const byte LED_BUILTIN = 12;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT); // Onboard LED
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
}

void loop() {
     digitalWrite(LED_BUILTIN, HIGH);  // turn on LED with voltage HIGH
      Serial.println("led on");
     delay(1000);                      // wait one second
     digitalWrite(LED_BUILTIN, LOW);   // turn off LED with voltage LOW
      Serial.println("led off");
     delay(1000);                      // wait one second
   
}