Arduino - Temperature Humidity Sensor - OLED Display

In this tutorial, we are going to learn:

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×SSD1306 I2C OLED Display 128x64
1×Temperature and Humidity Sensor DHT11
Or 1×Temperature and Humidity Sensor DHT22
4×Jumper Wires
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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

Arduino DHT11 Sensor OLED Wiring Diagram

Image is developed using Fritzing. Click to enlarge image

Arduino - DHT22 Module LCD Wiring

Arduino DHT22 Sensor OLED Wiring Diagram

Image is developed 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
  • Arduino add library
  • Search “SSD1306”, then find the SSD1306 library by Adafruit
  • Click Install button to install the library.
  • Arduino OLED library
  • You will be asked for intalling some other library dependencies
  • Click Install All button to install all library dependencies.
  • Arduino Adafruit GFX sensor library
  • Search “DHT”, then find the DHT sensor library by Adafruit
  • Click Install button to install the library.
  • Arduino DHT sensor library
  • You will be asked for intalling some other library dependencies
  • Click Install All button all library dependencies.
  • Arduino Adafruit Unified sensor library
  • 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(); }

※ NOTE THAT:

Code for DHT11 and DHT22 are identical except for one line of code. Library for DHT11 and DHT22 are the same.

Video Tutorial

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