int ledPin = 13;
int delaytime = 1000;
boolean ledstate = false;

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  while (ledstate == false) {
    digitalWrite(ledPin, HIGH);
    delay(delaytime);
    digitalWrite(ledPin, LOW);
    delay(delaytime);
    ledstate = true;
  }
}