Digital DS18B20

Overview #

The DS18B20 digital temperature sensor is a 1-Wire sensor. So it communicates with a master card via a 1-Wire bus. Several sensors can be connected to the same 1-Wire bus. In addition, each sensor has a unique address, so there is no risk of conflict.


A 1-Wire bus is conventionally composed of the three wires: a ground, a power (5V) and a data. A single external component is required to operate a 1-Wire bus: a simple 4.7K ohm resistor in pull-resistance to the power supply on the data pin.

In the second figure, you can see a water proof version of this sensor for outdoor deployment.


Documentation for this sensor is available here.

Connecting to Arduino #

To use a 1-Wire sensor, you need to include the OneWire library. In addition, using the Dallas Temperature library makes getting the temperature easy.

Remember that if you downloaded the whole .zip sketch file you already have all these libraries.


Code example #

 * DS18B20 temperature sensor tester

// First we include the libraries
#include <OneWire.h>
#include <DallasTemperature.h>
// Data wire is plugged into pin 2 on the Arduino 
#define ONE_WIRE_BUS 2 

// Setup a oneWire instance to communicate with any OneWire devices  
// (not just Maxim/Dallas temperature ICs) 
OneWire oneWire(ONE_WIRE_BUS); 

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

void setup() 
 // start serial port 
 Serial.println("Dallas Temperature IC Control Library Demo"); 
 // Start up the library 

void loop() 
 // call sensors.requestTemperatures() to issue a global temperature 
 // request to all devices on the bus 

 Serial.print(" Requesting temperatures..."); 
 sensors.requestTemperatures(); // Send the command to get temperature readings 

 Serial.print("Temperature is: "); 
 Serial.print(sensors.getTempCByIndex(0)); // Why "byIndex"?  
   // You can have more than one DS18B20 on the same bus.  
   // 0 refers to the first IC on the wire 
The raw source of the sketch example is visible here.


2018 - Muhammad Ehsan, Mamour Diop & Congduc Pham