Arduino - Temperature Humidity Sensor - OLED Display

In this tutorial, we are going to learn:

How to read the temperature and humidity from DHT11 sensor and display it on an OLED.
How to read the temperature and humidity from DHT22 sensor and display it on an OLED.

Arduino DHT11/DHT22 temperature humidity sensor OLED display

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B
1	×	SSD1306 I2C OLED Display 128x64
1	×	DHT11 Temperature and Humidity Sensor
1	×	Jumper Wires
1	×	(Optional) 9V Power Adapter for Arduino
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno

You can use DHT22 sensor instead of DHT11 sensor.

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.

About OLED display, DHT11 and DHT22 Temperature Humidity Sensor

If you do not know about OLED display, DHT11 and DHT22 temperature humidity sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino - DHT11 Module LCD Wiring

This image is created using Fritzing. Click to enlarge image

Arduino - DHT22 Module LCD Wiring

Arduino DHT22 Sensor OLED Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code - DHT11 Sensor - OLED

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-humidity-sensor-oled-display */ #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 DHTPIN 2 // pin connected to DHT11 sensor #define DHTTYPE DHT11 Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C DHT dht(DHTPIN, DHTTYPE); 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 dht.begin(); // initialize DHT11 the temperature and humidity sensor displayString.reserve(10); // to avoid fragmenting memory when using String } void loop() { float humi = dht.readHumidity(); // read humidity float tempC = dht.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 Steps

Open Arduino IDE, Go to Tools Manage Libraries

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 Arduino
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

Arduino Code - DHT22 Sensor - OLED

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-humidity-sensor-oled-display */ #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 DHTPIN 2 // pin connected to DHT22 sensor #define DHTTYPE DHT22 Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C DHT dht(DHTPIN, DHTTYPE); 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 dht.begin(); // initialize DHT22 the temperature and humidity sensor displayString.reserve(10); // to avoid fragmenting memory when using String } void loop() { float humi = dht.readHumidity(); // read humidity float tempC = dht.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(); }