Arduino - DHT22 - LCD
We will learn how to program Arduino to read temperature and humidity from DHT22 module and display them on LCD I2C.
Hardware Required
| 1 | × | Arduino UNO or Genuino UNO | |
| 1 | × | USB 2.0 cable type A/B | |
| 1 | × | LCD I2C | |
| 1 | × | DHT22 module | |
| 1 | × | Jumper Wires | |
| 1 | × | (Optional) 9V Power Adapter for Arduino | |
| 1 | × | (Recommended) Screw Terminal Block Shield for Arduino Uno |
Or you can buy the following sensor kit:
| 1 | × | DIYables Sensor Kit 30 types, 69 units |
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.
About DHT22 and LCD
If you do not know about DHT22 sensor and LCD (pinout, how it works, how to program ...), learn about them in the following tutorials:
Wiring Diagram
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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-dht22-lcd
*/
#include <LiquidCrystal_I2C.h>
#include "dht22.h"
#define DHT22_PIN 2
LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows
DHT dht22(DHT22_PIN, DHT22);
void setup()
{
dht22.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 = dht22.readHumidity(); // read humidity
float tempC = dht22.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:
The I2C address of LCD can vary according to the manufacturers. In the code, we used 0x27 that is specified by DIYables manufacturer
Quick Steps
- Connect Arduino to PC via USB cable
- Open Arduino IDE, select the right board and port
- On Arduino IDE, Go to Tools Manage Libraries
- Search “DHT”, then find the DHT sensor library by Adafruit
- Click Install button to install the library.
- You will be asked for intalling some other library dependencies
- Click Install All button all library dependencies.
- Search “LiquidCrystal I2C”, then find the LiquidCrystal_I2C library by Frank de Brabander
- Click Install button to install 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
If LCD displays nothing, see Troubleshooting on LCD I2C
Video Tutorial
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