PIR and arduino


I'm trying to use a PIR sensor following the below blog


The problem is that is detecting always a movement. I have tried to attach a multimeter between the ground and the Output (which is the one that is wired to the Arduino input pin for reading) but the voltage goes up and down (1.15 - 4.29) all the time.

Is something wrong with this sensor?

What is the best (not too expensive) PIR sensor for Arduino ?

Are you moving, when you did this test ?

Is there anything in your vicinity which is moving, or which is generating a variable amount of heat or IR ?

It is probably working, and the place where you are doing this, is not quiet enough.

This seems to be a useless device. I suggest you go and read the 69 comments about it at that other forum post you linked to.

Hi, I have this problem too. But this happen only with http POST request. Maybe this is hardware problem.

Try test with this:

I think arduino don't need resistor for PIR.

Also try to change jumpers (H or L) or sensors setting (sensitivity & time).