Wiznet makers

• Source: Renzo Mischianti – mischianti.org

Introduction: Building Reliable IoT with Wired Ethernet

With its dual-core processor and versatile connectivity options, the ESP32 is ideal for various IoT applications.
The release of Core 3 brought native Ethernet protocol support, making it easier to use wired connections with full capabilities like SSL/TLS.
This guide focuses on using the ESP32 with the W5500 Ethernet module to enable secure and reliable HTTPS-based networking.

Core Hardware & Technology

Hardware Requirements

• ESP32 development board
  (e.g., ESP32 Dev Kit v1, TTGO T-Display, NodeMCU ESP-32S, ESP32-S3-DevKitC-1, etc.)
• W5500 Ethernet module (or W5500 Lite)
• Jumper wires
• Breadboard (optional)

W5500 Device Overview

• Hardware-based TCP/IP support (TCP, UDP, IPv4, ICMP, etc.)
• 32KB internal buffer, 8 independent hardware sockets
• Up to 80MHz SPI speed, low-power mode, Wake-on-LAN
• Auto-negotiation for full/half-duplex
• 3.3V operation, 5V tolerant IO

Ethernet Setup Configuration

#define ETH_PHY_TYPE        ETH_PHY_W5500
#define ETH_PHY_ADDR        1
#define ETH_PHY_CS          5
#define ETH_PHY_IRQ         15
#define ETH_PHY_RST         4

SPI.begin(ETH_SPI_SCK, ETH_SPI_MISO, ETH_SPI_MOSI);
ETH.begin(ETH_PHY_TYPE, ETH_PHY_ADDR, ETH_PHY_CS, ETH_PHY_IRQ, ETH_PHY_RST, SPI);

Then use Network.onEvent(onEvent) to monitor connection events, and optionally set hostname via ETH.setHostname().

Simple HTTP Request Example

Testing HTTP request using httpbin.org:

void testClient(const char * host, uint16_t port) {
  NetworkClient client;
  if (!client.connect(host, port)) return;
  client.println("GET /get HTTP/1.1");
  client.println("Host: httpbin.org");
  client.println("Connection: close");
  client.println();
  while (client.connected() && !client.available());
  while (client.available()) Serial.write(client.read());
  client.stop();
}

 HTTPS Request Implementation

For secure requests, use NetworkClientSecure, and for testing you can bypass the certificate using client.setInsecure():

NetworkClientSecure client;
client.setInsecure();
client.connect("httpbin.org", 443);

 Example Output

ETH Started  
ETH Connected  
ETH Got IP: 'eth0'  
inet 192.168.1.137 netmask 255.255.255.0 gateway 192.168.1.1  

connecting to httpbin.org  
HTTP/1.1 200 OK  
{
  "url": "https://httpbin.org/get",
  ...
}

 How to Register a Certificate

Download the site’s root certificate (e.g., Amazon Root CA 1) using your browser → Export as PEM → Paste into a const char* rootCA = R"(...)" variable → Use client.setCACert(rootCA);

Conclusion

ESP32 Core 3 with WIZnet W5500 enables easy and secure integration of wired Ethernet into your IoT systems.
With native protocol support for Ethernet, SSL/TLS, and more, this guide helps you fully leverage the ESP32's capabilities across:

• Smart home and lighting control
• Remote sensor networks
• Industrial safety systems
• Real-time communication infrastructure