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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Sat, 6 Jun 1998 19:23:08 GMT
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Original-From:
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John Duff <JNDUFF@RA.avoidspamCLAND.NET>
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Reply-To:
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JNDUFF@CLAND.nomorespamNET
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Viewed:
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2157 times
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Justin,
Interfacing a GPS to the handyboard is straight forward. Most GPS receivers
comply with the National Marine Electronics Association (NMEA) standards. They
transmit their information in ASCII "sentences" which are framed by a $ at the
beginning and <cr><lf> at the end. The data elements, such as lat, lon, elevation,
speed and direction are comma delimited and their position in the sentence is
determined by the NMEA standard. It is simply a matter of counting commas to
identify any of the elements. Error checking is limited to a calculated checksum
which is transmitted at the end of the sentence. It should be easy to recalculate
this value (it is the XOR of all the data elements), and compare with the
transmitted value.
I have my Tripmate GPS unit connected, and I pull out current position. I use a
V2X compass connected to SPI for heading info. Several good sites related to
GPS and the NMEA standards are available. Here is a link to one you might try.
ftp://sundae.triumf.ca/pub/peter/index.html#links
If interested, I can send you the IC program I use.
John
GJZ@aol.com wrote:
> i have been looking thru the libraries that people have posted on the web,
> particularly the ones that allow serial communication. i am not sure how the
> system works, but there are numerous routines which turn handshake on and off,
> as well as routines which will time out if there is no response from the
> receiving device. i am not sure what handshake is, i am guessing that it is a
> "ready check". i am wondering how the protocol for sending data is set up,
> and if there is a way to access the bare bones I/O that the HC11 comes with.
> is the difference extra software procedures that the HB uses to insure proper
> data transmission? is there any way that one can program the HB to use simple
> start/stopbit protocol to receive data. in particular, i am interested in
> interfacing the HB with a GPS receiver, which i know are designed to
> communicate with a microcontroller. what type of transfer protocol is used in
> this application? if anyone has info on libraries that allow this kind of
> communication, please let me know. or would this have to be done thru
> assembly language? thanks for your help.
>
> Justin D. Gullotta.. , Engineer,
> Rensselaer Polytechnic Institute.
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Message has 1 Reply:
 | | Re: serial communications
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| (...) I too have done this, with both a Garmin GPS-II+ and a Garmin GPS-35PC. I have posted segments of the code necessary to do this to the Handyboard list before, so if you look through the archives and grep for "WE7U", you should find them. If (...) (27 years ago, 8-Jun-98, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | serial communications
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| i have been looking thru the libraries that people have posted on the web, particularly the ones that allow serial communication. i am not sure how the system works, but there are numerous routines which turn handshake on and off, as well as (...) (27 years ago, 6-Jun-98, to lugnet.robotics.handyboard)
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