---
title: "How to Add PoE-Powered Ethernet with W5500 on XIAO ESP32-S3 Plus"
url: "https://maker.wiznet.io/jakelee/resellers/how-to-add-poe-powered-ethernet-with-w5500-on-xiao-esp32-s3-plus/"
markdown_url: "https://maker.wiznet.io/jakelee/resellers/how-to-add-poe-powered-ethernet-with-w5500-on-xiao-esp32-s3-plus/md"
type: "VAR: Value-Added Reseller Products"
author: "Seeed Studio"
author_url: "https://openelab.io/products/seeed-studio-xiao-w5500-ethernet"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "Seeed Studio"
original_url: "https://openelab.io/products/seeed-studio-xiao-w5500-ethernet"
published: "2026-01-24"
language: "en"
hardware: ["Seeed Studio XIAO ESP32-S3 Plus"]
likes: 0
views: 851
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# How to Add PoE-Powered Ethernet with W5500 on XIAO ESP32-S3 Plus

> Add W5500 10/100 Ethernet + PoE to XIAO ESP32-S3 Plus. Hardwired TCP/IP enables stable wired IoT with low MCU load.

Original author: Seeed Studio (source: https://openelab.io/products/seeed-studio-xiao-w5500-ethernet)

## Components

- **Seeed Studio XIAO ESP32-S3 Plus** x 1

## Article

## Step 1: Understanding the Hardware

This “XIAO W5500 Ethernet Adapter” is effectively a compact PoE-ready dev board that combines **XIAO ESP32-S3 Plus** with the **WIZnet W5500** Ethernet controller and a standard **RJ45 10/100Mbps** port. It integrates **IEEE 802.3af PoE** (listed with an isolated PoE module and power conversion) so you can run the board using a single Ethernet cable for both data and power.

Key W5500 implementation hooks relevant to firmware and performance:

**Hardwired TCP/IP stack**, **8 hardware sockets**, **32KB internal buffer**, **SPI up to 80MHz** (W5500 feature set)

Ethernet/protocol set shown on the product page: **10/100Mbps**, **TCP/UDP/ICMP/IPv4/ARP/IGMP/PPPoE**

Hardware detail noted by the seller: **W5500 INTn wired to ESP32-S3 GPIO D16** (a v1.2 wiring fix)

## Step 2: Software/Firmware Setup

The product page does not include project-specific code, so the snippet below is **conceptual integration based on WIZnet ioLibrary (not project-specific)**. Use it as a mental model: initialize the W5500 buffers, configure network settings, then create sockets using W5500’s hardware socket engine.

// Conceptual integration example based on WIZnet ioLibrary (not project-specific)
// W5500 uses hardware sockets + hardwired TCP/IP; MCU talks to W5500 over SPI.

uint8_t tx_size[8] = {2,2,2,2,2,2,2,2}; // conceptual per-socket TX split
uint8_t rx_size[8] = {2,2,2,2,2,2,2,2}; // conceptual per-socket RX split

// Initialize W5500 internal memory for sockets (ioLibrary-style)
wizchip_init(tx_size, rx_size);

// Next steps (conceptual):
// 1) set MAC/IP/GW/DNS
// 2) open a TCP/UDP socket
// 3) send/recv via W5500 socket registers/APIs

Practical setup notes for this specific board:

Ensure the SPI pins and **INTn (D16)** mapping match your firmware framework (Arduino/ESP-IDF/ESPHome). The page explicitly calls out the INT wiring change.

If you’re using PoE, validate the board’s power path (PoE module + conversion) and confirm your load budget based on the listed PoE implementation.

## FAQ

**Q1: Why use W5500 instead of running Ethernet with a software TCP/IP stack on ESP32-S3?**
A: W5500 is a hardwired TCP/IP controller, meaning key protocol work is handled in the Ethernet chip rather than your MCU firmware. In practice, that reduces application RAM pressure and CPU cycles compared with maintaining a full software stack, while also giving you 8 dedicated hardware sockets and a 32KB internal buffer for stable streaming and always-on connections in embedded/industrial IoT.

**Q2: How is W5500 connected to XIAO ESP32-S3 Plus on this adapter?**
A: The W5500 connects to the ESP32-S3 host over **SPI**, with an **INTn interrupt** line used to signal events like received packets or socket state changes. The product page specifically notes the W5500 **INTn pin is wired to D16** (v1.2 wiring fix), which is important for reliable interrupt-driven networking in frameworks such as ESPHome/ESP-IDF.

**Q3: What performance and deployment benefits does this design target?**
A: The design targets “wired reliability + simple installation.” You get **10/100Mbps Ethernet** via W5500 and **Power over Ethernet (IEEE 802.3af)** so a single cable can deliver both connectivity and power. For deployed nodes (building automation, industrial monitoring), PoE reduces wiring complexity, while W5500 hardware sockets help maintain stable connections under continuous operation.

**Q4: What stability advantages come from W5500’s hardwired stack and hardware sockets?**
A: Hardwired TCP/IP typically improves determinism because packet handling and socket state machines live in fixed-function hardware rather than competing with application tasks. With **8 hardware sockets** and **internal buffering**, the W5500 can manage multiple simultaneous connections with consistent behavior, which is useful for gateways, proxies, telemetry, and long-running services where you want fewer firmware-side edge cases and less tuning.

**Q5: How does W5500 Ethernet compare to Wi-Fi for IoT nodes using ESP32-S3?**
A: Ethernet is preferred when you need predictable connectivity and fewer RF-related failures. This adapter keeps Wi-Fi/BLE available on the ESP32-S3 while adding wired Ethernet through W5500 and optionally powering the node via PoE. That hybrid approach is useful for always-on infrastructure (controllers, proxies, monitoring devices) where Wi-Fi can be variable but BLE/Wi-Fi is still valuable for commissioning or local services.

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Source: https://maker.wiznet.io/jakelee/resellers/how-to-add-poe-powered-ethernet-with-w5500-on-xiao-esp32-s3-plus/