GPS001 not receiving ?

Hi, Yesterday my AXE210 starter pack and the GPS001 GPS receiver arrived, great ! i builded a axe 210 board to fit the GPS receiver so it could connect to my computer and all went well for one little detail, the GPS module seems to refuse to receive signals. It see's sattelites (11) and dumps NMEA info to the computer but according to the coordinates i'm living somewhere in Asia :).

I used the supplied antenna and had it running for hours in the open air, the status led is blinking with an interval of ~ 4 seconds and the RSSI led stays of.

a dump of the NMEA data received:

$GPRMC,173259.00,V,4907.8000,N,12303.6000,W,,,290106,,,N*54
$GPGGA,173259.00,4907.8000,N,12303.6000,W,0,00,0.0,,M,,M,,*43
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,10,05,57,295,,09,54,242,,04,51,083,,02,34,175,*72
$GPGSV,3,2,10,07,32,067,,20,13,057,,14,10,320,,17,03,190,*74
$GPGSV,3,3,10,01,01,350,,30,01,296,*71

anyone had any luck using this module ?

TIA dave !
 

Technical

Technical Support
Staff member
$GPGGA,173259.00,4907.8000,N,12303.6000,W,0,00,0.0,,M,,M,,*43

Data 6 and 7 means position 'fix unavailable', '0' satellites in use.

ie the unit is not locking onto a satellite. the other data is therefore invalid.

Therefore the unit is not seeing 11 satellites - its not finding any! Check the antenna connections carefully.
 
Your right !

I used the antenna from a GPS mouse laying around, for this i had to cut off the coax cable from the GPS antenna i ordered with it ( GPS Antenna (GPS002)) and now i've got a fix and a void warranty on the antenna :-(

It looks like the antenna techsupplies is shipping is incorrect or malfunctioning.
 
getting data from the gps module isn't that difficult, the only problem is the timing of the serin command, the picaxe is just to slow to read all the info from a NMEA message at once and there arent enough variables to store all the info. You have to use a qualifier with the serin command and read the nmea info multiple times, each time for a different part of the nmea info you want and store it in SFR.

example:

use the b0 variable as a dummy to put all the not wanted info in.

getLatitude:
serin 7,T4800,("$GPRMC"),b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b0,b1,b2,b3,b4,b0,b5,b6,b7,b8,b0,b9

'put in sfr

poke $c6,b1
poke $c7,b2
poke $c8,b3
poke $c9,b4
poke $ca,b5
poke $cb,b6
poke $cc,b7
poke $cd,b8
poke $ce,b9
return


I can post my test program to give you some help.

i'm thinking to of making a support chip which receives the gps data and stores it so the picaxe can query it for the info you want, the only problem is that i have to learn ASM for it (and buy a programmer) so this will take weeks of time.

maybe an idea for the guys at picaxe co. to sell ?

http://www.rfsolutions.co.uk has a tool called LSViewer wich you can use with the AXE210 board connected to you pc (use the MAX chip, not a picaxe !!) and test/configure the GPS module.


Edited by - dave_h on 2/10/2006 10:41:34 AM

Edited by - dave_h on 2/10/2006 10:42:36 AM
 

tarzan

Senior Member
Thanks Dave
Yes; please do post your code.
I was thinking something along the lines of a serial buffer.
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