Wiznet makers

1. Project Overview & Features

Core Functionality:

• This project reads temperature and humidity data from a DHT22 sensor and transmits it to an MQTT broker via W5500 Ethernet or Wi-Fi.
• The system supports asynchronous MQTT communication using the AsyncMQTT_ESP32 library, ensuring efficient and non-blocking message handling.

Problem Solved & Use Case:

• Allows real-time remote monitoring of environmental conditions.
• Ideal for IoT applications, such as smart home automation and industrial monitoring.

Key Features:

• Hardware: ESP32, W5500 Ethernet module, DHT22 sensor
• Network: Supports both Ethernet (W5500) and Wi-Fi connectivity
• Protocol: MQTT
• Data Handling: JSON-based message formatting for structured transmission

2. Hardware & Software Stack

Hardware Components:

• Microcontroller: ESP32
• Network Module: W5500 Ethernet (SPI Interface)
• Sensor: DHT22 Temperature & Humidity Sensor

Software Components:

• Programming Language: C++ (Arduino IDE)
• Libraries Used:
  • AsyncMQTT_ESP32: Non-blocking MQTT communication
  • Adafruit Sensor & DHT_U: Sensor data collection
  • ArduinoJson: JSON data formatting
• Network Protocols: MQTT, TCP/IP

3. Key Parts of the Source Code

Ethernet Connection Setup

void setup() {
  Serial.begin(115200);
  // Initialize Ethernet
  Ethernet.init(ETH_CS_PIN);
  Ethernet.begin(mac, ip);
  // Setup MQTT broker connection
  mqttClient.setServer(MQTT_HOST, MQTT_PORT);
  mqttClient.setCallback(mqttCallback);
}

void connectToMqtt() {
  while (!mqttClient.connected()) {
    Serial.print("Connecting to MQTT...");
    if (mqttClient.connect("ESP32Client")) {
      Serial.println("Connected");
      // Subscribe to a topic
      mqttClient.subscribe("sensor/data");
    } else {
      Serial.print("Failed, rc=");
      Serial.print(mqttClient.state());
      Serial.println(" Retrying in 5 seconds...");
      delay(5000);
    }
  }
}

void readSensorData() {
  sensors_event_t event;
  dht.temperature().getEvent(&event);
  float temperature = event.temperature;
  dht.humidity().getEvent(&event);
  float humidity = event.relative_humidity;
  
  // Format data as JSON
  StaticJsonDocument<256> doc;
  doc["temperature"] = temperature;
  doc["humidity"] = humidity;
  
  char jsonBuffer[512];
  serializeJson(doc, jsonBuffer);
  
  // Publish data to MQTT topic
  mqttClient.publish("sensor/data", jsonBuffer);
}

3. Comparison with Traditional MQTT Implementations

✅ Advantages:

Asynchronous Processing:

• Uses AsyncMQTT_ESP32 for non-blocking communication.
• Improves system responsiveness and efficiency.

Better Scalability:

• Compatible with various boards, including ESP32 and multiple Ethernet modules (W5500, ENC28J60, etc.).

❌ Disadvantages:

Increased Complexity:

• Asynchronous programming requires a deeper understanding compared to traditional synchronous implementations.

Library Dependency:

• The project heavily relies on AsyncMQTT_ESP32, which may require maintenance and updates to remain compatible.

4. Suggested Improvements & Enhancements

✔ Security: Implement TLS/SSL encryption for MQTT to enhance data security.
✔ Error Handling: Add mechanisms to detect and handle network failures, sensor errors, and MQTT disconnections.
✔ Data Storage: Enable local storage (SD card) or cloud-based database integration for long-term data logging.
✔ Real-time Monitoring: Integrate with Node-RED or other visualization tools to display real-time sensor data.