Simple Web Server WiFi

In this example, a simple web server lets you blink an LED via the web. This example will print the IP address of your WiFi Shield (once connected) to the Arduino Software (IDE) serial monitor. Once you know the IP address of our board, you can open that address in a web browser to turn on and off the LED on pin 9.

If the IP address of your shield is yourAddress:
http://yourAddress/H turns the LED on
http://yourAddress/L turns it off

This example is written for a network using WPA encryption. For WEP or WPA, change the Wifi.begin() call accordingly.

Hardware Required

  • Arduino WiFi Shield
  • Shield-compatible Arduino or Genuino board
  • (optional) Six analog sensors attached to Analog Pins 0-5


The WiFi shield uses pins 10, 11, 12, and 13 for the SPI connection to the HDG104 module. Digital pin 4 is used to control the slave select pin on the SD card.

You should have access to a 802.11b/g wireless network that connects to the internet for this example. You will need to change the network settings in the sketch to correspond to your particular networks SSID.

For networks using WPA/WPA2 Personal encryption, you need the SSID and password. The shield will not connect to networks using WPA2 Enterprise encryption.

WEP network passwords are hexadecimal strings known as keys. A WEP network can have 4 different keys; each key is assigned a "Key Index" value. For WEP encrypted networks, you need the SSID, the key, and key number.

image developed using Fritzing. For more circuit examples, see the Fritzing project page

In the above image, the Arduino or Genuino board would be stacked below the WiFi shield.


  WiFi Web Server

 A simple web server that shows the value of the analog input pins.
 using a WiFi shield.

 This example is written for a network using WPA encryption. For
 WEP or WPA, change the Wifi.begin() call accordingly.

 * WiFi shield attached
 * Analog inputs attached to pins A0 through A5 (optional)

 created 13 July 2010
 by dlf (Metodo2 srl)
 modified 31 May 2012
 by Tom Igoe


#include <SPI.h>
#include <WiFi.h>

char ssid[] = "yourNetwork";      // your network SSID (name)
char pass[] = "secretPassword";   // your network password
int keyIndex = 0;                 // your network key Index number (needed only for WEP)

int status = WL_IDLE_STATUS;

WiFiServer server(80);

void setup() {
  //Initialize serial and wait for port to open:
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only

  // check for the presence of the shield:
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WiFi shield not present");
    // don't continue:
    while (true);

  String fv = WiFi.firmwareVersion();
  if (fv != "1.1.0") {
    Serial.println("Please upgrade the firmware");

  // attempt to connect to Wifi network:
  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to SSID: ");
    // Connect to WPA/WPA2 network. Change this line if using open or WEP network:
    status = WiFi.begin(ssid, pass);

    // wait 10 seconds for connection:
  // you're connected now, so print out the status:

void loop() {
  // listen for incoming clients
  WiFiClient client = server.available();
  if (client) {
    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c =;
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println("<!DOCTYPE HTML>");
          // output the value of each analog input pin
          for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
            int sensorReading = analogRead(analogChannel);
            client.print("analog input ");
            client.print(" is ");
            client.println("<br />");
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
    // give the web browser time to receive the data

    // close the connection:
    Serial.println("client disonnected");

void printWifiStatus() {
  // print the SSID of the network you're attached to:
  Serial.print("SSID: ");

  // print your WiFi shield's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print("IP Address: ");

  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.println(" dBm");

See Also:

Last revision 2015/09/17 by SM