ESP32 - Temperature Humidity Sensor

This tutorial instructs you how to use ESP32 to read temperature and humidity value from DHT11 or DHT22 sensors, and print it to Serial Monitor.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Temperature and Humidity Sensor DHT11
1×(Optional) Temperature and Humidity Sensor DHT22
1×10 kΩ resistor
1×Breadboard
n×Jumper Wires
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Introduction to DHT11 and DHT22 Temperature and Humidity Sensor

In short, the DHT22 sensor is a more accurate, larger range but more expensive than DHT11. Let's see the common and differences between them

The commons

  • The same pinout
  • The same wiring to ESP32
  • The similar ESP32 code

The differences

The below table show the detaied 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

DHT11 and DHT22 Pinout

DHT11 and DHT22 sensor includes 4 pins:

  • GND pin: connect this pin to GND (0V)
  • VCC pin: connect this pin to VCC (3.3V)
  • DATA pin: the pin is used to communicate between the sensor and ESP32
  • NC pin: Not connected
  • DHT11 and DHT22 temperature and humidity sensor Pinout

We highily recommend you using DHT11 and DHT22 sensor modules. The modules have a built-in resistor and have only three pin: VCC, GND, and DATA pins.

DHT11 and DHT22 temperature and humidity module Pinout

The pins order on the module's can be different between manufacturers. Please check the pin labels printed on the module carefully.

Wiring Diagram between DHT11/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 - DHT11 Sensor Wiring

wiring diagram between esp32 dht11 temperature and humidity sensor

This image is created using Fritzing. Click to enlarge image

ESP32 - DHT22 Sensor Wiring

wiring diagram between esp32 dht22 temperature and humidity sensor

This image is created using Fritzing. Click to enlarge image

ESP32 - DHT11 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.

wiring diagram between esp32 dht11 temperature and humidity module

This image is created using Fritzing. Click to enlarge image

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.

wiring diagram between esp32 dht22 temperature and humidity module

This image is created using Fritzing. Click to enlarge image

ESP32 Code - DHT11

/* * 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-temperature-humidity-sensor */ #include <DHT.h> #define DHT_SENSOR_PIN 21 // ESP32 pin GIOP21 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 tempC = dht_sensor.readTemperature(); // read temperature in Fahrenheit float tempF = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(tempC) || isnan(tempF) || 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(tempC); Serial.print("°C ~ "); Serial.print(tempF); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

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-temperature-humidity-sensor */ #include <DHT.h> #define DHT_SENSOR_PIN 21 // ESP32 pin GIOP21 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 tempC = dht_sensor.readTemperature(); // read temperature in Fahrenheit float tempF = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(tempC) || isnan(tempF) || 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(tempC); Serial.print("°C ~ "); Serial.print(tempF); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

Two above codes have only one line different.

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
  • ESP32 add library
  • Type “DHT” on the search box, then look for the DHT sensor library by Adafruit
  • Install the library by clicking on Install button.
  • ESP32 DHT sensor library
  • A windows appears to ask you to install dependencies for the library
  • Install all dependencies for the library by clicking on Install All button.
  • ESP32 Adafruit Unified sensor library
  • 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
    Autoscroll Show timestamp
    Clear output
    9600 baud  
    Newline  

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