What is the difference between Arduino Ethernet and UNO?

Arduino is a microcontroller board that is programmed using online available software. It is very useful for both hardware and software development in electronics projects. It has many different types. This article will elaborate on some key differences between Arduino Ethernet and Arduino UNO boards.

Differences Between Arduino UNO and Arduino Ethernet

The Arduino UNO is a very popular board by Arduino that is widely used. Arduino Ethernet is an advanced version of Arduino UNO. Although both use an ATMega328P microprocessor, Arduino Ethernet has a WIZnet W5100 TCP IP Ethernet Controller as an extra feature for wireless connectivity. The differences between Arduino UNO and Arduino Ethernet are serial communication, LED pin, SD card support, PoE support, and connector. These differences are explained below.

WIZnet Ethernet Controller

The Arduino Ethernet has a WIZnet Ethernet controller, therefore it does not need the USB to Serial driver chip that is present in Arduino UNO. In Arduino Ethernet, pin 10 is specified for the WIZnet interface.

Digital Input Output Pins

Arduino UNO and Arduino Ethernet have 14 digital input/output pins; however, this number is reduced to 9 in Arduino Ethernet. This is because the pin is reserved for the SD card and pins 10,11,12, and 13 are specified to connect the board to the Ethernet Module.

Serial Communication

The Arduino Ethernet uses Serial Clock Line (SCL) and Serial Data Line (SDA) for serial communication with other devices. They are used for asynchronous half-duplex communication. In this type of communication, two-way communication occurs between devices, but not simultaneously. These two pins are near the AREF pin on Arduino Ethernet. However, in Arduino UNO SDA and SCL pins are not present. It has two general pins D18 and D19 that can be programmed for SDA or SCL or any other function.


Arduino UNO as well as Arduino Ethernet have separate LED pins. The LED pin on Arduino UNO is pin 13 whereas on Arduino Ethernet the LED pin is pin 9.

SD Card Reader

The Arduino Ethernet differs from Arduino UNO because it has an extra feature of SD card support. The SD card is used to store files necessary for network communication. It can be configured using the SD Library by Arduino. Pin 4 of Arduino Ethernet is specified for the SD card. The Arduino UNO does not have this feature.

Powering Arduino Board

Arduino UNO and Arduino Ethernet both are recommended to be operated in the voltage range from 7V to 12V. They can be powered by using a USB connector or by supplying power through an external battery on VCC and GND pin. However, the Arduino Ethernet has an extra feature to power the board. It has an optional Power Over Ethernet (PoE) module that is used to extract power from conventional Ethernet cables. This module is IEEE 802.3af compliant and has very low ripple or noise in output voltage. It can provide an output voltage of up to 9V, which is enough to operate an Arduino Ethernet board.


As the Arduino Ethernet board supports Ethernet cable; therefore, it has an RJ45 connector where the Ethernet cable is connected. Arduino UNO does not have an RJ45 connector because it does not support Ethernet cable.


Arduino UNO and Arduino Ethernet both are very useful microcontroller boards that are used in prototyping and many electronic devices because they can easily be programmed. The key difference between them lies in Ethernet connectivity that is supported in Arduino Ethernet boards but not present in Arduino UNO. There are some other differences like LED pin, power, connector, and SD card reader are also present.

About the author


I am an Electrical Engineer. I love to write about electronics. I am passionate about writing and sharing new ideas related to emerging technologies in the field of electronics.