const int NUM_LEDS = 8;
const int DELAY_TIME = 100; // Adjust this for speed control

void setup() {
  // Set pins 2 to 9 as output
  DDRD = B11111111; // Set pins 2 to 7 as output
}

void loop() {
  for (int i = 0; i < 0 + NUM_LEDS; i++) {
    // Turn on LED at pin i
    PORTD |= (1 << i);
    delay(DELAY_TIME);
    // Turn off LED at pin i
    PORTD &= ~(1 << i);
  }
}