#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// MAX485 module connections
const int MAX485_DE = 2;  // DE pin for the MAX485 module
const int MAX485_RE = 3;  // RE pin for the MAX485 module

// LCD module connections
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);

  // Initialize MAX485 pins
  pinMode(MAX485_DE, OUTPUT);
  pinMode(MAX485_RE, OUTPUT);

  // Set initial state of DE and RE (Receiver mode)
  digitalWrite(MAX485_DE, LOW);
  digitalWrite(MAX485_RE, LOW);

  lcd.print("ESP32 RS485");
  lcd.setCursor(0, 1);
  lcd.print("Waiting...");
}

void loop() {
  // Transmit data from ESP32 A to ESP32 B
  sendData("Hello from A", MAX485_DE, MAX485_RE);

  delay(2000); // Adjust as needed

  // Transmit data from ESP32 B to ESP32 A
  sendData("Hello from B", MAX485_DE, MAX485_RE);
  
  delay(2000); // Adjust as needed
}

void sendData(const char *data, int DE, int RE) {
  // Switch to transmitter mode
  digitalWrite(DE, HIGH);
  digitalWrite(RE, HIGH);

  Serial.println("Transmitting: " + String(data));
  
  // Transmit data
  Serial.write(data);
  
  // Switch back to receiver mode
  digitalWrite(DE, LOW);
  digitalWrite(RE, LOW);

  // Display received data on LCD
  lcd.clear();
  lcd.print("Received:");
  lcd.setCursor(0, 1);
  
  while (Serial.available() > 0) {
    char receivedChar = Serial.read();
    lcd.write(receivedChar);
  }

  delay(1000); // Display received data for 1 second
}