* Time
This document was created by Steven Baltakatei Sandoval on
~2020-07-23T22:27Z~ under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It
-was updated by Steven Baltakatei Sandoval on ~2020-07-25T19:34Z~
+was updated by Steven Baltakatei Sandoval on ~2020-10-12T22:22Z~
** Development Task list
*** Set up prototype unit
-**** Solder wire for PPS signal
+**** DONE Solder wire for PPS signal
+***** 2020-07-25T20:03Z; bktei> Soldered pins to permit accessibility.
+ CLOSED: [2020-07-25 Sat 20:03]
**** Follow guide
- [[https://ozzmaker.com/forums/topic/connecting-gps-pps-pin/][Ozzmaker post]] on ~PPS~ wiring and a [[https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html][guide]] recommendation.
- [[http://www.satsignal.eu/raspberry-pi/Schmidt-RPZ-NTP-2016.pdf][Schmidt article]] on Raspberry Pi Zero time server.
- [[https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html][GPSD dev ref]] page for ~gpsd~ interfacing with ~ntp~.
+- [[https://raspberryautomation.com/connect-multiple-ds18b20-temperature-sensors-to-a-raspberry-pi/][Raspberry Autom]] article on specifying custom GPIO pin.
*** Document prototype unit
+**** TODO Integrate DHCP details from gregledet tutorial
+http://www.gregledet.net/computers/building-a-stratum-1-ntp-server-with-a-raspberry-pi-4-and-adafruit-ultimate-gps-hat/
+**** TODO Note working ntp.conf file
+
+#+BEGIN_EXAMPLE
+# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
+
+driftfile /var/lib/ntp/ntp.drift
+logfile /var/log/ntp.log
+
+# Leap seconds definition provided by tzdata
+leapfile /usr/share/zoneinfo/leap-seconds.list
+
+# Enable this if you want statistics to be logged.
+statsdir /var/log/ntpstats/
+
+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
+
+
+# You do need to talk to an NTP server or two (or three).
+#server ntp.your-provider.example
+server time.nist.gov iburst minpoll 5 maxpoll 5
+server tick.usno.navy.mil iburst minpoll 5 maxpoll 5
+server 0.us.pool.ntp.org iburst minpoll 5 maxpoll 5
+server 0.us.pool.ntp.org iburst minpoll 5 maxpoll 5
+server 0.us.pool.ntp.org iburst minpoll 5 maxpoll 5
+server 0.us.pool.ntp.org iburst minpoll 5 maxpoll 5
+
+# 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: <http://www.pool.ntp.org/join.html>
+#pool 0.debian.pool.ntp.org iburst
+#pool 1.debian.pool.ntp.org iburst
+#pool 2.debian.pool.ntp.org iburst
+#pool 3.debian.pool.ntp.org iburst
+
+# PPS Kernel mode
+server 127.127.22.0 minpoll 4 maxpoll 4 true
+fudge 127.127.22.0 flag3 1 refid kPPS
+
+# GPS PPS reference (NTP2)
+server 127.127.28.2 minpoll 4 maxpoll 4
+fudge 127.127.28.2 refid SHM2
+
+# GPS Serial data reference (NTP0)
+server 127.127.28.0 minpoll 4 maxpoll 4 prefer
+fudge 127.127.28.0 time1 +0.593 refid GPS
+
+# Fix False tickers
+tos mindist 0.5
+
+# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
+# details. The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
+# might also be helpful.
+#
+# 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 -4 default kod notrap nomodify nopeer noquery limited
+restrict -6 default kod notrap nomodify nopeer noquery limited
+
+# Local users may interrogate the ntp server more closely.
+restrict 127.0.0.1
+restrict ::1
+
+# Needed for adding pool entries
+restrict source notrap nomodify noquery
+
+# Clients from this (example!) subnet have unlimited access, but only if
+# cryptographically authenticated.
+#restrict 192.168.123.0 mask 255.255.255.0 notrust
+
+
+# If you want to provide time to your local subnet, change the next line.
+# (Again, the address is an example only.)
+#broadcast 192.168.123.255
+
+# If you want to listen to time broadcasts on your local subnet, de-comment the
+# next lines. Please do this only if you trust everybody on the network!
+#disable auth
+#broadcastclient
+#+END_EXAMPLE
+
+**** TODO Integreate References
+- Some explanations for ~time1~, ~flag1~, ~flag3~, ~refid~, etc. strings in ntp.conf: [[http://doc.ntp.org/4.2.8/drivers/driver28.html][link]].
+- NTP Basics (what "system peer" means): [[https://kb.meinbergglobal.com/kb/time_sync/ntp/ntp_basics][link]].
+- GPSD guide indicating PPS signals should be preferred over GPS signals: [[https://gpsd.gitlab.io/gpsd/gpsd-time-service-howto.html#_feeding_ntpd_from_gpsd][link]]
+
** Narrative
The ~ninfacyzga-01~ device is equipped with an Ozzmaker BerryGPS-IMU
module which provides time and location data to ~gpsd~. The time is
~T_PULSE~ pin to GPIO 18.
Connect the ~T_PULSE~ connection on the BerryGPS-IMU-3 to GPIO pin 18
-in order to enable ~gpsd~ to read the PPS signal for forwarding to
-~ntp~.
+(ex: with solder and wire) in order to provide the PPS data signal
+generated by the BerryGPS-IMU to the Raspberry Pi. Processing of this
+data signal is handled by adding a line to ~/boot/config.txt~ in the
+next section ("Install Software").
**** Install Software
-Run the following command to install the required packages.
-: $ sudo apt install usbmount eject gpsd gpsd-clients python-gps pps-tools ntp
-
These instructions assume that ~gpsd~ has already been setup to
provide NMEA sentences to ~gpspipe~ for location. See the ~README.org~
in ~doc/location~ for details. Basically, ~gpsd~ needs to be told via
-its ~/etc/default/gpsd~ configuration file of which ~/dev/tty???~ will
+its ~/etc/default/gpsd~ configuration file of which ~/dev/ttyS0~ will
provide the raw GPS module data.
+***** Install packages via ~apt~
+Run the following command to install the required packages.
+: $ sudo apt install usbmount eject gpsd gpsd-clients python-gps pps-tools ntp
+
+***** Modify ~/boot/config.txt~
+In order to tell the Raspberry Pi to expect PPS data on ~BCM 18~ (pin
+number 12; see [[https://pinout.xyz/][RaspPi pinout]]), add the following line to
+~/boot/config.txt~ as described on [[https://ozzmaker.com/forums/topic/problems-with-pps-on-a-pi0w-running-raspian-and-attached-to-a-berrygps-imuv3/][this Ozzmaker page]]:
+
+: dtoverlay=pps-gpio,gpiopin=18
+
+PPS data can be confirmed by running:
+
+#+BEGIN_EXAMPLE
+$ sudo su -
+# ppstest /dev/pps0
+trying PPS source "/dev/pps0"
+found PPS source "/dev/pps0"
+ok, found 1 source(s), now start fetching data...
+source 0 - assert 1595708074.003644641, sequence: 219 - clear 0.000000000, sequence: 0
+source 0 - assert 1595708075.003709620, sequence: 220 - clear 0.000000000, sequence: 0
+source 0 - assert 1595708076.003779580, sequence: 221 - clear 0.000000000, sequence: 0
+source 0 - assert 1595708077.003850580, sequence: 222 - clear 0.000000000, sequence: 0
+#+END_EXAMPLE
+
+***** Add udev rule
+As per [[https://www.slsmk.com/how-to-setup-a-gps-pps-ntp-time-server-on-raspberry-pi/][the slsmk.com]] guide, create symbolic links expected by ~ntp~
+pointing to the PPS device. This may be performed by creating the file:
+
+: /etc/udev/rules.d/09-pps.rules
+
+with the contents:
+
+#+BEGIN_EXAMPLE
+KERNEL=="ttyAMA0", SUBSYSTEM=="tty", DRIVER=="", OWNER=="root", GROUP=="tty", MODE=="0777", SYMLINK+="gps0"
+#+END_EXAMPLE
+
+***** Modify ~/etc/modules~
+For older versions of Raspberry Pi, it may be necessary to explicitly
+require the ~pps-gpio~ module to be loaded by making sure
+~/etc/modules~ contains the line:
+
+: pps-gpio
+
+According to [[https://www.raspberrypi.org/forums/viewtopic.php?p=757747#p757747][this]] post on 2015-05-13T09:14 by [[https://www.raspberrypi.org/forums/memberlist.php?mode=viewprofile&u=31454][ame]] on the Raspberry Pi
+forums,
+
+#+BEGIN_QUOTE
+rowlandski wrote:
+> Hi,
+>
+> I want the RPi to load/probe the w1-gpio module on boot.
+>
+> I have added:
+>
+> sudo modprobe w1-gpio
+>
+> To the etc/modules file, but on boot it is not loaded.
+> I have checked this by the lsmod command. If i then enter the above line manually and then check it's there loaded.
+>
+> What's wrong with my line on code in the modules file?
+>
+> Thanks
+
+You no longer need to load modules for some devices. It's handled by devicetree.
+
+Search for "devicetree" on the forum, or start here:
+https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=97314
+#+END_QUOTE
+
+As of 2020-07-25, using Raspbian Buster 10 with a BerryGPS-IMU v3,
+~/etc/modules~ did not need to be modified.
+
+***** Remove DHCP client hooks
+As per [[https://www.slsmk.com/how-to-setup-a-gps-pps-ntp-time-server-on-raspberry-pi/][this]] guide, "remove ntp DHCP hook (so that it doesn't override ntp settings)".
+
+This can be performed by running the following command (shown in
+script form for readability):
+
+#+BEGIN_EXAMPLE
+if [ -f "/etc/dhcp/dhclient-exit-hooks.d/ntp" ]; then
+ mv /etc/dhcp/dhclient-exit-hooks.d/ntp /etc/dhcp/dhclient-exit-hooks.d/xxxntp-orig;
+else
+ echo "NTP exit hook does not exist";
+fi;
+#+END_EXAMPLE
+
*** Normal Startup
*** Normal Operation
*** Normal Shutdown
projects / EVA-2020-02.git / blobdiff