Read Multiple DHT11 Temperature Sensor with single Wemos

Assalam-o-Alaikum!

Once again welcome to my Temperature sensor tutorials series. As you know we are working on DHT11 temperature sensor, previously we successfully completed our sensor programming with MySQL and PHP programming. We added our sensor data into database and then retrieved it using PHP. In today’s tutorial we are going to read multiple sensors and then we will save it into database. If you not read my previous tutorial, please read it frist from here:

http://ice786pk.com/?p=565

Now lets start our lesson.

We need to connect two DHT11 temperature sensors on two pins (data pin). It is your choice to select pins, I selected D1 and D2, D1 for reading first sensor D2 for second sensor. Now second thing you have to do is connecting + and – wires. You both wire should connect with same pin. Now your hardware requirement is OK. Here is code for arduino:-

//include libraries
#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h> 
#include <dht.h>
#define dht_apin D1 // Analog Pin sensor is connected to
#define dht_apin2 D2 // Analog Pin sensor is connected to
dht DHT,DHT2;

float get_temperature,get_humidity,get_temperature2,get_humidity2;
//Access point credentials
const char* ssid = "My WiFi";
const char* pwd = "Iam@007";
const char* host = "http://192.168.8.102";
String get_host = "http://192.168.8.102";
int read_data = 0;
int live_delay  = 3000; // Its mean 3 seconds wait to enter first record
int actual_delay_times  = 5; //  Its mean that 5 time of live delay to enter record for actual data
WiFiServer server(80);  // open port 80 for server connection

void setup() 
{
  Serial.begin(115200); //initialise the serial communication
  delay(20);
  
  //defining the pins, i/p and o/p
  pinMode(dht_apin, OUTPUT);
  pinMode(dht_apin, INPUT);
  digitalWrite(dht_apin, LOW);

         
  //connecting to wifi
  Serial.print("Connecting to wifi ");
  Serial.println(ssid);
  WiFi.begin(ssid, pwd);
  
  //attempt to connect to wifi
  while (WiFi.status() != WL_CONNECTED)
  
  {
    delay(1000);
    Serial.print("."); //progress with dots until the wifi is connected
  }
   
    //starting the server
    server.begin();
    Serial.print("This is your ip address: ");
    Serial.print("http://");
    Serial.print(WiFi.localIP());
    Serial.println("/");  
}

void loop()
{
    
    WiFiClient client = server.available();
    if (!client)
    {
      return;
    }
    
    //wait for the data to be sent from client
    
    while(!client.available())
    {
      delay(1);
    }
  DHT.read11(dht_apin);
  DHT2.read11(dht_apin2);
   
  get_temperature =   DHT.temperature;
  get_humidity    =   DHT.humidity;
  get_temperature2 =   DHT2.temperature;
  get_humidity2    =   DHT2.humidity;
    //Read the first line of the request
    String request = client.readStringUntil('\r');
    Serial.println(request);
    client.flush();
    
   int value = LOW; // set the thermometer off initially
   
   
    //check the index of the browser and act accordingly 
    if (request.indexOf("/Thermo=ON") != -1) 
    {
        digitalWrite(dht_apin, HIGH);
        digitalWrite(dht_apin2, HIGH);

        value = HIGH;
        
       
       
        //save the data to mysql, access the php file to write
        HTTPClient http;
        String url = get_host+"/temperature/add.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);
        read_data++;
        
        if(read_data > actual_delay_times)
        {
        String url = get_host+"/temperature/add_real_data.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);
        Serial.println(url);     
        http.begin(url);
        //GET method
        int httpCode = http.GET();
        if(httpCode > 0)
        {
          Serial.printf("[HTTP] GET...code: %d\n", httpCode);
          if(httpCode == HTTP_CODE_OK)
          {
              String payload = http.getString();
              Serial.println(payload);
          }
       }
        read_data = 0;
        }


        Serial.println(url);     
        http.begin(url);
       
        //GET method
        int httpCode = http.GET();
        if(httpCode > 0)
        {
          Serial.printf("[HTTP] GET...code: %d\n", httpCode);
          if(httpCode == HTTP_CODE_OK)
          {
              String payload = http.getString();
              Serial.println(payload);
          }
       }
       else
       {
            Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
       }
          http.end();
          delay(live_delay);
   }

    if (request.indexOf("/Thermo=OFF") != -1)
    {
      digitalWrite(dht_apin, LOW);
      digitalWrite(dht_apin2, LOW);
      value = LOW;
    } 
      
      //Return the response
      client.println("HTTP/1.1 200 OK");
      client.println("Content-Type: text/html");

      if (request.indexOf("/AlwaysOn") != -1) 
      {
        digitalWrite(dht_apin, HIGH);
        digitalWrite(dht_apin2, HIGH);
        value = HIGH;
        
        
        
        client.println("Refresh: 5");
      }

      client.println("");
      client.println("<!DOCTYPE HTML>");
      client.println("<html>");
      client.println("<body style=background-color:skyblue> </body>");
      client.println("<style> h1 {text-align: center}</style>");
      client.println("<style> h3 {text-align: center}</style>");
      client.println("<style> b {text-align: center}</style>");
      client.println("<style> p {text-align: center}</style>");
      client.println("<head><style>div.relative{position:relative; left:200px; height:20px; width:350px; border:2px solid #73AD21;}</style></head>");
      client.println();
      
      
      if(request.indexOf("/AlwaysOn") != -1)
      {
        client.print("<h3>Always On<h3>");
        
          client.println("<h3>Current Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>"); 
          client.println("<h3>Current Humidity: <h3>"+String(get_humidity)+"<b> %.</b>");
        //save the data to mysql, with http client
      HTTPClient http;
        String url = get_host+"/temperature/add.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);
      
        read_data++;
        
        if(read_data > actual_delay_times)
        {
        String url = get_host+"/temperature/add_real_data.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);
        Serial.println(url);     
        http.begin(url);

        //using GET method to write to sql
        int httpCode = http.GET();
        if(httpCode > 0)
       {
          Serial.printf("[HTTP] GET...code: %d\n", httpCode);
            if(httpCode == HTTP_CODE_OK)
            {
              String payload = http.getString();
              Serial.println(payload);
            }
        }
        read_data = 0;
        }

      Serial.println(url);     
      http.begin(url);

      //using GET method to write to sql
      int httpCode = http.GET();
      if(httpCode > 0)
      {
          Serial.printf("[HTTP] GET...code: %d\n", httpCode);
            if(httpCode == HTTP_CODE_OK)
            {
              String payload = http.getString();
              Serial.println(payload);
            }
      }
         else
         {
            Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
         }
          http.end();
       //delay(3000);
    }
        
     else if(value == HIGH)
     {
          client.print("<h3>On Once<h3>");

          // client.println("<br>"); 
          client.println("<h3>Current Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>"); 
          client.println("<h3>Current Humidity: <h3>"+String(get_humidity)+"<b> %.</b>"); 
      }
      else if(value == LOW)
      {
          client.print("<h3>Off<h3>");
         // client.println("<br>"); 
          client.println("<h3>Last Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>"); 
          client.println("<h3>Last Humidity: <h3>"+String(get_humidity)+"<b> %.</b>"); 
      }
 
      client.println("<br><br>");
      //create buttons
      client.println("<a href=\"/Thermo=ON\"\"><button>Turn On Once </button></a>");
      client.println("<a href=\"/AlwaysOn\"\"><button>Keep It On </button></a>");
      client.println("<a href=\"/Thermo=OFF\"\"><button>Turn Off </button></a><br />");
      client.println("<p>"+get_host+"/temperature/show.php</p>");
      
      // if there are incoming bytes available from the server, read them and print them:
     if (client.available()) 
     {
       char c = client.read();
       client.print(c);
     }
  
      client.println("</html>");

}

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//include libraries

#include <ESP8266HTTPClient.h>

#include <ESP8266WiFi.h>

#include <dht.h>

#define dht_apin D1 // Analog Pin sensor is connected to

#define dht_apin2 D2 // Analog Pin sensor is connected to

dht DHT,DHT2;

float get_temperature,get_humidity,get_temperature2,get_humidity2;

//Access point credentials

const char* ssid = "My WiFi";

const char* pwd = "Iam@007";

const char* host = "http://192.168.8.102";

String get_host = "http://192.168.8.102";

int read_data = 0;

int live_delay = 3000; // Its mean 3 seconds wait to enter first record

int actual_delay_times = 5; // Its mean that 5 time of live delay to enter record for actual data

WiFiServer server(80); // open port 80 for server connection

void setup()

{

Serial.begin(115200); //initialise the serial communication

delay(20);

//defining the pins, i/p and o/p

pinMode(dht_apin, OUTPUT);

pinMode(dht_apin, INPUT);

digitalWrite(dht_apin, LOW);

//connecting to wifi

Serial.print("Connecting to wifi ");

Serial.println(ssid);

WiFi.begin(ssid, pwd);

//attempt to connect to wifi

while (WiFi.status() != WL_CONNECTED)

{

delay(1000);

Serial.print("."); //progress with dots until the wifi is connected

}

//starting the server

server.begin();

Serial.print("This is your ip address: ");

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

Serial.print(WiFi.localIP());

Serial.println("/");

}

void loop()

{

WiFiClient client = server.available();

if (!client)

{

return;

}

//wait for the data to be sent from client

while(!client.available())

{

delay(1);

}

DHT.read11(dht_apin);

DHT2.read11(dht_apin2);

get_temperature = DHT.temperature;

get_humidity = DHT.humidity;

get_temperature2 = DHT2.temperature;

get_humidity2 = DHT2.humidity;

//Read the first line of the request

String request = client.readStringUntil('\r');

Serial.println(request);

client.flush();

int value = LOW; // set the thermometer off initially

//check the index of the browser and act accordingly

if (request.indexOf("/Thermo=ON") != -1)

{

digitalWrite(dht_apin, HIGH);

digitalWrite(dht_apin2, HIGH);

value = HIGH;

//save the data to mysql, access the php file to write

HTTPClient http;

String url = get_host+"/temperature/add.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);

read_data++;

if(read_data > actual_delay_times)

{

String url = get_host+"/temperature/add_real_data.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);

Serial.println(url);

http.begin(url);

//GET method

int httpCode = http.GET();

if(httpCode > 0)

{

Serial.printf("[HTTP] GET...code: %d\n", httpCode);

if(httpCode == HTTP_CODE_OK)

{

String payload = http.getString();

Serial.println(payload);

}

read_data = 0;

}

Serial.println(url);

http.begin(url);

//GET method

int httpCode = http.GET();

if(httpCode > 0)

{

Serial.printf("[HTTP] GET...code: %d\n", httpCode);

if(httpCode == HTTP_CODE_OK)

{

String payload = http.getString();

Serial.println(payload);

}

else

{

Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());

}

http.end();

delay(live_delay);

}

if (request.indexOf("/Thermo=OFF") != -1)

{

digitalWrite(dht_apin, LOW);

digitalWrite(dht_apin2, LOW);

value = LOW;

}

//Return the response

client.println("HTTP/1.1 200 OK");

client.println("Content-Type: text/html");

if (request.indexOf("/AlwaysOn") != -1)

{

digitalWrite(dht_apin, HIGH);

digitalWrite(dht_apin2, HIGH);

value = HIGH;

client.println("Refresh: 5");

}

client.println("");

client.println("<!DOCTYPE HTML>");

client.println("<html>");

client.println("<body style=background-color:skyblue> </body>");

client.println("<style> h1 {text-align: center}</style>");

client.println("<style> h3 {text-align: center}</style>");

client.println("<style> b {text-align: center}</style>");

client.println("<style> p {text-align: center}</style>");

client.println("<head><style>div.relative{position:relative; left:200px; height:20px; width:350px; border:2px solid #73AD21;}</style></head>");

client.println();

if(request.indexOf("/AlwaysOn") != -1)

{

client.print("<h3>Always On<h3>");

client.println("<h3>Current Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>");

client.println("<h3>Current Humidity: <h3>"+String(get_humidity)+"<b> %.</b>");

//save the data to mysql, with http client

HTTPClient http;

String url = get_host+"/temperature/add.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);

read_data++;

if(read_data > actual_delay_times)

{

String url = get_host+"/temperature/add_real_data.php?temp="+String(get_temperature)+"&humidity="+String(get_humidity)+"&home_temp="+String(get_temperature2)+"&home_humidity="+String(get_humidity2);

Serial.println(url);

http.begin(url);

//using GET method to write to sql

int httpCode = http.GET();

if(httpCode > 0)

{

Serial.printf("[HTTP] GET...code: %d\n", httpCode);

if(httpCode == HTTP_CODE_OK)

{

String payload = http.getString();

Serial.println(payload);

}

read_data = 0;

}

Serial.println(url);

http.begin(url);

//using GET method to write to sql

int httpCode = http.GET();

if(httpCode > 0)

{

Serial.printf("[HTTP] GET...code: %d\n", httpCode);

if(httpCode == HTTP_CODE_OK)

{

String payload = http.getString();

Serial.println(payload);

}

else

{

Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());

}

http.end();

//delay(3000);

}

else if(value == HIGH)

{

client.print("<h3>On Once<h3>");

// client.println("<br>");

client.println("<h3>Current Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>");

client.println("<h3>Current Humidity: <h3>"+String(get_humidity)+"<b> %.</b>");

}

else if(value == LOW)

{

client.print("<h3>Off<h3>");

// client.println("<br>");

client.println("<h3>Last Temperature: <h3>"+String(get_temperature)+"<b> deg C.</b>");

client.println("<h3>Last Humidity: <h3>"+String(get_humidity)+"<b> %.</b>");

}

client.println("<br><br>");

//create buttons

client.println("<a href=\"/Thermo=ON\"\"><button>Turn On Once </button></a>");

client.println("<a href=\"/AlwaysOn\"\"><button>Keep It On </button></a>");

client.println("<a href=\"/Thermo=OFF\"\"><button>Turn Off </button></a><br />");

client.println("<p>"+get_host+"/temperature/show.php</p>");

// if there are incoming bytes available from the server, read them and print them:

if (client.available())

{

char c = client.read();

client.print(c);

}

client.println("</html>");

}

As you can see in above code that we are getting two sensors data and then calling two tables. Now you need code to handle these requests. Here is PHP code for first sensor:-

<?php
include_once('inc.inc');

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
date_default_timezone_set("Asia/Karachi");
$val = $_GET['temp'];
$humd = $_GET['humidity'];

$home_val = $_GET['home_temp'];
$home_humd = $_GET['home_humidity'];


$date = date('Y-m-d');
$time = date('H:i:s');
$sql = "INSERT INTO temps(temp,humidity,home_temp,home_humidity,dated,time) VALUES ($val,$humd,$home_val,$home_humd,'$date','$time');";

if ($conn->query($sql) === TRUE) {
    echo "Saved Successfully!";
} else {
    echo "Error:" . $sql . "<br>" . $conn->error;
}

$conn->close();
?>

<?php

include_once('inc.inc');

// Check connection

if ($conn->connect_error) {

die("Connection failed: " . $conn->connect_error);

}

date_default_timezone_set("Asia/Karachi");

$val = $_GET['temp'];

$humd = $_GET['humidity'];

$home_val = $_GET['home_temp'];

$home_humd = $_GET['home_humidity'];

$date = date('Y-m-d');

$time = date('H:i:s');

$sql = "INSERT INTO temps(temp,humidity,home_temp,home_humidity,dated,time) VALUES ($val,$humd,$home_val,$home_humd,'$date','$time');";

if ($conn->query($sql) === TRUE) {

echo "Saved Successfully!";

} else {

echo "Error:" . $sql . "<br>" . $conn->error;

}

$conn->close();

and here is code for second sensor:-

<?php
include_once('inc.inc');

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
date_default_timezone_set("Asia/Karachi");
$val = $_GET['temp'];
$humd = $_GET['humidity'];

$home_val = $_GET['home_temp'];
$home_humd = $_GET['home_humidity'];


$date = date('Y-m-d');
$time = date('H:i:s');
$sql = "INSERT INTO temps_real(temp,humidity,home_temp,home_humidity,dated,time) VALUES ($val,$humd,$home_val,$home_humd,'$date','$time');";

if ($conn->query($sql) === TRUE) {
    echo "Saved Successfully!";
} else {
    echo "Error:" . $sql . "<br>" . $conn->error;
}

$conn->close();
?>

<?php

include_once('inc.inc');

// Check connection

if ($conn->connect_error) {

die("Connection failed: " . $conn->connect_error);

}

date_default_timezone_set("Asia/Karachi");

$val = $_GET['temp'];

$humd = $_GET['humidity'];

$home_val = $_GET['home_temp'];

$home_humd = $_GET['home_humidity'];

$date = date('Y-m-d');

$time = date('H:i:s');

$sql = "INSERT INTO temps_real(temp,humidity,home_temp,home_humidity,dated,time) VALUES ($val,$humd,$home_val,$home_humd,'$date','$time');";

if ($conn->query($sql) === TRUE) {

echo "Saved Successfully!";

} else {

echo "Error:" . $sql . "<br>" . $conn->error;

}

$conn->close();

As you can see there is no difference except $_GET[] values. You can write single page code for both sensors. To store data of these sensors you also need 2 tables, here is MySQL table schema:-

DROP TABLE IF EXISTS `temps`;
CREATE TABLE `temps` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `temp` int(11) NOT NULL,
  `humidity` int(11) DEFAULT NULL,
  `home_temp` int(11) DEFAULT NULL,
  `home_humidity` int(11) DEFAULT NULL,
  `time` time DEFAULT NULL,
  `dated` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

DROP TABLE IF EXISTS `temps_real`;
CREATE TABLE `temps_real` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `temp` int(11) NOT NULL,
  `humidity` int(11) DEFAULT NULL,
  `home_temp` int(11) DEFAULT NULL,
  `home_humidity` int(11) DEFAULT NULL,
  `time` time DEFAULT NULL,
  `dated` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;