SparkFun Electronics - One Wire Digital Temperature Sensor

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One Wire Digital Temperature Sensor - DS18B20

sku: SEN-00245

Description: This is the latest DS18B20 1-Wire digital temperature sensor from Maxim IC. Reports degrees C with 9 to 12-bit precision, -55C to 125C (+/-0.5C). Each sensor has a unique 64-Bit Serial number etched into it - allows for a huge number of sensors to be used on one data bus. This is a wonderful part that is the corner stone of many data-logging and temperature control projects.

Features:

Unique 1-Wire® interface requires only one port pin for communication
Each device has a unique 64-bit serial code stored in an onboard ROM
Multidrop capability simplifies distributed temperature sensing applications
Requires no external components
Can be powered from data line. Power supply range is 3.0V to 5.5V
Measures temperatures from –55°C to +125°C (–67°F to +257°F)
±0.5°C accuracy from –10°C to +85°C
Thermometer resolution is user-selectable from 9 to 12 bits
Converts temperature to 12-bit digital word in 750ms (max.)
User-definable nonvolatile (NV) alarm settings
Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition)
Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system

Datasheet: DS18B20

Pricing

	536 in stock backorder allowed

$4.25	price
$3.83	10-99 (10% off)
$3.40	100+ (20% off)

	quantity

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Comments

8 comments

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	by ScottS +6.8 \| December 12, 2008 at 9:50 AM +1.9
This is super easy to hook up to an arduino. 5v to pin 3, ground pin 1 and hook up a digital line to pin 2. Make sure to put a 4.7k resistor between pin 3 and 2. You can find some sample code here: http://www.arduino.cc/playground/Learning/OneWire. The temperature sensitivity is great. have fun!

	by jatkins +2.1 \| May 28, 2009 at 6:58 AM 0
Really helpful - easily got it working now. Thx :).

FlyByPC

+2.3

| September 3, 2009 at 7:44 PM

Fun little devices -- accurate and cheap. They're also insanely easy to wire up. When Maxim says "one wire," they mean it; you can even power it using the data line if you're careful about timings and provide a strong pull-up when needed. Developing code to drive them is nontrivial, though (various layers include bit timings, commands and ROM codes etc), but once it's working, they're very reliable.

	by Ribster +1.1 \| September 7, 2009 at 9:37 AM 0
Thx. for the link ScottS. Excellent sensor that's a huge package in a small box. The best temperature sensor to have in your toolkit. With so much on board capability you will save memory and processing time. Please consider carrying more 1-wire devices: http://www.maxim-ic.com/pl_list.cfm/filter/21/ln/en

	by mcstellar +1.4 \| November 25, 2009 at 10:49 PM 0
Miles Burton has an easy to use Arduino library for this sensor here: DallasTemperature Library It currently supports the DS18B20, DS18S20 and DS1822.

	by I2C Master +3.1 \| December 12, 2009 at 3:29 PM 0
Mine does not work and i am using mine with a PICAxe. Help me someone, KATE!!!!

	by TomTheGeek +2.4 \| December 28, 2009 at 8:44 PM 0
I am also having problems getting this to work with a Picaxe-08M. Are these the old style sensors? The Picaxe manual states "Note the readtemp command does not work with the older DS1820 as they have a different internal resolutiom." If these are the old style that should be listed in the product description.

David

+1.5

| December 30, 2009 at 4:09 PM

I've ordered these from here in September and they were the DS18B20's. They are actually labeled on the face of the IC but you'll have to use a magnifying glass and strong light to read it to verify what you have. A brief description of the differences between versions: The DS18B20's have 12 bit resolution capabilties. The original DS1820's (note lack of B or S) have 9 bit resolution. The DS18S20 (note S) was meant as a drop-in replacement for the original DS1820. It gets a 12 bit temp value but rounds it to a 9 bit value. You CAN however get 12 bit resolution with the DS18S20's but it requires extra calculations/reading of registers to be done that the DS18B20's don't require. The DS18B20's also allow you to specify 9, 10, 11, or 12 bit resolution programmatically. Taking 9 bit values takes less time and power.