void setup() {
  // put your setup code here, to run once:
  volatile char *dir;
  dir = 0x30; //DDRF – Port F Data Direction Register
  *dir = 0xFF; // set PORT F as output port
}

void loop() {
  // put your main code here, to run repeatedly:
  volatile long i;
  volatile char *out;
  out = 0x31; //PORTF – Port F Data Register

  *out = 0xC0; //0
  for (i = 0; i < 450000; i++);

  *out = 0xF9; //1
  for (i = 0; i < 450000; i++);

  *out = 0xA4; //2
  for (i = 0; i < 450000; i++);

  *out = 0xB0; //3
  for (i = 0; i < 450000; i++);

  *out = 0x99; //4
  for (i = 0; i < 450000; i++);

  *out = 0x92; //5
  for (i = 0; i < 450000; i++);

  *out = 0x82; //6
  for (i = 0; i < 450000; i++);

  *out = 0xF8; //7
  for (i = 0; i < 450000; i++);

  *out = 0x80; //8
  for (i = 0; i < 450000; i++);

  *out = 0x98; //9
  for (i = 0; i < 450000; i++);

}