Motion/Prox Detection
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Hello,
I was wondering what the best way to sense motion or proximity would
be. The application that i am doing is to simply detect if someone
is approaching a door, like you would see at the grocery store, etc.
I was just hoping that someone could shed some light on the methods
that are used to do this...
Thanks,
Jared
I was wondering what the best way to sense motion or proximity would
be. The application that i am doing is to simply detect if someone
is approaching a door, like you would see at the grocery store, etc.
I was just hoping that someone could shed some light on the methods
that are used to do this...
Thanks,
Jared
Comments
> Hello,
>
> I was wondering what the best way to sense motion or proximity
would
> be. The application that i am doing is to simply detect if someone
> is approaching a door, like you would see at the grocery store,
etc.
> I was just hoping that someone could shed some light on the methods
> that are used to do this...
>
> Thanks,
> Jared
I'm in the process of doing something similar. I found at Wal-Mart
some $9.00 Sidewalk motion/light units. I hacked them and was able to
get a active low motion sensor that runs on 5 volts. I'm having
troubles with making it work with other devices attached, but it
works great by is self with a BS2.
Shawn
> I was wondering what the best way to sense motion or proximity would
> be. The application that i am doing is to simply detect if someone
> is approaching a door, like you would see at the grocery store, etc.
> I was just hoping that someone could shed some light on the methods
> that are used to do this...
The cheapest way is to use pulsed infrared with an IR detector module.
Pulse the IRLED at 38 - 40kHz with an IR detector module, and sample
the modules output pin. A logic 0 indicates the IR energy is being reflected
back onto the detector [noparse][[/noparse] someone close ]. A logic 1 indicates no reflected
IR [noparse][[/noparse] no one there ].
You can also use a continous IR beam across a doorway similar to the
grocery store type, and detect breaks in the beam in a similar way, but the
intermittent pulse method uses less power, and components will last longer.
Using 38-40kHz IR detector modules with pulsed IR helps avoid false
triggers from ambient IR energy sources. IR energy striking the face of
the module is ignored unless it's modulated at the band-pass frequency
of the detector.
Parallax has some nice goodies here:
http://search.atomz.com/search/?sp-q=infrared&sp-a=sp052fd900
We have some here:
http://www.rentron.com/remote.htm
Regards,
-Bruce
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