Subject:
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Re: Using the IR Port to simultaneously send and receive for proximity sensing
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 16 Apr 1999 13:07:06 GMT
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Original-From:
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John Cooper <robots@jpsc.AVOIDSPAMco.uk>
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Reply-To:
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robots@jpsc.co.uk*stopspammers*
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Viewed:
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1211 times
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> A reflection from an object 2 feet away would return in 4 nanoseconds.
> Each data bit of the transmission takes an enormous 417 microseconds, so
> the reflection is delayed by one hundred thousandth of a bit time. As
> even the shortest message contains 77 bits
Ah, this is a vital piece of information I had hitherto missed. I had been
puzzling over the 30ms delay which makes the Mark R. David proximity
detector work, 77 times 417us is 32ms - Mark is sampling right at the end
of the transmission. My FORTH version is not working at the moment, I
wonder if timing differences mean that I am now missing the end of the IR
flash - I'll try a 16ms delay before sampling, then another 16ms delay
before continuing to make sure the pulse is finished.
--
John & James Cooper, Wallington, UK
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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