PIR false positives

With the sparkfun PIR motion sensor, I get massive numbers of false positives. I do not see any way to tune down the sensitivity. My first thought is to catch one, hold a second, and check for another - maybe this will help. But looking at my current logs I think I will start dropping real positives. humph. Is my GPIO timing out on the open collector/interrupt at some point? I kind of doubt it, but who knows. Are these “real” false positives caused by EMI or temperature shift? perhaps my garage door shaking with wind does it, but I kind of doubt it since if I stand there and shake the door with my arm about as hard as I can I do not see the hits.

Any other ideas? Thanks!

With the sparkfun PIR motion sensor…

A what?

Do you have a pullup resistor on the alarm pin?


It sure sounds like its floating on the output. But lighting will mess them up too

[quote author=Coding Badly link=topic=263699.msg1860270#msg1860270 date=1409279322]

blah44: With the sparkfun PIR motion sensor...

A what?


Passive Infra Red.

The question was intended to elicit a link. Given the fact that Sparkfun sells at least two PIR sensors providing advice without knowing which device is a fools errand.

Well, it was this one - https://www.sparkfun.com/products/8630

Tho I was thinking it did not matter too much - it does not have a sensitivity adjuster, and it functions as a simple open collector. Still not sure where my problem is, or if it is recoverable.


el_supremo: Do you have a pullup resistor on the alarm pin?


10k between the 5V input and the alarm pin.

Now post your code (in code tags).


The datasheet specifically states: Operating Voltage 12 V. SlvrSrfr (et al) indicates 5V may not work... https://www.sparkfun.com/products/8630#comment-4eaad841757b7fd351001a70 https://www.sparkfun.com/products/8630#comment-4eaad83f757b7fd3510010f4 https://www.sparkfun.com/products/8630#comment-51d08ed1ce395f357e000000

ahmad offers a potential solution... https://www.sparkfun.com/products/8630#comment-4eaad847757b7fd351004461

c19274 offers a different solution... https://www.sparkfun.com/products/8630#comment-4eaad84a757b7fd3510056d3

MattiasF appears to have analyzed the problem (follow the link in his post)... https://www.sparkfun.com/products/8630#comment-5188d871ce395f6c1d000000

Member #40615 offers yet another solution... https://www.sparkfun.com/products/8630#comment-5071ee77757b7fd81b000000

In other words, you paid $10 for a $2 FleaBay device when you could have paid $10 for a $10 Parallax device...

http://www.parallax.com/product/28033 http://www.parallax.com/product/28032 http://www.parallax.com/product/555-28027

Parallax recently had a great sale on the Rev A sensors. I bought a fist full of them. Every one has worked flawlessly and has worked exactly as documented. I suggest you stop wasting your time and buy a decent sensor.