void setup() {
  Serial.begin(9600);

  pinMode(1, INPUT_PULLUP);
  pinMode(2, OUTPUT);
  pinMode(13, OUTPUT);
}

unsigned long interval = 1000;
unsigned long koha = millis();

void loop() {
  
  unsigned long ahora = millis();
  if(ahora - koha >= interval){
    Serial.println(ahora);
    koha = ahora;
    
  }

  digitalWrite(13, HIGH);
  delay(2000);
  digitalWrite(13, LOW);
  delay(5000);
}