Hi Deven, Before configuring chrony or gpsd you will want to verify that kpps is working.
There are two kernel modules that provide kpps clients, pps-gpio (gpio) and pps-ldisc (serial control line). If you are bringing the timepulse signal in gpio, you will be using the pps-gpio kernel module. You may need to configure which gpio is to used. This is probably done with the device tree. If either module is being loaded, you should see a device (e.g. pps0) in /sys/class/pps. If your GPS has a lock and the pps kernel module is configured properly, you should see timestamps updating every second, e.g. $cat /sys/class/pps/pps0/assert 1455831692.018636856#178 Are you seeing those? Rob Calhoun On Thu, Feb 18, 2016 at 10:25 AM, Deven Hickingbotham <dev...@pacbell.net> wrote: > I'm developing a Python 3 app on a Raspberry Pi running Wheezy (Debian > 7.8). I need help selecting the right version of Chrony to use and > configuring PPS. My GPS is an Adafruit Ultimate GPS Hat using ttyAMA0 with > PPS on GPIO pin 4. My app is a mobile one. It may have internet access > via cell phone, but should primarily use PPS. Time accuracy requirement is > only +/- 5ms. > > I installed Chrony. It is v1.24. I added the changes suggested here to > chrony.conf: > > > http://www.catb.org/gpsd/gpsd-time-service-howto.html#_feeding_chrony_from_gpsd > > The full chrony.conf appears at the end of this post, but these two lines > I believe are the important ones: > > refclock SHM 0 refid GPS precision 1e-1 offset 0.9999 delay 0.2 > refclock SOCK /var/run/chrony.ttyAMA0.sock refid PPS > > I suspect the reference to /var/run/chrony.ttyAMA0.sock may not be correct. > > Here is the output of chronyc sources: > > pi@gps ~/SystemFiles $ chronyc sources > 210 Number of sources = 6 > MS Name/IP address Stratum Poll LastRx Last sample > > ============================================================================ > ^* pacific.latt.net 3 6 4 +682us[+6549us] +/- > 80ms > ^? 216.152.240.220 0 6 10y +0ns[ +0ns] +/- 0ns > ^? 207.196.240.30 0 6 10y +0ns[ +0ns] +/- 0ns > ^+ resolver1.level3.net 3 6 1 -357us[ -357us] +/- > 107ms > #x GPS 0 4 14 +346ms[ +347ms] +/- 2838us > #? PP 0 4 10y +0ns[ +0ns] +/- 0ns > > Note the last line shows PP, not PPS. > > So I'd like help getting Chrony 1.24 working with PPS and also some advice > as to whether I should upgrade to 2.3. > > Thanks! > > > ========================================== > chrony.conf: > > # This the default chrony.conf file for the Debian chrony package. After > # editing this file use the command 'invoke-rc.d chrony restart' to make > # your changes take effect. John Hasler <jhas...@debian.org> 1998-2008 > > # See www.pool.ntp.org for an explanation of these servers. Please > # consider joining the project if possible. If you can't or don't want to > # use these servers I suggest that you try your ISP's nameservers. We mark > # the servers 'offline' so that chronyd won't try to connect when the link > # is down. Scripts in /etc/ppp/ip-up.d and /etc/ppp/ip-down.d use chronyc > # commands to switch it on when a dialup link comes up and off when it goes > # down. Code in /etc/init.d/chrony attempts to determine whether or not > # the link is up at boot time and set the online status accordingly. If > # you have an always-on connection such as cable omit the 'offline' > # directive and chronyd will default to online. > # > # Note that if Chrony tries to go "online" and dns lookup of the servers > # fails they will be discarded. Thus under some circumstances it is > # better to use IP numbers than host names. > > ##server 0.debian.pool.ntp.org offline minpoll 8 > ##server 1.debian.pool.ntp.org offline minpoll 8 > ##server 2.debian.pool.ntp.org offline minpoll 8 > ##server 3.debian.pool.ntp.org offline minpoll 8 > server 0.us.pool.ntp.org > server 1.us.pool.ntp.org > server 2.us.pool.ntp.org > server 3.us.pool.ntp.org > > > # Look here for the admin password needed for chronyc. The initial > # password is generated by a random process at install time. You may > # change it if you wish. > > keyfile /etc/chrony/chrony.keys > > # Set runtime command key. Note that if you change the key (not the > # password) to anything other than 1 you will need to edit > # /etc/ppp/ip-up.d/chrony, /etc/ppp/ip-down.d/chrony, /etc/init.d/chrony > # and /etc/cron.weekly/chrony as these scripts use it to get the password. > > commandkey 1 > > # I moved the driftfile to /var/lib/chrony to comply with the Debian > # filesystem standard. > > driftfile /var/lib/chrony/chrony.drift > > # Comment this line out to turn off logging. > > log tracking measurements statistics > logdir /var/log/chrony > > # Stop bad estimates upsetting machine clock. > > maxupdateskew 100.0 > > # Dump measurements when daemon exits. > > dumponexit > > # Specify directory for dumping measurements. > > dumpdir /var/lib/chrony > > # Let computer be a server when it is unsynchronised. > > local stratum 10 > > # Allow computers on the unrouted nets to use the server. > > allow 10/8 > allow 192.168/16 > allow 172.16/12 > > # This directive forces `chronyd' to send a message to syslog if it > # makes a system clock adjustment larger than a threshold value in seconds. > > logchange 0.5 > > # This directive defines an email address to which mail should be sent > # if chronyd applies a correction exceeding a particular threshold to the > # system clock. > > # mailonchange root@localhost 0.5 > > # This directive tells chrony to regulate the real-time clock and tells it > # Where to store related data. It may not work on some newer motherboards > # that use the HPET real-time clock. It requires enhanced real-time > # support in the kernel. I've commented it out because with certain > # combinations of motherboard and kernel it is reported to cause lockups. > > # rtcfile /var/lib/chrony/chrony.rtc > > # If the last line of this file reads 'rtconutc' chrony will assume that > # the CMOS clock is on UTC (GMT). If it reads '# rtconutc' or is absent > # chrony will assume local time. The line (if any) was written by the > # chrony postinst based on what it found in /etc/default/rcS. You may > # change it if necessary. > # rtconutc > > # set larger delay to allow the NMEA source to overlap with > # the other sources and avoid the falseticker status > refclock SHM 0 refid GPS precision 1e-1 offset 0.9999 delay 0.2 > refclock SOCK /var/run/chrony.ttyAMA0.sock refid PPS > > -- > To unsubscribe email chrony-users-requ...@chrony.tuxfamily.org with > "unsubscribe" in the subject. > For help email chrony-users-requ...@chrony.tuxfamily.org with "help" in > the subject. > Trouble? Email listmas...@chrony.tuxfamily.org. > >
