Publish and Subscribe to Ubidots ESP8266

UbidotsEsp8266.ino

/*************************************************************************************************
 * This Example sends harcoded data to Ubidots and serves as example for users that have devices
 * based on ESP8266 chips
 *
 * This example is given AS IT IS without any warranty
 *
 * Made by Jose García @https://github.com/jotathebest/ , 
 * adapted from the original WiFiClient ESP8266 example
 *************************************************************************************************/

/****************************************
 * Include Libraries
 ****************************************/

#include <PubSubClient.h>
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <stdio.h>


/****************************************
 * Define Constants
 ****************************************/

#define WIFISSID "..." // Put your WifiSSID here
#define PASSWORD "..." // Put your wifi password here
#define TOKEN "...." // Put your Ubidots' TOKEN
#define VARIABLE_LABEL "temperature" // Assing the variable label
#define VARIABLE_TO_SUBSCRIBE "humidity"
#define DEVICE_LABEL "pycon" // Assig the device label
#define MQTT_CLIENT_NAME "...." // MQTT client Name, put a Random ASCII

char mqttBroker[] = "industrial.api.ubidots.com";
char payload[700];
char topic[150];

// Space to store values to send
char str_val[6];


/****************************************
 * Initializate constructors for objects
 ****************************************/

ESP8266WiFiMulti WiFiMulti;
WiFiClient ubidots;
PubSubClient client(ubidots);


/****************************************
 * Auxiliar Functions
 ****************************************/
 
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i=0;i<length;i++) {
  Serial.print((char)payload[i]);
  }
  Serial.println();
} 


void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
  Serial.println("Attempting MQTT connection...");

  // Attempt to connect
  if (client.connect(MQTT_CLIENT_NAME, TOKEN,"")) {
    Serial.println("connected");
  } else {
    Serial.print("failed, rc=");
    Serial.print(client.state());
    Serial.println(" try again in 2 seconds");
    // Wait 2 seconds before retrying
    delay(2000);
  }
  }
}


/****************************************
 * Main Functions
 ****************************************/

void setup() {
  Serial.begin(115200);
  pinMode(A0, INPUT);
  WiFiMulti.addAP(WIFISSID, PASSWORD);
  Serial.println();
  Serial.println();
  Serial.print("Wait for WiFi... ");

  while(WiFiMulti.run() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  client.setServer(mqttBroker, 1883);
  client.setCallback(callback);
}

void loop() {

  if (!client.connected()) {
    reconnect();
    // Subscribes for getting the value of the control variable in the temperature-box device
    char topicToSubscribe[200];
    sprintf(topicToSubscribe, "%s", ""); // Cleans the content of the char
    sprintf(topicToSubscribe, "%s%s", "/v1.6/devices/", DEVICE_LABEL);
    sprintf(topicToSubscribe, "%s/%s/lv", topicToSubscribe, VARIABLE_TO_SUBSCRIBE);
    Serial.println("subscribing to topic:");
    Serial.println(topicToSubscribe);
    client.subscribe(topicToSubscribe);
  }

  // Values to send
  float temperature = random(0, 9);

  /* 4 is mininum width, 2 is precision; float value is copied onto str_temp*/
  dtostrf(temperature, 4, 2, str_val);

  sprintf(topic, "%s", ""); // Cleans the topic content
  sprintf(topic, "%s%s", "/v1.6/devices/", DEVICE_LABEL);

  sprintf(payload, "%s", ""); // Cleans the payload content
  sprintf(payload, "{\"%s\":", VARIABLE_LABEL); // Adds the variable label   
  sprintf(payload, "%s {\"value\": %s", payload, str_val); // Adds the value
  sprintf(payload, "%s } }", payload); // Closes the dictionary brackets

  client.publish(topic, payload);
  client.loop();
  delay(1000);
}