Arduino W5100 Ethernet Shield



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Price  €16.32 



The is an Arduino Ethernet Shield using the Wiznet W5100 ethernet chip. It allows an Arduino board to connect to the internet. The Wiznet W5100 ethernet chip provides a network (IP) stack capable of both TCP and UDP. It supports up to four simultaneous socket connections. The standard Arduino Ethernet library can be used to write sketches which connect to the internet via a standard RJ45 Ethernet jack using the shield.

The is the latest revision of this shield, which adds a micro-SD card slot, that can be used to store files for serving over the network. It is compatible with the Arduino Uno and Mega (using the Ethernet library). The on-board SD card can be accessed using the SD library which is included with the current version of Arduino.

This latest revision of the shield also includes a reset controller, to ensure that the W5100 Ethernet module is properly reset on power-up. Previous revisions of the shield were not compatible with the Mega and needed to be manually reset after power-up. The reset button on the shield resets both the W5100 and the Arduino board.

Communicating with the W5100 and SD Card is done via the SPI bus (through the ICSP header). Digital pins 11, 12, and 13 are used on the Duemilanove and pins 50, 51, and 52 on the Mega. On both boards, pin 10 is used to select the W5100 and pin 4 for the SD card. These pins cannot be used for general I/O. On the Mega, the hardware SS pin, 53, is not used to select either the W5100 or the SD card, but it must be kept as an output or the SPI interface won't work.

Note that because the W5100 and SD card share the SPI bus, only one can be active at a time. If you are using both peripherals in your program, this should be taken care of by the corresponding libraries. If you're not using one of the peripherals in your program, however, you'll need to explicitly deselect it. To do this with the SD card, set pin 4 as an output and write a high to it. For the W5100, set digital pin 10 as a high output.


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Please note this board is not manufactred by Modtronix! We do not have control of the brand and quality of components used! We have however carefully selected suppliers that consistently supply quality products. For boards using durable, brand name components, also have a look at our own "Manufactured by Modtronix" range of SBC and accessory boards.



  • Operating voltage 5V (supplied from the Arduino Board)
  • Ethernet Controller: W5100 with internal 16K buffer
  • Micro-SD card slot
  • Connection speed: 10/100Mb
  • Connection with Arduino on SPI port Requires an Arduino board (not included)

Additional Arduino Products

We stock a wide variety of Arduino compatible sensors, modules, shields and other accessories. Seeing that this is a 5V board, all accessories must be 5v compatible! Browse our menu at the top of this page (or use search box) for our full range of accessories. Following are some lists (created by search terms) of compatible accessories.

Documentation, Sample Code and Resources

  • There is plenty of documentation on the internet for this module, just search for "arduino w5100". There is an official Arduino page with lots of info here, the Sparkfun page also has a lot of information..
  • To post a question, or share code, see our user forum.

What is included

  • 1 x Arduino W5100 Ethernet Shield