const int relayPin = 27;

void setup() 
{
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  pinMode(relayPin, OUTPUT);
}

void loop() 
{
  digitalWrite(relayPin, HIGH);
  Serial.println("ON");
  delay(2000);

  digitalWrite(relayPin, LOW);
  Serial.println("OFF");
  delay(2000);
}