What is the output of a GPS receiver, how to parse it and how it communicates with uC

[shirazi2589]

Hey all,
I am doing a project on Vehicle Tracking system using GPS. I want to learn about the output of a GPS Receiver, how to parse it, how does it communicate with a uC(I am using 8051). And how to interact with a GSM modem.I know GSM modem works on AT commands.Where can I get more info on AT commands. Or is there any good books available on At commands..Pls help

 

[bitter]

Re: GPS and GSM modem

See GSM Module's user manual .
BTW: Which GSM module do you use?

 

[asic1984]

Re: GPS and GSM modem

Hi Shirazi,

usually GPS devices can output ASCII messages which contains informations that you can use.

the output messages is in NMEA format. NMEA data

Thanks and Best Wishes.

 

[ferdem]

Re: GPS and GSM modem

GPS receivers start to output NMEA sentences when they are powered. I have used two different gps modules and their default data rates were 9600bps. I did not need to change this rate. Here an example GPS output:

$GPGGA,174233.551,4003.8861,N,10512.5838,W,1,04,5.8,1593.0,M,-20.7,M,,0000*51
$GPGSA,A,3,30,22,31,12,,,,,,,,,10.6,5.8,8.9*0B
$GPGSV,2,1,08,31,68,170,31,22,30,119,36,30,22,079,36,12,11,046,32*7D
$GPGSV,2,2,08,14,51,047,20,32,38,309,,11,28,285,,20,11,306,*73
$GPRMC,174233.551,A,4003.8861,N,10512.5838,W,0.07,84.92,200510,,,A*4A
$GPVTG,84.92,T,,M,0.07,N,0.1,K,A*3C
$GPGGA,174234.551,4003.8370,N,10512.6372,W,1,04,2.8,1285.8,M,-20.7,M,,0000*54
$GPGSA,A,3,30,22,31,12,,,,,,,,,4.1,2.8,3.0*3C
$GPRMC,174234.551,A,4003.8370,N,10512.6372,W,0.62,352.44,200510,,,A*70

Check these links:
SparkFun Electronics
https://www.sparkfun.com/tutorial/GPSTracking/raw_5-20-10.zip
SparkFun Electronics

 

[eziggurat]

Re: GPS and GSM modem

As for the GPS receiver, it depends want one you use. If you are using Ublox, you have the option of UBX or NMEA. To talk to the GPS receiver, you would have to use the USART of the micro. For example code, type nmea parser, you should be able to find code which can port to your micro very easily. As for the GSM modem, the AT commands are pretty similar with most modules in the market. Like at+csq, at+creg, at+cced etc.. are similar with most modems. You would have consult with your GSM AT command manual to find out more about the AT commands. To talk to it, you would have to send ascii via the USART in your micro. Overall two usarts is required from your micro to talk to the GPS module and GSM.