const int LEDPIN=13;
void setup() {
  // put your setup code here, to run once:
pinMode(LEDPIN, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(LEDPIN, HIGH); // Turn the LED on
delay(1000); // Wait for a second
digitalWrite(LEDPIN, LOW); // Turn the LED off
delay(1000);
}