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DS18B20 Temperature Sensor

Posted by

Ekostra Electronics

April 11, 2025

On April 5, 2025

DS18B20 Digital Temperature Sensor

Precision 1-Wire Interface Temperature Measurement for Arduino and Microcontrollers

Introduction

The DS18B20 is a digital temperature sensor with ±0.5°C accuracy over the range of -10°C to +85°C. It uses the 1-Wire communication protocol, allowing multiple sensors to be connected on a single data line.

Key Features

🌡️ High Accuracy

±0.5°C from -10°C to +85°C

🔌 Simple Wiring

1-Wire interface (single data line)

🔄 Multi-Drop

Multiple sensors on one bus

🔋 Parasitic Power

Can operate without external power

Technical Specifications

Temperature Range	-55°C to +125°C
Accuracy	±0.5°C (-10°C to +85°C)
Resolution	User-selectable 9-12 bits
Supply Voltage	3.0V to 5.5V
Current Draw	1mA (active), 750nA (standby)
Conversion Time	750ms max (12-bit resolution)
Interface	1-Wire
Package Options	TO-92, SOIC, µSOP

Pin Configuration

Pin	Description	Connection
1 (GND)	Ground	GND
2 (DQ)	Data I/O (1-Wire)	Digital Pin (with 4.7KΩ pull-up)
3 (VDD)	Power Supply (optional)	3.3V-5V (for powered mode)

Note: The 4.7KΩ pull-up resistor between DQ and VDD is required for proper operation

Wiring Diagrams

Standard (Powered) Mode

// Connections:
// VDD → 3.3V/5V
// DQ  → Digital Pin (with 4.7KΩ pull-up to VDD)
// GND → GND

// Connections:

// VDD → 3.3V/5V

// DQ → Digital Pin (with 4.7KΩ pull-up to VDD)

// GND → GND

Parasitic Power Mode

// Connections:
// VDD → GND
// DQ  → Digital Pin (with 4.7KΩ pull-up to 3.3V/5V)
// GND → GND

// Connections:

// VDD → GND

// DQ → Digital Pin (with 4.7KΩ pull-up to 3.3V/5V)

// GND → GND

Library Setup

Install the OneWire and DallasTemperature libraries
Include the required libraries:

Arduino

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

1
2

#include <OneWire.h>
#include <DallasTemperature.h>
Initialize the sensor:

#define ONE_WIRE_BUS 2 // Data wire connected to digital pin 2

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

void setup() {
  Serial.begin(9600);
  sensors.begin();
}

#define ONE_WIRE_BUS 2 // Data wire connected to digital pin 2

OneWire oneWire(ONE_WIRE_BUS);

DallasTemperature sensors(&oneWire);

void setup() {

Serial.begin(9600);

sensors.begin();

}

Basic Temperature Reading

void loop() {
  sensors.requestTemperatures(); // Send command to all sensors
  float tempC = sensors.getTempCByIndex(0); // First sensor
  
  Serial.print("Temperature: ");
  Serial.print(tempC);
  Serial.println("°C");
  
  delay(1000);
}

void loop() {

sensors.requestTemperatures(); // Send command to all sensors

float tempC = sensors.getTempCByIndex(0); // First sensor

Serial.print("Temperature: ");

Serial.print(tempC);

Serial.println("°C");

delay(1000);

}

Advanced Features

Multiple Sensors

void loop() {
  sensors.requestTemperatures(); // Send command to all sensors
  float tempC = sensors.getTempCByIndex(0); // First sensor
  
  Serial.print("Temperature: ");
  Serial.print(tempC);
  Serial.println("°C");
  
  delay(1000);
}

void loop() {

sensors.requestTemperatures(); // Send command to all sensors

float tempC = sensors.getTempCByIndex(0); // First sensor

Serial.print("Temperature: ");

Serial.print(tempC);

Serial.println("°C");

delay(1000);

}

Resolution Control

void setHighResolution() {
  sensors.setResolution(12); // 9-12 bits (0.0625°C resolution)
  
  Serial.print("Resolution: ");
  Serial.println(sensors.getResolution());
}

void setHighResolution() {

sensors.setResolution(12); // 9-12 bits (0.0625°C resolution)

Serial.print("Resolution: ");

Serial.println(sensors.getResolution());

}

Fahrenheit Conversion

float getTempF() {
  float tempC = sensors.getTempCByIndex(0);
  return DallasTemperature::toFahrenheit(tempC);
}

float getTempF() {

float tempC = sensors.getTempCByIndex(0);

return DallasTemperature::toFahrenheit(tempC);

}

Troubleshooting

Sensor Not Detected

Verify 4.7KΩ pull-up resistor is installed
Check wiring connections (GND must be connected)
Try different digital pin

Incorrect Readings (-127°C)

Check sensor is properly wired
Ensure adequate power supply
Try shorter wires (especially in parasitic mode)

Unstable Values

Add 0.1μF capacitor between VDD and GND
Use proper pull-up resistor (4.7KΩ recommended)
Implement software filtering

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