W5100 Ethernet Shield on Mega 2560, UNO R3

Name: W5100 Ethernet Shield on Mega 2560, UNO R3
Brand: Kunkune
SKU: SKU-96c0854a36c9
Price: 10.01 USD
Availability: InStock
Rating: 4.6 (5 reviews)

W5100 Ethernet Shield on Mega 2560, UNO R3 - Main image

W5100 Ethernet Shield on Mega 2560, UNO R3 — rear view

W5100 Ethernet Shield on Mega 2560, UNO R3 — pin detail

$10.01 ~~$13.9~~ In stock

Category: Arduino Shields

W5100 Ethernet Shield for Arduino MEGA 2560 and UNO R3

The W5100 Ethernet Shield plugs onto the Arduino Uno R3 or Mega 2560 and adds wired 10/100Mbps Ethernet via an RJ45 connector, using the Wiznet W5100 chip which handles TCP/IP in hardware — offloading the network stack from the ATmega328P. A micro SD card slot on the shield shares the SPI bus for data logging alongside network operation. The Arduino Ethernet library provides a straightforward API compatible with both the Uno and Mega.

Wiznet W5100 chip — hardware TCP/IP stack (TCP, UDP, ICMP, IPv4, ARP, IGMP, PPPoE)
10/100Mbps Ethernet — auto-negotiation, RJ45 connector
Micro SD card slot — SPI shared bus, separate CS
Arduino Ethernet library compatible
Fits Uno R3 and Mega 2560

Specification	Value
Ethernet chip	Wiznet W5100
Speed	10/100Mbps
Protocols	TCP, UDP, ICMP, IGMP, ARP
Concurrent sockets	4
SD card	Micro SD, SPI

Best for

Arduino web servers, wired IoT sensor nodes, REST API clients, network-triggered relays, NTP time synchronisation, and data logging to a local network server.

Why Kunkune

Shipped from UK stock. 60-day returns, no minimum order. Fast Royal Mail delivery.

Buying in bulk? For orders of 10+ units, contact us for trade pricing.

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (4.6 / 5 · 5 reviews)

Emma ★★★★★ Oct 17, 2026

I plugged this into my Mega 2560 and the Wiznet chip was recognized instantly by the Arduino IDE—no extra drivers needed. The RJ45 connection feels sturdy and the board sits flush without any wobble. It’s been running a simple web server for two days now without a single dropout.

Kevin ★★★★★ Oct 13, 2026

The RJ45 jack clicked in solid on the first try and it's been holding a steady 10/100 link to my router for a week now. Pairs fine with my Uno R3 too, no bent pins or wobbly stacking.

George ★★★★★ Oct 12, 2026

Plugged it straight into my Mega 2560 and it seated fine, no bent pins or loose fit. The RJ45 jack locks the cable in tight and I'm getting a solid 10/100 link for my little home sensor page. Ran the web server sketch without touching a single wire.