From mwallace@sps1.phys.vt.edu  Mon Aug  3 12:05:51 1998
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Date: Mon, 3 Aug 1998 11:16:50 -0400 (EDT)
From: Mark Wallace <mwallace@sps1.phys.vt.edu>
To: alf.kuchenbuch@usa.net
Cc: handyboard@media.mit.edu
Subject: Re: Polaroid trouble again
In-Reply-To: <35C5C521.446B@eikon.e-technik.tu-muenchen.de>
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	I had this same problem when I got mine a few weeks ago.  I ended up
putting a capacitor from pin 1 to pin 3 on U2 of the sonar driver board.
I also had to take out the 1k resistor from the BINH.  It kept
BINH at 1 V instead of Zero and that seamed to cause problems.
	As for the 6 ft problem,  it should be closer to 9 ft.  I think
the problem there is the IC code you used.  If you used the code for
SONAR.C from the HB web site then there is a problem with it.  What that
program does is take the difference in time from the internal clock.  the
problem is that in the code it says that if the difference between start
time and currnet time is negative too much time has elapsed.  Well,  this
has a 16 bit counter so when the difference is greater the about 32,700 it
becomes negative.  If you do the math, that means at about 9 ft that
happens so it tell you you are out of range.  
	The way I fixed this was to slow the clock down.
	
I looked up information on the motorola web page and found where the
prescalers were for the clock. 
	If you want to slow it down by a factor of four you can just add
this line to you program in sonar_init()

	bit_set(0x1024, 1);

I believe bit_set(0x1024, 2); will slow it down by a factor of 8 and
bit_set(0x1024, 3); will slow it down by a factor of 16.  
	There are better ways of fixing this problem but they appear much
more complicated.  For example the motorola chip has an overflow flag that
says when the internal clock flips.  You could incorporate that into your
code instead of slowing the clock down.  Good luck and I hope this helps.

Mark Wallace

 e-mail  mawalla3@vt.edu
         mwallace@sps1.phys.vt.edu
Web page http://sps1.phys.vt.edu/~mwallace/index.html

"What a waste it would be after 4 billion tortuous years of evolution if
the dominant organism contrived its own self-destruction"
                                        Carl Sagan

On Mon, 3 Aug 1998, Alf Kuchenbuch wrote:

> Hi!
> I am having trouble with my Polaroid sonar: 
> When I keep my HB hooked up
> to external power, I will only get correct readings up to 20 inches. As
> soon as I use battery power without hooking it up to external power, the
> readings are correct up to 6 feet, not more! This sound like EMI, I
> guess. I tried all the capacitor tricks from HB mailing list, but in
> vain. Do you know a fix that works? 
>  
> Alf H. Kuchenbuch
> 


From mawalla3@vt.edu  Wed Aug 12 13:10:06 1998
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Date: Wed, 12 Aug 1998 12:13:45 -0400
To: Handyboard@media.mit.edu
From: Mark Wallace <mawalla3@vt.edu>
Subject: serial library for C++ 
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Hello,
	I have a handy board with poloroid transducers and I am trying use the
results of my distance measurments in a C++ program on the computer.  I
have found programs on the handyboard web page that should alow the
handyboard to transmit information over the serial line.  What I am looking
for is if anyone knows were I could find a serial for Microsofts
Visual C++ 5.0.  I would like to find one that is free or sharware but any
information on any serial that will work would be appreciated.
Thanks.
Mark Wallace

 e-mail  mawalla3@vt.edu
	 mwallace@sps1.phys.vt.edu
web page http://sps1.phys.vt.ede/~mwallace

"What a waist it would be after 4 billion tortuous years of evolution if
the dominant organism contrived its own self-distruction"
			Carl Sagan


From aarone@sirius.com  Wed Aug 12 13:42:19 1998
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From: "Aaron Edsinger" <aarone@sirius.com>
To: "Mark Wallace" <mawalla3@vt.edu>
Cc: "handy" <handyboard@media.mit.edu>
Subject: Re: serial library for C++ 
Date: Wed, 12 Aug 1998 12:53:41 -0700
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  Check out this site.  It works well.  The only problem I had was timing
issues when trying to read and write to the port too quickly.

http://www.codeguru.com/show.cgi?general=/misc/misc_toc.shtml


-----Original Message-----
From: Mark Wallace <mawalla3@vt.edu>
To: Handyboard@media.mit.edu <Handyboard@media.mit.edu>
Date: Wednesday, August 12, 1998 9:25 AM
Subject: serial library for C++


>Hello,
> I have a handy board with poloroid transducers and I am trying use the
>results of my distance measurments in a C++ program on the computer.  I
>have found programs on the handyboard web page that should alow the
>handyboard to transmit information over the serial line.  What I am looking
>for is if anyone knows were I could find a serial library for Microsofts
>Visual C++ 5.0.  I would like to find one that is free or sharware but any
>information on any serial librarys that will work would be appreciated.
>Thanks.
>Mark Wallace
>
> e-mail  mawalla3@vt.edu
> mwallace@sps1.phys.vt.edu
>web page http://sps1.phys.vt.ede/~mwallace
>
>"What a waist it would be after 4 billion tortuous years of evolution if
>the dominant organism contrived its own self-distruction"
> Carl Sagan
>

