The DS18B20 is a three pin digital thermometer that provides digital temperature measurements as 9 to 12-bit packets over a single wire serial connection. Its temperature range is between -55 and 125 degrees celcius, with very good accuracy of 0.5 degrees between -10 and 85 degrees Celcius.

It can convert a temperature to a 12 bit reading in 750ms.

The device datasheet can be downloaded from here.

Required libraries to use the DS18B20

In order to use the temperature sensor, on e muct include the Arduino Library for Maxim Temperature Integrated Circuits developed by Miles Burton. Constructing a DallasTemperature instance requires two a reference to a OneWire object. OneWire is another library developed by MIles Burton, that provides onewire or MicroLan capabilities. Costructing a OneWire object simply requires the ardiuno pin that will communicate to the single wire device.

The program to read the temperature will therefore look as follows:

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

// use pin 10 to read temperature
OneWire oneWire(10);

DallasTemperature dallasTemperature(&oneWire);


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

void loop()
{
  dallasTemperature.requestTemperatures();

  // as we only have one device, the index of the thermometer
  //is 0
  float temp = dallasTemperature.getTempCByIndex(0);

  Serial.print("Temperature: ");
  Serial.println (temp);

  delay(800);
}