#define F_CPU 1000000UL
#include <avr/io.h>
#include <avr/interrupt.h>

 ISR(INT0_vect)
{
 ADCSRA|= 1<<ADSC;
}

 ISR(ADC_vect)
 {
     PORTB=ADCH;
 }

int main(void)
{

     ADCSRA=0x8B;
     ADMUX=0x00;
MCUCR =0x0F;                // Trigger INT0 on rising edge
    GICR = 0x40;            // Enable INT0
     sei();
    while(1)
    {

    }