GPS time sync with chrony and ESE serial device

[Devren Yener]

Hello,

I am trying to configure a Linux box to sync time over a serial cable with an old GPS clock we have. I seem to be getting the expected data over the serial cable, but I cannot get the gpsd and chrony configuration working to actually sync the time. I have looked through the HOWTO document at https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html, and I am at a loss regarding what else I can try.

The device is an “ESE Master Clock ES-102”. It does not give full GPS data, but only an ASCII timestamp and a 1PPS signal. Here is the output of sudo cat /dev/ttyS0:

03-02-20  062:14:46:29
03-02-20  062:14:46:30
03-02-20  062:14:46:31
03-02-20  062:14:46:32
03-02-20  062:14:46:33
-- etc. --

Here is the output of sudo ppscheck /dev/ttyS0:

# Seconds  nanoSecs   Signals
1583178535 982155392 TIOCM_CTS
1583178535 982872736 TIOCM_CTS
1583178535 983212265 TIOCM_CTS
1583178535 983520491 TIOCM_CTS
1583178535 983912653 TIOCM_CTS
-- etc. --

But when I do the following things, there is no signal:

• gpsmon: no output, either from the daemon when it is running, or directly from /dev/ttyS0 when the daemon is not running.
• ntpshmmon: no output
• chronyc sources: no response is ever received either from the SOCK or from the SHM, after putting in the config from the HOWTO.

I am running Ubuntu 18.04, and I obtained my software with sudo apt install chrony pps-tools gpsd. I tried to make sure that the PPS support is enabled in gpsd. When I query gpsd -l, I see that “PPS” is listed in the drivers, and the following comments appear:

# Socket export enabled.
# Shared memory export enabled.
# DBUS export enabled
# Time service features enabled.
# PPS enabled.

I stopped the systemd gpsd.service, and instead ran gpsd in the foreground, with debugging, and I got the message dump below. Please let me know if you have any idea of what might be wrong, or what else I can try!

Thanks very much,
Devren Yener

---

$ sudo gpsd -b -n -N -D4 /dev/ttyS0
gpsd:INFO: launching (Version 3.17)
gpsd:INFO: listening on port gpsd
gpsd:PROG: NTP: shmat(0,0,0) succeeded, segment 0
gpsd:PROG: NTP: shmat(32769,0,0) succeeded, segment 1
gpsd:PROG: NTP: shmat(65538,0,0) succeeded, segment 2
gpsd:PROG: NTP: shmat(98307,0,0) succeeded, segment 3
gpsd:PROG: NTP: shmat(131076,0,0) succeeded, segment 4
gpsd:PROG: NTP: shmat(163845,0,0) succeeded, segment 5
gpsd:PROG: NTP: shmat(196614,0,0) succeeded, segment 6
gpsd:PROG: NTP: shmat(229383,0,0) succeeded, segment 7
gpsd:PROG: successfully connected to the DBUS system bus
gpsd:PROG: shmget(0x47505344, 8936, 0666) for SHM export succeeded
gpsd:PROG: shmat() for SHM export succeeded, segment 262152
gpsd:INFO: stashing device /dev/ttyS0 at slot 0
gpsd:PROG: no /etc/gpsd/device-hook present, skipped running ACTIVATE hook
gpsd:INFO: SER: opening read-only GPS data source type 2 and at '/dev/ttyS0'
gpsd:INFO: SER: speed 9600, 8N1
gpsd:PROG: Probing "Garmin USB binary" driver...
gpsd:PROG: Probe not found "Garmin USB binary" driver...
gpsd:PROG: Probing "GeoStar" driver...
gpsd:PROG: Sent GeoStar packet id 0xc1
gpsd:PROG: Probe not found "GeoStar" driver...
gpsd:PROG: Probing "Trimble TSIP" driver...
gpsd:INFO: SER: speed 9600, 8O1
gpsd:INFO: SER: speed 9600, 8N1
gpsd:PROG: Probe not found "Trimble TSIP" driver...
gpsd:PROG: Probing "iSync" driver...
gpsd:INFO: SER: speed 9600, 8N1
gpsd:INFO: SER: speed 9600, 8N1
gpsd:PROG: Probe not found "iSync" driver...
gpsd:PROG: no probe matched...
gpsd:INFO: gpsd_activate(2): activated GPS (fd 6)
gpsd:PROG: KPPS:/dev/ttyS0 checking /sys/devices/virtual/pps/pps0/path, /dev/ttyS0
gpsd:INFO: KPPS:/dev/ttyS0 RFC2783 path:/dev/pps0, fd is 8
gpsd:INFO: KPPS:/dev/ttyS0 pps_caps 0x1133
gpsd:INFO: KPPS:/dev/ttyS0 have PPS_CANWAIT
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS will be used
gpsd:PROG: PPS:/dev/ttyS0 thread launched
gpsd:INFO: PPS:/dev/ttyS0 ntpshm_link_activate: 1
gpsd:INFO: device /dev/ttyS0 activated
gpsd:INFO: running with effective group ID 20
gpsd:INFO: running with effective user ID 111
gpsd:INFO: startup at 2020-03-02T19:55:55.000Z (1583178955)
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Interrupted system call
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:WARN: PPS:/dev/ttyS0 unchanged state, ppsmonitor sleeps 10
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out
-- etc. --