---
title: "Arduino Nano + WIZ550io: A Compact Ethernet Upgrade in 5 Steps (W5500 Hardwired TCP/IP)"
url: "https://maker.wiznet.io/junlee0615/projects/arduino-nano-wiz550io-a-compact-ethernet-upgrade-in-5-steps-w5500-hardwired-tcp-ip/"
markdown_url: "https://maker.wiznet.io/junlee0615/projects/arduino-nano-wiz550io-a-compact-ethernet-upgrade-in-5-steps-w5500-hardwired-tcp-ip/md"
type: "UCC: User Created Content"
author: "ntewinkel"
author_url: "https://www.instructables.com/Arduino-Nano-with-WIZ550io-Easy-Internet/"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "ntewinkel"
original_url: "https://www.instructables.com/Arduino-Nano-with-WIZ550io-Easy-Internet/"
published: "2026-01-08"
language: "en"
tags: ["WIZ550io", "W5500", "Arduino", "Ethernet", "Webserver"]
hardware: ["Arduino Nano R3", "WIZnet WIZ550io"]
likes: 0
views: 995
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# Arduino Nano + WIZ550io: A Compact Ethernet Upgrade in 5 Steps (W5500 Hardwired TCP/IP)

> Wire a WIZ550io to an Arduino Nano, update the Ethernet library for W5500, then run the WebServer example to verify wired networking.

Original author: ntewinkel (source: https://www.instructables.com/Arduino-Nano-with-WIZ550io-Easy-Internet/)

## Components

- **Arduino Nano R3** x 1 ([docs](https://www.farnell.com/datasheets/1682238.pdf))
- **WIZnet WIZ550io** x 1 ([docs](https://docs.wiznet.io/Product/ioModule/wiz550io))
- Software: **Arduino IDE** ([docs](https://www.arduino.cc/en/software))

## Article

## Introduction

Let’s start with the motivation.

The Arduino Nano is compact and convenient—until you plug in a full-size Ethernet shield and lose that neat, tiny form factor.

This project shows a cleaner approach: pair the Nano with **WIZnet WIZ550io**, a much smaller Ethernet module, wire just a handful of pins, and you’ve got a compact wired-network Nano setup.

---

## WIZnet Product Integration

Here’s what’s happening in the simplest form:

**Arduino Nano → SPI → WIZ550io (W5500) → Ethernet LAN**

WIZ550io brings a hardwired TCP/IP Ethernet controller into your Nano project without the bulk of a full shield.

---

## Technical Implementation

We’ll do this in three practical chunks: wiring, library setup, and a quick webserver test.

### 1) Hardware wiring (the 9-pin hookup)

Place the Nano and WIZ550io on a breadboard (the author mounts them back-to-back so the USB cable and Ethernet cable both fit nicely), then connect the pins exactly as listed in Figure 2.

One safety note is non-negotiable: **do not connect Nano SPI.2 (5V) to the WIZ550io power pins**. WIZ550io is a 3.3V device.

### 2) Update the Ethernet library for W5500/WIZ550io

The author uses WIZnet’s Ethernet library because WIZ550io requires newer W5500 support.

Download **WIZ_Ethernet_Library** from GitHub.

Copy the `Ethernet` folder into your Arduino `Libraries` directory (this overrides the built-in Ethernet library).

Open `Libraries/Ethernet/utility/w5100.h` and make sure **only the correct board define** is enabled.

For WIZ550io, the key line is:

#define W5500_ETHERNET_SHIELD // WIZ550io, ioShield series of WIZnet

Optional (nice quality-of-life): enable the WIZ550io’s assigned MAC address:

#define WIZ550io_WITH_MACADDRESS

### 3) Smoke test with the built-in WebServer example

Now let’s prove it works.

In Arduino IDE: **File → Examples → Ethernet → WebServer**

If needed for certain Apple/AirPort networks, change the IP (author example):

IPAddress ip(10,0,1,177); // on an Apple wifi network

Upload, connect Ethernet to your LAN, then open a browser to your IP.

You should see a simple page listing analog input values. Even with nothing connected, it’s perfect as a “does Ethernet work?” test.

---

## Reproduction Guide

Follow these steps exactly, and you’ll be online quickly.

**Wire the 9 connections** (Figure 2)

**Install/override the Ethernet library** with WIZnet’s WIZ_Ethernet_Library

**Set the correct W5500/WIZ550io define** in `w5100.h`

**Upload the WebServer exampleOpen a browser to your device IP** and confirm the page loads

---

## Core Features and Performance

Here’s what this setup gives you:

**Compact wired Ethernet** on a Nano without a full-size shield

**Hardwired TCP/IP offload (W5500 class)** for stable socket handling

A fast validation workflow: wiring → library define → WebServer test

---

## Code Snippet

Here’s the one line people most often forget—selecting the correct chip family in `w5100.h`.

#define W5500_ETHERNET_SHIELD // WIZ550io, ioShield series of WIZnet

If this is wrong, everything else can look correct and still fail.

---

## Applications and Extensions

Once the WebServer example works, you can build from there:

Add sensors and serve readings over HTTP

Make a tiny REST endpoint for home automation

Push data to an MQTT broker *(planned)*

Add SD logging on a different platform *(planned)*

---

## Conclusion

To wrap up: this is a simple, practical recipe for giving an Arduino Nano a reliable Ethernet connection—without the bulk.

WIZ550io keeps the wiring manageable, the footprint small, and the software path familiar through Arduino’s Ethernet examples.

---

Source: https://maker.wiznet.io/junlee0615/projects/arduino-nano-wiz550io-a-compact-ethernet-upgrade-in-5-steps-w5500-hardwired-tcp-ip/