void setup() {
  // put your setup code here, to run once:
  volatile char *portf;
  portf = (char *) 0x30;
  *portf = 0xFF;
}

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

  // Glow LSB LED only (bit 0)
  //volatile char *output;
  //output = 0x31;
  //*output = 0x01;

  // Glow MSB LED only (bit 7)
  //volatile char *output;
  //output = 0x31;
  //*output = 0x80;

  // Glow LSB 2 LEDs only (bit 0 & bit 1)
  //volatile char *output;
  //output = 0x31;
  //*output = 0x03;

  // Glow MSB 2 LEDs only (bit 7 & bit 6)
  //volatile char *output;
  //output = 0x31;
  //*output = 0xC0; 

  // Glow LSB 4 LEDs only (bit 0 to bit 3)
  //volatile char *output;
  //output = 0x31;
  //*output = 0x07;

  // Glow MSB 4 LEDs only (bit 7 to bit 4)
  //volatile char *output;
  //output = 0x31;
  //*output = 0xF0;

  // Glow all 8 LEDs
  //volatile char *output;
  //output = 0x31;
  //*output = 0xFF; 

  // Glow all ODD no LEDs
  //volatile char *output;
  //output = 0x31;
  //*output = 0xAA; // 0101 0101 55  -   1010 1010 AA

  // Glow all EVEN no LEDs
  //volatile char *output;
  //output = 0x31;
  //*output = 0x55; // 0101 0101 55  -   1010 1010 AA

  // Glow LEDs of bit7, bit4, bit3, bit1
  volatile char *output;
  output = 0x31;
  *output = 0x4D; // 0100 1101 4D
}