Gpsdate is a simple tool which reads date and time from a GPS receiver connected via serial port (or a CDC ACM virtual serial port over USB) and saves it as a local time on Linux.
The program waits for a specified maximum time until a valid $GPRMC NMEA
sentence is received. If the GPS receiver is not fixed and no valid time
information is received, the local time remains unchanged.
git clone https://github.com/adamheinrich/gpsdate # Or download as zip
cd gpsdate
make
Connect the GPS receiver and obtain ts device name. Mine is /dev/ttyACM0 as
found in dmesg:
$ dmesg | tail
...
[22625.034377] usb 1-1.1: new full-speed USB device number 9 using ehci_hcd
[22625.128637] cdc_acm 1-1.1:1.0: ttyACM0: USB ACM device
Then check if it sends back NMEA sentences, e.g. using cat:
$ stty -F /dev/ttyACM0 9600 # Optional
$ cat /dev/ttyACM0
$GPRMC,191745.80,V,,,,,,,160314,,,N*7B
$GPVTG,,,,,,,,,N*30
Now you can gpsdate to change local time:
# ./gpsdate /dev/ttyACM0
Local time was: 2014-03-16 20:19:06 (CET)
GPS time is: 2014-03-16 19:19:07 (UTC)
Successfully updated local time.
Note that changing time requires root privileges. To achieve this, run:
sudo ./gpsdate /dev/ttyACM0
It is possible to change the default baud rate or a timeout. Run the program
with option -h for a complete list of options:
$ ./gpsdate -h
Usage: ./gpsdate [options] port
Sets time from a GPS receiver connected to a serial port as a local time.
Options:
-b <baudrate> Sets baud rate. Only a limited set of baud rates {2400,
4800, ..., 230400} is supported (Default 9600 baud).
-t,-d <timeout> Sets the maximum timeout in seconds or 0 for no timeout
(Default 10 seconds)
-h Displays this help.
Gpsdate is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
See COPYING for details.