Home Assistant PoE Voice & Presence Satellite

Building a PoE Voice and Presence Satellite for Home Assistant with W5500

sophia

Published November 09, 2026

Original author: UbiTrichOriginal source (new tab)

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Components

Hardware components

WIZnet - W5500

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WIZnet parts

W5500 Datasheet

Project description

Overview

What if a smart home device could handle voice commands, detect room occupancy, and connect to the network using just one Ethernet cable?

Developed by Filip Lettrich as a bachelor's thesis project, this open-source smart home satellite combines an ESP32-S3 microcontroller, WIZnet W5500 Ethernet controller, voice processing, and presence sensors in a compact ceiling-mounted design.

The project demonstrates how wired Ethernet and Power over Ethernet (PoE) can support smart home devices that need both network connectivity and continuous power.

How It Works

The device combines two smart home functions: voice interaction and presence detection.

For voice interaction, an INMP441 I2S MEMS microphone captures audio, while the ESP32-S3 supports local wake-word detection using microWakeWord.

For presence detection, the design combines a PIR motion sensor with a 24 GHz mmWave radar. This allows the system to distinguish movement from stationary presence, helping home automation respond to whether a room is occupied.

The device integrates with Home Assistant through ESPHome and also provides a WebSocket proxy for the Loxone ecosystem.

Hardware Configuration

Component	Specification	Role
Microcontroller	ESP32-S3-WROOM-1U-N16R8	Main processing and device control
Ethernet	WIZnet W5500	SPI Ethernet connectivity
PoE module	Silvertel Ag9905M	Converts PoE input to 5V DC
Radar	HLK-LD2410, 24 GHz	Presence detection
Microphone	INMP441, I2S	Voice input
PCB	80 mm circular, 4-layer	Ceiling-mounted hardware design

The board uses an ESP32-S3 with 16 MB Flash and 8 MB PSRAM, providing resources for the firmware and audio processing.

Why W5500 Matters

The WIZnet W5500 provides the wired Ethernet interface between the ESP32-S3 and the local network.

Instead of relying on Wi-Fi for connectivity, this design uses an SPI-connected Ethernet controller alongside a PoE power module.

The roles are clearly separated:

ESP32-S3: Processes voice input, sensor data, and smart home functions.

W5500: Provides Ethernet connectivity and hardware TCP/IP capabilities.

PoE module: Supplies power through the Ethernet cable.

Home Assistant: Integrates voice and presence information into home automation.

This approach is particularly interesting for ceiling-mounted devices, where providing both power and network connectivity through a single cable can simplify installation.

Open-Source Design and Limitations

The repository includes KiCad 9 hardware files, ESPHome firmware configuration, a custom PIR sensor component, enclosure designs, and supporting documentation.

The author also documents two limitations of the first hardware revision.

First, the current PCB supports only PoE Mode B. Switches supplying power through Mode A require a compatible midspan injector.

Second, the Murata PIR sensor proved difficult to hand-solder, so the prototype uses a conventional through-hole PIR module instead.

These details make the project a useful reference for developers evaluating their own PoE-enabled smart home hardware.

Why This Project Is Interesting

Many smart home projects focus primarily on application features. This project also addresses the physical design of a smart home device: connectivity, power delivery, sensor integration, and installation.

For WIZnet, it is an example of how the W5500 can be integrated into a custom ESP32-based product rather than used only on a separate development board.

The same design approach could be explored for other Ethernet-connected building automation devices, including occupancy sensors, room controllers, and environmental monitoring nodes.