[ntp:questions] Sure GPS: Programming it now works

unruh unruh at wormhole.physics.ubc.ca
Fri Apr 8 00:12:14 UTC 2011

On 2011-04-07, unruh <unruh at wormhole.physics.ubc.ca> wrote:
> On 2011-04-07, Uwe Klein <uwe at klein-habertwedt.de> wrote:
>> unruh wrote:
>>> Somewhat more awkward than Terje's program, but it works.
>> I've collected a bit of information
>> 	http://wiederlinge.de/cgi-bin/lnwiki.cgi/147
>> and wrote a basic parser script:
>> 	http://wiederlinge.de/cgi-bin/lnwiki.cgi/150
>> Terje added some info too.
>> I will add the commands stuff to my script
>> in ~10days. no time now.
>> Feel free to add.
> Actually a more complete set of instructions that can be sent under the
> MTK protocol is in 
> gpsd.googlecode.com/files/MTK_NMEA_Packet_0.71_Sanav.pdf
> I of course have no idea which of these are actually valid for the
> particular chipset that the Sure board uses. 
> This list includes the command  251($PMTK251) --change serial bitrate command,
>  missing from the ETEK list. It also includes a rich set of Datum for the models used.
> I do not know if the Sure can be changed from the WGS1984 Datum, in case
> anyone might want to use, for example, number 147 -- Old Egyptian(1907)
> datum instead.

OK, the Sure chip does seem to respond to a number of those commands. I
tried to change the Datum, query the datum,  and all  worked. I tried 
a few of the other, especially query commands (The 300 commands seem to 
be to change stuff, the 400 level commands are the query commands, 
and the 500 level are the responses to the 400 level commands. Thus 330
is set datum, 430 is query datum, and 530 is the response to 430
The 300  commands get a response of PMTK001,3 if they are successful.

Query 604 (Firmware Version query) give unsupported command error, but
605 (Release query) works.

Ie, this list of commands seems to be much more complete than the Etek

Again there is no requirement as to timing of sending the commands, but
the replies come after the nmea sentences. Ie, it may be that if you
wait for a break, you can immediately parse the next packet from the
board  to find out what the answers are. 

I am also quite impressed with the sensitivity. I am sitting inside my
office (on the east side of the building with huge trees just outside
the window, and am getting timeing lockon.) 


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