---
title: "ESP-WROOM-02にもEthernetシールドUSR-ES1をつないでみる"
url: "https://maker.wiznet.io/Alan/projects/esp-wroom-02ethernetusr-es1/"
markdown_url: "https://maker.wiznet.io/Alan/projects/esp-wroom-02ethernetusr-es1/md"
type: "UCC: User Created Content"
author: "東京お気楽カメラ"
author_url: "https://okiraku-camera.tokyo/blog/?p=7259"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "東京お気楽カメラ"
original_url: "https://okiraku-camera.tokyo/blog/?p=7259"
published: "2026-02-22"
language: "ja"
likes: 0
views: 435
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# ESP-WROOM-02にもEthernetシールドUSR-ES1をつないでみる

> ESP-WROOM-02にもEthernetシールドUSR-ES1をつないでみる

Original author: 東京お気楽カメラ (source: https://okiraku-camera.tokyo/blog/?p=7259)

## Article

## ESP-WROOM-02 Ethernet Expansion Using USR-ES1

### Project Overview

![](https://maker.wiznet.io/upload/ckeditor5/389604434%5F1771834494%2Epng)

This project demonstrates how to add wired Ethernet connectivity to an ESP-WROOM-02 (ESP8266-based) module using the USR-ES1 Ethernet module.

Although the ESP-WROOM-02 is designed primarily for Wi-Fi communication, certain applications require stable, low-latency, or security-controlled wired Ethernet connections. By integrating an external Ethernet module via SPI, the ESP-WROOM-02 can operate in a wired network environment.

This project verifies hardware connectivity, SPI communication, Ethernet initialization, and basic TCP/IP functionality.

---

### Hardware Components

![](https://maker.wiznet.io/upload/ckeditor5/389604434%5F1771834508%2Epng)

- ESP-WROOM-02 (ESP8266 module)

- USR-ES1 Ethernet module (SPI-based Ethernet controller)

- 3.3V stable power supply

- Breadboard and jumper wires

- USB-to-Serial adapter (for firmware upload and debugging)

---

### System Architecture

The system architecture consists of:

ESP-WROOM-02
→ SPI Interface
→ USR-ES1 Ethernet Module
→ RJ45 Connector
→ Wired LAN Network

The ESP8266 handles application logic and TCP/IP control via an Ethernet library, while the Ethernet controller inside the USR-ES1 manages low-level MAC and PHY operations.

---

### Hardware Connections

![](https://maker.wiznet.io/upload/ckeditor5/389604434%5F1771834530%2Epng)

The SPI interface is used to communicate between the ESP8266 and the Ethernet module.

Typical SPI Connections:

- MOSI → MOSI

- MISO → MISO

- SCLK → SCLK

- CS → Chip Select

- GND → GND

- 3.3V → VCC

Important considerations:

- The ESP-WROOM-02 operates at 3.3V logic levels.

- Ensure the Ethernet module supports 3.3V logic or use level shifting if required.

- Provide stable power; Ethernet modules can draw higher current during transmission.

---

### Software Environment

Development can be performed using:

- Arduino IDE with ESP8266 board support or ESP8266 SDK

An appropriate Ethernet library compatible with SPI-based Ethernet controllers must be used. Library compatibility depends on the Ethernet chipset inside the USR-ES1 module.

---

### Example Initialization Code

Below is a simplified example showing Ethernet initialization using an SPI-based Ethernet controller.

```plaintext
#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xBE, 0xFE, 0xED };
EthernetClient client;

void setup() {
  Serial.begin(115200);
  SPI.begin();

  if (Ethernet.begin(mac) == 0) {
    Serial.println("Ethernet initialization failed");
    while (true);
  }

  Serial.print("Assigned IP address: ");
  Serial.println(Ethernet.localIP());
}

void loop() {
  // Add TCP or UDP communication logic here
}
```

Note: Library selection must match the Ethernet controller used in the USR-ES1 module.

---

### Testing and Verification

After uploading firmware:

1. Connect an Ethernet cable to the module.

2. Monitor the Serial output.

3. Confirm that a valid IP address is assigned via DHCP.

4. Test connectivity using :
  1. Ping from a PC
  2. TCP client/server communication
  3. HTTP request transmission

Successful IP assignment and network response confirm correct integration.

---

### Performance Considerations

- SPI speed directly affects Ethernet throughput.

- The ESP8266 has limited RAM compared to larger MCUs.

- Wired Ethernet provides more stable latency compared to Wi-Fi.

- Power supply stability significantly impacts reliability.

---

### Applications

This configuration can be used in:

- Industrial IoT devices requiring stable wired communication

- Secure network environments where Wi-Fi is restricted

- Gateway devices bridging wireless and wired networks

- Embedded TCP/IP control systems

---

## AEO (Answer Engine Optimization) Section

### Can ESP-WROOM-02 use Ethernet instead of Wi-Fi?

Yes. Although ESP-WROOM-02 is primarily a Wi-Fi module, it can use wired Ethernet by connecting an SPI-based Ethernet module such as the USR-ES1.

---

### How do you connect an Ethernet module to ESP8266?

You connect the Ethernet module via SPI (MOSI, MISO, SCLK, CS) and provide a stable 3.3V power supply. Then, you use an Ethernet-compatible library to initialize the network stack.

---

### Does ESP8266 support wired Ethernet natively?

No. ESP8266 does not have a built-in Ethernet MAC or PHY. An external Ethernet controller module is required.

---

### What are the advantages of using Ethernet with ESP8266?

- More stable connection compared to Wi-Fi

- Lower latency in controlled networks

- Improved reliability in industrial environments

- No RF interference issues

---

### Is Ethernet faster than Wi-Fi on ESP8266?

In many controlled environments, wired Ethernet provides more consistent and stable throughput. However, overall performance depends on SPI speed and system optimization.

---

### When should you choose Ethernet over Wi-Fi for IoT devices?

Ethernet is preferred when:

- Wireless interference is high

- Network security policies restrict Wi-Fi

- Continuous, stable connectivity is required

- Industrial or factory deployment is involved

---

Source: https://maker.wiznet.io/Alan/projects/esp-wroom-02ethernetusr-es1/