Arduino - Temperature Humidity Sensor - LCD

We will learn how to:

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×LCD I2C
1×Temperature and Humidity Sensor DHT11
Or 1×Temperature and Humidity Sensor DHT22
n×Jumper Wires
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About DHT11, DHT22 and LCD

If you do not know about DHT11, DHT22 temperature sensor and LCD (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino - DHT11 Module Wiring

Arduino DHT11 temperature and humidity LCD Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino - DHT22 Module Wiring

Arduino DHT22 temperature and humidity LCD Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Real wiring for DHT11

Arduino DHT11 LCD Wiring

Image is developed using Fritzing. Click to enlarge image

Arduino Code - DHT11 Sensor - LCD I2C

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-humidity-sensor-lcd */ #include <LiquidCrystal_I2C.h> #include "DHT.h" #define DHTPIN 2 #define DHTTYPE DHT11 LiquidCrystal_I2C lcd(0x3F, 16, 2); // I2C address 0x3F, 16 column and 2 rows DHT dht(DHTPIN, DHTTYPE); void setup() { dht.begin(); // initialize the sensor lcd.init(); // initialize the lcd lcd.backlight(); // open the backlight } void loop() { delay(2000); // wait a few seconds between measurements float humi = dht.readHumidity(); // read humidity float tempC = dht.readTemperature(); // read temperature lcd.clear(); // check if any reads failed if (isnan(humi) || isnan(tempC)) { lcd.setCursor(0, 0); lcd.print("Failed"); } else { lcd.setCursor(0, 0); // start to print at the first row lcd.print("Temp: "); lcd.print(tempC); // print the temperature lcd.print((char)223); // print ° character lcd.print("C"); lcd.setCursor(0, 1); // start to print at the second row lcd.print("Humi: "); lcd.print(humi); // print the humidity lcd.print("%"); } }

Quick Steps

  • Connect Arduino to PC via USB cable
  • Open Arduino IDE, select the right board and port
  • On Arduino IDE, Go to Tool Manage Libraries
  • Arduino add library
  • Search “DHT”, then find the DHT sensor library by Adafruit
  • Click Install button to install the library.
  • Arduino DHT sensor library
  • You will be ased for intall some other library dependancies
  • Click Install All button all library dependancies.
  • Arduino Adafruit Unified sensor library
  • Search “LiquidCrystal I2C”, then find the LiquidCrystal_I2C library by Frank de Brabander
  • Click Install button to install LiquidCrystal_I2C library.
  • Arduino LiquidCrystal I2C library
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Make enviroment around sensor hotter or colder
  • See the result in LCD
  • Arduino DHT11 LCD Wiring

    Image is developed using Fritzing. Click to enlarge image

If LCD displays nothing, see Troubleshooting on LCD I2C

Arduino Code - DHT22 Sensor - LCD I2C

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-humidity-sensor-lcd */ #include <LiquidCrystal_I2C.h> #include "DHT.h" #define DHTPIN 2 #define DHTTYPE DHT22 LiquidCrystal_I2C lcd(0x3F, 16, 2); // I2C address 0x3F, 16 column and 2 rows DHT dht(DHTPIN, DHTTYPE); void setup() { dht.begin(); // initialize the sensor lcd.init(); // initialize the lcd lcd.backlight(); // open the backlight } void loop() { delay(2000); // wait a few seconds between measurements float humi = dht.readHumidity(); // read humidity float tempC = dht.readTemperature(); // read temperature lcd.clear(); // check if any reads failed if (isnan(humi) || isnan(tempC)) { lcd.setCursor(0, 0); lcd.print("Failed"); } else { lcd.setCursor(0, 0); // start to print at the first row lcd.print("Temp: "); lcd.print(tempC); // print the temperature lcd.print((char)223); // print ° character lcd.print("C"); lcd.setCursor(0, 1); // start to print at the second row lcd.print("Humi: "); lcd.print(humi); // print the humidity lcd.print("%"); } }

※ NOTE THAT:

Code for DHT11 and DHT22 are identical except for one line of code. Library for DHT11 and DHT22 are the same.

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