View source for Neo FreeRunner GPS

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GTA02 GPS Hardware

GTA02 using the u-blox 4 hardware and could use u-blox 4 Assist Online GPS A-GPS servces. GTA02 hardware design not comply with official Assist Offline service requirement.

Assist Online/Offline comparsion

th "A"GPS support could cut TTFF time from 40 secs to 10-20 seconds. And the valid time of assist now download is about 4 hours. You could also check the following address:

Due to the u-blox 4 need to have extra flash to storage up to 14 days of offline data (90 KBytes).

Assist Online

Each download package could have up to 4 hours vaild data to assist TTFF. For u-blox Assist Online, you have to provide approximate longitude/latitude and time to get the corresponds "almanac" and "ephemeris" package. This might be base on application design for how to provide the longitude/latitude. User could select the location area from list menu or world map, or better implementation using the GSM/wi-fi location technique/service.

u-blox Assist Online implementation

For GTA02 default shipment image, there is no A-GPS/GPS supported software inside. You could find the u-blox A-GPS online implementation document here:

And implementation code in following address.

Here is a brief script to run this application:

  1. !/bin/sh

echo 1 >/sys/bus/platform/drivers/neo1973-pm-gps/neo1973-pm-gps.0/pwron

./agps-onlinec -c full -u youraccount -k yourpasswd -la 25.073270 -lo 121.574805 -p 999999.00

cat /dev/ttySAC1

Assist Now account application

And account application is send a mail to

without content and title. And not all mail account are accepted/could get reply. since the protocol is pretty straight forward, implement an extra proxy to scale up user should be easy.

Assist Offline

Up to 14 days of assist TTFF data

u-blox Assist Offline implementation

Due to the u-blox 4 need to have extra flash to storage up to 14 days of offline data (90 KBytes), GTA02 don't have it. I would very interested if there is another way to twist it around, but not likely, so far. Offline sample data you could find in the following addesss:

And u-blox did provided source code of Assist offline server implementation and ubx header, you could find it here:

UBX protocol

Sample header could be found here: ubx.h

GPS test program

Openmoko projects has a GPS test program called AGPS UI in following address: