#include <HardwareSerial.h>

// Define UART instances
HardwareSerial uart1(1); // UART1
HardwareSerial uart2(2); // UART2

String baseMessage = "Message";
int counter = 0;

void setup() {
  Serial.begin(115200);
  Serial.println("ESP32 Full-Duplex UART Echo Demo");

  // UART1: TX=GPIO17, RX=GPIO5
  uart1.begin(115200, SERIAL_8N1, 5, 17);

  // UART2: TX=GPIO18, RX=GPIO16
  uart2.begin(115200, SERIAL_8N1, 16, 18);

  // Send initial message via UART1
  uart1.print(baseMessage);
  Serial.println("Sent initial message: " + baseMessage);
}

void loop() {
  // Check if UART1 received anything
  if (uart1.available()) {
    String msg = uart1.readString();
    Serial.print("UART1 <<-- ");
    Serial.println(msg);

    // Append counter and send back via UART2
    String response = baseMessage + "_" + String(++counter);
    uart2.print(response);
    Serial.print("UART2 -->> ");
    Serial.println(response);
  }

  // Check if UART2 received anything
  if (uart2.available()) {
    String msg = uart2.readString();
    Serial.print("UART2 <<-- ");
    Serial.println(msg);

    // Append counter and send back via UART1
    String response = baseMessage + "_" + String(++counter);
    uart1.print(response);
    Serial.print("UART1 -->> ");
    Serial.println(response);
  }

  delay(2000); // Small delay to avoid flooding CPU
}