// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(D7, OUTPUT); // oder : pinMode(LED_BUILTIN, OUTPUT); oder : pinMode(2, OUTPUT);
  pinMode(D6, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(D7, LOW);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);  // Lampe aus
  while(digitalRead(D6) == LOW)
    yield;
  digitalWrite(LED_BUILTIN, LOW);
  for (int i=0; i<8; i++)
  {
    digitalWrite(D7, HIGH);
    delay(20);
    digitalWrite(D7, LOW);
    delay(20);      
  }
  delay(500);
}