Ubuntu 16.04 with ntpd using NEMA/PPS..

Howard Leadmon howard at leadmon.net
Sun Jul 10 16:15:54 UTC 2016

> Howard Leadmon wrote:
> > I have found postings saying that PPS in the kernel is present in
> > 16.04 now, but everything I have found has
> > not resulting in a working time server.   If PPS is indeed in the
> > 16.04 LTS version of the OS, can anyone point me to a definitive
> > guide and possibly configs to get this going.    As it seems no
> > matter what I do, running ntptime never tells me I have PPS active in
> > the kernel.
> You didn't tell us how your PPS signal is connected to the computer. It
> be connected at the serial port, which also gets the NMEA data or it could
> connected at a parallel port or a GPIO pin. Did you load the appropriate
> kernel module? You can check it with the command

 I have a Garmin 18x which is connected into the serial port on the back of
my HP DL-380 G7 server, using USB as some articles suggest to power it up.
I have even run the ppstest, and and it showed I had a pps stream coming in,
as well as connected to the serial port and I could watch the NEMA data
flowing in on the board, so it appears at least hardware wise I should be
OK.  Trust me, I have thought it just getting the gpsmod for my pi2 and
turning it into a time machine so to speak.

> lsmod|grep pps

 The above command shows me:

# lsmod|grep pps
pps_ldisc              16384  3
pps_core               20480  3 pps_ldisc

 So I am guessing the PPS stuff is in the kernel.

> in a terminal. There is some documentation in the kernel source. Use the
> command
> apt-get source linux-image-$(uname -r)
> to get the kernel source and then have a look at the file "linux-
> 4.4.0/Documentation/pps/pps.txt". I'm not sure if that is good enough, but
> it isn't, please tell us a bit more where your pps signal is connected and
> you tried to make it work.
> Nils
 If you have any other questions on the setup, by all means let me know, and
thanks for the reply..

Howard Leadmon

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