MAX3232 RS232 to TTL serial module

/*
 * ==================================================================
 *  Generated by Codey.online  —  https://www.codey.online
 * ==================================================================
 *  Project   : MAX3232 RS232 to TTL Serial Bridge
 *  Board     : Arduino UNO (arduino:avr:uno)
 *  Parts     : MAX3232 RS232 to TTL Serial Converter Module
 *  Libraries : none (built-in)
 *
 *  Codey Online is an AI-powered browser IDE for Arduino and ESP32.
 *  Describe your project and Codey writes the code, draws the wiring
 *  diagram and uploads it to your board, straight from the browser.
 *  This code is free to use, modify and share, without warranty.
 * ==================================================================
 */

#include <SoftwareSerial.h>

const uint8_t RX_PIN = 2; // Connect to MAX3232 TXD
const uint8_t TX_PIN = 3; // Connect to MAX3232 RXD

SoftwareSerial rs232Serial(RX_PIN, TX_PIN);

void setup() {
  Serial.begin(115200);
  rs232Serial.begin(9600);

  Serial.println(F("--- MAX3232 RS232 Bridge Ready ---"));
  Serial.println(F("Type in the Serial Monitor (115200 baud) to send over RS232 (9600 baud)."));
  Serial.println(F("Any response from the RS232 device will appear here."));
}

void loop() {
  // Forward characters from the USB Serial Monitor to the RS232 module
  while (Serial.available() > 0) {
    char c = Serial.read();
    rs232Serial.write(c);
  }

  // Forward characters from the RS232 module to the USB Serial Monitor
  while (rs232Serial.available() > 0) {
    char c = rs232Serial.read();
    Serial.write(c);
  }
}

/*
 * ==================================================================
 *  Generated by Codey.online  —  https://www.codey.online
 * ==================================================================
 *  Project   : RS232 Communication with MAX3232 and ESP32
 *  Board     : ESP32 DEVKIT V1 (esp32:esp32:esp32doit-devkit-v1)
 *  Parts     : MAX3232 RS232 to TTL Serial Converter Module
 *  Libraries : none (built-in)
 *
 *  Codey Online is an AI-powered browser IDE for Arduino and ESP32.
 *  Describe your project and Codey writes the code, draws the wiring
 *  diagram and uploads it to your board, straight from the browser.
 *  This code is free to use, modify and share, without warranty.
 * ==================================================================
 */

// MAX3232 RS232 Demo for ESP32 DEVKIT V1
// Uses Hardware Serial2: GPIO 16 (RX2) and GPIO 17 (TX2)

const int RX_PIN = 16;
const int TX_PIN = 17;

unsigned long lastSendTime = 0;
const unsigned long sendInterval = 2000; // Send a test string every 2 seconds
int messageCounter = 0;

void setup() {
  // USB Serial Monitor
  Serial.begin(115200);
  while (!Serial && millis() < 2000);

  // RS232 Port on Serial2 (9600 baud, 8N1)
  Serial2.begin(9600, SERIAL_8N1, RX_PIN, TX_PIN);

  Serial.println("--- MAX3232 RS232 Bridge Initialized ---");
  Serial.println("Tip: Short DB9 pins 2 & 3 for an automatic loopback test.");
}

void loop() {
  // Periodically send a message out via RS232
  if (millis() - lastSendTime >= sendInterval) {
    lastSendTime = millis();
    messageCounter++;

    String msg = "RS232 Test Message #" + String(messageCounter);
    Serial2.println(msg);
    Serial.print("[RS232 TX] ");
    Serial.println(msg);
  }

  // Print any incoming data from the RS232 interface
  if (Serial2.available()) {
    Serial.print("[RS232 RX] ");
    while (Serial2.available()) {
      char inChar = (char)Serial2.read();
      Serial.print(inChar);
    }
  }

  // Forward any user input from Serial Monitor to RS232
  if (Serial.available()) {
    char outChar = (char)Serial.read();
    Serial2.write(outChar);
  }
}