Subject:
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Re: serial communications
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 9 Jun 1998 03:56:45 GMT
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Original-From:
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John Duff <jnduff@ra(IHateSpam).cland.net>
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Reply-To:
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jnduff@STOPSPAMMERScland.net
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Viewed:
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1181 times
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Justin
Here is the file. Please feel free to modify/improve. I'm a doctor not a
programmer, and I better keep my day job.
Notice it borrows Randy Sargent's and Dr. Richard F. Drushel's routines found in
serialio.c and math.c, both on the handy board web site.
This program could be used with any NEMA compliant GPS receiver. The Tripmate
has two quirks: First, the DTR line is taken high to turn on the receiver.
Second, after power up, the receiver sends an ASCII string 'ASTRAL' and waits for
the computer to respond with the same string. I handled this by connecting two
DB9 plugs together, shorting pins 2 and 3 (the Rx and Tx pins) on the GPS side
and then connecting these to pin 3 on the handyboard end. This causes the
'Astral' string transmitted by the GPS unit to echo back and trick the GPS. Also
connect pin 4 (DTR) to a lead and plug into any +5 v location on the handy board.
Then connect the jumpered plug to the handy board serial adapter (GPS outputs at
RS-232 signal levels, need to change to TTL.) Now when the handy board is turned
on, the GPS unit is powered up and begins to acquire satalites. Sit back and wait
untill you have a valid signal, and you're in business. I've made this sound
hard, but it takes 15 minutes and a little solder.
I started to write a routine for calculating the checksum and compare with
transmitted, but never finished. What I have is at the end of the file. Possibly
someone would like to finish it. I would appreciate any improvements. Thanks
John
GJZ@aol.com wrote:
> John,
>
> yes i would appreciate getting the IC program you use. need the GPS receiver
> that is used be a board, or may it be interfaced with a handheld unit. i was
> planning on getting a board, such as the motorola oncore series. if it is
> possible to interface the HB with a handheld unit? thank you in advance for
> your generosity.
>
> Justin D. Gullotta.. , Engineer,
> Rensselaer Polytechnic Institute.
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