Beginner Ethernet Shield V1.1

Some simple server code that will will make arduino pin 4 high and low from a simple web page.

//zoomkat 12-18-10
//routerbot code
//for use with IDE 0021
//open serial monitor to see what the arduino receives
//use the \ slash to escape the " in the html 
//address will look like http://192.168.1.102:84/ when submited
//for use with W5100 based ethernet shields

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte ip[] = { 192, 168, 1, 102 }; // ip in lan
byte gateway[] = { 192, 168, 1, 1 }; // internet access via router
byte subnet[] = { 255, 255, 255, 0 }; //subnet mask
Server server(84); //server port

String readString; 
 
 //////////////////////

void setup(){

pinMode(4, OUTPUT); //pin selected to control
//start Ethernet
Ethernet.begin(mac, ip, gateway, subnet);
server.begin();

//enable serial data print 
Serial.begin(9600); 
Serial.println("servertest1"); // so I can keep track of what is loaded
}

void loop(){
// Create a client connection
Client client = server.available();
if (client) {
while (client.connected()) {
if (client.available()) {
char c = client.read();

//read char by char HTTP request
if (readString.length() < 100) {

//store characters to string 
readString += c; 
//Serial.print(c);
} 

//if HTTP request has ended
if (c == '\n') {

///////////////
Serial.println(readString);

  //now output HTML data header

  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println();

client.println("<HTML>");
   client.println("<HEAD>");
     client.println("<TITLE>Arduino GET test page</TITLE>");
   client.println("</HEAD>");
   client.println("<BODY>");
    
    client.println("<H1>HTML form GET example</H1>");

    client.println("<FORM ACTION=\"http://192.168.1.102:84\" method=get >");

    client.println("Pin 4 \"on\" or \"off\": <INPUT TYPE=TEXT NAME=\"LED\" VALUE=\"\" SIZE=\"25\" MAXLENGTH=\"50\">
");

        client.println("<INPUT TYPE=SUBMIT NAME=\"submit\" VALUE=\"Change Pin 4!\">");

    client.println("</FORM>");
    
client.println("
");

   client.println("</BODY>");
client.println("</HTML>");

  delay(1);
  //stopping client
client.stop();

/////////////////////
if(readString.indexOf("on") >0)//checks for on
           {
             digitalWrite(4, HIGH);    // set pin 4 high
             Serial.println("Led On");
             }
if(readString.indexOf("off") >0)//checks for off
           {
             digitalWrite(4, LOW);    // set pin 4 low
             Serial.println("Led Off");
             }
//clearing string for next read
readString="";
  
}}}}}