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PIR connection question

Started by MikeG, October 22, 2007, 11:40:01 PM

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MikeG

Jon:

What does the output stage of the PIR sensor look like?  Is the output pulled down when the sensor is not triggered, or does it float?  Here's my situation: I have two switches in my system that I'd like to connect to P6 and P7 to make use of the onboard pull up provided by the Setup jumpers.  If I then connect a PIR to an input other than P6 or P7, do I have to provide my own pull down resistor?  I don't see this addressed anywhere, as all the code examples provided in the forum appear to use P6 or P7 for the PIR input.

--Mike

JonnyMac

You can connect the sensor to any pin; the inactive output is either driven low or pulled low on th device (not sure which, will have to contact Parallax).
Jon McPhalen
EFX-TEK Hollywood Office

MikeG

Thanks, Jon, this works just fine using P5 as the input.  I was confused because I may have a defective PIR, which I'll address in another thread.

JonnyMac

Here's a secret on the other pins (P0..P5): the ULN2x03 input stage acts like a weak pull-down.  That said, I've also connected the PIR to a Parallax Bord-of-Education that does not have pull-ups pull-downs on it.
Jon McPhalen
EFX-TEK Hollywood Office