ESP8266 DHT11 Arduino Webserver Source Code Tutorial

Making Projects with ESP8266 is always fun. In this tutorial we will learn to interface ESP8266 with DHT11 or DHT22 sensor, Read Temperature(also capable of Humidity) information and send it to RETE IOT server using MQTT protocol.

Before You Jump Into Tutorial:

Read this tutorial >> Rete IOT introduction and ESP8266 Switch Control Tutorial

Other ESP Projects >> Facebook Chat Device Control Using ESP8266

Video Demo OF DHT11 ESP8266 Interfacing:

DHT11 Library Download and Installation:

Click Here to download ESP8266 library for arduino
Extract The zip file >> COPY DHT folder to >> Your C Drive
Paste it in Document Folder of your C Drive
Open Arduino IDE, You are all set

If you are New To ESP8266 Arduino:

Follow this tutorial , if you are new , and don’t have idea about ESP8266. In this tutorial , I have explained how to install esp8266 library in Arduino IDE.

DHT11 Datasheet:

If you want to learn more about DHT11, you can checkout this datasheet.

Circuit Diagram:

Download DHT11 ESP8266 code and Upload:

Click Here to Download DHT11 ESP8266 source code
Change Your home wifi SSID and Password Name

const char* ssid = "YourWIFIName"; // change to your home wifi name
const char* password = "YourWifiPassword"; //  change to your home wifi password

1 2	const char* ssid = "YourWIFIName"; // change to your home wifi name const char* password = "YourWifiPassword"; // change to your home wifi password

Login to Reteiot.com , If you dont have one account, Please sign up.
In the esp8266 arduino source code, change your Rete IOT email ID

 client.publish("YourEmailID@gmail.com/Temperature", toBeSend);

1	client.publish("[email protected]/Temperature", toBeSend);

ESP8266 DHT11 Source Code:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h> 

#define DHTTYPE DHT11 
// Update these with values suitable for your network.

const char* ssid = "YourWifiName"; // change to your home wifi name
const char* password = "YourWifiPassword"; //  change to your home wifi password
const char* mqtt_server = "io.reteiot.com"; // MQTT broker Name 

const int DHTPin = 5;

// Initialize DHT sensor.
DHT dht(DHTPin, DHTTYPE);
static char fahrenheitTemp[7];
  static char celsiusTemp[7];
static char humidityTemp[7];


WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

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) {
    digitalWrite(BUILTIN_LED, LOW);
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  
  Serial.println("WiFi connected");
  digitalWrite(BUILTIN_LED, HIGH);
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

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();

  // Switch on the LED if an 1 was received as first character
  if ((char)payload[0] == 'o' && (char)payload[1]== 'n') { // Here we are comparing if ON command is coming from server. 
      
  //  digitalWrite(D7, HIGH);
    digitalWrite(D3, HIGH);
   
  } else {
   // digitalWrite(D7, LOW); // else turn off led 
    digitalWrite(D3, LOW);
    
  }

}

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 (client.connect(clientId.c_str())) {
      Serial.println("connected");
      
       digitalWrite(BUILTIN_LED, HIGH);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
   dht.begin();
  pinMode(BUILTIN_LED, OUTPUT);     // on board led for mqtt status indication.
//  pinMode(D7, OUTPUT); // our Buzzer is connected to D7
  pinMode(D3, OUTPUT); // lED
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  digitalWrite(BUILTIN_LED, HIGH);
  digitalWrite(D3, LOW);
}

int readTemp(){
  delay(5000);
 float f = dht.readTemperature(true);  
 float t = dht.readTemperature();
 float h = dht.readHumidity();
 
  if (isnan(f)) {
       Serial.println("Failed to read from DHT sensor!");
       strcpy(fahrenheitTemp, "Failed");   
  }
  else{
   
              //
           //    Serial.print("Humidity: ");
          //    Serial.print(h);
         //     Serial.print(" %\t Temperature: ");
         //     Serial.print(t);
         //     Serial.print(" *C ");
        //      Serial.print(f);
         //     Serial.print(" *F\n ");
              
             String jsonToSend = String(t) ;
             char toBeSend[100];
             jsonToSend.toCharArray(toBeSend, sizeof(toBeSend));
             Serial.print(jsonToSend); 
             Serial.print("\n"); 
             client.publish("satyasankar09@gmail.com/Temperature", toBeSend);
  }
  
}
void loop() {

  if (!client.connected()) {
     digitalWrite(BUILTIN_LED, LOW);
    reconnect();
  }
  readTemp();
  client.loop();

}

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#include <ESP8266WiFi.h>

#include <PubSubClient.h>

#include <Adafruit_Sensor.h>

#include <DHT.h>

#include <DHT_U.h>

#define DHTTYPE DHT11

// Update these with values suitable for your network.

const char* ssid = "YourWifiName"; // change to your home wifi name

const char* password = "YourWifiPassword"; // change to your home wifi password

const char* mqtt_server = "io.reteiot.com"; // MQTT broker Name

const int DHTPin = 5;

// Initialize DHT sensor.

DHT dht(DHTPin, DHTTYPE);

static char fahrenheitTemp[7];

static char celsiusTemp[7];

static char humidityTemp[7];

WiFiClient espClient;

PubSubClient client(espClient);

long lastMsg = 0;

char msg[50];

int value = 0;

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) {

digitalWrite(BUILTIN_LED, LOW);

delay(500);

Serial.print(".");

}

randomSeed(micros());

Serial.println("");

Serial.println("WiFi connected");

digitalWrite(BUILTIN_LED, HIGH);

Serial.println("IP address: ");

Serial.println(WiFi.localIP());

}

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();

// Switch on the LED if an 1 was received as first character

if ((char)payload[0] == 'o' && (char)payload[1]== 'n') { // Here we are comparing if ON command is coming from server.

// digitalWrite(D7, HIGH);

digitalWrite(D3, HIGH);

} else {

// digitalWrite(D7, LOW); // else turn off led

digitalWrite(D3, LOW);

}

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 (client.connect(clientId.c_str())) {

Serial.println("connected");

digitalWrite(BUILTIN_LED, HIGH);

} else {

Serial.print("failed, rc=");

Serial.print(client.state());

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

// Wait 5 seconds before retrying

delay(5000);

}

void setup() {

dht.begin();

pinMode(BUILTIN_LED, OUTPUT); // on board led for mqtt status indication.

// pinMode(D7, OUTPUT); // our Buzzer is connected to D7

pinMode(D3, OUTPUT); // lED

Serial.begin(115200);

setup_wifi();

client.setServer(mqtt_server, 1883);

client.setCallback(callback);

digitalWrite(BUILTIN_LED, HIGH);

digitalWrite(D3, LOW);

}

int readTemp(){

delay(5000);

float f = dht.readTemperature(true);

float t = dht.readTemperature();

float h = dht.readHumidity();

if (isnan(f)) {

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

strcpy(fahrenheitTemp, "Failed");

}

else{

// Serial.print("Humidity: ");

// Serial.print(h);

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

// Serial.print(t);

// Serial.print(" *C ");

// Serial.print(f);

// Serial.print(" *F\n ");

String jsonToSend = String(t) ;

char toBeSend[100];

jsonToSend.toCharArray(toBeSend, sizeof(toBeSend));

Serial.print(jsonToSend);

Serial.print("\n");

client.publish("[email protected]/Temperature", toBeSend);

}

void loop() {

if (!client.connected()) {

digitalWrite(BUILTIN_LED, LOW);

reconnect();

}

readTemp();

client.loop();

}

Compile and Upload the code.
Now You can see the Temperature sensor on your Rete IoT dashboard.

Hope You Find this tutorial useful.

If you Like, Please share with your friends, so others will get benefited.

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Before You Jump Into Tutorial:

Video Demo OF DHT11 ESP8266 Interfacing:

DHT11 Library Download and Installation:

If you are New To ESP8266 Arduino:

DHT11 Datasheet:

Circuit Diagram:

Download DHT11 ESP8266 code and Upload:

ESP8266 DHT11 Source Code:

If you Like, Please share with your friends, so others will get benefited.