| Re: Reading GPS NMEA via serial port [message #43316 is a reply to message #43083] |
Mon, 04 April 2005 15:43  |
andrew.cool
Messages: 47
Registered: July 2003
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Member |
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b_gom@hotmail.com wrote in message news:<1111525509.015828.49450@z14g2000cwz.googlegroups.com>...
> Andrew,
>
> I assume you converted the byte array into a string. Is the NMEA string
> you posted what you get, or what you expect to get?
I'll answer my own post - it may help someone else who starts out as
bone ignorant as me of matters GPS.
My GPS unit (Fortuna out of Taiwan) uses the SiRF chipset, which follows
(by default) the SiRF Binary Protocol, which is a whole different kettle
of kippers from human readable NMEA ASCII strings.
Alas, the crappy little manual provided with my GPS unit didn't see fit to
mention any of this...
So the crazy, mixed up stream of bytes I was seeing is entirely kosher
afterall - you just have to decode them according to the SiRF Protocol.
Or, you can send the GPS unit a command to switch it into NMEA mode.
Here's a link to a very good Windows utility called SiRFDemo, that can
toggle between SiRF and NMEA, and display all the GPS info :-
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=25575
And for completeness, here's one place to download a copy of the
SiRF Binary Protocol, so that you can decode all those byte values that
stream out of the GPS unit :-
http://www.rayming.com/download/SiRF%20Binary%20Protocol.pdf
I haven't progressed much further on my own code recently, as I've
been busy renovating the house prior to sale, buying a new car for the
wife, and now the space bar on my laptop at home has done a John Paul II,
and stopped responding.
And Soccer season starts next week for the 3 females in the household,
so there goes my weekends too... :-(
But I remain determined to read this blasted GPS thingy! Certainly the
serial dll from the RSI User Contrib site works well.
Andrew (who's getting there slowly) Cool
Adelaide, Oz
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