SENSORS/ACTUATORS

Arduino Nano 33 IoT - Temperature Humidity Sensor - LCD

This guide shows you how to use the Arduino Nano 33 IoT to measure humidity and temperature with DHT11 or DHT22 sensors and display the results on an I2C LCD screen.

Hardware Preparation

1	×	Arduino Nano 33 IoT
1	×	Micro USB Cable
1	×	LCD I2C 16x2
1	×	DHT11 Temperature and Humidity Sensor
1	×	Optionally, 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 DHT11, DHT22 and LCD

If you're new to using the DHT11, DHT22, LCD, and Arduino Nano 33 IoT, please check out these tutorials:

These tutorials explain how DHT11, 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 DHT11, DHT22 and LCD.

Wiring Diagram

Sometimes the Arduino Nano 33 IoT does not give enough power to the LCD display. If you see nothing on the LCD, use an external power source for it. Below are wiring diagrams for different cases. Remember, the DHT22 sensor works with 5V or 3.3V, so you can connect the VCC pin of the DHT22 to either a 3.3V pin or a 5V pin.

Arduino Nano 33 IoT - DHT11 Module LCD I2C Wiring

The wiring diagram between Arduino Nano and 33 IoT DHT11 module LCD

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT - DHT22 Module LCD I2C Wiring

Wiring plan using a breadboard. Power the Arduino Nano 33 IoT with a USB cable, and use the Arduino board to power the LCD screen.

The wiring diagram between Arduino Nano and 33 IoT DHT22 module LCD

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT Code - DHT11 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-temperature-humidity-sensor-lcd */ #include <DHT.h> #include <LiquidCrystal_I2C.h> #define DHT_SENSOR_PIN 2 // The Arduino Nano 33 IoT pin connected to DHT11 sensor #define DHT_SENSOR_TYPE DHT11 LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27 (from DIYables LCD), 16 column and 2 rows DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { dht_sensor.begin(); // initialize the DHT sensor lcd.init(); // initialize the lcd lcd.backlight(); // open the backlight } void loop() { float humi = dht_sensor.readHumidity(); // read humidity float tempC = dht_sensor.readTemperature(); // read temperature lcd.clear(); // check whether the reading is successful or not if (isnan(tempC) || isnan(humi)) { lcd.setCursor(0, 0); lcd.print("Failed"); } else { lcd.setCursor(0, 0); // display position lcd.print("Temp: "); lcd.print(tempC); // display the temperature lcd.print("°C"); lcd.setCursor(0, 1); // display position lcd.print("Humi: "); lcd.print(humi); // display the humidity lcd.print("%"); } // wait a 2 seconds between readings delay(2000); }

※ NOTE THAT:

The LCD I2C address might be different for each maker. In our code, we used the address 0x27 as provided by the DIYables company.

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 on the Libraries icon on the left side of the Arduino IDE.
Type DHT into the search box and 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 parts of the library. Click the Install All button to add everything you need.

Arduino Nano 33 IoT Adafruit Unified sensor library

Type LiquidCrystal I2C in the search box, then look for 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 from above and paste it into the Arduino IDE.
Click the Upload button in the Arduino IDE to compile the code and send it to your Arduino Nano 33 IoT board.
Change the sensor's temperature by making it colder or hotter. For example, place the sensor near a hot cup of coffee.
Check the results on the LCD screen.

If your LCD screen stays blank, check this guide for help: Troubleshooting on LCD I2C

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-temperature-humidity-sensor-lcd */ #include <DHT.h> #include <LiquidCrystal_I2C.h> #define DHT_SENSOR_PIN 2 // The Arduino Nano 33 IoT pin connected to DHT22 sensor #define DHT_SENSOR_TYPE DHT22 LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27 (from DIYables LCD), 16 column and 2 rows DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { dht_sensor.begin(); // initialize the DHT sensor lcd.init(); // initialize the lcd lcd.backlight(); // open the backlight } void loop() { float humi = dht_sensor.readHumidity(); // read humidity float tempC = dht_sensor.readTemperature(); // read temperature lcd.clear(); // check whether the reading is successful or not if (isnan(tempC) || isnan(humi)) { lcd.setCursor(0, 0); lcd.print("Failed"); } else { lcd.setCursor(0, 0); // display position lcd.print("Temp: "); lcd.print(tempC); // display the temperature lcd.print("°C"); lcd.setCursor(0, 1); // display position lcd.print("Humi: "); lcd.print(humi); // display the humidity lcd.print("%"); } // wait a 2 seconds between readings delay(2000); }

The two pieces of code above are the same except for one line.

Video Tutorial

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