Description

Introduction

Using Internet of Things (IOT), we can control any electronic equipment in homes and industries. Moreover, you can read a data from any sensor and analyse it graphically from anywhere in the world. Here, we can read temperature and humidity data from DHT11 sensor and upload it to a ThingSpeak cloud using Arduino Uno and ESP8266-01 module. Arduino Uno is MCU, it fetch a data of humidity and temperature from DHT11 sensor and Process it and give it to a ESP8266 Module.ESP8266 is a WiFi module, it is one of the leading platform for Internet of Things. It can transfer a data to IOT cloud.

Demonstration Video

Hardware Requirements

• Arduino Uno
• ESP8266-01
• DHT11
• AMS1117-3.3V
• 9V battery

Software Requirements

• Arduino IDE

Circuit and Working

First make the connection as shown in fig: 1.1.The 2^nd pin is of  DHT11 is a data pin, it can send  a temperature and humidity value to the 5^th pin of Arduino Uno.1^st and 4^th pin of DHT11 is a Vcc and Gnd and 3^rd pin is no connection. The Arduino Uno process a temperature and humidity value and send it to a ESP8266 WiFi module. The Tx and Rx pin of ESP8266 is connected to the 2^nd (Rx) and 3^rd (Tx) of Arduino Uno. Make sure that input voltage of ESP8266 must be 3.3V, not a 5V (otherwise it would damage a device).For that, we are using AMS1117 Voltage regulator circuit. It can regulate a voltage from 9V to 3.3V and will give it to Vcc pin of ESP8266.The Ch_Pd is a chip enable pin of ESP8266 and should be pullup to 3.3V through 3.3KΩ resistor. For reset the module pull down the RST pin of ESP8266 to Gnd.ESP8266 have 2 GPIO pins GPIO 0 and GPIO 2.

Fig: 1.1 Circuit diagram for monitoring Humidity and Temperature in IOT cloud

Construction and Testing

ThingSpeak is an open source platform to store and retrieve a data for Internet of Things application. To use this, you need to register in ThingSpeak cloud and then login to your account. After create a new channel with temperature in one field and humidity in another field as shown in Fig: 1.2. Once you created a new channel, it will generate a two API keys, they are READ API keys and WRITE API keys. First, copy the WRITE API keys from ThingsSpeak and paste it into the line (String apiKey = “OX9T8Y9OL9HD0UBP”;) of the program. Next, replace the Host_Name and Password with your WiFi name and WiFi password in the two lines given below in the program. (String Host_Name = “Pantech” and String Password = “pantech123”)

The Arduino program Uses DHT library, if it is not presented in your arduino IDE, select SketchàInclude libraryàManage librariesàInstall DHT Sensor library. Then compile the program and upload to a Arduino Uno through Arduino IDE. Ensure that WiFi modem and internet connection in your Smartphone or PC are working properly. After uploaded a program, the Temperature and Humidity data is uploaded on ThingSpeak platform. You can see it graphically in the private view window of your channel as shown in Fig: 1.3. And you can able to see the uploaded data from serial port of Arduino IDE.

Fig: 1.2: Creating new channel on ThingSpeak cloud

 

Fig: 1.3: Graphical representation of Humidity and Temperature data

Arduino code

#include "DHT.h"

#include 

#define DHTPIN 5                       // Digital Pin 5

#define DHTTYPE DHT11                  // We are Using DHT11

String apiKey = "OX9T8Y9OL9HD0UBP";    // Edit this API key according to your Account

String Host_Name = "Pantech";         // Edit Host_Name

String Password = "pantech123";          // Edit Password

SoftwareSerial ser(2, 3);              // RX, TX

int i=1;

DHT dht(DHTPIN, DHTTYPE);              // Initialising Pin and Type of DHT

void setup() {                

Serial.begin(115200);                  // enable software serial

ser.begin(115200);                     // reset ESP8266

ser.println("AT+RST");               // Resetting ESP8266

dht.begin();                        // Enabling DHT11

char inv ='"';

String cmd = "AT+CWJAP";

       cmd+= "=";

       cmd+= inv;

       cmd+= Host_Name;

       cmd+= inv;

       cmd+= ",";

       cmd+= inv;

       cmd+= Password;

       cmd+= inv;

ser.println(cmd);                    // Connecting ESP8266 to your WiFi Router

  }

// the loop 

void loop() {

  int humidity =  dht.readHumidity();             // Reading Humidity Value

  int temperature = dht.readTemperature();        // Reading Temperature Value

  String state1=String(humidity);                 // Converting them to string 

  String state2=String(temperature);              // as to send it through URL

 

  String cmd = "AT+CIPSTART=\"TCP\",\"";          // Establishing TCP connection

  cmd += "184.106.153.149";                       // api.thingspeak.com

  cmd += "\",80";                                 // port 80

  ser.println(cmd);

  Serial.println(cmd);

 if(ser.find("Error")){

    Serial.println("AT+CIPSTART error");

    return;

  }

String getStr = "GET /update?api_key=";         // prepare GET string

  getStr += apiKey;

  getStr +="&field1=";

  getStr += String(state1);                       // Humidity Data

  getStr +="&field2=";

  getStr += String(state2);                       // Temperature Data

  getStr += "\r\n\r\n";

  cmd = "AT+CIPSEND=";

  cmd += String(getStr.length());                // Total Length of data

  ser.println(cmd);

  Serial.println(cmd);

 

if(ser.find(">")){

    ser.print(getStr);

    Serial.print(getStr);

  }

  else{

    ser.println("AT+CIPCLOSE");                  // closing connection

    // alert user

    Serial.println("AT+CIPCLOSE");

  }

 delay(1000);                                  // Update after every 15 seconds

}

Other Applications

We can also include a sensor like gas, infrared, ultrasonic sensors based on their requirements. Moreover, it is possible to control the relay, actuators through internet once a sensor values are going above/below predetermined values.