PIR sensor digital out and no signal on input

hi there,

I have a problem and I think it is a misunderstanding in general because I have similar problems with other sensors.

I got a PIR sensor to track moving objects. It has a digital and analog output. If I measure the voltage on the sensor directly everything seems working, let's say on the digital out is straight 5V if theres a moving object. If I plug it right into my arduino I got nearly nothing except the signal noise. I also plugged in the ground pin.

If I'm taking it right on the digital input pin there should also be 5V if there's a moving, shouldn't it?!

The sensor has VCC of 5V.

Thanks in advance! Regards, Chris

There's a recent thread like this here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1241846987

Thanks AWOL! I didn't find via search.

This is one step closer to my problem but I still don't get it. I don't get why there hsa to be a resistor and where it is placed (parallel or serial).

I try getting my answers on the topics. Thanks for your help.

Chris

Searching via the built in forum search is not good at all. The admins can just turn it off and replace it with a text telling people to search via google or replace it with a google search input field. For now you can search via google by entereing

site:arduino.cc search term

If you post a rough schematic of your circuit, perhaps including the PIR part number, maybe we can provide more concrete help?

Searching via the built in forum search is not good at all.

I would disagree, I have used it many times to locate a thread. The trick is choosing the right key words and getting the pull down option of time limiting correct. Also the "one result per thread" should be permanently ticked.

If I'm taking it right on the digital input pin there should also be 5V if there's a moving, shouldn't it?!

We don't know if you won't tell us what sensor you are using.

oh I’m sorry, sure I tell you the name and description of the sensor. I bought it at Conrad Electronics store in Germany.

hygrosens / www.hygrosens.com
PIR-STD

3-12V VCC
usage: 1.0mA / active 1.4mA
distance 4-12m (choice via soldering bridges)
frequency 0.2 - 10hz
digital out: open collektor max 30V, 20mA
analog out: 0.5UB +/- 0.5Ub

The 8 pins are:

1 analog out 0V to VCC (depends on input, in my case 5V from Arduino)
2 reference VCC/2
3 ground
4 digital out O.C. max 20mA
5 ground
6 VCC
7 optional photo diode
8 optional photo diode

Hope that’s enough. I got datasheets as pdf here but there’s hardly news in it.

Thanks again and best regards,
Chris

PS: Some additional info:

www.conrad.de → article nr 72500 - 62
hygrosens article nr. PIR-T1-M1-L0

There are some pics on conrad.de if you search via article nr. sorry, it’s in german…

open collektor

That's about the only bit we needed to know!

What AWOL means is that if the digital output is an open collector it will only give you 5v output if you put a pull up resistor between the output pin and 5v or you enable the Arduino's internal pull ups.

I tried all combinations with voltage and output pins and pull up resistor but it doesn’t change anything. or let’s say, i can’t interpret the values. here are the values (analog):

no movement: 0.5 floats a bit up and down
movement: goes up to 0.75 and then down to zero. then floats random and goes back to 0.5

what makes the reading very hard is that it sometimes goes down to zero, sometimes not. and the values are so narrow that you can’t make a code that is repeatable and save.

so still trying… if you have suggestions… they are very welcome :smiley:

thanks!
chris

PS: with simpledigital firmata and pd i monitored the digital values as well: i get a 1 without movement and if there’s a detection it goes down to 0, then back to 1 and then 0, then it stays at 1. i wish i could get clear values or at least smooth out with software… :-/

Did you use a pull-up resistor when you were measuring the voltages? You must.

I tried all combinations with voltage and output pins and pull up resistor but it doesn't change anything

But have you tried anything with an input pin?

Sensor output to Analogue 0, Analogue 0 also through a 10K resistor to +5V. Sensor ground to arduino ground, sensor supply to ? (will it work off just 5V?), sensor supply ground to arduino ground.

yes, sure. i meant the output of the sensor and of course the input of the arduino.

the resistor still does nothing or nothing changes at all. i think i have to cope with the floating and smooth via software/puredata. i try to manage it with clippings. i think the floating on movements from nearly constant 0.5 to 0 and then to 0.75 means the speed and direction of movement. i think measured on an oscilloscope you can do pretty more with those values. regarding digital out of the sensor a random floating between 0 and 1 is still useless :-/

maybe i have to make the sensor more insensitive or something.

i think it's nothing to discuss here. if i got news i'll post.

you helped me a lot, thanks! chris

the resistor still does nothing or nothing changes at all

But if you have an open collector output from your sensor, and a pull up resistor doesn't change anything I can't help but think it is not being wired up correctly.

I know you believe it is but what you are seeing just doesn't make any sense.