const int Led1 = D7;

void setup() {
  // initialize digital pin Led1 as an output.
  pinMode(Led1, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(Led1, HIGH);  // turn the LED on (HIGH is the voltage level)
  delay(200);                      // wait
  digitalWrite(Led1, LOW);   // turn the LED off by making the voltage LOW
  delay(200);                      // wait
}