I believe he just wants to check if the object is within 12 inches from the
source. Easy to do, by reflection of IR pulses. If the concern is regarding
the distance, 12 to 16 inches is ok. Just make sure you fire the IR LED with
high current, short time, for best results. You can use a PIC to do both
things: send a certain frequency of fires and check if the same pattern can
be detected back.




----- Original Message -----
From: Douglas Butler <dbutler@IMETRIX.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, August 24, 2001 6:33 PM
Subject: Re: [PIC]:Using IR....determing position?


> Are you intending to use the time it takes for the IR to reach the
> target, or are you thinking of using the drop in amplitude with range?
> The first will require very fast timing.  The second will mistake poor
> visability or power variations for range changes.
>
> Sherpa Doug
>
> > -----Original Message-----
> > From: Micro Eng [mailto:micro_eng@HOTMAIL.COM]
> > Sent: Friday, August 24, 2001 12:06 PM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [PIC]:Using IR....determing position?
> >
> >
> > I am trying to decide if I can use an IR setup to determine
> > if something is
> > in range.  I could use ultrasonic, but I wondered if IR might
> > be easier.
> > All I want is PIC watching the inputs and if the box is moved within a
> > certain range (12"-16") turn on an LED.  Simple in concept....
> >
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