Subject:
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Re: IR
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 23 May 1997 11:25:10 GMT
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Original-From:
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Pandit Panburana <PDP@IXihatespam.NETCOM.COM>
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Viewed:
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3899 times
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Hi Fred,
I do not know exactly of your situation with the IR detector/emitter
arrangement. I found that it sometimes picks up noise
occassionally.
I also found that with small resister in the range that you are
using
(330ohms), the
range is too much for what I needed. I use the current limit
resister
of
1K instead to limit the range down to about 6" to 7".
I also use the Radio Shack IR LED and the detector.
-Pandit
----------
> From: Fred Cass <FCass@nextwavetel.com>
> To: 'Handyboard'
<IMCEAX400-c=US+3Ba=+20+3Bp=NEXTWAVE+20TELECOM+3Bo=NORTHEAST+3Bdda+3ASMT
P=ha
ndyboard+40media+2Emit+2Eedu+3B@nextwavetel.com>
> Subject: IR
> Date: Thursday, May 22, 1997 9:30 AM
>
> Hello all,
>
> I've been playing with IR proximity sensors, and wonder if anyone can
> provide some suggestions.
>
> I hooked up an IR LED (Radio Shack 'high output IR LED') to the
> Handyboard's IR output with a 330ohm resistor in series (the smallest
> value resister I had on hand) . And I use poke(0x1000,0x40) to turn it
> on (I think that's what I used)...
> I ordered a bunch of IR detectors from Jameco, of the 32kHz variety. I
> ordered those to try and set up Keith Soldavin's IR multiplexor. I
> would imagine those wouldn't work well with the IR LEDs described above
> since the Handyboard modulates 'em at 38kHz.
> So I also bought a couple of the Radio Shack 38kHz detectors.
> First I tried testing them by turning on the IR output (checking with
> camcorder to see if working - ok), then loading HBTEST.C and running
> Testdigitals();. Well after a while of testing, I came to the
> conclusion that since testdigitals(); was so full of delays from waiting
> for the LCD screen to update, I was missing most of the hits. So then I
> wrote a quick program that played a tone (tone(440.,.03);) whenever the
> port was on, and then I got tons of readings.
> Ok, let me finally get to my point here. :)
> 1. I had a very difficult time getting any consistent reflectance
> readings. Does anyone have any suggestions for perhaps setting up the
> emitter/detector so that the detector only sees the reflection, and
> misses a lot of the noise? One thing I noticed happening was that it
> seemed to detect motion rather than just the straight reflection (in
> other words, it wouldn't detect anything unless I moved it quickly in
> front of the emitter/detector. If I stopped moving, it stopped
> detecting. Could this mean that the detectors really aren't 38kHz?)
> 2. Is there any way to change the frequency of the IR output so I could
> use the 32kHz IR detectors? If not, no big deal, I'll build Keith's
> circuit which is set up for 32kHz....
>
> Thanks for any input,
> -=Fred Cass=-
> fcasshb@usa.net
>
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