GPSpvt Files

README - GPSpvt

GPSpvt - A program to read PVT (Position, Velocity, Time) from a GARMIN GPS
via the USB port in its *native* USB mode.

Device info, as received from the device, and PVT will be printed to screen and
saved to file 'gpspvt.log'.

Tested on device 'GARMIN GPSmap 76CSx' (marine-type, handheld GPS), which has
the Garmin GPS Product_ID: 292, and Garmin GPS SoftwareVersion: 3.90, and has
lsusb info: 'ID 091e:0003 Garmin International GPS (various models)'.

GPSpvt will probably run on most Garmin GPS, and print out device info. But to
get viable PVT data, the GPS must support A800 protocol / D800 datatype.

For reference see the document: 'Garmin Device Interface Specification,
May 19, 2006, May 19, 2006, Drawing Number: 001-00063-00 Rev. C'
(file: Garmin Device Interface Specification (May 19, 2006).pdf).

Make sure the kernel module 'garmin_gps' is *NOT* loaded; otherwise USB is
blocked! When the module is loaded, the GPS will show up as a device under
/dev/ttyUSB*. GPSpvt will print out a 'Resource busy' message, when it cannot
start because the module is loaded!

To remove a loaded module type: 'sudo modprobe -r garmin_gps'.

Requires Python Version 3.x (developed on 3.5.2).


Starting GPSpvt and Connecting to the GPS

   You'll find the Connection Status of the GPS on: Main Menu -> Setup ->
   Interface, but strangley you can't initiate a connection manually.

   Do this:
   - Switch the GPS Off
   - Connect GPS and computer with a USB cable
   - Start GPSpvt (it will keep trying to make a connection)
   - Switch the GPS On
   - GPSpvt will connect and will now communicate with the GPS


Atmospheric pressure sensor

    While there is an atmospheric pressure sensor in the GPS, it can't be
    read out to a computer. Answer from Garmin Support to my question:
    "There aren't any Garmin GPS where the air pressure can be read out".
    Too bad.