#define IRQ0 __vector_1
#define TIMER __vector_7
#define SIGNAL __attribute__ ((signal))

#define PORTB   (*(volatile unsigned char *)(0x38))
#define DDRB    (*(volatile unsigned char *)(0x37))
#define DDRD    (*(volatile unsigned char *)(0x31))
#define INPUTD  (*(volatile unsigned char *)(0x30))
#define GIMSK   (*(volatile unsigned char *)(0x5b))
#define SREG    (*(volatile unsigned char *)(0x5f))
#define TCCR0   (*(volatile unsigned char *)(0x53))
#define TIMSK   (*(volatile unsigned char *)(0x59))
#define MCUCR   (*(volatile unsigned char *)(0x55))

int ir_sense = 0;

int counter = 0;

void TIMER(void) SIGNAL;

void TIMER(void)
{
    // Quando counter for igual a 57, terá passado 4 segundos desde que a IRQ0 foi ativada
    counter++;
    if (counter == 57)
    {
        PORTB = 0x00;
        TCCR0 = TCCR0 & 0xf8;
        counter = 0;
    }
}

void IRQ0(void) SIGNAL;

void IRQ0(void)
{
    if (ir_sense == 0)
    {	
        TCCR0 = TCCR0 | 0x05;
        MCUCR = MCUCR | 0x03;
	ir_sense = 1;
    }
    else
    {
        TCCR0 = TCCR0 & 0xf8;
        MCUCR = MCUCR & 0xfe;
	PORTB = 0xff;
	ir_sense = 0;
        counter = 0;
    }
}

int main(void) {
    SREG  = SREG  | 0x80;
    TIMSK = TIMSK | 0x02;
    GIMSK = GIMSK | 0x40;
    TCCR0 = TCCR0 & 0xf8;
    MCUCR = MCUCR | 0x03;
    MCUCR = MCUCR & 0xfe;
    DDRB = 0xff;
    DDRD = 0x00;
    PORTB = 0xff;
    while(1) { }
    return 0;
}