/* DARLAN VIVIAN
   EDUARDO A. P. ALCHIERI
   THIAGO MEREGE PEREIRA */

/* I/O PORT B, DATA DIRECTION REGISTER (0 -> in, 1 -> out) */
#define DDRB    (*(volatile unsigned char *)(0x17 + 0x20))

/* I/O PORT B, DATA REGISTER */
#define PORTB   (*(volatile unsigned char *)(0x18 + 0x20))

/* SREG, STATUS REGISTER */
#define SREG (*(volatile unsigned char *)(0x5F))

/* TIMER/COUNTER0 CONTROL REGISTER */
#define TCCR0 (*(volatile unsigned char *)(0x53))

/* TIMSK, TIMER INTERRUPT MASK */
#define TIMSK (*(volatile unsigned char *)(0x59))

#define TIMER0 __vector_7

#define SIGNAL __attribute__ ((signal))

unsigned char count = 0x00;

int main(void) {
 
    /* Enable interrupts */
    SREG = 0x80;

    /* Select CK/1024 */
    TCCR0 = 0x05;
    
    /* Enable Timer/Counter0 Interrupt */
    TIMSK = 0x02;

    /* Set the whole port (all bits) to "output" */
    DDRB = 0xff;

    while(1) {}
        return 0;

}

void TIMER0 (void) SIGNAL;

void TIMER0 (void) {
    count++;
    /*(8000000/(2*1024*256))*16 = 244 */
    if (count == 244) {
       
    /* Turns on/off all PORTB leds after 16 seconds */
       PORTB = ~PORTB;
       count = 0;
   }

}