Ads by esp32io.com
ESP32 - DHT22 - OLED
This tutorial instructs you how to read the temperature and humidity from DHT22 module and display it on an OLED.
Hardware Used In This Tutorial
| 1 | × | ESP-WROOM-32 Dev Module | |
| 1 | × | USB Cable Type-C | |
| 1 | × | SSD1306 I2C OLED Display 128x64 | |
| 1 | × | DHT22 Module | |
| 1 | × | Jumper Wires | |
| 1 | × | (Recommended) ESP32 Screw Terminal Adapter |
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 these links are affiliate links. We may earn a commission on your purchase at no extra cost to you. We appreciate it.
Introduction to OLED display, DHT22 Temperature Humidity Sensor
If you do not know about OLED display, and DHT22 temperature humidity sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:
- ESP32 - OLED tutorial
- ESP32 - DHT22 tutorial
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 Code - DHT22 Sensor - OLED
/*
* 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-oled
*/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define DHT22_PIN 2 // The ESP32 pin GPIO23 connected to DHT22 sensor
Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C
DHT dht22(DHT22_PIN, DHT22);
String displayString;
void setup() {
Serial.begin(9600);
// initialize OLED display with address 0x3C for 128x64
if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
while (true);
}
delay(2000); // wait for initializing
oled.clearDisplay(); // clear display
oled.setTextSize(2); // text size
oled.setTextColor(WHITE); // text color
oled.setCursor(0, 10); // position to display
dht22.begin(); // initialize DHT22 the temperature and humidity sensor
displayString.reserve(10); // to avoid fragmenting memory when using String
}
void loop() {
float humi = dht22.readHumidity(); // read humidity
float tempC = dht22.readTemperature(); // read temperature
// check if any reads failed
if (isnan(humi) || isnan(tempC)) {
displayString = "Failed";
} else {
displayString = String(tempC, 1); // one decimal places
displayString += "°C";
displayString += String(humi, 1); // one decimal places
displayString += "%";
}
Serial.println(displayString); // print the temperature in Celsius to Serial Monitor
oledDisplayCenter(displayString); // display temperature and humidity on OLED
}
void oledDisplayCenter(String text) {
int16_t x1;
int16_t y1;
uint16_t width;
uint16_t height;
oled.getTextBounds(text, 0, 0, &x1, &y1, &width, &height);
// display on horizontal and vertical center
oled.clearDisplay(); // clear display
oled.setCursor((SCREEN_WIDTH - width) / 2, (SCREEN_HEIGHT - height) / 2);
oled.println(text); // text to display
oled.display();
}
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.
- Click to the Libraries icon on the left bar of the Arduino IDE.
- Search “SSD1306”, then find the SSD1306 library by Adafruit
- Click Install button to install the library.
- You will be asked for intalling some other library dependencies
- Click Install All button to install all library dependencies.
- Search “DHT”, then find the DHT sensor library by Adafruit
- Click Install button to install the library.
- You will be asked for intalling some other library dependencies
- Click Install All button all library dependencies.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to ESP32
- Put the sensor on hot and cold water, or grasp the sensor by your hand
- See the result on OLED and Serial Monitor
※ NOTE THAT:
The about code automatically horizontal and vertical center aligns the text on OLED display
Video Tutorial
Making video is a time-consuming work. If the video tutorial is necessary for your learning, please let us know by subscribing to our YouTube channel , If the demand for video is high, we will make the video tutorial.
