Re: GPS time sync with chrony and ESE serial device

[David J Taylor]

[]
Thank you David and Greg for the further info and links about PPS. David, in 
the first link, this is a great detailed procedure, but my situation is not 
exactly the same, because the author is using pps_gpio in a Raspberry Pi, 
while my signal is coming through a serial port. I imagine I somehow need to 
choose and locate a different driver instead of pps_gpio? I’ve never done 
anything with kernel modules before. I did try the commands lsmod|grep pps 
and dmesg|grep pps, and I find that I do have pps_core installed and 
running, but it is “used by” ptp, which seems to be associated with the 
ethernet adapter rather than the serial port.

The driver on the NTP.org page sounds great, but again I have no idea how to 
get it on my system.  Do I have to install ntpd in place of chrony, and will 
the driver come with the package?
==========================

Devren, the standard for NTP on a serial port is that the PPS signal is sent 
on the DCD line.  Some drivers can detect that.  With Windows, some drivers 
with 3rd party hardware don't detect that properly, hence the 
loopback-ppsapi-provder.dll driver developed by Meinberg:

 https://kb.meinbergglobal.com/kb/time_sync/ntp/using_pps_signals_on_windows

I've not used an equivalent driver with Linux as I always buy modules with 
PPS, and the Raspberry Pi doesn't directly support a DCD line.  A "two wire" 
connection suffices (TX, PPS, GND & 3.3V).  I have always used reference NTP 
and not Chrony, as Chrony doesn't support Windows as reference clocks.

Cheers,
David
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