ESP8266 and Node-RED with MQTT (Publish and Subscribe)

/*****

 

 All the resources for this project:

 http://randomnerdtutorials.com/

 

*****/

#include <ESP8266WiFi.h>

#include <PubSubClient.h>

#include "DHT.h"

// Uncomment one of the lines bellow for whatever DHT sensor type you're using!

#define DHTTYPE DHT11   // DHT 11

//#define DHTTYPE DHT21   // DHT 21 (AM2301)

//#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321

// Change the credentials below, so your ESP8266 connects to your router

const char* ssid = "PTS-2F";

const char* password = "";

// Change the variable to your Raspberry Pi IP address, so it connects to your MQTT broker

const char* mqtt_server = "iot.eclipse.org";

// Initializes the espClient. You should change the espClient name if you have multiple ESPs running in your home automation system

WiFiClient espClient;

PubSubClient client(espClient);

// DHT Sensor - GPIO 5 = D1 on ESP-12E NodeMCU board

const int DHTPin = 5;

// Lamp - LED - GPIO 4 = D2 on ESP-12E NodeMCU board

const int lamp = 4;

// Initialize DHT sensor.

DHT dht(DHTPin, DHTTYPE);

// Timers auxiliar variables

long now = millis();

long lastMeasure = 0;

// Don't change the function below. This functions connects your ESP8266 to your router

void setup_wifi() {

  delay(10);

  // We start by connecting to a WiFi network

  Serial.println();

  Serial.print("Connecting to ");

  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {

    delay(500);

    Serial.print(".");

  }

  Serial.println("");

  Serial.print("WiFi connected - ESP IP address: ");

  Serial.println(WiFi.localIP());

}

// This functions is executed when some device publishes a message to a topic that your ESP8266 is subscribed to

// Change the function below to add logic to your program, so when a device publishes a message to a topic that 

// your ESP8266 is subscribed you can actually do something

void callback(String topic, byte* message, unsigned int length) {

  Serial.print("Message arrived on topic: ");

  Serial.print(topic);

  Serial.print(". Message: ");

  String messageTemp;

  

  for (int i = 0; i < length; i++) {

    Serial.print((char)message[i]);

    messageTemp += (char)message[i];

  }

  Serial.println();

  // Feel free to add more if statements to control more GPIOs with MQTT

  // If a message is received on the topic room/lamp, you check if the message is either on or off. Turns the lamp GPIO according to the message

  if(topic=="alex9ufoRoom/lamp"){

      Serial.print("Changing Room lamp to ");

      if(messageTemp == "on"){

        digitalWrite(lamp, HIGH);

        Serial.print("On");

      }

      else if(messageTemp == "off"){

        digitalWrite(lamp, LOW);

        Serial.print("Off");

      }

  }

  Serial.println();

}

// This functions reconnects your ESP8266 to your MQTT broker

// Change the function below if you want to subscribe to more topics with your ESP8266 

void reconnect() {

  // Loop until we're reconnected

  while (!client.connected()) {

    Serial.print("Attempting MQTT connection...");

    // Attempt to connect

    /*

     YOU MIGHT NEED TO CHANGE THIS LINE, IF YOU'RE HAVING PROBLEMS WITH MQTT MULTIPLE CONNECTIONS

     To change the ESP device ID, you will have to give a new name to the ESP8266.

     Here's how it looks:

       if (client.connect("ESP8266Client")) {

     You can do it like this:

       if (client.connect("ESP1_Office")) {

     Then, for the other ESP:

       if (client.connect("ESP2_Garage")) {

      That should solve your MQTT multiple connections problem

    */

    if (client.connect("ESP8266Client")) {

      Serial.println("connected");  

      // Subscribe or resubscribe to a topic

      // You can subscribe to more topics (to control more LEDs in this example)

      client.subscribe("alex9ufoRoom/lamp");

    } else {

      Serial.print("failed, rc=");

      Serial.print(client.state());

      Serial.println(" try again in 5 seconds");

      // Wait 5 seconds before retrying

      delay(5000);

    }

  }

}

// The setup function sets your ESP GPIOs to Outputs, starts the serial communication at a baud rate of 115200

// Sets your mqtt broker and sets the callback function

// The callback function is what receives messages and actually controls the LEDs

void setup() {

  pinMode(lamp, OUTPUT);

  

  dht.begin();

  

  Serial.begin(115200);

  setup_wifi();

  client.setServer(mqtt_server, 1883);

  client.setCallback(callback);

}

// For this project, you don't need to change anything in the loop function. Basically it ensures that you ESP is connected to your broker

void loop() {

  if (!client.connected()) {

    reconnect();

  }

  if(!client.loop())

    client.connect("ESP8266Client");

  now = millis();

  // Publishes new temperature and humidity every 30 seconds

  if (now - lastMeasure > 30000) {

    lastMeasure = now;

    // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)

    float h = dht.readHumidity();

    // Read temperature as Celsius (the default)

    float t = dht.readTemperature();

    // Read temperature as Fahrenheit (isFahrenheit = true)

    float f = dht.readTemperature(true);

    // Check if any reads failed and exit early (to try again).

    if (isnan(h) || isnan(t) || isnan(f)) {

      Serial.println("Failed to read from DHT sensor!");

      return;

    }

    // Computes temperature values in Celsius

    float hic = dht.computeHeatIndex(t, h, false);

    static char temperatureTemp[7];

    dtostrf(hic, 6, 2, temperatureTemp);

    

    // Uncomment to compute temperature values in Fahrenheit 

    // float hif = dht.computeHeatIndex(f, h);

    // static char temperatureTemp[7];

    // dtostrf(hic, 6, 2, temperatureTemp);

    

    static char humidityTemp[7];

    dtostrf(h, 6, 2, humidityTemp);

    // Publishes Temperature and Humidity values

    client.publish("alex9ufoRoom/temp", temperatureTemp);

    client.publish("alex9ufoRoom/humi", humidityTemp);

    

    Serial.print("alex9ufoRoom/temp : ");

    Serial.print(temperatureTemp);

    Serial.print("%C \t alex9ufoRoom/humi : ");

    Serial.print(humidityTemp);

    Serial.println(" % ");

    

    

    Serial.print("Humidity: ");

    Serial.print(h);

    Serial.print(" %\t Temperature: ");

    Serial.print(t);

    Serial.print(" *C ");

    Serial.print(f);

    Serial.print(" *F\t Heat index: ");

    Serial.print(hic);

    Serial.println(" *C ");

    // Serial.print(hif);

    // Serial.println(" *F");

  }

}