
  DDRD = 0x0; //PORTD bit 2 as input
  PORTD = 0x04;//configure to use pull up resistor
  /* set PORTB BIT IN PIN 13 as output */
  DDRB |= 0x20;// DDRB5 pin 13 as output
  EIMSK |= 0b00000001;//Enable ext interrupt INT0
  EICRA |= 0b00000010;//Trig. INT0 on falling edge
  bit5 = 1 << 5;//set bit 5 to 1 shifting 5 times
  sei();//Enable interrupts 
  while (true) { 
      PORTB = state;//change state
  } 
  return 0; 
} 
// #include <avr/io.h>
// int main()
// {
//   init();
//   DDRD = 0x00;//configure DDRD1, pin 2 as input
//   DDRB = 0x20;
//   PORTD = 0x04;//configure to use pull up resistor
//   //PORTB = 0x20;
//   Serial.begin(9600);//set serial to 9600 bps 
  
//   do{
// 	byte input=PIND & 0x04; //read pin 2 in port D
//     input = input >> 2;
// 	Serial.println(input);
  
//   if (input == 0){
//     PORTB = 0x20;
//   } 
//   else {
//     PORTB = 0x00;
//   }
//   }while(true);
  
 
// }