void setup() {
  // put your setup code here, to run once:
  volatile char *dirf = 0x30;//portf direction register
  volatile char *outf = 0x31;//portf data register
  volatile long i;
  *dirf = 0x01;//portf direction value
  *outf = 0x01;//portf data value
  while(1){
    *outf=*outf^0x01; //by using XOR led will blink
    for(i=0;i<100000;i++);
  }
}

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

}