ESP32 - Temperature Sensor - OLED

This tutorial instructs you how to read the temperature from DS18B20 one wire sensor 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	×	DS18B20 Temperature Sensor (WITH Adapter)
1	×	DS18B20 Temperature Sensor (WITHOUT Adapter)
1	×	Breadboard
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.

Buy Note: Numerous DS18B20 sensors available in the market are of poor quality. We strongly advise purchasing the sensor from the DIYables brand via the link above; we conducted tests, and it performed reliably.

Introduction to OLED and DS18B20 Temperature Sensor

If you do not know about OLED and DS18B20 Temperature Sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

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.

We suggest purchasing a DS18B20 sensor that comes with a wiring adapter for easy connection. The adapter has a built-in resistor, eliminating the need for a separate one in the wiring.

ESP32 Code - Temperature from DS18B20 Temperature Sensor and display it on 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-temperature-sensor-oled */ #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 13 // The ESP32 pin GPIO13 connected to DS18B20 sensor's data 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 DS18B20(&oneWire); // pass oneWire to DallasTemperature library String temperature; 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 DS18B20.begin(); // initialize the sensor temperature.reserve(10); // to avoid fragmenting memory when using String } void loop() { DS18B20.requestTemperatures(); // send the command to get temperatures float tempCelsius = DS18B20.getTempCByIndex(0); // read temperature in Celsius temperature = String(tempCelsius, 2); // two decimal places temperature += "°C"; Serial.println(temperature); // print the temperature in Celsius to Serial Monitor oledDisplayCenter(temperature); } 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 “DallasTemperature” on the search box, then look for the DallasTemperature library by Miles Burton.
Click Install button to install DallasTemperature library.

You will be asked to install the dependency. Click Install All button to install OneWire library.

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

※ NOTE THAT:

The about code automatically horizontal and vertical center aligns the text on OLED display

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