Ubuntu 16.04 with ntpd using NEMA/PPS..

Nils Kassube kassube at gmx.net
Sun Jul 10 13:22:45 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 
could be connected at the serial port, which also gets the NMEA data or 
it could be connected at a parallel port or a GPIO pin. Did you load the 
appropriate kernel module? You can check it with the command

lsmod|grep pps

in a terminal. There is some documentation in the kernel source. Use the 

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 if it isn't, please tell us a bit more where your pps signal 
is connected and what you tried to make it work.


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