Subject:
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Re: Polaroid sonar problems
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 1 Mar 1999 23:53:58 GMT
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Original-From:
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Will Bain <willbain@cs#AntiSpam#.umt.edu>
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Viewed:
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1463 times
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Guy Berg wrote:
> Our group is still struggling with the polaroid sonar. We can't get any
> coherent reading, only readings that are in the range 470-515, which
> aren't effected by the measured distance.
> We have the capacitor and resistor installed as required.
> We tried using a 150ms delay (instead of 50) and we average our
> readings, we tried taking every tenth reading and displaying it, but
> nothing seems to work.
I assume that your sonar pings (makes a clicking sound). If so, then
you may be getting a premature echo. You might try mounting the
transducer in putty to absorb vibration. You could try lengthening the
blanking interval to make sure that the "echo" is not just a
reverberation of the ping; this requires hooking up the blanking pin of
the sonar board to one of the unused digital outputs and sending it high
for an adequate period of time. Note that if you want to use all four
of the SPI pins as digital outs, you need to do a bit_set(0x1009, 0x3C)
in the initialization instead of bit_set(0x1009, 0x30). (I assume
you're executing sonar_init() prior to executing sonar_sample() )
Also, make sure you start off with the sonar code provided on the HB web
site before you make any modification to it (I screwed it up a couple
times myself, trying to improve it ;^)
Other than that, just verify all your connections using a multimeter.
Make sure that you have continuity between the echo pin on your Polaroid
6500 ranging module board (pin 7) and the sensor pin of HB input port 7
(the top pin of the three). I've seen dire warnings not to (A) plug in
the ribbon cable backwards, and (B) try to ping without the transducer
connected. I suppose there could be a fried chip somewhere, but without
an oscilloscope it would be very difficult to find.
Sorry I can't be more helpful :^(
--Will
, ,
__@_/ \_@__ |/
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)\ ) ( \ (\/\\,
~~~~~~~~~ ' ` ~~~~~~~~~~~ ` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Wendy Parson, The big thieves
Will Bain, hang the little ones.
& Tatoosh --Czech proverb
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Message is in Reply To:
 | | Polaroid sonar problems
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| hi! Our group is still struggling with the polaroid sonar. We can't get any coherent reading, only readings that are in the range 470-515, which aren't effected by the measured distance. We have the capacitor and resistor installed as required. We (...) (26 years ago, 1-Mar-99, to lugnet.robotics.handyboard)
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