Time server setup

Some steps to remember when setting up a Raspberry Pi based network time server.

Boot setup files

Add to /etc/modules

i2c-dev
pps-gpio

Add to /boot/config.txt

dtoverlay=pi3-miniuart-bt
dtoverlay=pps-gpio

Add to /boot/cmdline.txt at end of single line

init_uart_baud=9600

Installations

Install several extra tools

• ntp-utils
• ntpsec
• minicom
• gpsd
• pps
• pps-tools
• ptpd

Disable serial login on AMA0 device.

systemctl mask serial-getty@ttyAMA0.service

Disable unused services like cupsd.

Defaults

Update /etc/defaults/gpsd to

# Default settings for the gpsd init script and the hotplug wrapper.

# Start the gpsd daemon automatically at boot time
START_DAEMON="true"

# Use USB hotplugging to add new USB devices automatically to the daemon
USBAUTO="false"

# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES="/dev/ttyAMA0"

# Other options you want to pass to gpsd
GPSD_OPTIONS="-n"

Update /etc/defaults/ntpsec to

NTPD_OPTS="-g -N"

# Set to "yes" to ignore DHCP servers returned by DHCP.
IGNORE_DHCP=""

Update /etc/defaults/ptpd to

# /etc/default/ptpd

# Set to "yes" to actually start ptpd automatically
START_DAEMON=yes

# Add command line options for ptpd
PTPD_OPTS="-c /etc/ptpd2.conf"

Service setup files

Update /etc/ntpsec/ntp.conf to

# /etc/ntpsec/ntp.conf, configuration for ntpd; see ntp.conf(5) for help

driftfile /var/lib/ntpsec/ntp.drift
leapfile /usr/share/zoneinfo/leap-seconds.list

# You must create /var/log/ntpsec (owned by ntpsec:ntpsec) to enable logging.
statsdir /var/log/ntpsec/
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Comment this out if you have a refclock and want it to be able to discipline
# the clock by itself (e.g. if the system is not connected to the network).
#tos minclock 4 minsane 3

# Specify one or more NTP servers.

# pool.ntp.org maps to about 1000 low-stratum NTP servers.  Your server will
# pick a different set every time it starts up.  Please consider joining the
# pool: <https://www.pool.ntp.org/join.html>
pool 0.de.pool.ntp.org iburst maxpoll 5
#pool 1.de.pool.ntp.org iburst
#pool 2.de.pool.ntp.org iburst
#pool 3.de.pool.ntp.org iburst

# Access control configuration; see /usr/share/doc/ntpsec-doc/html/accopt.html
# for details.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don't allow configuration.
restrict default kod nomodify nopeer noquery limited

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# GPS Serial data reference (NTP0)
server 127.127.28.0
fudge 127.127.28.0 time1 +0.100 refid GPS

# GPS PPS reference (NTP1)
server 127.127.28.1 prefer
fudge 127.127.28.1 refid PPS

Update /etc/ptpd2.conf to

#
# config
#

ptpengine:interface=eth0
ptpengine:preset=masteronly
ptpengine:transport=ethernet
#ptpengine:transport=ipv4
ptpengine:ptp_timesource=GPS
ptpengine:ptp_clock_accuracy=ACC_100US
#ptpengine:prefer_ntp=Y

#ntpengine:enabled=Y

global:use_syslog=Y
global:log_status=Y

Final result

With some luck and reboots the ntpq -p command should show:

root@clock:/etc# ntpq -p
     remote                                   refid      st t when poll reach   delay   offset   jitter
=======================================================================================================
 0.de.pool.ntp.org                       .POOL.          16 p    -   32    0   0.0000   0.0000   0.0010
+SHM(0)                                  .GPS.            0 l   59   64  377   0.0000  -2.5372   0.6387
*SHM(1)                                  .PPS.            0 l   58   64  377   0.0000   0.0027   0.0020
-static.102.162.46.78.clients.your-serve 131.188.3.223    2 u    4   32  377  23.0398   5.2349   2.0621
-ntp1.sul.t-online.de                    172.20.96.197    2 u   29   32  377  24.0259   2.1013   3.3369
-kuehlich.com                            131.188.3.221    2 u   19   32  377  28.6138   4.2736   5.8902
-ntp2.wtnet.de                           10.129.9.96      2 u   26   32  377  28.5456  -9.2126   4.9001
+time.cloudflare.com                     10.48.8.4        3 u   19   32  377  18.1886   6.0767   5.8235
-telesto.hot-chilli.net                  131.188.3.222    2 u   26   32  277  24.0233   2.5571   5.9801
-nono.com                                242.71.143.169   2 u   10   32  377  25.0837   3.8292   3.0114

Which is good enough for me to play with.