Chrony and GPSD - Revision history

Sertonix: update links & use https

2023-08-25T21:32:48Z

update links & use https

← Older revision		Revision as of 21:32, 25 August 2023
Line 2:		Line 2:
	Sources such as:		Sources such as:

	* ~~http~~://www.rjsystems.nl/en/2100-ntpd-garmin-gps-18-lvc-gpsd.php		* https://www.rjsystems.nl/en/2100-ntpd-garmin-gps-18-lvc-gpsd.php
	* ~~http~~://lists.ntp.org/pipermail/questions/2005-November/007878.html		* https://lists.ntp.org/pipermail/questions/2005-November/007878.html

	Describe how to wire a Garmin gps 18 lvc to a serial port to grab the PPS (pulse-per-second) signal to create a Stratum 1 timesource. Other sources show using ntpd, and the [http://gpsd.berlios.de/gpsd.html gpsd man page] provides config snippets.		Describe how to wire a Garmin gps 18 lvc to a serial port to grab the PPS (pulse-per-second) signal to create a Stratum 1 timesource. Other sources show using ntpd, and the [http://gpsd.berlios.de/gpsd.html gpsd man page] provides config snippets.
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	#		#
	# For serial interfaces, options such as low_latency are recommended		# For serial interfaces, options such as low_latency are recommended
	# Also, ~~http~~://~~catb~~.~~org~~/gpsd/upstream-bugs.html#tiocmwait recommends		# Also, https://gpsd.gitlab.io/gpsd/upstream-bugs.html#tiocmwait recommends
	# setting the baudrate with stty		# setting the baudrate with stty
	# Uncomment the following lines if using a serial device:		# Uncomment the following lines if using a serial device:

LordMike: Replace incorrect acronym NEMA with correct NMEA

2021-03-13T19:38:02Z

Replace incorrect acronym NEMA with correct NMEA

Nangel: update to include the /dev/pps0 clock source

2020-02-06T20:57:38Z

update to include the /dev/pps0 clock source

← Older revision		Revision as of 20:57, 6 February 2020
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	* This shows all ~~three~~ methods of getting time from gpsd:		* This shows all four methods of getting time from gpsd:
	{{Cat\|/etc/chrony/chrony.conf\|<nowiki>		{{Cat\|/etc/chrony/chrony.conf\|<nowiki>
	server 0.pool.ntp.org		server 0.pool.ntp.org
Line 67:		Line 67:
	# SHM1 from gpsd (if present) is from the kernel PPS_LDISC		# SHM1 from gpsd (if present) is from the kernel PPS_LDISC
	# module. It includes PPS and will be accurate to a few ns		# module. It includes PPS and will be accurate to a few ns
	refclock SHM 1 offset 0.0 delay 0.1 refid ~~PPS~~		refclock SHM 1 offset 0.0 delay 0.1 refid NEMA+

	# SOCK protocol also includes PPS data and		# SOCK protocol also includes PPS data and
	# it also provides time within a few ns		# it also provides time within a few ns
	refclock SOCK /var/run/chrony.ttyS1.sock delay 0.0 refid SOCK		refclock SOCK /var/run/chrony.ttyS1.sock delay 0.0 refid SOCK

			# PPS is from the /dev/pps0 device. Note that
			# chronyd creates the /var/run/chrony.ttyS1.sock device, but
			# gpsd creates the /dev/pps0 device
			# openrc rules start gpsd /after/ chronyd, so /dev/pps0
			# is not created until after chronyd is started
			# If you want to use pps0, either edit the openrc rules
			# or add this source after gpsd is started

			# refclock PPS /dev/pps0 refid PPS


	# If you see something in ns... its good.		# If you see something in ns... its good.
Line 116:		Line 127:
	== Notes ==		== Notes ==

	* In /etc/chrony/chrony.conf, there are ~~three~~ possible time sources:		* In /etc/chrony/chrony.conf, there are four possible time sources:
	** SHM 0 (NEMA serial data)		** SHM 0 (NEMA serial data)
	** SHM 1 (NEMA with PPS)		** SHM 1 (NEMA with PPS)
	** SOCK (PPS 'proprietary' gpsd/chrony interface)		** SOCK (PPS 'proprietary' gpsd/chrony interface)
	* You only need 1 of them, although ~~all~~ 3 are shown above		** PPS (PPS only from the serial interface pulse)
			* You only need 1 of them, although 3 are shown above
	* In the example above, SHM1 is specified with a delay of 0.1 to prevent it from competing with the SOCK protocol		* In the example above, SHM1 is specified with a delay of 0.1 to prevent it from competing with the SOCK protocol
	** If you prefer to use the SHM1 source instead of SOCK, then either:		** If you prefer to use the SHM1 source instead of SOCK, then either:

Nangel: update conf.d/gpsd to match new gentoo init script

2020-02-06T20:52:21Z

update conf.d/gpsd to match new gentoo init script

← Older revision		Revision as of 20:52, 6 February 2020
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	* If the GPS 18 LVC is on /dev/ttyS1, then:		* If the GPS 18 LVC is on /dev/ttyS1, then:
	{{Cat\|/etc/conf.d/gpsd\|<nowiki>		{{Cat\|/etc/conf.d/gpsd\|<nowiki>
	# ~~The GPS device (/dev/ttyUSB0, /dev/ttyS0, ...)~~		# Copyright 1999-2010 Gentoo Foundation
			# Distributed under the terms of the GNU General Public License v2
	~~DEVICE="/dev/ttyS1"~~
	~~BAUDRATE="4800"~~

			# Config file for gpsd server
	# Optional arguments		# Optional arguments
	# Options include:		# Options include:
Line 30:		Line 29:
	# -S integer (default 2947) = set port for daemon		# -S integer (default 2947) = set port for daemon

	~~ARGS~~="-n -b"		GPSD_OPTIONS="-n -b"
			DEVICES="/dev/ttyS1"
			GPSD_SOCKET="/var/run/gpsd.sock"
			BAUDRATE="4800"

	# Serial setup		# Serial setup

Nangel at 20:50, 6 February 2020

2020-02-06T20:50:10Z

← Older revision		Revision as of 20:50, 6 February 2020
Line 43:		Line 43:
	</nowiki>		</nowiki>
	}}		}}


			{{Note\|As of v3.11, the init.d and conf.d files have been merged from gentoo.
			The purpose is to allow gpsd to start without editing /etc/conf.d/gpsd.
			Note that while gpsd will now start without editing the conf.d file, it will do so with no gps devices attached.

			Also note that if you are using a serial device it is still recommended to add the stty and setserial commands as noted in the example configuration above.}}


	* This shows all three methods of getting time from gpsd:		* This shows all three methods of getting time from gpsd:
	{{Cat\|/etc/chrony/chrony.conf\|<nowiki>		{{Cat\|/etc/chrony/chrony.conf\|<nowiki>

John3-16: Categorized: Server, Networking

2017-09-19T00:50:49Z

Categorized: Server, Networking

← Older revision		Revision as of 00:50, 19 September 2017
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	* Chrony creates the SOCK interface; chrony should be started before gpsd. If you restart chronyd for some reason, make sure you restart gpsd after.		* Chrony creates the SOCK interface; chrony should be started before gpsd. If you restart chronyd for some reason, make sure you restart gpsd after.
	* The SHM0 interface can be used with USB based gps devices. In this case, use /dev/ttyUSBX in the /etc/conf.d/gpsd file, and leave the stty and setserial lines commented out.		* The SHM0 interface can be used with USB based gps devices. In this case, use /dev/ttyUSBX in the /etc/conf.d/gpsd file, and leave the stty and setserial lines commented out.

			[[Category:Server]]
			[[Category:Networking]]

Nangel at 19:55, 25 December 2013

2013-12-25T19:55:24Z

← Older revision		Revision as of 19:55, 25 December 2013
Line 83:		Line 83:
	}}		}}

			== Chronyc ==

			If everything is working correctly, a chronyc 'sources' command should look like this:

			chronyc> sources
			210 Number of sources = 6
			MS Name/IP address Stratum Poll Reach LastRx Last sample
			===============================================================================
			#x NEMA 0 4 377 14 +684ms[ +684ms] +/- 252ms
			#+ PPS 0 4 377 13 +2040ns[+2060ns] +/- 50ms
			#* SOCK 0 4 377 7 +225ns[ +245ns] +/- 2217ns
			^? tick.tock.com 2 10 377 318 -5144us[-5144us] +/- 72ms
			^? time.keeper.net 3 10 377 720 -4571us[-4567us] +/- 139ms
			^? dead.time.server.org 0 10 0 10y +0ns[ +0ns] +/- 0ns

			* NEMA (SHM0) is "x" - its really unstable
			* PPS (SHM1) is good, but the delay of 0.1 makes it the not-preferred master
			* SOCK is the preferred master
			* The other NTP servers are only used if the local server goes down.

	== Notes ==		== Notes ==

Nangel: Use gpsd and chrony to create a stratum 1 timeserver

2013-12-25T19:48:30Z

Use gpsd and chrony to create a stratum 1 timeserver

New page

Sources such as:

* http://www.rjsystems.nl/en/2100-ntpd-garmin-gps-18-lvc-gpsd.php
* http://lists.ntp.org/pipermail/questions/2005-November/007878.html

Describe how to wire a Garmin gps 18 lvc to a serial port to grab the PPS (pulse-per-second) signal to create a Stratum 1 timesource. Other sources show using ntpd, and the [http://gpsd.berlios.de/gpsd.html gpsd man page] provides config snippets.

Alpine Linux gpsd package 3.9-r1 and higher has the necessary pps code to interface with chrony. This page lists all of the files for a complete, working example:

* /etc/modules needs to list the pps_ldisc module - you'll need to manually load it if not doing a reboot
{{Cat|/etc/modules|pps_ldisc}}
* If the GPS 18 LVC is on /dev/ttyS1, then:
{{Cat|/etc/conf.d/gpsd|<nowiki>
# The GPS device (/dev/ttyUSB0, /dev/ttyS0, ...)

DEVICE="/dev/ttyS1"
BAUDRATE="4800"

# Optional arguments
# Options include:
# -b = bluetooth-safe: open data sources read-only
# -n = don't wait for client connects to poll GPS
# -N = don't go into background
# -F sockfile = specify control socket location
# -G = make gpsd listen on INADDR_ANY
# -D integer (default 0) = set debug level
# -S integer (default 2947) = set port for daemon

ARGS="-n -b"

# Serial setup
#
# For serial interfaces, options such as low_latency are recommended
# Also, http://catb.org/gpsd/upstream-bugs.html#tiocmwait recommends
# setting the baudrate with stty
# Uncomment the following lines if using a serial device:
#
/bin/stty -F ${DEVICE} ${BAUDRATE}
/bin/setserial ${DEVICE} low_latency
</nowiki>
}}
* This shows all three methods of getting time from gpsd:
{{Cat|/etc/chrony/chrony.conf|<nowiki>
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org

initstepslew 30 0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org

# SHM0 from gpsd is the NEMA data at 4800bps, so is not very accurate
refclock SHM 0 delay 0.5 refid NEMA

# SHM1 from gpsd (if present) is from the kernel PPS_LDISC
# module. It includes PPS and will be accurate to a few ns
refclock SHM 1 offset 0.0 delay 0.1 refid PPS

# SOCK protocol also includes PPS data and
# it also provides time within a few ns
refclock SOCK /var/run/chrony.ttyS1.sock delay 0.0 refid SOCK

# If you see something in ns... its good.
# 1 second =
# 1000 ms =
# 1000000 us =
# 1000000000 ns

logchange 0.5
local stratum 10

logdir /var/log/chrony

keyfile /etc/chrony/chrony.keys
commandkey 10

dumpdir /var/log/chrony
driftfile /var/log/chrony/chrony.drift

allow all
</nowiki>
}}

== Notes ==

* In /etc/chrony/chrony.conf, there are three possible time sources:
** SHM 0 (NEMA serial data)
** SHM 1 (NEMA with PPS)
** SOCK (PPS 'proprietary' gpsd/chrony interface)
* You only need 1 of them, although all 3 are shown above
* In the example above, SHM1 is specified with a delay of 0.1 to prevent it from competing with the SOCK protocol
** If you prefer to use the SHM1 source instead of SOCK, then either:
*** comment out the SOCK protocol line
*** or reverse the delay values.
* Note that the SHM0 source (NEMA only, no PPS) is set to a higher delay - don't use it if you have PPS available.
** An example of where you would want to use SHM0 is a USB based gps receiver - they don't have the PPS line
* Chrony creates the SOCK interface; chrony should be started before gpsd. If you restart chronyd for some reason, make sure you restart gpsd after.
* The SHM0 interface can be used with USB based gps devices. In this case, use /dev/ttyUSBX in the /etc/conf.d/gpsd file, and leave the stty and setserial lines commented out.

← Older revision		Revision as of 19:38, 13 March 2021
Line 62:		Line 62:
	initstepslew 30 0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org		initstepslew 30 0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org

	# SHM0 from gpsd is the ~~NEMA~~ data at 4800bps, so is not very accurate		# SHM0 from gpsd is the NMEA data at 4800bps, so is not very accurate
	refclock SHM 0 delay 0.5 refid ~~NEMA~~		refclock SHM 0 delay 0.5 refid NMEA

	# SHM1 from gpsd (if present) is from the kernel PPS_LDISC		# SHM1 from gpsd (if present) is from the kernel PPS_LDISC
	# module. It includes PPS and will be accurate to a few ns		# module. It includes PPS and will be accurate to a few ns
	refclock SHM 1 offset 0.0 delay 0.1 refid ~~NEMA~~+		refclock SHM 1 offset 0.0 delay 0.1 refid NMEA+

	# SOCK protocol also includes PPS data and		# SOCK protocol also includes PPS data and
Line 113:		Line 113:
	MS Name/IP address Stratum Poll Reach LastRx Last sample		MS Name/IP address Stratum Poll Reach LastRx Last sample
	===============================================================================		===============================================================================
	#x ~~NEMA~~ 0 4 377 14 +684ms[ +684ms] +/- 252ms		#x NMEA 0 4 377 14 +684ms[ +684ms] +/- 252ms
	#+ PPS 0 4 377 13 +2040ns[+2060ns] +/- 50ms		#+ PPS 0 4 377 13 +2040ns[+2060ns] +/- 50ms
	#* SOCK 0 4 377 7 +225ns[ +245ns] +/- 2217ns		#* SOCK 0 4 377 7 +225ns[ +245ns] +/- 2217ns
Line 120:		Line 120:
	^? dead.time.server.org 0 10 0 10y +0ns[ +0ns] +/- 0ns		^? dead.time.server.org 0 10 0 10y +0ns[ +0ns] +/- 0ns

	* ~~NEMA~~ (SHM0) is "x" - its really unstable		* NMEA (SHM0) is "x" - its really unstable
	* PPS (SHM1) is good, but the delay of 0.1 makes it the not-preferred master		* PPS (SHM1) is good, but the delay of 0.1 makes it the not-preferred master
	* SOCK is the preferred master		* SOCK is the preferred master
Line 128:		Line 128:

	* In /etc/chrony/chrony.conf, there are four possible time sources:		* In /etc/chrony/chrony.conf, there are four possible time sources:
	** SHM 0 (~~NEMA~~ serial data)		** SHM 0 (NMEA serial data)
	** SHM 1 (~~NEMA~~ with PPS)		** SHM 1 (NMEA with PPS)
	** SOCK (PPS 'proprietary' gpsd/chrony interface)		** SOCK (PPS 'proprietary' gpsd/chrony interface)
	** PPS (PPS only from the serial interface pulse)		** PPS (PPS only from the serial interface pulse)
Line 137:		Line 137:
	*** comment out the SOCK protocol line		*** comment out the SOCK protocol line
	*** or reverse the delay values.		*** or reverse the delay values.
	* Note that the SHM0 source (~~NEMA~~ only, no PPS) is set to a higher delay - don't use it if you have PPS available.		* Note that the SHM0 source (NMEA only, no PPS) is set to a higher delay - don't use it if you have PPS available.
	** An example of where you would want to use SHM0 is a USB based gps receiver - they don't have the PPS line		** An example of where you would want to use SHM0 is a USB based gps receiver - they don't have the PPS line
	* Chrony creates the SOCK interface; chrony should be started before gpsd. If you restart chronyd for some reason, make sure you restart gpsd after.		* Chrony creates the SOCK interface; chrony should be started before gpsd. If you restart chronyd for some reason, make sure you restart gpsd after.