int ledDelay = 200;
unsigned long changeTime;
int m = HIGH;




void setup(){
  DDRB |= 0b00000100; // DDRD = DDRD | 0 x 04 
  changeTime = millis();
}

void loop() {
  if ((millis() - changeTime) > ledDelay) {
    changeTime = millis();
    m = !m; // if (m == HIGH) m == LOW, else m = HIGH
  }

  if (m == HIGH){
    PORTD |= 0x04;
  }
  
  if (m == LOW){
    PORTD &= !0x04;
  }
}