BluetoothSerial SerialBT;
const int LED = 23;
char Incoming_value = '0';

void setup() {
  Serial.begin(115200);
  Serial.println("ESP32 started");
  SerialBT.begin("ESP32test"); //Bluetooth device name
  Serial.println("The device started, now you can pair it with bluetooth!");
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LOW); 
}

void loop() {
  
  if (SerialBT.available()) {
    Incoming_value = SerialBT.read();   
    if(Incoming_value == '1')             
      digitalWrite(LED, HIGH);  
    else if(Incoming_value == '0')       
      digitalWrite(LED, LOW);   
    Serial.println(Incoming_value);        
  }
  delay(50);
}