Temperature Sensor with OLED - Arduino Tutorial

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Introduction

Combining digital electronics, programming, and data visualization, interfacing a DS18B20 temperature sensor module with an SSD1306 OLED I2C 128×64 display using an Arduino UNO microcontroller is an exciting and educational project. This project allows you to create a real-time temperature monitoring system that can be utilized in a variety of applications such as weather stations, HVAC systems, and more. The DS18B20 temperature sensor provides precise temperature readings in degrees Celsius, while the SSD1306 OLED display acts as a visual interface for the temperature data.

The DS18B20 is a digital temperature sensor that measures temperature and outputs the data in digital form. It is a small, inexpensive device that is widely used in various temperature-sensing applications. The DS18B20 temperature sensor uses a 1-Wire interface, which allows multiple sensors to be connected to the same bus while maintaining unique addresses for each sensor. This makes it ideal for use in applications where multiple temperature readings are required, such as in weather stations or HVAC systems.

Hardware Components

You will require the following hardware for Temperature Sensor OLED with Arduino.

S.no	Component	Value	Qty
1.	Arduino UNO	–	1
2.	USB Cable Type A to B	–	1
3.	OLED Display 128×64	SSD1306 I2C	1
4.	Temperature Sensor	DS18B20	1
5.	Power Adapter for Arduino	9V	1
6.	Resistor	4.7kΩ	1
7.	Breadboard	–	1
8.	Jumper Wires	–	1

Temperature Sensor OLED with Arduino

Include the required libraries:

#include <OneWire.h>
#include <DallasTemperature.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

OneWire.h the library is used to communicate with the DS18B20 temperature sensor using the OneWire protocol.
DallasTemperature.h the library is used to read the temperature data from the DS18B20.
Wire.h the library is used for I2C communication between the OLED display and the Arduino.
Adafruit_GFX.h and Adafruit_SSD1306.h libraries are used to control and display data on the SSD1306 OLED display.

Define the OLED display I2C address and pin numbers:

#define OLED_ADDRESS 0x3C
#define OLED_SDA 4
#define OLED_SCL 15
#define OLED_RST 16

Create objects for the DS18B20 temperature sensor and the OLED display:

OneWire oneWire(2);
DallasTemperature sensors(&oneWire);
Adafruit_SSD1306 display(OLED_ADDRESS, OLED_SDA, OLED_SCL, OLED_RST);

oneWire is an object of the OneWire class that is used to communicate with the DS18B20 temperature sensor. The OneWire class constructor takes the pin number of the data line as a parameter. In this case, the data line is connected to digital pin 2 of the Arduino.
sensors is an object of the DallasTemperature class that is used to read temperature data from the DS18B20. The DallasTemperature class constructor takes a pointer to the OneWire object as a parameter.
display is an object of the Adafruit_SSD1306 class that is used to control and display data on the OLED display. The Adafruit_SSD1306 class constructor takes the I2C address, SDA pin number, SCL pin number, and reset the pin number of the OLED display as parameters.

Set up the OLED display in the setup function:

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.display();
  sensors.begin();
}

display.begin initializes the OLED display and sets the power supply mode to SSD1306_SWITCHCAPVCC.
display.clearDisplay clears the display buffer.
display.setTextSize sets the text size to 1, which is the default size.
display.setTextColor sets the text color to white.
display.display updates the display with the data in the buffer.
sensors.begin initializes the DS18B20 temperature sensor.

Read temperature data and display it on the OLED display in the loop function:

void loop() {
  sensors.requestTemperatures();
  float temperatureC = sensors.getTempCByIndex(0);
  float temperatureF = (temperatureC * 9 / 5) + 32;
  
  display.clearDisplay();
  display.setCursor(0,0);
  display.print("Temperature");
  display.setCursor(0,15);
  display.print(temperatureC);
  display.print((char)223);
  display.print("C");
  display.setCursor(0,30);
  display.print(temperatureF);
  display.print((char)223);
  display.print("F");
  display.display();
  delay(1000);
}

sensors.requestTemperatures requests temperature data from the DS18B20 temperature sensor.
sensors.getTempCByIndex retrieves the temperature data in degrees Celsius. The getTempCByIndex function takes the index of the device as a parameter. In this case, since we only have one DS18B20 temperature sensor, we pass 0 as the index.
temperatureF calculates the temperature in degrees Fahrenheit using the formula (temperatureC * 9 / 5) + 32.
display.clearDisplay clears the display buffer.
display.setCursor sets the cursor position for the next character to be printed.
display.print displays the text on the OLED display. The print function takes a string or a character as a parameter.
display.display updates the display with the data in the buffer.
delay waits for the specified time in milliseconds. In this case, it waits for 1000 milliseconds, or 1 second.

Schematic

Make connections according to the circuit diagram given below.

Wiring / Connections

Arduino	Sensor
5V	VCC
GND	GND	GND
A4	SDA
A5	SCL
3V3		VCC
D2		ANALOG OUT

Installing Arduino IDE

First, you need to install Arduino IDE Software from its official website Arduino. Here is a simple step-by-step guide on “How to install Arduino IDE“.

Installing Libraries

Before you start uploading a code, download and unzip the following libraries at /Progam Files(x86)/Arduino/Libraries (default), in order to use the sensor with the Arduino board. Here is a simple step-by-step guide on “How to Add Libraries in Arduino IDE“.

Code

Now copy the following code and upload it to Arduino IDE Software.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <OneWire.h>
#include <DallasTemperature.h>

#define SCREEN_WIDTH 128 // OLED display width,  in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define SENSOR_PIN 2 // Arduino pin connected to DS18B20 sensor's DQ pin

Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C
OneWire oneWire(SENSOR_PIN);         // setup a oneWire instance
DallasTemperature tempSensor(&oneWire); // pass oneWire to DallasTemperature library

String tempString;

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

  tempSensor.begin();     // initialize the sensor
  tempString.reserve(10); // to avoid fragmenting memory when using String
}

void loop() {
  tempSensor.requestTemperatures();             // send the command to get temperatures
  float tempCelsius = tempSensor.getTempCByIndex(0);  // read temperature in Celsius

  tempString  = String(tempCelsius, 2); // two decimal places
  tempString += "°C";

  Serial.println(tempString); // print the temperature in Celsius to Serial Monitor
  oledDisplayCenter(tempString);
}

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();
}

Working Explanation

The setup() function in the code initializes the environment and set up the communication between the devices. It sets up the OLED display, initializes the temperature sensor, and configures the communication between the OLED display and the microcontroller.

The loop() function is called repeatedly in an infinite loop and is used to execute the main logic of the program. It reads the temperature data from the DS18B20 temperature sensor, converts the temperature data to either Celsius or Fahrenheit and displays the converted temperature data on the SSD1306 OLED display.

Applications

Home automation
Environmental monitoring
Medical devices
Industrial processes
Agricultural applications
DIY projects
Testing and debugging.

Conclusion.

We hope you have found this Temperature Sensor OLED Circuit very useful. If you feel any difficulty in making it feel free to ask anything in the comment section.