PIR Tutorial

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rico bravo
 
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PIR Tutorial

Post by rico bravo »

Ladyada,
When do you think you will have the PIR motion Sensor Tutorial ready for viewing, available for purchase on your website?
thanks
Rico Bravo

adafruit
 
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Re: PIR Tutorial

Post by adafruit »

sometime soon. its on the list but i have a few other sensors to do too and its very nice outside :D

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dstamand
 
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Re: PIR Tutorial

Post by dstamand »

Just played with the sensor, it work fine but this is very slow.
Last edited by dstamand on Sat Aug 22, 2009 9:47 pm, edited 1 time in total.

adafruit
 
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Re: PIR Tutorial

Post by adafruit »

check
http://www.adafruit.com/blog/2009/07/27 ... /#comments
someone posted up a link for speeding it up, very nice!

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taniwha
 
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Re: PIR Tutorial

Post by taniwha »

I've played with these parts a lot recently using a bunch of variants of the 2 stage lm324 circuit described in many of the PIR app notes - if you use the analog ref voltage from the Atmel carefully to set some of the voltages a lot of stuff becomes easier.

My goal's been to determine direction of a moving IR source - turns out to be harder than you think - you need hardware that runs well at the sub-hz level (big coupling caps, or a direct DC design) - and any 5hz+ noise needs to be nipped in the bud - the peak and trough in the waveform you're trying to process tend to be distorted by the RC charging in the rest of the circuit if too much is happening and they're not symmetrical

It's also worth noting that some of the 'fresnel' lenses out there are actually multiple lenses designed to create multiple pulses on the sensor from one movement making any movement detectable but fuzzing stuff up enough that the sort of information I'm after isn't doable

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chazcheadle
 
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Re: PIR Tutorial

Post by chazcheadle »

I think that you might want to look at this video.
http://www.youtube.com/watch?v=dGOgCnlizgU

The D203b sensor, which the parallax PIR module is based on has 2 pyroelectric sensors that during normal use cancel eachother's signals to filter out ambient light changes. If you separate the two sensors components as in the video, you can read motion changes from one to the other.

-chaz

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Re: PIR Tutorial

Post by adafruit »

wow that is neet stuff!
BTW, we have a pir tutorial now
www.ladyada.net/learn/pir.html
which explains how PIRs work

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