Arduino Nano - Temperature Humidity Sensor - OLED
This tutorial instructs you how to read the temperature and humidity from a DHT11/DHT22 sensor and display it on an OLED.
Hardware Preparation
You can use DHT22 sensor instead of DHT11 sensor.
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 the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.
Additionally, some of these links are for products from our own brand, DIYables.
Overview of OLED display, DHT11 and DHT22 Temperature Humidity Sensor
If you are unfamiliar with OLED display, DHT11 and DHT22 temperature humidity sensor (pinout, functionality, programming ...), the following tutorials can help you:
- Arduino Nano - OLED tutorial
Wiring Diagram
Arduino Nano - DHT11 Module LCD Wiring
This image is created using Fritzing. Click to enlarge image
Arduino Nano - DHT22 Module LCD Wiring
This image is created using Fritzing. Click to enlarge image
Arduino Nano Code - DHT11 Sensor - OLED
/*
* This Arduino Nano code was developed by newbiely.com
*
* This Arduino Nano code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano/arduino-nano-temperature-humidity-sensor-oled
*/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
#define OLED_WIDTH 128 // OLED display width, in pixels
#define OLED_HEIGHT 64 // OLED display height, in pixels
#define DHT_PIN 2 // The Arduino Nano pin connected to DHT11 sensor
#define DHT_TYPE DHT11
Adafruit_SSD1306 oled(OLED_WIDTH, OLED_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C
DHT dht(DHT_PIN, DHT_TYPE);
String temperature;
String humidity;
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(3); // text size
oled.setTextColor(WHITE); // text color
oled.setCursor(0, 10); // position to display
dht.begin(); // initialize DHT11 the temperature and humidity sensor
temperature.reserve(10); // to avoid fragmenting memory when using String
humidity.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)) {
temperature = "Failed";
humidity = "Failed";
} else {
temperature = String(tempC, 1); // one decimal places
temperature += char(247); // degree character
temperature += "C";
humidity = String(humi, 1); // one decimal places
humidity += "%";
}
Serial.print(tempC); // print to Serial Monitor
Serial.print("°C | " ); // print to Serial Monitor
Serial.print(humi); // print to Serial Monitor
Serial.println("%"); // print to Serial Monitor
oledDisplayCenter(temperature, humidity); // display temperature and humidity on OLED
}
void oledDisplayCenter(String temperature, String humidity) {
int16_t x1;
int16_t y1;
uint16_t width_T;
uint16_t height_T;
uint16_t width_H;
uint16_t height_H;
oled.getTextBounds(temperature, 0, 0, &x1, &y1, &width_T, &height_T);
oled.getTextBounds(temperature, 0, 0, &x1, &y1, &width_H, &height_H);
// display on horizontal and vertical center
oled.clearDisplay(); // clear display
oled.setCursor((SCREEN_WIDTH - width_T) / 2, SCREEN_HEIGHT / 2 - height_T - 5);
oled.println(temperature); // text to display
oled.setCursor((SCREEN_WIDTH - width_H) / 2, SCREEN_HEIGHT / 2 + 5);
oled.println(humidity); // text to display
oled.display();
}
Detailed Instructions
- Click to the Libraries icon on the left bar of the Arduino IDE.
- Look for “SSD1306” and then locate the SSD1306 library from Adafruit.
- Press the Install button to install the library.
- You will be requested to install some other library dependencies.
- Press the Install All button to complete the installation of all library dependencies.
- Search for “DHT” and locate the Adafruit DHT sensor library.
- Press the Install button to install the library.
- You will be requested to install some other library dependencies.
- Click the Install All button to install all of the library dependencies.
- Copy the code above and open it in the Arduino IDE.
- Click the Upload button in the Arduino IDE to send the code to the Arduino Nano.
- Place the sensor in hot and cold water, or hold it in your hand.
- Check the result on the OLED and Serial Monitor.
※ NOTE THAT:
The code in question automatically centers the text both horizontally and vertically on an OLED display.
Arduino Nano Code - DHT22 Sensor - OLED
/*
* This Arduino Nano code was developed by newbiely.com
*
* This Arduino Nano code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-nano/arduino-nano-temperature-humidity-sensor-oled
*/
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>
#define OLED_WIDTH 128 // OLED display width, in pixels
#define OLED_HEIGHT 64 // OLED display height, in pixels
#define DHT_PIN 2 // The Arduino Nano pin connected to DHT22 sensor
#define DHT_TYPE DHT22
Adafruit_SSD1306 oled(OLED_WIDTH, OLED_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C
DHT dht(DHT_PIN, DHT_TYPE);
String temperature;
String humidity;
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(3); // text size
oled.setTextColor(WHITE); // text color
oled.setCursor(0, 10); // position to display
dht.begin(); // initialize DHT22 the temperature and humidity sensor
temperature.reserve(10); // to avoid fragmenting memory when using String
humidity.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)) {
temperature = "Failed";
humidity = "Failed";
} else {
temperature = String(tempC, 1); // one decimal places
temperature += char(247); // degree character
temperature += "C";
humidity = String(humi, 1); // one decimal places
humidity += "%";
Serial.print(tempC); // print to Serial Monitor
Serial.print("°C | " ); // print to Serial Monitor
Serial.print(humi); // print to Serial Monitor
Serial.println("%"); // print to Serial Monitor
}
oledDisplayCenter(temperature, humidity); // display temperature and humidity on OLED
}
void oledDisplayCenter(String temperature, String humidity) {
int16_t x1;
int16_t y1;
uint16_t width_T;
uint16_t height_T;
uint16_t width_H;
uint16_t height_H;
oled.getTextBounds(temperature, 0, 0, &x1, &y1, &width_T, &height_T);
oled.getTextBounds(temperature, 0, 0, &x1, &y1, &width_H, &height_H);
// display on horizontal and vertical center
oled.clearDisplay(); // clear display
oled.setCursor((SCREEN_WIDTH - width_T) / 2, SCREEN_HEIGHT / 2 - height_T - 5);
oled.println(temperature); // text to display
oled.setCursor((SCREEN_WIDTH - width_H) / 2, SCREEN_HEIGHT / 2 + 5);
oled.println(humidity); // text to display
oled.display();
}
※ NOTE THAT:
The code for DHT11 and DHT22 is the same, apart from one line. The library used for both is also the same.