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Pyroelectric ("Passive") InfraRed sensors:

'''What is a PIR sensor?''' (http://www.adafruit.com/index.php?

main_page=product_info&cPath=35&products_id=189)

PIR sensors allow you to sense motion, almost always used to detect whether a

human has moved in or out of the sensors range. They are small, inexpensive, low-

power, easy to use and don't wear out. For that reason they are commonly found in

appliances and gadgets used in homes or businesses. They are often referred to

as PIR, "Passive Infrared", "Pyroelectric", or "IR motion" sensors.

PIRs are basically made of a pyroelectric sensor

(http://en.wikipedia.org/wiki/Pyroelectric) (which you can see above as the round

metal can with a rectangular crystal in the center), which can detect levels of

infrared radiation. Everything emits some low level radiation, and the hotter

something is, the more radiation is emitted. The sensor in a motion detector is

actually split in two halves. The reason for that is that we are looking to detect

motion (change) not average IR levels. The two halves are wired up so that they

cancel each other out. If one half sees more or less IR radiation than the other, the

output will swing high or low.

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PIR Motion Sensor Tutorial by adafruit (/member/adafruit/)

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Along with the pyroelectic sensor is a bunch of supporting circuitry, resistors and

capacitors. It seems that most small hobbyist sensors use the BISS0001 ("Micro

Power PIR Motion Detector IC")

(http://www.ladyada.net/media/sensors/BISS0001.pdf), undoubtedly a very

inexpensive chip. This chip takes the output of the sensor and does some minor

processing on it to emit a digital output pulse from the analog sensor.

For many basic projects or products that need to detect when a person has left or

entered the area, or has approached, PIR sensors are great. They are low power

and low cost, pretty rugged, have a wide lens range, and are easy to interface with.

Note that PIRs won't tell you how many people are around or how close they are to

the sensor, the lens is often fixed to a certain sweep and distance (although it can

be hacked somewhere) and they are also sometimes set off by house pets.

Experimentation is key!

Some basic stats

These stats are for the PIR sensor in the Adafruit shop which is very much like the

Parallax one

(http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/ProductID/83/Lis

t/0/Default.aspx?SortField=ProductName,ProductName). Nearly all PIRs will have

slightly different specifications, although they all pretty much work the same. If

there's a datasheet, you'll want to refer to it

Size: RectangularPrice: $10.00 at the Adafruit shop (http://www.adafruit.com/index.php?main_page=product_info&cPath=35&products_id=189)Output: Digital pulse high (3V) when triggered (motion detected) digital low whenidle (no motion detected). Pulse lengths are determined by resistors andcapacitors on the PCB and differ from sensor to sensor.Sensitivity range: up to 20 feet (6 meters) 110 degrees x 70 degrees detectionrangePower supply: 3.3V - 5V input voltage,BIS0001 Datasheet (http://www.ladyada.net/media/sensors/BISS0001.pdf) (thedecoder chip used)RE200B datasheet (http://www.ladyada.net/media/sensors/RE200B.pdf) (mostlikely the PIR sensing element used)NL11NH datasheet (http://www.ladyada.net/media/sensors/NL11NH.pdf)(equivalent lens used)Parallax Datasheet on their version of the sensor(http://www.ladyada.net/media/sensors/PIRSensor-V1.2.pdf)

More links!

A great page on PIR sensors from GLOLAB(http://www.glolab.com/pirparts/infrared.html)NYU sensor report(http://itp.nyu.edu/physcomp/sensors/Reports/PassiveInfraRedSensor)

Step 1: How does it work?

passive infrared (/tag/type-id/keyw ord-passive%20infrared/)

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Next » (/id/PIR-Motion-Sensor-Tutorial/step2/Lenses/)

View All Steps (/id/PIR-Motion-Sensor-Tutorial/?ALLSTEPS)

Download (/id/PIR-Motion-Sensor-Tutorial/?download=pdf)

PIR sensors are more complicated than many of the other sensors explained in

these tutorials (like photocells, (http://www.instructables.com/id/Photocell-tutorial/)

FSRs (http://www.instructables.com/id/FSR-Tutorial/) and tilt switches

(http://www.instructables.com/id/Tilt-Sensor-Tutorial/)) because there are multiple

variables that affect the sensors input and output. To begin explaining how a basic

sensor works, we'll use the rather nice diagram below (if anyone knows where it

originates plz let me know).

The PIR sensor itself has two slots in it, each slot is made of a special material that

is sensitive to IR. The lens used here is not really doing much and so we see that

the two slots can 'see' out past some distance (basically the sensitivity of the

sensor). When the sensor is idle, both slots detect the same amount of IR, the

ambient amount radiated from the room or walls or outdoors. When a warm body

like a human or animal passes by, it first intercepts one half of the PIR sensor,

which causes a positive differential change between the two halves. When the

warm body leaves the sensing area, the reverse happens, whereby the sensor

generates a negative differential change. These change pulses are what is

detected.

The PIR sensor itself

The IR sensor itself is housed in a hermetically sealed metal can to improve

noise/temperature/humidity immunity. There is a window made of IR-transmissive

material (typically coated silicon since that is very easy to come by) that protects

the sensing element. Behind the window are the two balanced sensors.

Check out the images for more details:

(/file/FXWS6GHFYNTA23Z/)

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Reply18 days ago

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5 months ago

SentryGunner (/member/SentryGunner)

Hello, can anybody please help me with this? I was wonderingif there was some sort of filter that I could place in front of thepir module, that would filter out any low temperature objectsand only allow high temperatures to trigger the sensor (bodyheat). I plan to mount the sensor on a rotating turret, and whenit spins I don't want the sensors to be triggered by the moving

background (walls, bookshelves, etc.) thanks.

AashishR1 (/member/AashishR1)

Hey! can the PIR sensor also detect a bird?

kavish laxkar (/member/kavish laxkar)

hi i am using PIR for last 2 months..Now i measured theoutput voltage and found it is 3.1 volt. (u said its 3.3v) Is myPIR is dead...or is working fine.? plz help

nmcnaughton (/member/nmcnaughton)

its not working for me. when i plug everything in and uploadthe sketch the led comes on and stays on. in the serialmonitor it says motion detected. my pir does not have ajumper on the back but it does have three pads. there is 2pots on it and i tried adjusting them but it didnt seem to help.i got the pir on ebay (http://tinyurl.com/led58rm) if any onecan help that would be great

(http://cdn.instructables.com/FC1/C8AJ/I9FGWNBF/FC1C8AJI9FGWNBF.LARGE.jpg)

Snick543 (/member/Snick543) . nmcnaughton (/member/nmcnaughton)

In the data sheet the pins you have marked are used to set thetrigger in either single or repeat modes. I tried using the systemin single trigger mode by soldering the 1st and 2nd pins but itseemed to heat up the system. I then soldered the 2nd and 3rdpins(Circled in Red) and it worked all right.

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(http://cdn.instructables.com/FRK/Y3Y2/IE2FZ9OY/FRKY3Y2IE2FZ9OY.LARGE.jpg)

nmcnaughton (/member/nmcnaughton) . Snick543 (/member/Snick543)

ok i may try soldering them together and see whathappens. :)

ShashiK3 (/member/ShashiK3) . nmcnaughton (/member/nmcnaughton)

Somewhat similar problem - My sensor detects even there isNO movement. So I changed the pots so that it lowerssensitivity. no help.

TrentonN1 (/member/TrentonN1) . nmcnaughton (/member/nmcnaughton)

Same problem and sensor can only get it to turn offafter a minute under a box.

sanjaygupta007 (/member/sanjaygupta007)

sanjaygupta007 (/member/sanjaygupta007)

Sasando_Rote (/member/Sasando_Rote)

how to if i want used 3 PIR for the sensor?

wymand (/member/wymand) . Sasando_Rote (/member/Sasando_Rote)

I have python code that monitors multiple sensors on my page.

http://tigermountainsprings.net/wp/index.php/6-pir-infrared-sensors-and-the-coop/

tonizey (/member/tonizey)

please how can i connect it to a loud alarm and an halogen

bulb?

mohamed.h.madyan (/member/mohamed.h.madyan)

Can i adjust the range to be 0.5 feet not 20 ? or it's fixed .

fadecomic (/member/fadecomic)

What does it mean if the LED is flashing at a very regularinterval? Almost like it's on a timer? It's not random.

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2 years ago

shantharoopan (/member/shantharoopan)

Excellent tutorial!!

Hats-off

Nawaz (/member/Nawaz)

If still required, Pictures in Step 1 is from the "Infrared PartsManual" by "GLOLAB corporation". Hope this helps :)

http://www.bucek.name/pdf/re200b.pdf

henrikekblad (/member/henrikekblad)

If you want to make your own wireless PIR sensor, try outMySensors motion sensor example:http://www.mysensors.org/build/motion(http://www.mysensors.org/build/motion)

Arduino library on Github:https://github.com/mysensors/ (https://github.com/mysensors/)

sriramsrikp (/member/sriramsrikp)

How to connect two PIR sensor in one circuit which connected

with one light??? If i cross either of the sensor means thesingle light which is connected to the circuit should glow.

Oliverhall (/member/Oliverhall)

Very nice tutorial! Just want to share this place where you canget the HC-SR501 PIR sensor for cheap:

http://voltatek.com/en/sensors/69-motion-sensor-m...(http://voltatek.com/en/sensors/69-motion-sensor-module-hc-

sr501-pyroelectric-ir-infrared-adjustable.html)

Sun Gear (/member/Sun Gear)

When testing, is the resistor necessary?

facelessbutcher (/member/facelessbutcher) . Sun Gear (/member/Sun Gear)

..the resistor is needed for testing with LED (to limit the

current)

nodoubtman (/member/nodoubtman)

what if i would like to turn on a relay when trigger?

thanks!

marC:)

fcharest1 (/member/fcharest1) . nodoubtman (/member/nodoubtman)

buy this

http://www.ebay.ca/itm/310566336050?ssPageName=STR...

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http://www.ebay.ca/itm/310566336050?ssPageName=STR...(http://www.ebay.ca/itm/310566336050?

ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649)

very easy to use

jonyeador (/member/jonyeador)

What would i have to do so that it alerts my phone when motion

is detected?

fcharest1 (/member/fcharest1) . jonyeador (/member/jonyeador)

gsm shield and a activated sim card and some electronic basic

supply

beardy (/member/beardy)

How much current can the module deliver to the output?

Great write up. Thanks.

badman5 (/member/badman5) . beardy (/member/beardy)

not really, he copy and pasted it from the website he linked.

mhaziq (/member/mhaziq)

Hey there guys, i would just like to know does the PIR motionworks with other programming such as C programming and

such. Another thing is, is it possible to do this: When sensor detects, LED lights up

When sensor x detect, LED would dim instead of off. Thanks. Your reply would be highly appreciated.

GraziCNU (/member/GraziCNU) . mhaziq (/member/mhaziq)

I actually just posted an Instructable recently that essentially does what youare asking. Only thing you would have to change in the code is the PWM

value in the analogWrite() function from 0 (which is totally off) to 50 or so(which would make the LED shine dimly).

bhermance (/member/bhermance)

WOW! Thanks for this tutorial!! I love it! Thanks for doing this!!!11 thumbs out of 10!!! :-)

stonez56 (/member/stonez56)

Hi, I would like to know if PIR sensor can tell me that the person in

range is moving toward to the left or right? Is it possible or Ineed something else to detect?

Thanks!

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Brennn10 (/member/Brennn10)

Are you still selling the sensors on your website?

senbalily (/member/senbalily) . Brennn10 (/member/Brennn10)

hi We sell this PIR sensor my web is http://en.nysenba.com and

my email is lily@sbcds.com

Mihaiu (/member/Mihaiu)

@mhaziq

Yes, it is possible to dim the LED upon detection.

alexbjj (/member/alexbjj)

Great tutorial. I am looking for tutorial where i can turn on some

kind of camera with motion sensor and arduino. Rurn iton,record some video or take a few pics and turn camera off. i

am very new in programming and arduino. Can you give someadvice where can i find something similar, please!

u29081778 (/member/u29081778)

How would you increase the sensitivity of the PIR sensor usingArduino? (using code)

I'm doing a project, and coding in Arduino.

Vick Jr (/member/Vick Jr)

I'm going to use one of these to detect opponents in air-soft

wars. Is there any material that i can cover the sensor with toprotect it from BBs but will still allow IR light through?

ringai (/member/ringai) . Vick Jr (/member/Vick Jr)

A 1/4 piece of Lexan (polycarbonate) should do the trick. You can heat formit to fit the pir using an automotive soldering iron and a suitable metal form.

It's a tricky thing to do, so practice in an open area, being wary ofoverheating the lexan, of any fumes, and of starting a fire.

ideliza28 (/member/ideliza28)

is it possible to change the LED into a servo, and if it is what

other changes do i have to do? thank you...

roslan bin ramli (/member/roslan bin ramli)

can we use this PIR sensor at night, for example, a remote

area with no road street lights. please reply...thank you..

roslan bin ramli (/member/roslan bin ramli)

This detector can detect a car? For example, a car on the

road. I make a mini project on road safety. I want to put thissensor to detect the car. Will it be applied? I just want to find

out.

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imakethings (/member/imakethings)

gr8 tutorial.. got one of these for 2 $

creator22 (/member/creator22)

i did this step and it doesn't work :( ideas???

TerryKing (/member/TerryKing)

Some more info here on using these with Arduino:

http://arduino-info.wikispaces.com/Brick-Pushbuttons%26OtherSwitches#Motion

Auger Duval (/member/Auger Duval)

I have just the sensor (TO9 can package) itself. A PIR D203S.

The datasheet tells me how to hook it up: 5V, Gnd and Signal(it is an analog device). But it tells me very little about the

signal I will be getting. Short of dragging out my O-scope anddoing the testing; do you know what type of signal I should

expect? This module from LA you use is nice, but I'm using myown uController so I wouldn't get the clean digital signal you

show. BTW Wonderful writeup! you would make my old collegeprofs proud.

Auger Duval (/member/Auger Duval) . Auger Duval (/member/Auger Duval)

opps, it a TO-5 package not a TO-9

kyle brinkerhoff (/member/kyle brinkerhoff)

huh, got 10 of these super cheep from my school used, now i

actually know what they do!

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