Difference between revisions of "GPS"

Revision as of 18:55, 13 July 2009

This page will summarize informations to connect GPS modules to your Armadeus board.

Introduction

GPS stands for Global Positioning System and is intended to allow one to knows its localization on Earth quite accuratly. See this Wikipedia article for more informations.

APF27Wireless hardware

The uBlox NEO-5M module is used on the APF27Wireless board. The specifications can be found here: http://www.ublox.com/en/gps-modules/pvt-modules/neo-5m.html

Other tested hardware

GPS receivers are generally driven through a low speed RS232 bus or USB.

RS232 modules

The following RS232 receivers were successfully tested:

• the GPS receiver of the Projet Aurore association. This autonomous receiver uses a standard NMEA GPS module that can be connected to the 3,3V RS232 port of your APF9328. All you need to do is to get the GND and TX signals out of this module and connect is to your GND and RX signals of your APF:
  

Recto

Verso

• the GPS receiver of the APF27 Wireless extension board

USB modules

These modules are mostly serial one with a RS232 <-> USB converter.

Usage

APF27 Wireless

• Configure Serial port 4 of your APF27 (38400 bauds 8N1):

 # stty -F /dev/ttySMX4 38400

• Test it: you'll get NMEA frames:

 # cat /dev/ttySMX4
 $GPGSV,3,1,12,01,80,354,,02,32,070,38,04,13,037,09,09,14,146,*78
  
 $GPRMC,164916.00,V,,,,,,,130709,,,N*7C
 
 $GPGGA,164916.00,,,,,0,00,99.99,,,,,,*6B

APF9328

• Configure Serial port 1 of your APF9328 (4800 bauds 8N1):

 # stty -F /dev/ttySMX1 4800

• Power on your GPS module
• Test it: you'll get NMEA frames:

 # cat /dev/ttySMX1
 $GPGGA,000026.032,,,,,0,00,,,M,0.0,M,,0000*53
 
 $GPGSA,A,1,,,,,,,,,,,,,,,*1E
 
 $GPRMC,000026.032,V,,,,,,,160406,,*2F
 
 $GPGGA,000027.032,,,,,0,00,,,M,0.0,M,,0000*52

There is a small tool (under development) in target/demos/gps/ that can help you to parse some NMEA frames.

NMEA Frames signification

• $GPGGA: Global Positioning System Fix Data
• $GPGLL: Geographic Position, Latitude/Longitude
• $GPGSA: GPS DOP and Active Satellites
• $GPGSV: GPS Satellites in View
• $GPRMB: Recommended Minimum Navigation Information
• $GPRMC: Recommended Minimum Specific GPS/TRANSIT Data

Troubleshots

• In case your Aurore GPS module is detected and then automatically removed from USB stack when you plug it on your PC, try to deinstall that:

$ sudo apt-get remove brltty

Links

• http://en.wikipedia.org/wiki/Global_Positioning_System
• http://vancouver-webpages.com/peter/nmeafaq.txt
• http://www.futuraelettronica.net/pdf_ita/8160-ET312.pdf
• Documentation sur le module GPS du projet Aurore