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INTERNET OF THING (IoT)

ESP32 - Temperature Humidity Sensor - LCD

This tutorial instructs you how to use ESP32 to read humidity and temperature value from DHT11/DHT22 sensors, and display on LCD I2C.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	LCD I2C 16x2
1	×	DHT11 Temperature and Humidity Sensor
1	×	(Optional) DHT22 Temperature and Humidity Sensor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

1

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DIYables Sensor Kit 30 types, 69 units

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Introduction to DHT11, DHT22 and LCD

We have specific tutorials about DHT11, DHT22 temperature sensor and LCD. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

Wiring Diagram

In some cases, ESP32 may not provide enough power for the LCD display. If LCD does not display anything, power LCD by external power source. The below are wiring diagram for some use cases. Note that the DHT22 sensor can works with 5V or 3.3V, so you can connect the VCC pin of DHT22 to 3.3V pin or 5V pin

ESP32 - DHT11 Module LCD I2C Wiring

Wiring diagram with breadboard, powering ESP32 via USB port, powering LCD via ESP32 board

ESP32 DHT11 sensor LCD 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.

If powering ESP32 via Vin pin and LCD with external power source

ESP32 DHT11 module LCD Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If powering ESP32 via USB port and powering LCD with external power source

ESP32 DHT11 LCD I2C Wiring Diagram

This image is created using Fritzing. Click to enlarge image

ESP32 - DHT22 Module LCD I2C Wiring

Wiring diagram with breadboard, powering ESP32 via USB port, powering LCD via ESP32 board

ESP32 DHT22 sensor LCD Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If powering ESP32 via Vin pin and LCD with external power source

ESP32 DHT22 module LCD Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If powering ESP32 via USB port and powering LCD with external power source

ESP32 DHT22 LCD I2C Wiring Diagram

This image is created using Fritzing. Click to enlarge image

ESP32 Code - DHT11 Sensor - LCD I2C

/* * 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-lcd */ #include <DHT.h> #include <LiquidCrystal_I2C.h> #define DHT_SENSOR_PIN 23 // ESP32 pin GPIO23 connected to DHT11 sensor #define DHT_SENSOR_TYPE DHT11 LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x3F, 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 can be different from each manufacturer. In the code, we used address of 0x27 that is specified by DIYables manufacturer

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

Type “LiquidCrystal I2C” on the search box, then look for the LiquidCrystal_I2C library by Frank de Brabander
Click Install button to install LiquidCrystal_I2C library.

ESP32 LiquidCrystal I2C library

Copy the above code and paste it to 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 in LCD

If LCD displays nothing, see Troubleshooting on LCD I2C

ESP32 Code - DHT22 Sensor - LCD I2C

/* * 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-lcd */ #include <DHT.h> #include <LiquidCrystal_I2C.h> #define DHT_SENSOR_PIN 23 // ESP32 pin GPIO23 connected to DHT22 sensor #define DHT_SENSOR_TYPE DHT22 LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x3F, 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); }

Two above code has only one line different.

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