🚀 Building Stable Ethernet MQTT Communication with ESP32 and W5500

If you're developing an embedded application with the ESP32 and need more stable network connectivity than Wi-Fi can offer, using the WIZnet W5500 Ethernet chip is a smart choice. In a detailed blog post by Hikoleaf, the author walks through how to implement MQTT communication over Ethernet using ESP32 + W5500, powered by the Arduino development environment.

🔧 Project Overview

The tutorial demonstrates how to connect the ESP32 microcontroller to a W5500 Ethernet module via SPI, then use MQTT to send and receive messages through a local broker.

🛠️ Core Components

• ESP32: Wi-Fi-enabled microcontroller with SPI support
• W5500: SPI-based Ethernet controller with built-in TCP/IP stack
• Arduino IDE: Used for code development
• Mosquitto (on Raspberry Pi): Acts as a local MQTT broker

📦 Step-by-Step Implementation

1. Hardware Wiring
Connect the W5500 module to the ESP32 using SPI pins (MOSI, MISO, SCLK, CS).

2. Arduino Library Setup
Install the following libraries:

• Ethernet
• PubSubClient

3. Code Implementation

• Initialize Ethernet using Ethernet.begin()
• Connect to the MQTT broker with PubSubClient
• Send and receive messages on subscribed topics

4. MQTT Broker Setup
Install and configure Mosquitto on a Raspberry Pi to act as your MQTT server.

🧪 Example Code Snippet

#include <Ethernet.h>
#include <PubSubClient.h>

byte mac[] = { 0x70, 0x69, 0x69, 0x2D, 0x30, 0x31 };
byte server[] = { 10, 0, 1, 5 };

void callback(char* topic, byte* payload, unsigned int length) {
  payload[length] = '\0';
  String msg = String((char*) payload);
  Serial.println(msg);
}

EthernetClient ethClient;
PubSubClient client(server, 1883, callback, ethClient);

This code initializes Ethernet, connects to the MQTT server, and listens for incoming messages.

✅ Why Use Ethernet on ESP32?

While ESP32 is known for its Wi-Fi capability, there are many reasons to choose Ethernet with W5500:

• 🚫 Avoid unstable or congested wireless networks
• 🔐 Improve security and isolation
• 📈 Ensure real-time data delivery in industrial environments

📘 Read the Full Tutorial

For complete wiring diagrams, full source code, and detailed setup instructions, check out the original blog post:

👉 W5500を使ってESP32でEthernet MQTT通信する

This guide is a must-read if you're building an IoT system with stable wired network communication using ESP32 and Rust or Arduino.