W5100 Ethernet LAN and Micro SD Card Adapter Shield for Arduino (uses Arduino Ethernet Driver)
The Wiznet W5100 Ethernet Shield for Arduino allows an Arduino board to connect to the internet. It is based on the Wiznet W5100 ethernet chip. The Arduino Ethernet Shield supports up to four simultaneous socket connections. Use the official Arduino Ethernet library to write your sketches for it.
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. In case you are using the W5100 Ethernet Shield together with an Arduino Mega, the W5100 could need a power-on reset. You can do this with a simple RC setup, or by assembling a STM812 reset controller (empty pads beside the reset button).
The W5100 Ethernet shield receives 5V from the Arduino Controller or max. 9V from the connected Arduino’s Vin pin.