The Arduino Ethernet shield allows an Arduino board to connect to a LAN using the Ethernet library.

General Information and schematics

Features:

• TCP/IP stack on board provided by the W5100 chip
• Allows the Arduino / Freeduino to access the Internet, as a server or a client
• Very small and efficient Library (Did I say the TCP/IP stack is embedded in the W5100 chip>)
• The shield comes with stackable shields
• Arduino communicates with the shield using SPI (But the complexity of SPI communication is hidden by the Library)
• micro-SD socket
• reset switch
• Compatible with Arduino MEGA

Sample Code

With the following code, the Arduino can access Google and search for "Arduino" and bring the result to the serial port.

#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 10, 0, 0, 177 };
byte server[] = { 64, 233, 187, 99 }; // Google


Client client(server, 80);


void setup()
{
Ethernet.begin(mac, ip);
Serial.begin(9600);


delay(1000);


Serial.println("connecting...");


if (client.connect()) {
Serial.println("connected");
client.println("GET /search?q=arduino HTTP/1.0");
client.println();
} else {
Serial.println("connection failed");
}
}


void loop()
{
if (client.available()) {
char c = client.read();
Serial.print(c);
}


if (!client.connected()) {
Serial.println();
Serial.println("disconnecting.");
client.stop();
for(;;)
;
}
}

This is the official Arduino Ethernet Shield, designed and manufactured by the Arduino team in Italy.