Re: [gpsd-dev] GPSd on FreeBSD

[Gary E. Miller]

Yo Daniel!

On Mon, 9 Sep 2019 17:08:30 +0930
"O'Connor, Daniel" <address@hidden> wrote:

> I have a Beaglebone Black running FreeBSD with a u-Blox NEO-M8T which
> I want to use as a time source.

Cool.  Many people do that without issue.

> It is connected to an internal UART and a timer channel is used for
> PPS capture.

Good.

> These end up as cuau2 (symlinked to /dev/gps0) and /dev/dmtpps
> (symlinked to /dev/pps0) respectively so my ntp.conf looks like:
> server 127.127.20.0 mode 0x12 minpoll 4 maxpoll 4 fudge  127.127.20.0
> time1 0 time2 0 flag1 1 stratum 0 refid GPS <snip>

Uh, don't do that!  You are trying to set time on the NMEA stream, which
will be jumpy on the oder of hundreds of ms.

You need to set the time on the PPS.  Check out the time-server howto.

> And it all looks good:

Not really.  Your NTP is not using the SHM(0).  Which is a good thing.
It should be using your SHM(1), your PPS.


> However I wanted to used GPSD to process the NMEA (mainly so I can
> monitor satellite visibility and the like), can it handle the two
> separate devices correctly?

Of course.  Very common.

> If I run gpsd like so..
> sudo ./gpsd -D5 -NnG /dev/gps0 /dev/pps0

Well, other than that sudo is bad, that is very common.  Running
in the foreground, with debug on high, degrades your timing quality.


> I get..
[...]
> gpsd:WARN: PPS:/dev/pps0 die: no TIOMCIWAIT, nor RFC2783 CANWAIT
> gpsd:PROG: PPS:/dev/pps0 gpsd_ppsmonitor exited.

Your system PPS is not correctly configured.  I'm not familiar enough
with BSD to say where...

> It seems it isn't actually opening /dev/pps0 (based on the -2 for FD)

No, re-read the message.  It just says it can not use TIOMCIWAIT.  It
should use KPPS instead, which is better, but that also failed.  I'm
not afmiliar enough with *BSD to know why, but it does work for others.

> The PPS API does work on this device:
> [gps 7:35] ~/gpsd
> >/usr/obj/arm-src/arm.armv7/tools/test/ppsapi/ppsapitest /dev/pps0

I'm unfamiliar with ppsapitest.  What does "ppscheck /dev/pps0" show?

> Examining the code shows a big chunk is Linux specific so I guess I
> will have to modify it but if someone has advice on what the "right
> way" to do is that would be great :)

When you compiled gpsd it auto-detects your system.  It will autodetect
many flavors of *BSD and work just fine.

Can you provide your compile logs?

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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