ESP32 - DHT22

This tutorial instructs you how to use ESP32 to read temperature and humidity value from DHT22 sensor, and print it to Serial Monitor. The tutorial provide instructions for both DHT22 sensor and DHT22 module.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	Temperature and Humidity Sensor DHT22
1	×	10 kΩ resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Introduction to DHT22 Temperature and Humidity Sensor

	DHT22
Operating Voltage	3 to 5V
The humidity range	0% to 100%
The humidity accuracy	± 2% to 5%
The temperature range	-40°C to 80°C
The temperature accuracy	± 0.5°C
The reading rate	0.5Hz (one time per 2 seconds)

DHT22 Pinout

DHT22 has two form: raw sensor and module:

DHT22 sensor includes 4 pins:

GND pin: connect this pin to GND (0V)
VCC pin: connect this pin to VCC (3.3V or 5V)
DATA pin: the pin is used to communicate between the sensor and ESP32
NC pin: Not connected

We highily recommend you using DHT22 module. The modules have a built-in resistor and have only three pin: VCC, GND, and DATA pins (or alternatively: +, -, and OUT pins).

Wiring Diagram between DHT22 and ESP32

Wiring to ESP32 is the same for both sensors. In orginal form, A resistor from 5K to 10K Ohms is required to keep the data line high and in order to enable the communication between the sensor and the ESP32

ESP32 - DHT22 Sensor Wiring

ESP32 DHT22 Temperature and humidity Sensor Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 - DHT22 Module Wiring

Most of DHT22 sensor modules have a built-in resistor, so you don't need to add it. it saves us some wiring or soldering works.

ESP32 DHT22 Temperature and humidity Module Wiring Diagram

This image is created using Fritzing. Click to enlarge image

ESP32 Code - DHT22

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-dht22 */ #include <DHT.h> #define DHT22_PIN 21 // ESP32 pin GPIO21 connected to DHT22 sensor DHT dht22(DHT22_PIN, DHT22); void setup() { Serial.begin(9600); dht22.begin(); // initialize the DHT22 sensor } void loop() { // read humidity float humi = dht22.readHumidity(); // read temperature in Celsius float tempC = dht22.readTemperature(); // read temperature in Fahrenheit float tempF = dht22.readTemperature(true); // check whether the reading is successful or not if ( isnan(tempC) || isnan(tempF) || isnan(humi)) { Serial.println("Failed to read from DHT22 sensor!"); } else { Serial.print("Humidity: "); Serial.print(humi); Serial.print("%"); Serial.print(" | "); Serial.print("Temperature: "); Serial.print(tempC); Serial.print("°C ~ "); Serial.print(tempF); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

Quick Instructions

If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
Do the wiring as above image.
Connect the ESP32 board to your PC via a micro USB cable
Open Arduino IDE on your PC.
Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
On Arduino IDE, Navigate to Tools Manage Libraries

Type “DHT” on the search box, then look for the DHT sensor library by Adafruit
Install the library by clicking on Install button.

A windows appears to ask you to install dependencies for the library
Install all dependencies for the library by clicking on Install All button.

Copy one of the above code and open with Arduino IDE
Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
Make the sensor colder or hotter. For example, putting the sensor near a hot cup of coffee
See the result on Serial Monitor. It looks like the 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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