void setup() {
  Serial.begin(115200);
}

/* Z funkcijo delay() */

void loop() {
  Serial.println("ALARM");
  delay(500);
}

/* Z funkcijo millis() */

void loop() {
  static unsigned long Prejsni_cas = 0;
  unsigned long zdej = millis();

  if (zdej - Prejsni_cas >= 500) {
    Serial.print("ALARM");
    Prejsni_cas = millis();
  }
}

/*

unsigned long changeTime;
int casDelay = 500;
bool m = HIGH;

void setup() {
  Serial.begin(115200);
  chaneTime = millis();
}

void loop() {
  if (millis() - chaneTime > casDelay) {
    chaneTime = millis();
    m = !m;
  }

  if (m == LOW) Serial.println("vklop");
    else if (m == HIGH) Serial.println(("izklop"));
}

*/