DS18B20 Temperature Sensor with ESP32 DOIT Kit v1

Introduction

The DS18B20 is a digital temperature sensor that provides highly accurate temperature readings over a range of -55°C to +125°C. Unlike analog sensors, it communicates over the OneWire protocol, which means multiple DS18B20 sensors can be connected to a single pin of the ESP32.

Key features include:

• Digital output (no need for ADC).
• High accuracy (±0.5°C in most of its range).
• Wide voltage range (3.0V to 5.5V).
• Each sensor has a unique 64-bit serial code, allowing multiple sensors on one bus.

In this tutorial, we will:

• Connect the DS18B20 to the ESP32.
• Use the OneWire and DallasTemperature libraries to read values.
• Print temperature readings on the Serial Monitor.

Components Required

• ESP32 DOIT Kit v1
• DS18B20 Temperature Sensor (waterproof version works too)
• 4.7kΩ Pull-up Resistor
• Breadboard and jumper wires

ESP32 & DS18B20 Pin Connections

⚡ Important: Connect a 4.7kΩ resistor between DATA and VCC (pull-up resistor).

Install Required Libraries

Before coding, install the following libraries in Arduino IDE:

1. OneWire by Jim Studt / Paul Stoffregen
2. DallasTemperature by Miles Burton

Arduino Code

#include <OneWire.h>
#include <DallasTemperature.h>

// Data wire is connected to GPIO 26
#define ONE_WIRE_BUS 26

// Setup a oneWire instance
OneWire oneWire(ONE_WIRE_BUS);

// Pass oneWire reference to Dallas Temperature
DallasTemperature sensors(&oneWire);

void setup() {
  Serial.begin(115200);
  sensors.begin(); // Start DS18B20 sensor
}

void loop() {
  sensors.requestTemperatures(); // Send command to get temperature
  float temperatureC = sensors.getTempCByIndex(0); // Read temperature in °C

  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.println(" °C");

  delay(1000); // Wait 1 second
}

Step-by-Step Code Explanation

Include Libraries

#include <OneWire.h>
#include <DallasTemperature.h>

Adds support for OneWire and DS18B20 communication.

Define Pin

#define ONE_WIRE_BUS 26

Data pin of DS18B20 connected to GPIO 26.

Initialize OneWire & DallasTemperature

OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

Creates communication objects.

Setup Function

sensors.begin();

Starts sensor communication.

Loop Function

sensors.requestTemperatures();
float temperatureC = sensors.getTempCByIndex(0);

Requests and reads temperature (sensor at index 0 if only one connected).

Print Output

Serial.println("Temperature: ... °C");

Displays temperature on Serial Monitor.

Real-Life Applications of DS18B20 with ESP32

• 🌡️ Weather stations (measuring outdoor temperature).
• 🏭 Industrial monitoring (machines, refrigeration systems).
• 🏠 Smart home automation (HVAC, heating, cooling).
• 🐠 Aquarium monitoring (with waterproof DS18B20).
• 🌱 Agriculture & greenhouses (soil and environment monitoring).

Troubleshooting

• No readings → Check pull-up resistor between DATA and VCC.
• -127°C output → Sensor not detected (check wiring).
• 85°C output → Sensor not initialized properly (reset ESP32).
• Multiple sensors → Use getDeviceCount() and unique addresses.