---
title: "mros2-esp32-eth1"
url: "https://maker.wiznet.io/TheoIm/projects/mros2-esp32-eth1/"
markdown_url: "https://maker.wiznet.io/TheoIm/projects/mros2-esp32-eth1/md"
type: "UCC: User Created Content"
author: "yamati"
author_url: "https://github.com/yamati-kz/mros2-esp32-eth1"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "yamati"
original_url: "https://github.com/yamati-kz/mros2-esp32-eth1"
published: "2026-04-14"
language: "en"
likes: 0
views: 281
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# mros2-esp32-eth1

> ESP32-S3 uses W5500 Ethernet over SPI to run as a standalone ROS 2 node, enabling stable RTPS communication without Wi-Fi or external agents.

Original author: yamati (source: https://github.com/yamati-kz/mros2-esp32-eth1)

## Article

## What the Project Does

This project enables an embedded microcontroller (ESP32-S3) to function as a **native ROS 2 node** communicating directly with a ROS 2 host over Ethernet.

Instead of relying on:

- Wi-Fi (which introduces latency and instability), or

- micro-ROS Agent (which requires an intermediate PC),

the system uses:

- **mROS 2 (embedded ROS 2 runtime)**

- **RTPS over UDP/IP**

- **W5500-based wired Ethernet**

As a result, the ESP32:

- participates directly in ROS 2 Pub/Sub

- subscribes and publishes topics

- operates as an independent network node

In practical terms, this means:

- A ROS 2 PC publishes data → ESP32 receives it directly

- No bridge, no agent, no Wi-Fi dependency

---

## System Architecture

At a high level, the system is structured as a layered network stack running on the ESP32-S3:

![](https://maker.wiznet.io/upload/ckeditor5/634768278%5F1776674455%2Epng)

**Generated By Gemini**

```plaintext
Application (ROS 2 Node)
    ↓
mROS 2 API
    ↓
embeddedRTPS (Discovery + Data)
    ↓
UDP/IP (lwIP)
    ↓
ESP-IDF Ethernet Driver
    ↓
SPI Interface
    ↓
W5500 (WIZ850io)
    ↓
Ethernet Network
    ↓
ROS 2 Host (Ubuntu)
```

This structure clearly separates:

- application logic (ROS 2)

- middleware (RTPS)

- transport (UDP/IP)

- physical interface (Ethernet via W5500)

---

## System Block Diagram

```plaintext
[ROS 2 Host PC]
        │
        │ Ethernet
        ▼
   [Router / Switch]
        │
        ▼
[WIZ850io (W5500)]
        │  SPI
        ▼
   [ESP32-S3 MCU]
        │
        ▼
[mROS 2 Node Application]
```

The key takeaway is that **WIZnet sits at the network boundary**, bridging the MCU and the physical Ethernet network.

---

## Where WIZnet Fits

This project uses the **WIZnet W5500**, embedded in the WIZ850io module.

### Hardware Role

The W5500 is connected to the ESP32-S3 via SPI and provides:

- Ethernet PHY + MAC

- RJ45 connectivity

- External network interface

ESP32-S3 ←SPI→ W5500 ←Ethernet→ Network

### Software Role

W5500 is integrated at the ESP-IDF Ethernet driver layer:

```plaintext
esp_eth_mac_t *mac = esp_eth_mac_new_w5500(&w5500_config, &mac_config);
esp_eth_phy_t *phy = esp_eth_phy_new_w5500(&phy_config);
```

These functions:

- instantiate the W5500 MAC/PHY drivers

- register it as the system’s Ethernet interface

After initialization:

- DHCP assigns an IP address

- The IP is passed to RTPS via:

mros2_setIPAddrRTPS(ipaddr);

This step is critical:
**it connects the ROS 2 communication stack to the physical Ethernet network via W5500.**

---

## Data Flow in the System

At runtime, communication follows a deterministic pipeline:

```plaintext
ROS 2 Message (Host)
    ↓
RTPS (Discovery + Data)
    ↓
UDP Packet
    ↓
lwIP Stack
    ↓
ESP-IDF Ethernet Driver
    ↓
W5500 (SPI)
    ↓
Ethernet Cable
    ↓
ESP32 Callback Execution
```

Incoming data is received through:

- RTPS discovery (SPDP, SEDP)

- UDP unicast payload

- callback execution in the application layer

This enables true **end-to-end ROS 2 communication without intermediaries**.

---

## Why WIZnet is Used in This Project

The choice of W5500 is not incidental—it directly addresses the limitations of Wi-Fi-based embedded ROS systems.

### 1. Deterministic Communication

Wi-Fi introduces variable latency due to interference and contention.
Ethernet provides stable and predictable timing, which is critical for robotics.

### 2. Reliable Connectivity

Wired connections eliminate:

- signal drops

- reconnection issues

- RF interference

### 3. Clean Architecture

By separating:

- computation (ESP32)

- networking (W5500)

the system becomes:

- more modular

- easier to debug

- easier to scale

### 4. Practical Robotics Fit

The project explicitly targets ROS 2 environments where:

- real-time messaging matters

- network stability is more important than mobility

---

## Key Takeaway

This project is not just an Ethernet add-on.

It demonstrates a complete architecture where:

- **ESP32-S3 acts as a native ROS 2 node**

- **W5500 provides a stable wired network interface**

- **RTPS runs directly over Ethernet without middleware bridges**

In short:

**WIZnet W5500 enables embedded devices to participate in ROS 2 networks as first-class nodes, using reliable wired communication instead of unstable wireless links.**

---

## FAQ

**Q: Why use the W5500 instead of Wi-Fi for this project?**
A: W5500 enables wired Ethernet with stable, deterministic latency, which is critical for ROS 2 RTPS communication. Unlike Wi-Fi, it avoids interference, packet loss, and unpredictable delays in robotics environments.

---

**Q: How is the W5500 connected to the ESP32-S3?**
A: It is connected via SPI using pins for MISO, MOSI, SCK, and CS, along with optional INT and RESET. The ESP-IDF Ethernet driver initializes it using `esp_eth_mac_new_w5500()` and `esp_eth_phy_new_w5500()`.

---

**Q: What role does W5500 play in this system?**
A: W5500 acts as the Ethernet interface, handling MAC/PHY and enabling the ESP32 to send and receive UDP/IP packets for RTPS communication with the ROS 2 host.

---

**Q: Can this project run without a micro-ROS Agent?**
A: Yes. The system uses mROS 2 and embeddedRTPS, allowing direct ROS 2 communication over Ethernet without requiring an external agent or bridge PC.

---

**Q: How does this compare to using LwIP-only or other Ethernet chips?**
A: With W5500, Ethernet is offloaded to dedicated hardware, reducing MCU overhead and improving reliability. Compared to Wi-Fi or software-only stacks, it offers more stable communication, which is essential for real-time ROS 2 systems.

---

## Tags

#W5500 #WIZnet #ESP32S3 #Ethernet #ROS2 #mROS2 #embeddedRTPS #SPI #IoT #Robotics #UDP #RTPS

---

Source: https://maker.wiznet.io/TheoIm/projects/mros2-esp32-eth1/