Adds sample for Ethernet Shield.

EhternetShield/EhternetShield.ino

@@ -0,0 +1,87 @@
+#include <SPI.h>
+#include <Ethernet.h>
+
+byte mac[] = {0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC};  // for local network.
+const char server[] = "192.168.11.4"; // local web server
+const int LED = 7;
+
+EthernetClient client;
+
+const int BUF_DATA_SIZE = 100;
+char buf[BUF_DATA_SIZE];
+int pos = 0;
+
+void connectServer() {
+  if(client.connect(server, 80)) {
+    Serial.println("Connected.");
+    client.println("GET /~twopack/cgi-bin/test.cgi HTTP/1.0");
+    client.println("Host: 192.168.11.4");
+    client.println("Connection: close");
+    client.println("");
+  } else {
+    Serial.println("Failed to connect.");
+  }
+}
+
+void switchLED(int led) {
+  if(led == 0) {
+    digitalWrite(LED, LOW);
+  } else if(led == 1) {
+    digitalWrite(LED, HIGH);
+  }
+}
+
+int analyze(char *data) {
+  Serial.print(data);
+  if(strlen(data) == strlen("led:0\n")) {
+    char led = data[4];
+    data[4] = '\0';
+    if(strcmp(data, "led:") == 0) {
+      if(led == '0') {
+        return 0;
+      } else if(led == '1') {
+        return 1;
+      } 
+    }
+  }
+  return -1;
+}
+
+void setup() {
+  Serial.begin(9600);
+  pinMode(LED, OUTPUT);
+  digitalWrite(LED, HIGH);
+
+  if(Ethernet.begin(mac) == 0) {
+    Serial.println("Failed to get ipaddress by DHCP.");
+    while(1); // stop
+  }
+  delay(1000);
+}
+
+void loop() {
+  if(client.available()) {
+    buf[pos] = client.read();
+    if(buf[pos] == '\n') {
+      buf[pos + 1] = '\0';
+      int led = analyze(buf);
+      if(led == 1 || led == 0) {
+        switchLED(led);
+      }
+      pos = 0;
+    } else {
+      pos++;
+      if(pos >= BUF_DATA_SIZE) {
+        pos = 0;  // through unknown data.
+      }
+    }
+  }     
+
+  if(!client.connected()) {
+    Serial.println("Disconnecting.");
+    client.stop();
+
+    delay(1000);
+    connectServer();
+  }
+}