const int RELAY_PIN = 0;  // the esp8266 pin, which connects to the IN pin of relay

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin as an output.
  pinMode(RELAY_PIN, OUTPUT);
  Serial.begin(9600);
}

// the loop function runs over and over again forever
void loop() {
  //type of this relay work when change mode
  pinMode(RELAY_PIN, INPUT);
  Serial.println("off");
  delay(2000);
  pinMode(RELAY_PIN, OUTPUT);
  Serial.println("on");
  delay(2000);


  
}