Sensor Publisher rev_03

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    - Project: Sensor Publisher
    - Source Code NOT compiled for: Arduino Nano ESP32
    - Source Code created on: 2025-08-04 13:43:02

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/****** SYSTEM REQUIREMENTS *****/
/****** SYSTEM REQUIREMENT 1 *****/
    /* Publicar las variables de temperatura y humedad en */
    /* formato JSON mediante MQTT, usando la librería DHT */
    /* y el pin D2 del Arduino Nano ESP32. */
/****** SYSTEM REQUIREMENT 2 *****/
    /* Ensure MQTT publishes temperature and humidity in */
    /* JSON format using the DHT sensor on pin D2 of the */
    /* Arduino Nano ESP32, with WiFi connectivity for */
    /* real-time data transmission. */
/****** END SYSTEM REQUIREMENTS *****/

/* START CODE */
/****** DEFINITION OF LIBRARIES *****/
#include <DHT.h>                 // https://github.com/adafruit/DHT-sensor-library
#include <WiFi.h>                // WiFi library for ESP32
#include <PubSubClient.h>        // MQTT client library

/****** FUNCTION PROTOTYPES *****/
void setup(void);
void loop(void);
void reconnectMQTT(void);
void publishSensorData(void);

/***** DEFINITION OF DIGITAL INPUT PINS *****/
const uint8_t TempHum_DHT22_DOUT_PIN_D2 = 2;

/****** DEFINITION OF LIBRARIES CLASS INSTANCES*****/
DHT dht(TempHum_DHT22_DOUT_PIN_D2, DHT22);

// WiFi credentials
const char* ssid = "your_SSID";             // Replace with your WiFi SSID
const char* password = "your_PASSWORD";     // Replace with your WiFi password

// MQTT broker details
const char* mqtt_server = "broker.hivemq.com"; // Replace with your MQTT broker address
const int mqtt_port = 1883;                     // MQTT port
const char* mqtt_topic = "sensor/temperature_humidity"; // MQTT topic

WiFiClient espClient;
PubSubClient client(espClient);

unsigned long lastPublishTime = 0;
const unsigned long publishInterval = 5000; // Publish every 5 seconds

void setup(void)
{
  // Initialize serial communication
  Serial.begin(9600);

  // Initialize DHT sensor
  dht.begin();

  // Configure WiFi connection
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected");

  // Configure MQTT server
  client.setServer(mqtt_server, mqtt_port);
}

void loop(void)
{
  if (!client.connected())
  {
    reconnectMQTT();
  }
  client.loop();

  unsigned long currentMillis = millis();
  if (currentMillis - lastPublishTime >= publishInterval)
  {
    lastPublishTime = currentMillis;
    publishSensorData();
  }
}

void reconnectMQTT()
{
  // Loop until reconnected
  while (!client.connected())
  {
    Serial.print("Attempting MQTT connection...");
    // Create a client ID
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect
    if (client.connect(clientId.c_str()))
    {
      Serial.println("connected");
    }
    else
    {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void publishSensorData()
{
  // Read temperature and humidity
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Check if reads are valid
  if (isnan(humidity) || isnan(temperature))
  {
    Serial.println("Failed to read from DHT sensor");
    return;
  }

  // Create JSON payload
  String payload = "{";
  payload += "\"temperature\": " + String(temperature, 2) + ",";
  payload += "\"humidity\": " + String(humidity, 2);
  payload += "}";

  // Publish JSON payload
  if (client.publish(mqtt_topic, payload.c_str()))
  {
    Serial.println("Published data: " + payload);
  }
  else
  {
    Serial.println("Failed to publish data");
  }
}