SENSORS/ACTUATORS

Arduino Nano 33 IoT - Temperature Humidity Sensor

This guide shows how to use the Arduino Nano 33 IoT to get temperature and humidity readings from DHT11 or DHT22 sensors and display them on the Serial Monitor.

Arduino Nano 33 IoT Temperature and humidity Sensor

Hardware Preparation

1	×	Arduino Nano 33 IoT
1	×	Micro USB Cable
1	×	DHT11 Temperature Humidity Sensor Module
1	×	DHT22 Temperature Humidity Sensor Module
1	×	10 kΩ resistor
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 and DHT22 Temperature and Humidity Sensor

In summary, the DHT22 sensor is more precise and covers a wider range, but it is also more expensive than the DHT11. Let's explore what they have in common and how they are different.

The commons

The pin setup is the same
The wiring for the Arduino Nano 33 IoT is the same
The Arduino Nano 33 IoT code is very similar

The differences

The table below shows the detailed differences between DHT11 and DHT22.

	DHT22	DHT11
The price	low cost	ultra low cost
The humidity range	0% to 100%	20% to 80%
The humidity accuracy	± 2% to 5%	5%
The temperature range	-40°C to 80°C	0°C to 50°C
The temperature accuracy	± 0.5°C	± 2°C
The reading rate	0.5Hz (one time per 2 seconds)	1Hz (one time per second)
Dimension	15.1mm x 25mm x 7.7mm	15.5mm x 12mm x 5.5mm
Operating Voltage	3 to 5V	3 to 5V

DHT11 and DHT22 Pinout

The DHT11 and DHT22 sensors have four pins.

GND pin: Connect this pin to the ground (0V).
VCC pin: Connect this pin to the power supply (3.3V or 5V).
DATA pin: Use this pin to send and receive information between the sensor and the Arduino Nano 33 IoT.
NC pin: This pin is not used.

DHT11 and DHT22 temperature and humidity sensor Pinout

We highly suggest using the DHT11 and DHT22 sensor modules. These modules have a built-in resistor and only three pins: one for power (VCC or +), one for ground (GND or -), and one for data (DATA or OUT).

DHT11 and DHT22 temperature and humidity module Pinout

image source: diyables.io

Different companies might put the pins in a different order. Please look carefully at the pin labels printed on the module.

Wiring Diagram between DHT11/DHT22 and Arduino Nano 33 IoT

The wiring for both sensors to the Arduino Nano 33 IoT is the same. They need a resistor between 5K and 10K ohms to keep the data line turned on and to help the sensor talk to the Arduino Nano 33 IoT.

Arduino Nano 33 IoT - DHT11 Sensor Wiring

The wiring diagram between Arduino Nano and 33 IoT DHT11 Temperature and humidity Sensor

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT - DHT22 Sensor Wiring

The wiring diagram between Arduino Nano and 33 IoT DHT22 Temperature and humidity Sensor

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT - DHT11 Module Wiring

Most DHT22 sensor modules already include a resistor, so you don't have to add one. This makes the wiring and soldering easier.

The wiring diagram between Arduino Nano and 33 IoT DHT11 Temperature and humidity Module

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT - DHT22 Module Wiring

Most DHT22 sensor modules already include a resistor, so you don't have to add one. This saves you some wiring or soldering work.

The wiring diagram between Arduino Nano and 33 IoT DHT22 Temperature and humidity Module

This image is created using Fritzing. Click to enlarge image

Arduino Nano 33 IoT Code - DHT11

/* * 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 */ #include <DHT.h> #define DHT_SENSOR_PIN 3 // The Arduino Nano 33 IoT pin D31 connected to DHT11 sensor #define DHT_SENSOR_TYPE DHT11 DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { Serial.begin(9600); dht_sensor.begin(); // initialize the DHT sensor } void loop() { // read humidity float humi = dht_sensor.readHumidity(); // read temperature in Celsius float temperature_C = dht_sensor.readTemperature(); // read temperature in Fahrenheit float temperature_F = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(temperature_C) || isnan(temperature_F) || isnan(humi)) { Serial.println("Failed to read from DHT sensor!"); } else { Serial.print("Humidity: "); Serial.print(humi); Serial.print("%"); Serial.print(" | "); Serial.print("Temperature: "); Serial.print(temperature_C); Serial.print("°C ~ "); Serial.print(temperature_F); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

Arduino Nano 33 IoT Code - DHT22

/* * 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 */ #include <DHT.h> #define DHT_SENSOR_PIN 3 // The Arduino Nano 33 IoT pin D31 connected to DHT22 sensor #define DHT_SENSOR_TYPE DHT22 DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { Serial.begin(9600); dht_sensor.begin(); // initialize the DHT sensor } void loop() { // read humidity float humi = dht_sensor.readHumidity(); // read temperature in Celsius float temperature_C = dht_sensor.readTemperature(); // read temperature in Fahrenheit float temperature_F = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(temperature_C) || isnan(temperature_F) || isnan(humi)) { Serial.println("Failed to read from DHT sensor!"); } else { Serial.print("Humidity: "); Serial.print(humi); Serial.print("%"); Serial.print(" | "); Serial.print("Temperature: "); Serial.print(temperature_C); Serial.print("°C ~ "); Serial.print(temperature_F); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

The two codes above are different by only one line.

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.
Open the Library Manager by clicking the Library Manager icon on the left side of the Arduino IDE.
Type Adafruit DHT in the search box and find the DHT sensor library by Adafruit.
Click the Install button to install the library.

A window might pop up asking if you want to install the components for the library.
Click the Install All button to add all the required components.

Arduino Nano 33 IoT Adafruit Unified sensor library

Copy one of the codes above and open it with the Arduino IDE. Click the Upload button in the IDE to build and send the code to your Arduino Nano 33 IoT board. Change the sensor's temperature by making it colder or hotter—for example, by placing it near a hot cup of coffee. Then, check the result in the Serial Monitor. It should look like the image below.

COM6

Send

Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 32.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 29.00°C ~ 84.20°F Humidity: 32.00% | Temperature: 29.00°C ~ 84.20°F Humidity: 31.00% | Temperature: 29.00°C ~ 84.20°F

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