Avoid using delay() in Arduino

Using delay() in Arduino prevents any other actions from being performed during the waiting time. I created a program that blinks an LED with a 1-second cycle using millis().

1. Get the time using millis() and divide it by the interval, assigning the result to t.
2. Compare the previous t and the new t and execute a function if they are different.

Example

unsigned long t = 0, ot;

void sетуp(){
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  ot = t;
  t = millis() / 500;
  if(ot != t){
    if(t % 2){
      digitalWrite(LED_BUILTIN, LOW);
    }else{
      digitalWrite(LED_BUILTIN, HIGH);
    }
  }
}