SENSORS/ACTUATORS

Arduino Nano 33 IoT - DHT22 - LCD

This guide shows you how to program the Arduino Nano 33 IoT to measure temperature and humidity using a DHT22 sensor and display the data on an I2C LCD.

Hardware Preparation

1	×	Arduino Nano 33 IoT
1	×	Micro USB Cable
1	×	LCD I2C 16x2
1	×	DHT22 Temperature and Humidity Sensor
1	×	Breadboard
1	×	Jumper Wires
1	×	Optionally, DC Power Jack
1	×	Recommended: Screw Terminal Expansion Board for Arduino Nano
1	×	Recommended: Breakout Expansion Board for Arduino Nano
1	×	Recommended: Power Splitter for Arduino Nano

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of DHT22 and LCD

If you're new to using the DHT22, LCD, and Arduino Nano 33 IoT, please check out these tutorials:

These tutorials explain how DHT22 and LCD work, their pinouts, how to connect them to the Arduino Nano 33 IoT, and how to program Arduino Nano 33 IoT to work with the DHT22 and LCD.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT Code - DHT22 Sensor - LCD I2C

/* * This Arduino Nano 33 IoT code was developed by newbiely.com * * This Arduino Nano 33 IoT code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-iot/arduino-nano-33-iot-dht22-lcd */ #include <DHT.h> #include <LiquidCrystal_I2C.h> #define DHT22_PIN 2 // The Arduino Nano 33 IoT pin connected to DHT22 sensor LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27 (from DIYables LCD), 16 column and 2 rows DHT dht22(DHT22_PIN, DHT22); void setup() { dht22.begin(); // initialize the DHT22 sensor lcd.init(); // initialize the lcd lcd.backlight(); // open the backlight } void loop() { float humidity = dht22.readHumidity(); // read humidity float temperature = dht22.readTemperature(); // read temperature lcd.clear(); // check whether the reading is successful or not if (isnan(temperature) || isnan(humidity)) { lcd.setCursor(0, 0); lcd.print("Failed"); } else { lcd.setCursor(0, 0); // display position lcd.print("Temp: "); lcd.print(temperature); // display the temperature lcd.print("°C"); lcd.setCursor(0, 1); // display position lcd.print("Humi: "); lcd.print(humidity); // display the humidity lcd.print("%"); } // wait a 2 seconds between readings delay(2000); }

※ NOTE THAT:

The LCD I2C address may be different for each manufacturer. In our code, we used the 0x27 address, which is provided by the DIYables manufacturer.

Detailed Instructions

If you are new to the Arduino Nano 33 IoT, be sure to check out our Getting Started with Arduino Nano 33 IoT tutorial. Then, follow these steps:

Connect the components to the Arduino Nano 33 IoT board as depicted in the diagram.
Use a USB cable to connect the Arduino Nano 33 IoT board to your computer.
Launch the Arduino IDE on your computer.
Select the Arduino Nano 33 IoT board and choose its corresponding COM port.
Click the Libraries icon on the left side in the Arduino IDE.
Type DHT in the search box, then find the DHT sensor library by Adafruit.
Click the Install button to add the library.

A window appears asking if you want to add the necessary tools for the library. Click the Install All button to add all the needed tools.

Arduino Nano 33 IoT Adafruit Unified sensor library

Type LiquidCrystal I2C in the search box and find the LiquidCrystal_I2C library by Frank de Brabander.
Click the Install button to add the LiquidCrystal_I2C library.

Arduino Nano 33 IoT LiquidCrystal I2C library

Copy the code above and paste it into the Arduino IDE.
Click the Upload button to compile the code and send it to the Arduino Nano 33 IoT board.
Change the temperature near the sensor—for example, put it close to a hot cup of coffee.
Watch the result on the LCD.

If your LCD screen stays blank, check out the guide on fixing LCD I2C issues: Troubleshooting on LCD I2C

Video Tutorial

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