DHT11+MQTT-2 NodeMCU will publish realtime temperature and humidity to MQTT broke

NodeMCU will publish realtime temperature and humidity to MQTT broker every 6 seconds,you can use a MQTT client software to subscribe the topic “Alex9ufo-DHT11-Command” and see the published data from NodeMCU.

If you use MQTT client software to send a MQTT message “0” or “1” with topic “Alex9ufo-DHT11-Command”, NodeMCU will do some action as per your command. In our code, you will see message “0” will make NodeMCU print Humidity and Message “1” will make NodeMCU print temperature.

/*

 * Use NodeMCU to drive DHT11 and send temperature/humidity value to MQTT server

 * Tutorial URL http://osoyoo.com/2016/11/24/use-nodemcu-to-send-temperaturehumidity-data-to-mqtt-iot-broker/

 * CopyRight John Yu

 *  

 *  Connection Graph

 *  NodeMCU  DHT11 sensor

 *  3.3v     VCC

 *  D3       DATA

 *  GND      Ground

 *  

 */

#include <ESP8266WiFi.h>

#include <PubSubClient.h>

#include <dht.h>

dht DHT;

#include <Wire.h>  // This library is already built in to the Arduino IDE

#include <LiquidCrystal_I2C.h> //This library you can add via Include Library > Manage Library > 

LiquidCrystal_I2C lcd(0x27, 16, 2);   

//*0x27 means the address of this 1602 I2C LCD display,different lcd may have the different address,

// Define NodeMCU D3 pin to as temperature data pin of  DHT11

#define DHT11_PIN D3

// Update these with values suitable for your network.

//const char* ssid = "******";//put your own wifi ssid here

//const char* password = "******";// put your wifi password here

const char* ssid = "PTS-2F";//put your wifi ssid here

const char* password = "" ;//put your wifi password here

const char* mqtt_server = "broker.mqtt-dashboard.com";

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

WiFiClient espClient;

PubSubClient client(espClient);

long lastMsg = 0;

char msg[50];

int value = 0;

void setup_wifi() {

   delay(100);

  // We start by connecting to a WiFi network

    Serial.print("Connecting to ");

    Serial.println(ssid);

    WiFi.begin(ssid, password);

    while (WiFi.status() != WL_CONNECTED) 

    {

      delay(500);

      Serial.print(".");

    }

  randomSeed(micros());

  Serial.println("");

  Serial.println("WiFi connected");

  Serial.println("IP address: ");

  Serial.println(WiFi.localIP());

}

void callback(char* topic, byte* payload, unsigned int length) 

{

  Serial.print("Command is : [");

  Serial.print(topic);

  int p =(char)payload[0]-'0';

  int chk = DHT.read11(DHT11_PIN);

  // if MQTT comes a 0 message, show humidity

  if(p==0) 

  {

    Serial.println("to show humidity!]");

    Serial.print(" Humidity is: " );

    Serial.print(DHT.humidity, 1);

    Serial.println('%');

    

    lcd.clear();

    lcd.setCursor(0, 0);

    lcd.print("Alex9ufo1602-I2C-LCD"); // Start Print text to Line 1

    lcd.setCursor(0, 1);

    lcd.print("Humidity:"); // Start Print text to Line 1

    lcd.print(DHT.humidity);

    lcd.setCursor(13,1);

    lcd.print(' %');

    

  } 

  // if MQTT comes a 1 message, show temperature

  if(p==1)

  {

  // digitalWrite(BUILTIN_LED, HIGH);

    Serial.println(" is to show temperature!] ");

  int chk = DHT.read11(DHT11_PIN);

   Serial.print(" Temp is: " );

   Serial.print(DHT.temperature);

   Serial.println(' C');

   

   lcd.clear();

   lcd.setCursor(0, 0);

   lcd.print("Alex9ufo1602-I2C-LCD"); // Start Print text to Line 1

   lcd.setCursor(0, 1);

   lcd.print("Temp is:"); // Start Print text to Line 1

   lcd.print(DHT.temperature, 1);

   lcd.print((char)223);

   lcd.print("C");

  }

  Serial.println();

} //end callback

void reconnect() {

  // Loop until we're reconnected

  while (!client.connected()) 

  {

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

    // Create a random client ID

    String clientId = "ESP8266Client-";

    clientId += String(random(0xffff), HEX);

    // Attempt to connect

    //if you MQTT broker has clientID,username and password

    //please change following line to    if (client.connect(clientId,userName,passWord))

    if (client.connect(clientId.c_str()))

    {

      Serial.println("connected");

     //once connected to MQTT broker, subscribe command if any

      client.subscribe("Alex9ufo-DHT11-Command");

    } else {

      Serial.print("failed, rc=");

      Serial.print(client.state());

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

      // Wait 6 seconds before retrying

      delay(6000);

    }

  }

} //end reconnect()

void setup() {

  Serial.begin(115200);

  setup_wifi();

  client.setServer(mqtt_server, 1883);

  client.setCallback(callback);

  int chk = DHT.read11(DHT11_PIN);

  Serial.print(" Starting Humidity: " );

  Serial.print(DHT.humidity, 1);

  Serial.println('%');

  Serial.print(" Starting Temparature ");

  Serial.print(DHT.temperature, 1);

  Serial.println('C');

  lcd.begin();   // initializing the LCD

  lcd.backlight(); // Enable or Turn On the backlight 

}

void loop() {

  if (!client.connected()) {

    reconnect();

  }

  client.loop();

  long now = millis();

  // read DHT11 sensor every 6 seconds

  if (now - lastMsg > 6000) {

     lastMsg = now;

     int chk = DHT.read11(DHT11_PIN);

     String msg="real time temperature: ";

     msg= msg+ DHT.temperature;

     msg = msg+" C ;real time Humidity: " ;

     msg=msg+DHT.humidity ;

     msg=msg+"%";

     char message[58];

     msg.toCharArray(message,58);

     Serial.println(message);

     //publish sensor data to MQTT broker

    client.publish("alex9ufo-DHT11-Data", message);

  }

}