Interfacing Temperature & Humidity Sensor with Arduino

Temperature & Humidity Sensor with Arduino

• You can download the complete source code here by clicking on the button below.
• Download .rar file, extract this file and enjoy the complete simulation code.

Block Diagram

• First of all, I would like to explain you the algorithm with the help of a block diagram.
• It will help in better understanding of an algorithm.
• The block diagram for interfacing of temperature and humidity sensor with Arduino is given in the figure below.

• Power supply in necessary to turn the whole system ON.
• DHT11 is connected with the Arduino UNO.
• Arduino UNO reads the data from the DHT11 sensor and displays the obtained data on the serial monitor.
• That data will also be displayed on the LCD.

Circuit Diagram

• The complete wiring diagram for this project is shown in the figure below.

• You can run this project properly, by making the circuit first, identical to the circuit diagram shown in the figure above.
• The analog pin A3 of the Arduino UNO will help us in reading the data from the sensor.
• The other two pins of the sensor are connected to the supply of 5V and ground respectively as you can see from the above figure.

Flow Chart

• The flow chart will help you to understand the flow of the program while executing.
• The flow chart for this project is shown in the figure below.

• The data from the sensor can be estimated on the serial monitor only after opening the serial port
• Then data will be displayed on the LCD and at end serial port must be closed in order to avoid the exchange of unwanted commands.

Source Code Description

• The source code for this project is given below.
• You have to just copy and paste the code given below in your Arduino software after properly interfacing DHT11 with the Arduino.
• After uploading the code onto your Arduino board you will be able to observe the humidity and temperature and humidity level on serial monitor.

#include<dht.h>// DHT11 humidity sensor library
#include<LiquidCrystal.h> //LCD library
dht DHT; //Creating sensor object
#define DHT11_PIN A3 // Sensor is connected to Arduino pin 3
LiquidCrystal lcd(8, 9, 10, 11, 12, 13);// LCD connected with Arduino on these pins
void setup()
{
  Serial.begin(9600); //setting baud rate
  Serial.println("   =====================================================");
  Serial.println("   ||   Welcome to Temperarue and Humidity Detector   ||");
  Serial.println("   =====================================================");
  Serial.println("");
  lcd.begin(20, 4); // initialinzing the LCD order
  lcd.setCursor(4,1); //Setting the cursor on LCD
  lcd.print("Welcome to");//printing on LCD
  lcd.setCursor(2,2);
  lcd.print("Humidity detector");
  delay(2000);//adding delay of 2 secons or 2000 msec
  }
void loop()//method used to run the code repeatedly
{
  int chk = DHT.read11(DHT11_PIN); //Reading data from sensor
  Serial.print(" Humidity = ");//prints on the serial monitor
  Serial.print(DHT.humidity);// prints obtained humidity on serial port
  Serial.print(" g/m^3");

  lcd.clear();//clears all the data on LCD
  delay(1000);//adding delay of 1 second
  lcd.display(); //starting the display of LCD after clearing
  lcd.setCursor(0,0);
  lcd.print("Humidity=");
  lcd.print(DHT.humidity);
  lcd.print(" g/m^3");
  
  Serial.print("    \tTemperature = ");//prints on the serial monitor
  Serial.print(DHT.temperature, 1);//prints obtained temperature on serial port
  Serial.println(" degrees");

  lcd.setCursor(0,1);
  lcd.print("Temperature=");//prints on LCD
  lcd.print(DHT.temperature, 1);//prints the obtained temperature on LCD
  lcd.print(" deg");

  lcd.setCursor(1,2);
  lcd.print("www.TheEngineering");
  lcd.setCursor(4,3);
  lcd.print("Projects.com");

  delay(2000);//adding the delay of 2 seconds
  }  

• I am going to explain you that how this code is working!
• First of all I have added the library in the libraries folder at the destination where the Arduino software is installed.
• I have defined DHT11’s library in the source code then.
• Then I have defined the library for LCD.
• I have defined the pin at which DHT11 is attached with the Arduino board.
• Then I have defined the Arduino pins at which the LCD in interface.
• Then by opening the serial port I have started to print the level of temperature and humidity on the serial monitor as well as on the 20×4 LCD.
• At the end, I have added the delay of 2 seconds so that the speed of the data to be printed on the serial monitor can be reduced to some extent in order to observe properly.
• This was the brief description of the source code.