Posted 27 January 2018 by Yassine18 Comments Non classé

Measure temperature/humidity using DHT11 + LCD i2c + Arduino

Hello there,

Before proceeding, if you need to buy DHT11 sensor, check Seeedstudio by clicking here !

In this tutorial we gonna see how to simply use the DHT11 module, It’s a module that can measure ambient temperature 0-50°C and humidity up to 95% RH (Relative humidity), it’s very good for Home Automation projects or DIY projects for daily use.

Also there are a lot of modules that have the same function as this one, you can check them here:

For this we gonna need

DHT 11 (obvious 😃 ) note here that I’m using 3 pins version there are 4 pins one.

Arduino board here I’ll use Uno
LCD i2c screen
Breadboard and jump wires

The LCD i2c is totally optional but usually used with this module as a classic learning project, in case you don’t know how to use one check here:LCD i2c tutorial.

The LCD I used is a I2C version, there are the standard versions but they require a lot of pins, and also in this case you’ll need another library and code functions.

Wiring:

DHT11 (3 pins version) wired with LCD i²c and an Arduino

Libraries:

DHT library: Download library here

LCD i2c New_Liquid_Crystal library: Download LCD i2c library here

Codes

You can download the codes: Download codes here or check below:

Code 1:

The code 1 works with the Serial monitor, it shows the ambient temperature in °C and humidity in %RH, and refresh every 1s.

#include <dht.h> //DHT library

dht DHT; //Declaring dht entity named DHT

#define DHT11_PIN 7 //DHT data pin

void setup(){
  Serial.begin(9600);
}

void loop()
{
  int chk = DHT.read11(DHT11_PIN); //Read data temperature from DHT11 pin
  Serial.print("Temperature = ");  //Show ambient temperature and humidity every 1s
  Serial.println(DHT.temperature);
  Serial.print("Humidity = ");
  Serial.println(DHT.humidity);
  delay(1000);
}

#include <dht.h> //DHT library

dht DHT; //Declaring dht entity named DHT

#define DHT11_PIN 7 //DHT data pin

void setup(){

Serial.begin(9600);

}

void loop()

{

int chk = DHT.read11(DHT11_PIN); //Read data temperature from DHT11 pin

Serial.print("Temperature = "); //Show ambient temperature and humidity every 1s

Serial.println(DHT.temperature);

Serial.print("Humidity = ");

Serial.println(DHT.humidity);

delay(1000);

}

Code2:

The second code works with LCD i²c screen, it shows both temperature and humidity over there.

//This code is to use with DHT11 Temperature/humidity sensor with LCD i2c screen
//We measure the values of the temperature and humidity then print them on the screen every second
//Refer to Surtrtech channel on youtube or blogger for more information or how to use the LCD i2c

#include <dht.h> //DHT and LCD libraries
#include <LiquidCrystal_I2C.h>

#define I2C_ADDR 0x27 
#define BACKLIGHT_PIN 3
#define En_pin 2
#define Rw_pin 1
#define Rs_pin 0
#define D4_pin 4
#define D5_pin 5
#define D6_pin 6
#define D7_pin 7

LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

dht DHT; //Declaring the DHT as a dht type to use it later

#define DHT11_PIN 7 //Declaring where the DHT signal pin is wired

void setup(){
  lcd.begin (16,2);
  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(HIGH);
  lcd.home ();
}

void loop()
{
  lcd.clear();
  lcd.setCursor(0,0);
  int chk = DHT.read11(DHT11_PIN); //Reading data from the module
  lcd.print("Temp: ");
  lcd.print(DHT.temperature); //Showing temperature value (before that you can do some math to get the temperature in Farnheit)
  lcd.print(" C");
  lcd.setCursor(0,1);
  lcd.print("Humidity: ");
  lcd.println(DHT.humidity); //Showing humidity percentage
  lcd.print(" %");
  delay(1000); //Refreshing every 1s
}

//This code is to use with DHT11 Temperature/humidity sensor with LCD i2c screen

//We measure the values of the temperature and humidity then print them on the screen every second

//Refer to Surtrtech channel on youtube or blogger for more information or how to use the LCD i2c

#include <dht.h> //DHT and LCD libraries

#include <LiquidCrystal_I2C.h>

#define I2C_ADDR 0x27

#define BACKLIGHT_PIN 3

#define En_pin 2

#define Rw_pin 1

#define Rs_pin 0

#define D4_pin 4

#define D5_pin 5

#define D6_pin 6

#define D7_pin 7

LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

dht DHT; //Declaring the DHT as a dht type to use it later

#define DHT11_PIN 7 //Declaring where the DHT signal pin is wired

void setup(){

lcd.begin (16,2);

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

lcd.setBacklight(HIGH);

lcd.home ();

}

void loop()

{

lcd.clear();

lcd.setCursor(0,0);

int chk = DHT.read11(DHT11_PIN); //Reading data from the module

lcd.print("Temp: ");

lcd.print(DHT.temperature); //Showing temperature value (before that you can do some math to get the temperature in Farnheit)

lcd.print(" C");

lcd.setCursor(0,1);

lcd.print("Humidity: ");

lcd.println(DHT.humidity); //Showing humidity percentage

lcd.print(" %");

delay(1000); //Refreshing every 1s

}

Yassine View All

Automation and Electrical Engineer, Electronics amateur trying to share my little projects.

18 thoughts on “Measure temperature/humidity using DHT11 + LCD i2c + Arduino” Leave a comment ›

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CAGRI DURMAZ says:

17 February 2019 at 21 h 15 min

Thank you

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Danny A Meadows says:

20 February 2019 at 16 h 04 min

Very good video but poor audio?.

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- Yassine says:
  
  20 February 2019 at 18 h 37 min
  
  Sorry it’s a bit a old, sometimes I don’t have the right setups
  
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george222 says:

13 March 2019 at 13 h 54 min

How am I supposed to open the rar file and paste to arduino?

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- Yassine says:
  
  13 March 2019 at 14 h 00 min
  
  Hi, if you’re talking about the libraries they’re in .ZIP format just go to Arduino IDE -> Sketch -> Include library -> Add .ZIP library and look for the library file and it will install.
  For the codes just extract the .RAR file and you’ll find codes .INO there.
  
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  - jerry says:
    
    22 March 2022 at 8 h 21 min
    
    help, how to add it into library i dont get it
    
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Pingback: Arduino Contactless Thermometer with MLX90614 + OLED / LCD – SURTR TECHNOLOGY
NABHAAN says:

25 May 2019 at 13 h 58 min

Arduino: 1.8.3 (Windows 10), Board: “Arduino/Genuino Uno”

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: expected ‘)’ before numeric constant

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

DHT11_LCD:24: error: ‘D7_pin7’ was not declared in this scope

LiquidCrystal_I2C lcd ( I2C_ADDR 0x27 ,En_pin 2 ,Rw_pin 1 ,Rs_pin 0 ,D4_pin 4 ,D5_pin 5 ,D6_pin 6 ,D7_pin7 ) ;

^

D:\DHT11_LCD\DHT11_LCD.ino: In function ‘void setup()’:

DHT11_LCD:33: error: ‘class LiquidCrystal_I2C’ has no member named ‘setBacklightPin’

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

^

DHT11_LCD:33: error: ‘POSITIVE’ was not declared in this scope

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

^

Multiple libraries were found for “dht.h”
Used: C:\Users\User\Documents\Arduino\libraries\DHT
Not used: C:\Users\User\Documents\Arduino\libraries\DHTLib
exit status 1
expected ‘)’ before numeric constant

This report would have more information with
“Show verbose output during compilation”
option enabled in File -> Preferences.
So this happened. PLEASE HELP

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- Yassine says:
  
  25 May 2019 at 19 h 18 min
  
  Hello, first please read that you have multiple DHT libraries !!! So use only one and delete the other
  
  Multiple libraries were found for “dht.h”
  Used: C:\Users\User\Documents\Arduino\libraries\DHT
  Not used: C:\Users\User\Documents\Arduino\libraries\DHTLib
  
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FWWI says:

23 June 2019 at 18 h 24 min

what the fuck is this why i have to use this web side just post the code no need to download the code
i don’t trust you . sorry bud but it can be a virus

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Pingback: Arduino based home humidifier with Seeeduino Nano and Grove Atomization module + DHT11 + OLED – SURTR TECHNOLOGY
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king331 says:

2 July 2023 at 17 h 09 min

Arduino:1.8.19 (Windows 10), Board:”Arduino Uno”

sketch_jul02c:25:3: error: ‘lcd’ was not declared in this scope

lcd.begin (16,2);

^~~

sketch_jul02c:26:37: error: ‘POSITIVE’ was not declared in this scope

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

^~~~~~~~

sketch_jul02c:33:3: error: ‘lcd’ was not declared in this scope

lcd.clear();

^~~

exit status 1

‘lcd’ was not declared in this scope

i followed all the steps but these errors occured any idea what the problem might be?

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Measure temperature/humidity using DHT11 + LCD i2c + Arduino

Wiring:

Libraries:

Codes

Code 1:

Code2:

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Yassine View All

18 thoughts on “Measure temperature/humidity using DHT11 + LCD i2c + Arduino” Leave a comment ›

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Wiring:

Libraries:

Codes

Code 1:

Code2:

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