Working Arduino MQTT client that connects to Lelylan.

mqtt-lelylan-local.ino

/* -------------------------------------------------------
 * Install https://github.com/andreareginato/pubsubclient
 * It sets the max packet size to 512 bytes.
 * ------------------------------------------------------- */

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

// Update these with values suitable for your network.
byte mac[] = { 0xA0, 0xA0, 0xBA, 0xAC, 0xAE, 0x12 };

/* device credentials */
char* deviceId = "51dfdc22d033a99721000001";         // set your device id (will be the MQTT client username)
char* deviceSecret = "8eb6a0c2d0bf6140e9b72c2eb7c2222b3252c5e4d765f7f67da810ad8da8742f"; // set your device secret (will be the MQTT client password)

/* device topics */
char* outTopic = "devices/51dfdc22d033a99721000001/set"; // where physical updates are published
char* inTopic = "devices/51dfdc22d033a99721000001/get";  // where lelylan updates are received

/* sample payload published to lelylan */
/* (to get the desired property-id go to the device settings and click on the type link) */
char* payload = "{\"properties\":[{ \"id\": \"518c92abd033a9473f000001\", \"value\": \"on\" }]}";

/* access settings */
byte server[] = { 192, 168, 1, 101 }; // MQTT server address
char* clientId = "mqtt-client-1";     // MQTT client id (max 23 bytes)

/* communication definition */
void callback(char* topic, byte* payload, unsigned int length); // subscription callback
EthernetClient ethClient;                                       // ethernet client
PubSubClient client(server, 1883, callback, ethClient);         // mqtt client
byte ip[] = { 192, 168, 1, 100 };  // LOCAL

/* arduino setup */
void setup() {
  Serial.begin(9600);
  delay(500);

  Ethernet.begin(mac, ip);
  Serial.print("Connected with IP: ");
  Serial.println(Ethernet.localIP());

  lelylanConnection(); // MQTT server connection
}

/* arduino loop */
void loop() {
  lelylanConnection();
}

/* MQTT server connection */
void lelylanConnection() {
  // add reconnection logics
  if (!client.connected()) {
    // connection to MQTT server
    if (client.connect(clientId, deviceId, deviceSecret)) {
      Serial.print("[OK] Connected with MQTT");
      lelylanSubscribe();  // topic subscription
      lelylanPublish();    // topic publishing
    }
  }

  client.loop();
}

/* MQTT publish */
void lelylanPublish() {
  client.publish(outTopic, payload);
}

/* MQTT subscribe */
void lelylanSubscribe() {
  client.subscribe(inTopic);
}

// debug to show the received message
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Receiving subscribed message");
  Serial.println(topic);
  Serial.write(payload, length);
}

Hi ya,

I am trying to learn arduino and MQTT can you please explain the code in detail. i want to use the code with my local MQTT server.

Regards
Satyam

A bit late. http://lelylan.github.io/lab-projects/arduino-ethernet-light/#code