인터럽트 - 상승엣지

#include 
#include 

unsigned char led = 0xfe;

interrupt [EXT_INT0] void exint0(void)
{ 
    if(led!=0x7f) led = (led << 1) | 0x01; 
    else led = 0xfe; 
    PORTC = led;
    delay_ms(5);
}

void main(void)
{
    DDRC = 0xff; 
    PORTC = led;
    DDRD = 0x00; 
    SREG.7 = 1; 
    EIMSK |= 0x01; 
    EICRA = 3; 
    while(1);
}