This week we do step 1 of our on-air light.  We make the arduino check the status of the live Ustream channel.

To do this we use an ethernet shield to poll the Ustream API to check the status of our strem.  We learn how to setup the ethernet shield and then poll a web server.

We also introduce you to JSON and a new JSON Library in this episode of Let’s Make It.

Downloads

Checking the Ustream Stream

/*############################ CHECKING THE USTREAM FEED ################################
       This sketch will read a stream status from ustream to determine if the
       stream is up "live" or down.
       
       It controls pin 13 to light an LED if the stream is live.

 
   From: Mike Myers (http://mikemyers.me)  @netnutmike
       Let's Make It Episode 6 (http://tech-zen.tv/index.php/shows/let-s-make-it/episodes/59-sensor-fun-with-arduino-1-massive-failure-but-4-successes-let-s-make-it-episode-6)
       
       http://tech-zen.tv
       
       For the sample code, show notes, contact information and many more 
       videos, visit the show page at http://tech-zen.tv/letsmakeit

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################################################################################*/

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

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = {  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress server(199,66,238,68); // Ustream
int controlPin = 13;

int reading=false;
int chpos = 0;
char rtnchar[500];
int islive;


// Initialize the Ethernet client library
// with the IP address and port of the server 
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;

void setup() {
  int weconnected;
  
  // Setup Control Pin
  pinMode(controlPin, OUTPUT);
  
 // Open serial communications and wait for port to open:
  Serial.begin(9600);

  do {
  // start the Ethernet connection:
    Serial.println("Trying to get IP Address");
    if (Ethernet.begin(mac) == 0) {
      Serial.println("Failed to configure Ethernet using DHCP, Trying Again in 1 minute");
      weconnected = false;
      delay(60000);
   
    } else {
      Serial.println(Ethernet.localIP());
      weconnected = true;
    }
  } while (!weconnected);
  
  // give the Ethernet shield a second to initialize:
  delay(1000);
  Serial.println("connecting...");

  
}

void loop()
{
  checkStream();
  delay(60000);
}

void checkStream()
{
  reading=false;
  chpos=0;
  aJsonObject* root;
  
  // if you get a connection, report back via serial:
  if (client.connect(server, 80)) {
    Serial.println("connected");
    // Make a HTTP request:
    client.println("GET /json/channel/tech-zen-tv/getValueOf/status HTTP/1.0");
    client.println();
  } 
  else {
    // kf you didn't get a connection to the server:
    Serial.println("connection failed");
    digitalWrite(controlPin, LOW);
  }
  
  while (client.connected()) {
    // if there are incoming bytes available 
    // from the server, read them and print them:
    if (client.available()) {
      char c = client.read();
      if (c == '{') {
        reading=true;
        }
      
      if (reading) {
        rtnchar[chpos] = c;
        ++chpos;
        //Serial.print(chpos);
        Serial.print(c);
        } 
      }
    }
    
  rtnchar[chpos] = '\0';
  islive = false;
  Serial.println();

  root = aJson.parse(rtnchar);

  if (root != NULL) {
      //Serial.println("Parsed successfully 1 " );
      aJsonObject* query = aJson.getObjectItem(root, "results"); 

       if (strcmp(query->valuestring, "live") == 0) {
         islive = true;
         }
        
        if (islive==true) {
          Serial.println("It's Live");
          digitalWrite(controlPin, HIGH);
        } else {
          Serial.println("No Stream");
          digitalWrite(controlPin, LOW);
        }
  }
  
  root=NULL;
  Serial.println("disconnecting.");
  Serial.println();
  
  client.stop();
    
    
}