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WiFi Twitter Client

This example no longer works as the Twitter authentication mode has changed, and is no longer compatible with the Arduino library.

The Arduino Yún supports OAuth through Temboo. Learn more in the Temboo documentation.

This example shows you how to answer a HTTP request using a WiFi shield. It parses the XML returned, and looks for <text>this is a tweet</text>.

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 board

Circuit

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 would be stacked below the WiFi shield.

Code:

/*
  Wifi Twitter Client with Strings
 
 This sketch connects to Twitter using using an Arduino WiFi shield.
 It parses the XML returned, and looks for <text>this is a tweet</text>
 
 This example is written for a network using WPA encryption. For
 WEP or WPA, change the Wifi.begin() call accordingly.
 
 This example uses the String library, which is part of the Arduino core from
 version 0019.  
 
 Circuit:
 * WiFi shield attached to pins 10, 11, 12, 13
 
 created 23 apr 2012
 modified 31 May 2012
 by Tom Igoe
 
 This code is in the public domain.
 
 */

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

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

int status = WL_IDLE_STATUS; // status of the wifi connection

// initialize the library instance:
WiFiClient client;

const unsigned long requestInterval = 30*1000;    // delay between requests; 30 seconds

// if you don't want to use DNS (and reduce your sketch size)
// use the numeric IP instead of the name for the server:
//IPAddress server(199,59,149,200);    // numeric IP for api.twitter.com
char server[] = "api.twitter.com";     // name address for twitter API

boolean requested;                     // whether you've made a request since connecting
unsigned long lastAttemptTime = 0;     // last time you connected to the server, in milliseconds

String currentLine = "";               // string to hold the text from server
String tweet = "";                     // string to hold the tweet
boolean readingTweet = false;          // if you're currently reading the tweet

void setup() {
  // reserve space for the strings:
  currentLine.reserve(256);
  tweet.reserve(150);
  //Initialize serial and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo 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);
  }
 
  // attempt to connect to Wifi network:
  while ( status != WL_CONNECTED) {
    Serial.print("Attempting to connect to SSID: ");
    Serial.println(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:
    delay(10000);
  }
  // you're connected now, so print out the status:
  printWifiStatus();
  connectToServer();
}

void loop()
{
  if (client.connected()) {
    if (client.available()) {
      // read incoming bytes:
      char inChar = client.read();

      // add incoming byte to end of line:
      currentLine += inChar;

      // if you get a newline, clear the line:
      if (inChar == '\n') {
        currentLine = "";
      }
      // if the current line ends with <text>, it will
      // be followed by the tweet:
      if ( currentLine.endsWith("<text>")) {
        // tweet is beginning. Clear the tweet string:
        readingTweet = true;
        tweet = "";
        // break out of the loop so this character isn't added to the tweet:
        return;
      }
      // if you're currently reading the bytes of a tweet,
      // add them to the tweet String:
      if (readingTweet) {
        if (inChar != '<') {
          tweet += inChar;
        }
        else {
          // if you got a "<" character,
          // you've reached the end of the tweet:
          readingTweet = false;
          Serial.println(tweet);  
          // close the connection to the server:
          client.stop();
        }
      }
    }  
  }
  else if (millis() - lastAttemptTime > requestInterval) {
    // if you're not connected, and two minutes have passed since
    // your last connection, then attempt to connect again:
    connectToServer();
  }
}

void connectToServer() {
  // attempt to connect, and wait a millisecond:
  Serial.println("connecting to server...");
  if (client.connect(server, 80)) {
    Serial.println("making HTTP request...");
    // make HTTP GET request to twitter:
    client.println("GET /1/statuses/user_timeline.xml?screen_name=arduino HTTP/1.1");
    client.println("Host: api.twitter.com");
    client.println("Connection: close");
    client.println();
  }
  // note the time of this connect attempt:
  lastAttemptTime = millis();
}  


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

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

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

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