Added WebClientRepeating example

Author: Tom Igoe

libraries/Ethernet/examples/WebClientRepeating/WebClientRepeating.ino

@@ -0,0 +1,111 @@
+/*
+  Repeating Web client
+ 
+ This sketch connects to a a web server and makes a request
+ using a Wiznet Ethernet shield. You can use the Arduino Ethernet shield, or
+ the Adafruit Ethernet shield, either one will work, as long as it's got
+ a Wiznet Ethernet module on board.
+ 
+ This example uses the String library, which is part of the Arduino core from
+ version 0019. It also uses DNS, by assigning the Ethernet client with a MAC address,
+ IP address, and DNS address.
+ 
+ Circuit:
+ * Ethernet shield attached to pins 10, 11, 12, 13
+ 
+ created 19 Apr 2012
+ by Tom Igoe
+ 
+ http://arduino.cc/en/Tutorial/WebClientRepeating
+ This code is in the public domain.
+ 
+ */
+
+#include <SPI.h>
+#include <Ethernet.h>
+
+// assign a MAC address for the ethernet controller.
+// fill in your address here:
+byte mac[] = { 
+  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
+// fill in an available IP address on your network here,
+// for manual configuration:
+IPAddress ip(10,0,0,20);
+
+// fill in your Domain Name Server address here:
+IPAddress myDns(1,1,1,1);
+
+// initialize the library instance:
+EthernetClient client;
+
+char server[] = "www.arduino.cc";
+
+unsigned long lastConnectionTime = 0;          // last time you connected to the server, in milliseconds
+boolean lastConnected = false;                 // state of the connection last time through the main loop
+const unsigned long postingInterval = 60*1000;  // delay between updates, in milliseconds
+
+void setup() {
+  // start serial port:
+  Serial.begin(9600);
+  // give the ethernet module time to boot up:
+  delay(1000);
+  // start the Ethernet connection using a fixed IP address and DNS server:
+  Ethernet.begin(mac, ip, myDns);
+  // print the Ethernet board/shield's IP address:
+  Serial.print("My IP address: ");
+  Serial.println(Ethernet.localIP());
+}
+
+void loop() {
+  // if there's incoming data from the net connection.
+  // send it out the serial port.  This is for debugging
+  // purposes only:
+  if (client.available()) {
+    char c = client.read();
+    Serial.print(c);
+  }
+
+  // if there's no net connection, but there was one last time
+  // through the loop, then stop the client:
+  if (!client.connected() && lastConnected) {
+    Serial.println();
+    Serial.println("disconnecting.");
+    client.stop();
+  }
+
+  // if you're not connected, and ten seconds have passed since
+  // your last connection, then connect again and send data:
+  if(!client.connected() && (millis() - lastConnectionTime > postingInterval)) {
+    httpRequest();
+  }
+  // store the state of the connection for next time through
+  // the loop:
+  lastConnected = client.connected();
+}
+
+// this method makes a HTTP connection to the server:
+void httpRequest() {
+  // if there's a successful connection:
+  if (client.connect(server, 80)) {
+    Serial.println("connecting...");
+    // send the HTTP PUT request:
+    client.println("GET /latest.txt HTTP/1.1");
+    client.println("Host: www.arduino.cc");
+    client.println("User-Agent: arduino-ethernet");
+    client.println("Connection: close");
+    client.println();
+
+    // note the time that the connection was made:
+    lastConnectionTime = millis();
+  } 
+  else {
+    // if you couldn't make a connection:
+    Serial.println("connection failed");
+    Serial.println("disconnecting.");
+    client.stop();
+  }
+}
+
+
+
+