I have an Arduino setup from which I can control my RGB LED strip from my computer using LAN.

It worked like a charm in the start, but after two days, my Ethernet Shield W5100 for Arduino Uno stopped working, and I can't figure out why.

When I connect the Ethernet Shield, the red LED "pwr" is solid red and the "FULLD" flashes orange every second.

The setup:

I have followed an Adafruit guide, connecting the Arduino as such: Image from Adafruit.com

On top of the Arduino, I have the Ethernet Shield. All this is powered by an 12V/4A power supply connected to the Arduinos 2.1mm jack.

As I said, this setup worked fine for a few days. While it was on, I noticed the Arduino getting somewhat hot, but some google searches assured me that Arduino Uno can handle high temperatures, so I did not pay any attention to it.

The LED strip is not too long - about 2 meters with about 150 LEDs.

What I have tried:

  • When I detach the Arduino from my breadboard, the Ethernet Shield will still not connect
  • I have tried connecting the Shield to another Power Supply (Computer USB) using another Arduino, but the Shield would still not connect.
  • I have added a debugging Serial.print message in the Arduino loop function. When using serial monitor, this message is printed over and over again (as if it is stuck in a reset loop)
  • I have verified for MAC address collisions, even changed the MAC address of the Shield multiple times.

Have I somehow burned the Ethernet Shield? Why won't it work anymore?

1 Answer 1


I'm sorry to tell you but i think you damaged your board severely that's because you took more energy from the pins than an arduino can handle.

150 LEDs takes way too much power for the arduino to handle as you can see here.

So you likely burnt something on your board and might have to replace it :/ make sure which board is damaged(the arduino itself or the shield) before replacing it.

If the ATmega328P(The chip on the arduino) is damaged then this should be an easy fix.

Instead of what you did, you shoud have powered the LED strip from another power supply(not from the arduino pins) and used the arduino to turn "this power supply" on and off(probably using transistors).

  • You are right. I should have an external power supply. The Arduino seems to have survived it with no problems, although it got pretty hot. The ethernet shield however, is dead :(. Thanks for the answer!
    – Janman
    Sep 16, 2015 at 9:11

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