LS20031 5Hz (66 Channel) GPS Receiver Hookup Guide
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Troubleshooting
Below are a few additional troubleshooting tips and tricks when using the LS20031 GPS receiver.
1.) GPS Lock Problems With No Satellites in View
If there are no satellites in view, try moving to a different location. Using any GPS receiver inside a building makes it difficult to get a GPS lock. This also applies to locations with objects (i.e. urban canyons) that can block the GPS receiver's view to satellites.
2.) GPS Lock Problems With Satellites in View
If your unit can see 4+ satellites but never gets a fix/lock, try sending a FULL_COLD_RESTART. A user a problem where the unit would report that it could see up to 9 satellites (the "09" in the below GSV sentences):
$GPGSV,3,1,09,05,,,39,29,,,31,26,,,42,02,,,38*7F
$GPGSV,3,2,09,21,,,20,15,,,18,30,,,29,10,,,24*72
$GPGSV,3,3,09,07,,,25*70
While the GPS could see 9 satellites, it never started producing position data / blinking the red LED. Try sending the following command. You will need to connect to the GPS receiver's Rx pin.
Serial.println("$PMTK104*37"); // FULL COLD RESTART
Details are listed in the MTK NMEA Packet User Manual. This resets the GPS's almanac, which very rarely comes with bad data. If you are using the older TinyGPS library, it only uses GGA and RMC sentences. Therefore, you could configure your unit to only send those values, and only once every 5 fixes (that is, 1Hz) using the following command:
Serial.println("$PMTK314,0,5,0,5,0,0,0,0,0,0,0,0,0,0,0,0,0*28");
3.) No Output When Using Examples in the TinyGPSPlus Library
The examples in the TinyGPSPlus Library require a satellite lock in order to view the parsed data. Try viewing the output using an FTDI to see if the GPS receiver is outputting NMEA sentences. If you are able to view NMEA sentences then the LS20031 is functional. You will probably just need to move to a different location to achieve a satellite lock or reset the GPS receiver as explained above.