#define F_CPU 8000000UL
#include <avr/io.h>           /* Include AVR std. library file */
#include <util/delay.h>         /* Include inbuilt defined Delay header file */
#include <avr/interrupt.h>

void int5_init(void)

{
   // Make sure you have connected a SW between PE1 (External Interrupt) and GND.
   cli();                 // Clear all the interrupts
   PORTE |= (1 << PE5);   // External SW PullUp
   DDRE &= ~(1 << PE5);   // External Interrupt Sensing Port(PE3) Input Port
   EICRB |=  (1<<ISC51);   // External Interrupt 5, Falling Edge Asynchronously Interrupt
   EIMSK |= (1 << INT5);;   // External Interrupt 5 enable
   sei();
}

int main()
{
  int i;
  DDRK = 0xFF;
  PORTK = 0;
  int5_init();                    // Initialization of INT5 Interrupt
  while(1) {
  }
}

ISR (INT5_vect)
{
  sei();
  PORTE |= (1 << PE5); 
  /*int5_init();*/
  PORTK = ~PORTK;
	EIMSK |= (1 << INT5);     // External Interrupt 0 enable
}