GPS Log Shield

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jose angel
 
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Joined: Mon Dec 08, 2008 5:47 pm

GPS Log Shield

Post by jose angel »

Hi,
I'm experiencing a strange behaviour with the GPS (EM-406A) used with the GPS log shield:
Everything works fine, but using any Ladyada's example code produces the same problem: the GPGGA information line.
I activate it using the "$PSRF103,0,0,1,1*25\r\n" command, but I only get *always* two GPGGA lines:

-one accurate line at the begining of the log:
$GPGGA,033128.102,4022.8511,N,00336.2877,W,0,03,,695.4,M,51.7,M,,0000*62
-another one (approx. 20' later) and incomplete:
$GPGGA,035112.956,,,,,0,00,,,M,0.0,M,,0000*58

Anyone has experienced something like that? This info was generated at home with the GPS not moving. Testing it on the car gave same results.
I'm very interested in registering altitude and GPGGA seems to be the only place to find it on NMEA codes.
Any idea?
Thanks in advance

Regards

Jose

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: GPS Log Shield

Post by adafruit »

do you get any GGA lines or just 2?

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jose angel
 
Posts: 3
Joined: Mon Dec 08, 2008 5:47 pm

Re: GPS Log Shield

Post by jose angel »

Hi Ladyada,

It's a pleasure having your support. A pity not to see you at the CCC this year.

Regarding the log, I got **only** those two lines showed.

As you could see by the time stamp, I spend part of the night messing with it. Got only two GPGGA.

One at the beginning with the correct GGA data line (first 9 lines of the log):

$GPRMC,033123.513,A,4022.8275,N,00336.2786,W,0.00,,081208,,*0A
$GPGSV,3,2,10,12,31,211,,17,25,081,28,28,19,044,46,05,17,219,*71
$GPGGA,033128.102,4022.8511,N,00336.2877,W,0,03,,695.4,M,51.7,M,,0000*62
$GPGSA,A,1,09,18,28,,,,,,,,,,,,*14
$GPGSV,3,1,10,15,75,126,,09,53,294,44,26,51,121,,18,35,290,44*7F
$GPGSV,3,2,10,12,31,211,,17,25,081,,28,19,044,43,05,17,219,*7E
$GPGSV,3,3,10,22,13,319,,10,03,174,*71
$GPRMC,033128.102,A,4022.8511,N,00336.2877,W,,,081208,,*1F
$GPGSA,A,2,09,18,28,,,,,,,,,,13.3,13.2,1.0*39


And other at the end (last 13 lines of the log):

$GPRMC,035108.000,A,4022.8590,N,00336.2922,W,1.80,131.57,081208,,*18
$GPGSA,A,3,09,18,28,12,22,,,,,,,,2.9,1.5,2.5*33
$GPGSV,3,1,10,15,66,138,,09,59,307,27,26,44,129,,12,39,214,14*75
$GPGSV,3,2,10,18,36,279,26,17,27,072,07,05,25,223,,22,17,313,22*7A
$GPGSV,3,3,10,28,12,044,18,30,01,222,*78
$GPGSA,A,3,18,28,12,22,,,,,,,,,9.6,2.9,9.2*3D
$GPGSV,3,1,10,15,66,138,,09,59,307,25,26,44,129,,12,39,214,14*77
$GPGSV,3,2,10,18,36,279,27,17,27,072,,05,25,223,,22,17,313,21*7F
$GPGSV,3,3,10,28,12,044,18,30,01,222,*78
$GPRMC,035110.000,A,4022.8572,N,00336.2905,W,1.65,139.48,081208,,*15
$GPGGA,035112.956,,,,,0,00,,,M,0.0,M,,0000*58
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,10,15,66,138,,09,59,308,,26,43,129,,12,40,215,*72

The log is about 300kb. If you want to see it all, I'll be pleasured to send.

This behaviour is quite strange: I'm telling the GPS to send me every second a GGA line using the "$PSRF103,0,0,1,1*25\r\n" command

Have any idea why it works this way? Is there any way to run a test routine on the GPS ?

Warm regards

Jose

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: GPS Log Shield

Post by adafruit »

yup
the best way to run a test is wire it up with an FTDI cable or with the arduino chip removed (see the user manual)
and connect with the sirfdemo software (download from http://www.ladyada.net/make/gpsshield/modules.html )
sirfdemo kinda sucks BUT you'll get a lot of details and more info about why it may be failing

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