Subject:
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Re: Sonar_closeup() doesn't work!
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 31 May 1999 09:50:35 GMT
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Original-From:
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Thomas Hauri <thomas.hauri@zhwin.+NoMoreSpam+ch>
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Viewed:
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1724 times
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Hi
resending a message posted a while ago.
Hi all
if anyone has problems using the 6500 series for distances below 35cm by
using the binh signal I have a possible solution to the problem. We also
expierienced problems using the sensors for distances between 15cm and
40cm. We finally found out that the digital chip (TL851) on the 6500
board gets huge voltage spikes making it detect an echo even if there
was none.
We solved the problem by adding an additional capacitior to the
powersupply.
THE REWORK
Solder a tantal c (1uF) directly to pin 3(Gnd) and pin 1 (+) of chip U2
(TL851).
This will filter the spikes keeping them from droping below 2.5 V.
If anyone has a better way of solving this problems please tell me.
cu TOM
hope this helps.
> I've downloaded sonar.c in Software/Libraries in Handy board homepage,
> and tested it with my H/B and Polarloid 6500 Sonar Module.
> Function sonar_sample() works well. But sonar_closeup() doesn't work.
> It always returns about 6700 regardless of Sonar's position while sonar_sample()
> returns 6700~23000. So I modified the code, but the function -sonar_closeup()
> always returns about 6700 until I make following changes:
> I changes the gap between INIT high and BINH high signal. That is,
> I rewrite following code in sonar_closeup() line 8
> while((peekword(0x100e) - start_time) < 1000 );
> as
> -> while((peekwork(0x100e -start_time) < 4800 );
> I change the gap 2000, 3000, and 4000, but It doesn't work till the value greater than
> 4800 - it is 2.40 ms. which is no better than sonar_sample().
>
> Who knows how I can measure more closer distance with this sonar module?
--
Thomas Hauri
ZHW Zuercher Hochschule Winterthur
University of applied sciences
IMS Institut of mechatronic systems
Technikumstr.9 /PF
CH-8401 Winterthur
Switzerland
Phone : +41 52 267 74 79
Fax : +41 52 268 74 79
Mail : Thomas.Hauri@zhwin.ch
HP : http://www.zhwin.ch
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