Hello i was wondering a few things about pir sensors and animals vs people. from what I'm reading most pir sensors can filter out between people and animals. i read a few things on it in forums and google but not sure how it really work. can someone help me out and explain how that works how does the pir sensor knows between people and animals? i have 2 sensors and some sample code it came with but not sure how in coding or hardware it works to know if its a person or animal?
I'm reading most pir sensors can filter out between people and animals.
According to adafruit, you can set the sensitivity of their PIR module, so perhaps it could be set to ignore a cat but trigger for a human.
hello thank you. the one i have has a different chip the the one from adafruit one. but it should work the same way correct? on the adafruit pir sensor you can adjust the sensitive and time on it the one i have no way to adjust that.
josephchrzempiec:
but it should work the same way correct?
You would need to ask your manufacturer about that. What does their datasheet say?
i got it from ebay. but where i got it from the guy no longer is around i think he closed his ebay store and i can not find any other ebay person that has the same as the one i got. but I'm Searching online for the same one.
it has a white pcb board a jumper on it says 1,2 set for Re_trig 2,3 pin says N_Retrig OMG i didn't notics this but it says radioshack on it cat number 2760347 it was in the front all of the time and i didn't know it LOL looking it up now.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/2760347_PM_EN.pdf
Those sensors are not very systematic, and they are sensitive to both temperature and movement in a way which is not very reliable.
Are you expecting people to be crawling on the floor ? If not, then aim the device so that it's region of maximum sensitivity is more than a metre above the floor.
You really need to install the device and then experimentally adjust both the position and sensitivity of the device with a test cat and a test human, to try to get the discrimination that you want.
A test cat? Have you ever tried to get a cat to co-operate?
yeah he set off the pir sensor
There is no magic in this. The PIR detector detects the amount of heat radiated by the object (whatever it is) and its rate of movement.
To the extent that a human is larger than a cat, and has more exposed skin, then at a certain distance, the human will be detected where the cat will not. But it depends. If the cat is much nearer, walks (runs) faster, has been sitting in the sun or in front of the heater, it will easily equate to a human. Having the PIR detector "looking" from ceiling height utilises the fact that humans are taller than cats or (many) dogs. If you have come in from the cold and are wearing a parka with the hood up and do not face the PIR, you may well be missed unless the room is warm and you are now colder than the background.
thank you Paul__B makes great sense there the pir sensor was sitting on my desk and facing out maybe why it picked up the cat but you are correct being high up on the walla might make a difference there i will try to use some packing tape to hold it up there where normal alarm systems are sitting in height and see if that makes a difference but once agian thank you Paul__B for the information.
The cat was on the desk?
well the pir sensor was on the edge of the desk and it was i guess picking up from the ground to mid level of the desk in height so he walked pass it and it did go off because i have a led on the output pin and when someone walks past it the led comes on for test and when he walked past the sensor the led came on.
i got 2 new sensors in the mail today they have 2 adjustable screws on them and a jumper much different design then the other one. From the email post this is what it says it haves
Infrared sensor with control circuit board
The sensitivity and holding time can be adjusted
PIR sensor LHI778
PIR IC sensor BISS0001
Working Voltage Range: DC 4.5V- 20V
Current drain:<60uA
Voltage Output: High/Low level signal:3.3V TTL output
Detection distance: 3--7M(can be adjusted)
Detection range: <140°
Delay time: 5-200S(can be adjusted, default 5s +-3%)
Blockade time: 2.5 S (default)
Trigger: L: Non-repeatable trigger H: Repeat Trigger (default)
Work temperature:-20-+80°C
Trigger Method: L unrepeatable trigger / H repeatable trigger
this is the ebay page.
http://www.ebay.com/itm/321350499678?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Paul__B:
The cat was on the desk?
Where else would it be?
fungus:
Paul__B:
The cat was on the desk?Where else would it be?
That's of course what I was thinking, but apparently it wasn't, but was pretty close nevertheless.
The sensitivity adjustment could certainly be useful, but the delay adjustment should be pretty irrelevant as you use the Arduino to perform timing and if you set it to no delay, you can make algorithmic decisions on what sort of triggering is occurring.
Hello i just wanted to update on the PIR sensor the other one i got from ebay which was a radio shack brand PIR sensor wasn't that good no way of sensitivity they said but it had to be done on some programing level that i couldn't understand so i did get 2 new sensors that can be change on the sensitivity with 2 screws to turn that did work. i put the sensor high normally where a alarm sensor would go and my cat walks past it and didn't set it off thank god LOL so thank you everyone for the information and help. this part of my project is done its for my home automated I'm working so thank you all.
Radioshack tends to sell crap. I bought one of those sensors and it is terrible. It doesn't have a Fresnel lens, at least I can't see the lines in it and its viewing angle is only 120 degrees, so they claim, when it is probably more like 90 degrees. It's very slow to react. I can actually swipe my hand past it fast enough to not register. So, just run really fast and you become invisible. Moreover, the jumper is on the FRONT, wtf? If you go to mount it, it looks weird in your case. Plus, it doesn't have a dial for sensitivity. It doesn't have an EN pin, which means when it first turns on, and stays on while calibration, then your components are active. So, if you were to connect a buzzer or solenoid valve, whatever, then the buzzer sounds off or the solenoid valve shoots water everywhere -for about 15 - 30 seconds!! Final review -Radioshack PIRs suck immensely. 1/5 stars
I recommend the Parallax Wide Angle PIR. It has 180 degree viewing angle, it has a sensitivity dial, which by the way changes the distance that it will pick up movement. Typically 30 feet is max, and can go down to about 5 feet. It comes with a built in LED which makes testing really nice. It is also very quick to react. 9 out of ten times the sensor caught me swiping my hand in front of the sensor although my hand was like a blur.
It also has an EN pin!!
Tested on cats, its picking them up just fine. They tend to figure it out really quickly, so they attempt to get behind the sensor, and reach for the component that makes noise only to be thwarted again by the sensor engaging the component.
You can get one from simplytronics.com (SimplyTronics Has Merged With Parallax - Parallax).
Hope this helps.
EvaTech i totally agree with radioshack sensor was junk the one i bought from ebay is a HC-SR501 Small PIR Sensor Module Pyroelectric Infrared Body/Motion Sensing thats what it says
Infrared sensor with control circuit board
The sensitivity and holding time can be adjusted
PIR sensor LHI778
PIR IC sensor BISS0001
Working Voltage Range: DC 4.5V- 20V
Current drain:<60uA
Voltage Output: High/Low level signal:3.3V TTL output
Detection distance: 3--7M(can be adjusted)
Detection range: <140°
Delay time: 5-200S(can be adjusted, default 5s +-3%)
Blockade time: 2.5 S (default)
Trigger: L: Non-repeatable trigger H: Repeat Trigger (default)
Work temperature:-20-+80°C
Trigger Method: L unrepeatable trigger / H repeatable trigger
and you know what i like this one it seen me come in and sensor went off with no problem and my cat walked around and didn't go off it know the difference between the height of where i put the sensor at so it's working great this is the ebay page i bought them from http://www.ebay.com/itm/321350499678?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
That looks like the Adafruit PIR, but you got it for a steal!! I don't like the lens, not fresnel again, like the radioshack one, which is probably why it is not sensing the cat. The one I have senses my cats well, but that's what I have mine for, so I am glad it does sense them. You can actually run these things without Arduino, btw.
You just need a MOSFET to boost the signal to a 5v relay and then you can switch over to 12v and power a lot of cool components, such as a buzzer or solenoid valve. Depends what your trying to do.
Glad you found a decent PIR.