Re: Fwd: GPSD Time Service HOWTO

[Greg Troxel]

Xavier Ruiz <xavier.ruiz@earthrover.farm> writes:

> In my case, I have a Piksi Multi RTK GNSS module
> https://www.swiftnav.com/piksi-multi that I am using in Linux 18.04 with
> ROS. This device is manufactured by Swift Navigation and they have their
> own protocol called SBP (Swift Navigation Binary Protocol) instead of using
> NMEA. The module also provides a PPS signal. We have a Nvidia Jetson Xavier
> as a host Arm computer. We connect the GPS with the Nvidia through ethernet.
> We have a way to extract the absolute time of the SBO message using a ROS
> (Robotics Operating System) wrapper of the Piksi GPS
> https://github.com/ethz-asl/ethz_piksi_ros. ROS is basically a robotics
> middleware that runs on Linux. My question is if I could use this absolute
> time from ROS in the gpsd pkg rather than from the serial NMEA msg in order
> to sync my clocks.

1) It would be nice if someone contributed code to gpsd to deal with
SBP, separately from your issue.  (I'm assuming this isn't present but
haven't relaly checked.)

2) What gpsd actually does is provide two shared-memory interfaces, one
for the navigation stream (NMEA typically, but can be e.g. binary
u-blox), and one for PPS.


You could have the code that extracts the navigation messages create a
shm segment and speak the protocol.  Or you could proxy those messages
into NMEA and feed them to gpsd.

Overall, I think you have some work to do but this is quite doable.

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