Re: [chrony-users] Newbie Help Needed

[Stuart Maclean <stuart@xxxxxxxxxxxxxxxxxx>]

Thanks to Miroslav's fantastic help, I think I have finally figured out
how to use chrony with my Chip Scale Atomic Clock on my embedded Linux
system.

I am just learning how to qualify how well I am keeping system time
aligned with my CSAC 'refclock' via chrony.  I thought I would share my
preliminary results, so that experts could comment on the finer points
that I do not yet fully understand.

My /etc/chrony.conf is this

refclock SOCK /var/run/chrony.serial.sock refid CSAC noselect

refclock SOCK /var/run/chrony.pps.sock refid PPS lock CSAC


My results, after about 12 hours of chronyd running, are

$ ./chronyc  sources
210 Number of sources = 2

MS Name/IP address         Stratum Poll Reach LastRx Last sample

===============================================================================

#? CSAC                          0   4   377    22   +344ns[ +326ns] +/-
  30us
#* PPS                           0   4   377    23    +16ns[   -2ns] +/-
  30us

$ ./chronyc  sourcestats
210 Number of sources = 2

Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset
Std Dev
==============================================================================

CSAC                        6   3    80     -0.009      0.009   -519ns
 67ns
PPS                        64  42  1009     +0.000      0.005     +2ns
3481ns

My own log file, which compares Linux system time at moment of my CSAC
PPS firing, is also showing me that my 'error' is within 30usec
consistently.

So far, my testing has been in a lab, with little or no temperature
fluctuation.  My real system is an undersea instrument, so will have to
deal with substantial temperature changes, but I am hoping chrony is the
way to go.

I am hoping my experience might help others with similar local
refclocks. The actual code to feed chronyd with data over the SOCK
interface was quite straightforward, thanks to Miroslav's own example code.

Thanks all

Stuart

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