esp8266-mqtt-pubsubclient.ino

#include <ESP8266WiFi.h>    // WiFi Library
#include <PubSubClient.h>   // MQTT library
#include <stdlib.h>         // For using rand()
 
const char *ssid =  "SSID";   // cannot be longer than 32 characters!
const char *pass =  "SSID_PASS";   //
 
const char *mqtt_server = "m11.cloudmqtt.com";
const int mqtt_port = 13378;
const char *mqtt_user = "oczjfgbx";
const char *mqtt_pass = "M80GkdpTpGH0";
const char *mqtt_client_name = "arduinoClient1"; // Client connections cant have the same connection name
 
#define BUFFER_SIZE 100
 
unsigned long previousMillis = 0;
const long interval = 10000;   
 
 
WiFiClient wclient;  //Declares a WifiClient Object using ESP8266WiFi
PubSubClient client(wclient, mqtt_server,  mqtt_port);  //instanciates client object
 
//Function is called when, a message is recieved in the MQTT server.
void callback(const MQTT::Publish& pub) {
  Serial.print(pub.topic());
  Serial.print(" => ");
  if (pub.has_stream()) {
    uint8_t buf[BUFFER_SIZE];
    int read;
    while (read = pub.payload_stream()->read(buf, BUFFER_SIZE)) {
      Serial.write(buf, read);
    }
    pub.payload_stream()->stop();
 
    //Check if the buffer is -1
    if(buf[0]=='-' && buf[1]=='1'){
		//Code to blink the LED -- its strange that I can't blink the LED for more than 1sec.
       digitalWrite(LED_BUILTIN, HIGH);
       delay(1000);
       digitalWrite(LED_BUILTIN, LOW);  
    }
     
    Serial.println("");
  } else
    Serial.println(pub.payload_string());
}
 
 
void setup() {
  // Setup console
  Serial.begin(115200);  //set the baud rate
  delay(10);
  Serial.println();
  Serial.println();
}
 
void loop() {
  if (WiFi.status() != WL_CONNECTED) {  //wifi not connected?
    Serial.print("Connecting to ");
    Serial.print(ssid);
    Serial.println("...");
    WiFi.begin(ssid, pass);
 
    if (WiFi.waitForConnectResult() != WL_CONNECTED)
      return;
    Serial.println("WiFi connected");
  }
 
  if (WiFi.status() == WL_CONNECTED) {
	//client object makes connection to server
    if (!client.connected()) {
      Serial.println("Connecting to MQTT server");
	  //Authenticating the client object
      if (client.connect(MQTT::Connect("mqtt_client_name")
                         .set_auth(mqtt_user, mqtt_pass))) {
        Serial.println("Connected to MQTT server");
        
		//Subscribe code
        client.set_callback(callback);
        client.subscribe("Temparture-sensor");
        
      } else {
        Serial.println("Could not connect to MQTT server");   
      }
    }
 
    if (client.connected())
      client.loop();
  }
 
  SendTempHumid();  // this will send the dummy temparature reading
}
 
// Non-Blocking delay
void SendTempHumid(){
  unsigned long currentMillis = millis();
 
  if(currentMillis - previousMillis >= interval) {  // checks if 10 delay is over
    // save the last time you read the sensor 
    previousMillis = currentMillis;   
 
    srand(currentMillis); //create a random value based on time
    int h = rand()%100; // sets value between 0-99
 
    if (isnan(h)) {
      Serial.println("Failed to read from DHT sensor!");
      //return; This will ensure that data is always sent
    }
 
    Serial.print("Temparture-sensor"); 
    Serial.print(h);
  
    client.publish("Temparture-sensor",String(h) );
  }
}