Subject:
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Re: IR Collision avoidance
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 3 Mar 1997 19:20:54 GMT
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Original-From:
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Matt Harlan <mjh10@AVOIDSPAMcornell.edu>
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Viewed:
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4196 times
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Actually, I built the
> portion of the transmitter that generates the 38Khz carrier, using a
> single 555, and on the same board built the 567 portion of the
> circuit, and then connected the signal on pin 5 of the 567 to pin 4
> on the 555 to gate the 555 on and off at 200Hz. Since the 567 is
> also generating the modulating frequency (a luxury you don't have on
> a standard remote-control setup, since the transmitter and the
> receiver are eletrically separate from each other), it doesn't even
> matter if the frequency drifts, because the frequency the detector is
> looking for will always match it. Feeding the output of one of the
> IR sensors to the input of the 567 (as shown on the spec sheet)
> allows the 567 to lock perfectly onto the modulated IR carrier, and
> produces a solid TTL-level output that can be fed to the Handy Board.
This is exactly the same scheme I use. I'm using an IR module from
Digi-key that has a side view, and five IR LED's spread around the front of
the module at different angles. I have quite a few outputs, thanks to a
little harware hacking, so I just turn on each LED individually and look
for a reflection. The onto the next LED. I can get a sweep from -60° to
60° this way.
\ | /
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\ | /
\ | /
\ | /
\ | /
\ | /
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\ *** /
* _ *
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Kinda like this. *'s are LED'S. the square is the IR module
Works pretty damn good. Adjust the LED current and you get a range from a
few inches to a few feet. Increase the current through the side LED's and
get better peripheral "vision".
I said a couple weeks ago that I would post a schematic and PCB pattern for
my sensor, and I will. Once my exams are over. I now realize that my
configureation is not the best for everybody, that whole digital output
thing. So, I'm working on a better way. Maybe something using the SPI.
Might even wipe up some code too, but no promises.
happy reflecting
harlan
_______________________
Matthew J. Harlan
Cornell University
Electrical Engineering
mjh10@cornell.edu
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Message has 1 Reply:
 | | Re: IR Collision avoidance
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| Matt, You mentioned an IR device from Digi-key. Can you expand (part no.) tel phone no. for Digi. Process analog info from IRs to digital data for HB? What IRs are compatible and where might I get this stuff. Your info into this would be greatly (...) (30 years ago, 5-Mar-97, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: IR Collision avoidance
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| (...) I have a few questions for you. How did you combine the 38khz and 500hz signal. In a design that I am working on now I have two signals similar to yours and an enable signal running into a three input AND gate. I haven't built it yet but it (...) (30 years ago, 2-Mar-97, to lugnet.robotics.handyboard)
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