Re: [gpsd-users] 1PPS issue with Jackson Labs Mini-PCIe GPS Module.

[Gary E. Miller]

Yo Lyle!

On Wed, 27 Apr 2016 14:28:09 +0000
Lyle Baker <address@hidden> wrote:

> > gpsd version 3.9 is old and unsupported.
> I've updated to Ubuntu 16.04 from 14.04. This version includes: gpsd:
> 3.15 (revision 3.15-2build1)

Better, but we can't really support anything but 3.16 or git head that is
from the gpsd tarballs.  We have no diea what Ubuntu may have done to the
binaries.

> > So this GPS sucks for timekeeping, hopefully good enough for you.  
> 
> I hope to have a new motherboard shortly where I can tie the TTL 1PPS
> output to a GPIO pin, but so far I've found even less information on
> how to make that work than I have the USB serial port version.

There is a lot of doc lately on using GPS HATs on Rasberry Pi's and
Odroids.  The gpsd INSTALL file has some info, and we are working on a
comprehensive HWOTO.

> > You do have KPPS for your ttyUSB, so if DCD is there you should see
> > it.  
> 
> If I run gtkterm, I can see the DCD line toggling on the display.

Good.  That confirms good PPS.

> ntpshmmon shows:
> 
> sample NTP0 1461764649.135457957 1461764649.134715195 1461764649.000000000 0  
> -1 
> sample NTP0 1461764650.135921285 1461764650.128227220 1461764650.000000000 0  
> -1 
> sample NTP0 1461764651.136068301 1461764651.132532795 1461764651.000000000 0  
> -1

Not good, PPS should be showing as NTP1.

Can you firm you had a 3D fix when you ran ntpshmmon?

> > If ntpshmmon does not show PPS, then run debug this way to give us
> > the PPS related stuff, without the other cruft.:
> >
> > # gpsd -nN -D 9 /dev/ttyUSB0 |& fgrep PPS
[...]
> gpsd:INFO: KPPS:/dev/ttyUSB0 pps_caps 0x1133 
> gpsd:INFO: KPPS:/dev/ttyUSB0 have PPS_CANWAIT 
> gpsd:INFO: KPPS:/dev/ttyUSB0 kernel PPS will be used
> gpsd:PROG: PPS:/dev/ttyUSB0 thread launched 
> gpsd:INFO: PPS:/dev/ttyUSB0 ntpshm_link_activate: 1 

Good, Kernel PPS was found and will be used.

> gpsd:ERROR: KPPS:/dev/ttyUSB0 kernel PPS failed Interrupted system call
> gpsd:ERROR: KPPS:/dev/ttyUSB0 kernel PPS failed Interrupted system call
> gpsd:ERROR: KPPS:/dev/ttyUSB0 kernel PPS failed Interrupted system call

Bad, gpsd is not seeing the DCD.

While gpsd is running, and you have a good 3D fix, check to see what 
PPS devices you have:

~ # ls /dev/pps* -l
crw------- 1 root root 253, 0 Apr 18 23:27 /dev/pps0

gpsd creates thoose, as needed, from the /dev/ttyUSB0.

You can see I have /dev/pps0.  Look at that with ppstest:

spidey Dir # ppstest /dev/pps2
trying PPS source "/dev/pps2"
found PPS source "/dev/pps2"
ok, found 1 source(s), now start fetching data...
source 0 - assert 0.000000000, sequence: 0 - clear  1461781467.000006924, 
sequence: 734187
source 0 - assert 0.000000000, sequence: 0 - clear  1461781468.000006776, 
sequence: 734188
source 0 - assert 0.000000000, sequence: 0 - clear  1461781469.000007231, 
sequence: 734189
^C

And tell me what you see.

> and ntpq still shows nothing for PPS

And once again, way too soon to be looking at ntpq.  Until ntpshmmon
shows NTP1 (or NTP2) it is pointless to look at ntpd or chronyd.

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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