---
title: "RP2040 + W6100 Mini Board"
url: "https://maker.wiznet.io/Lihan__/projects/rp2040-w6100-mini-board/"
markdown_url: "https://maker.wiznet.io/Lihan__/projects/rp2040-w6100-mini-board/md"
type: "UCC: User Created Content"
author: "nexp"
author_url: "https://nexp.tistory.com/m/4023#:~:text=RP2040%EC%9D%80%20%EC%A0%80%EB%A0%B4%281$%29%ED%95%98%EB%A9%B4%EC%84%9C%20%EC%84%B1%EB%8A%A5%20%EC%A2%8B%EC%9D%80%20MCU%EB%A1%9C%20Wiznet%EC%82%AC%EC%9D%98%20Ethernet,%EB%B0%B0%EC%B9%98%EB%A5%BC%20%ED%96%88%EA%B3%A0%20%ED%94%8C%EB%9E%98%EC%8B%9C%20%EB%A9%94%EB%AA%A8%EB%A6%AC%EB%8F%84%20%EC%9E%91%EC%9D%80%20%ED%8C%A8%ED%82%A4%EC%A7%80%EB%A1%9C%20%EC%84%A0%ED%83%9D%ED%96%88%EB%8B%A4."
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "nexp"
original_url: "https://nexp.tistory.com/m/4023#:~:text=RP2040%EC%9D%80%20%EC%A0%80%EB%A0%B4%281$%29%ED%95%98%EB%A9%B4%EC%84%9C%20%EC%84%B1%EB%8A%A5%20%EC%A2%8B%EC%9D%80%20MCU%EB%A1%9C%20Wiznet%EC%82%AC%EC%9D%98%20Ethernet,%EB%B0%B0%EC%B9%98%EB%A5%BC%20%ED%96%88%EA%B3%A0%20%ED%94%8C%EB%9E%98%EC%8B%9C%20%EB%A9%94%EB%AA%A8%EB%A6%AC%EB%8F%84%20%EC%9E%91%EC%9D%80%20%ED%8C%A8%ED%82%A4%EC%A7%80%EB%A1%9C%20%EC%84%A0%ED%83%9D%ED%96%88%EB%8B%A4."
published: "2025-09-24"
language: "en"
likes: 0
views: 1145
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# RP2040 + W6100 Mini Board

> Custom RP2040 mini-board couples Raspberry Pi’s $1 MCU with WIZnet W6100 Ethernet for a palm-sized, IPv4/IPv6-ready IoT platform offering single-chip TCP/IP

Original author: nexp (source: https://nexp.tistory.com/m/4023#:~:text=RP2040%EC%9D%80%20%EC%A0%80%EB%A0%B4%281$%29%ED%95%98%EB%A9%B4%EC%84%9C%20%EC%84%B1%EB%8A%A5%20%EC%A2%8B%EC%9D%80%20MCU%EB%A1%9C%20Wiznet%EC%82%AC%EC%9D%98%20Ethernet,%EB%B0%B0%EC%B9%98%EB%A5%BC%20%ED%96%88%EA%B3%A0%20%ED%94%8C%EB%9E%98%EC%8B%9C%20%EB%A9%94%EB%AA%A8%EB%A6%AC%EB%8F%84%20%EC%9E%91%EC%9D%80%20%ED%8C%A8%ED%82%A4%EC%A7%80%EB%A1%9C%20%EC%84%A0%ED%83%9D%ED%96%88%EB%8B%A4.)

## Article

### Project Overview

RP2040’s budget-friendly horsepower meets WIZnet’s feature-rich W6100 to create an ultra-small Ethernet node ideal for embedded web servers, gateways, or industrial sensors. Double-sided component placement and a trimmed 10-pin header shrink the board to roughly the same size as earlier single-chip W6100 SSM modules, yet it now hosts a full MCU. [Engineer's LAB](https://nexp.tistory.com/4023)

### Key Features

**Full IPv4/IPv6 stack in silicon** – zero CPU overhead for TCP/UDP, plus MAC+PHY inside W6100.

**33 MHz SPI on RP2040** – sustains high-throughput DMA transfers (configurable). [Engineer's LAB](https://nexp.tistory.com/4024?category=1202713)

**Tiny 2-layer PCB** – front/back placement, compact QSPI flash, 10-pin SSM footprint. [Engineer's LAB](https://nexp.tistory.com/4023)

### Hardware Setup

W6100’s SPI, INT, and RST lines map to RP2040 SPI0 (GPIO 16-19), leaving the second core free for user tasks. The 10-pin header exposes 3V3, GND, SPI, UART, and SWD, simplifying plug-in prototyping.

### Software Implementation

#### Core Functionality

```plaintext
#include <SPI.h> #include "Ethernet_Generic.h"

#define USING_W6100       true
#define USE_THIS_SS_PIN   17     // RP2040 EXP board #define SPI_X             spi0
#define SPI_ETHERNET_SETTINGS SPISettings(33000000, MSBFIRST, SPI_MODE0)

byte mac[] = {0x00,0x08,0xDC,0x00,0x00,0x00};

void setup() {
  Serial.begin(115200);
  Ethernet.init(USE_THIS_SS_PIN);   // tie W6100 to SPI0 @33 MHz
  Ethernet.begin(mac);              // DHCP
}

void loop() { /* user application */ }
```

### Network Architecture

The RP2040 communicates with W6100 over SPI; W6100 handles all Ethernet framing and protocol logic, surfacing a BSD-style socket API via the library. Users can stack additional sensors on I²C/SPI1 while core Ethernet traffic streams independently.

### Performance Results

Early DHCP + ping tests show immediate link-up and &lt;1 ms round-trip on a 100 Mbps LAN; iperf stress-tests are planned once final firmware is in place.

### Lessons Learned

Shared PCB real-estate across both sides drastically cuts board size without compromising signal integrity.

Keeping W6100 on RP2040 SPI0 avoids pin-mux headaches and lets the Pico SDK example code run unmodified.

### Future Improvements

Add PoE option via isolated 48 V module.

Break-out USB-C for power and serial in the same connector.

Publish KiCad sources and BOM for community spin-offs.

### Challenges & Solutions

| Challenge | Solution |
| --- | --- |
| Routing 100 Ω differential pairs on a 20 mm board | Swapped to compact MagJack daughtercard; kept short stub lengths |
| Limited pin count | 10-pin SSM header chosen; multiplexed SWD & UART via jumpers |
| Flash footprint | Selected 2 MB W25Q16JV in USON-8 package |

---

Source: https://maker.wiznet.io/Lihan__/projects/rp2040-w6100-mini-board/