void init_port();
void timer();

void setup() {
  // put your setup code here, to run once:
init_port();
timer();
volatile long i;
volatile int j=0;
Serial.begin(9600);
while(1)
{
  Serial.println(j,DEC);
  j++;
  for(i=0;i<500000;i++);
}
}

void timer()
{
  volatile char *timer2_TCCR2A = 0xB0;
  volatile char *timer2_TCCR2B = 0xB1;
  volatile short *timer2_TCNT2  = 0xB2;
  volatile short *timer2_OCR2A = 0xB3;
  volatile char *timer2_TIMSK2 = 0x70;

  timer2_TCCR2A = 0;
  *timer2_TCCR2B = 0;
  timer2_TCNT2 = 0;

  *timer2_TCCR2B = 0x0f;
  *timer2_OCR2A = 500000;
  *timer2_TIMSK2 = 0x02;
}

void init_port()
{
  volatile char *portf_dir = (volatile char *)0x30;
  *portf_dir = 0x01;
}

ISR(TIMER2_COMPA_vect)
{
  volatile char *out = (volatile char *)0x31;
  //volatile long i;
  *out ^= 0x01;
  

}

void loop() {
  // put your main code here, to run repeatedly:

}