void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial2.begin(115200);
  Serial.println("Hello, ESP32!");
}

void loop() {
  // put your main code here, to run repeatedly:
  while (Serial2.available()) {
    Serial.write(Serial2.read());
  }
  delay(10); // this speeds up the simulation
  Serial2.println("Loopback test.");
}