void setup() {
  Serial.begin(115200);
  pinMode(16, OUTPUT);
  pinMode(17, OUTPUT);
  pinMode(18, OUTPUT);
}

void loop() {
  digitalWrite(18, HIGH);
  delay(1000);
  digitalWrite(18, LOW);
  digitalWrite(17, HIGH);
  delay(1000);
  digitalWrite(17, LOW);
  digitalWrite(16, HIGH);
  delay(1000);
  digitalWrite(16, LOW);
}