Re: [time-nuts] beaglebone black, debian, NTP client
That's one thing that annoys me with those graphs. If you average jitter
it loses its meaning. What you then get is the mean deviation (aka offset).
Without an accompanying standard deviation (and a test that you actually
have a gausian distribution) this value is not worth much.
What I am talking about is
http://www.satsignal.eu/ntp/2015-03-21-23-BBB_offset.png
The before ("full" OS) and after ("console" OS) is strange by itself.
What kind of process is running that increases interrupt latency jitter
by a factor of 2-3? Why does the "console" OS still exhibit a jitter that
is a factor 2 to 3 higher than what i'd expect as interrupt jitter?
Attila Kinali
PS: could you please quote mails properly? It makes them much easier to
read.
http://pub.tsn.dk/how-to-quote.php
==
Attila,
The jitter is not averaged, and the RMS value is given in:
http://www.satsignal.eu/ntp/2015-03-21-23-BBB_offset.png
The Console BBB OS was recommended here. Likely the two were:
Full: bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img
Console: bone-debian-7.8-console-armhf-2015-03-01-2gb.img
The GPS has a jitter well under a a tenth of a microsecond, so someone else
will need to investigate why the jitter does not meet you expected levels,
as I have abandoned the BBB as it created too much RF interference, and has
far less support than the Raspberry Pi. Timekeeping on the RPi is quite
good enough for my purposes.
Unfortunately, my e-mail software makes it very difficult to do proper
quoting. I always do correct quoting with NNTP using Thunderbird, but I'm
unwilling to start putting chevrons at the start of every quoted line in
e-mail with my inferior e-mail software. Perhaps one day I'll change e-mail
software - it annoys me as well. At least it doesn't top-post, or use HTML!
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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Re: [time-nuts] beaglebone black, debian, NTP client
On Tue, 5 Jan 2016 10:37:08 -
"David J Taylor" wrote:
> hanks, Attila. I'm unsure where you are getting the figures from, but the
> graph shows 2.5 µs averaged jitter:
>
> http://www.satsignal.eu/ntp/2015-03-21-23-BBB_jitter.png
>
> with the reduced OS, and 2.5 to 4 µs with the fuller OS. The peak-to-peak
> will higher than those figures, of course.
That's one thing that annoys me with those graphs. If you average jitter
it loses its meaning. What you then get is the mean deviation (aka offset).
Without an accompanying standard deviation (and a test that you actually
have a gausian distribution) this value is not worth much.
What I am talking about is
http://www.satsignal.eu/ntp/2015-03-21-23-BBB_offset.png
The before ("full" OS) and after ("console" OS) is strange by itself.
What kind of process is running that increases interrupt latency jitter
by a factor of 2-3? Why does the "console" OS still exhibit a jitter that
is a factor 2 to 3 higher than what i'd expect as interrupt jitter?
Attila Kinali
PS: could you please quote mails properly? It makes them much easier to read.
http://pub.tsn.dk/how-to-quote.php
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] beaglebone black, debian, NTP client
On Sat, 2 Jan 2016 11:47:09 - "David J Taylor" wrote: I'm also using PPS with the BBB - you even commented on my Web page! http://www.satsignal.eu/ntp/BBB-vs-RPi.html Yes, I know. But I didn't mention your webpage, because there is something weird going on with your system. The jitter you are seeing is very high. And it depends on the load of the OS that seems to have many unnecessary processes running. Even if you don't use the timer unit, like Dan Drown did, you shouldn't see a jitter higher than 2-4us on the PPS pin (that's approximately half the interrupt latency of the BBB including kernel/software induced latency). But yours goes up to +/-12us, ie is 6-12 times higher. Attila Kinali === Thanks, Attila. I'm unsure where you are getting the figures from, but the graph shows 2.5 µs averaged jitter: http://www.satsignal.eu/ntp/2015-03-21-23-BBB_jitter.png with the reduced OS, and 2.5 to 4 µs with the fuller OS. The peak-to-peak will higher than those figures, of course. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
On Sat, 2 Jan 2016 11:47:09 - "David J Taylor" wrote: > I'm also using PPS with the BBB - you even commented on my Web page! > > http://www.satsignal.eu/ntp/BBB-vs-RPi.html Yes, I know. But I didn't mention your webpage, because there is something weird going on with your system. The jitter you are seeing is very high. And it depends on the load of the OS that seems to have many unnecessary processes running. Even if you don't use the timer unit, like Dan Drown did, you shouldn't see a jitter higher than 2-4us on the PPS pin (that's approximately half the interrupt latency of the BBB including kernel/software induced latency). But yours goes up to +/-12us, ie is 6-12 times higher. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
A couple of people have. If you look at the archives you'll find a few of those. Dan Drown sticks out a bit here, as he is AFAIK the only one who used a GPIO as a PPS input on the BBB: (last mail seen around december 2014) http://blog.dan.drown.org/beaglebone-black-timer-capture-driver/ http://blog.dan.drown.org/tcxo-beaglebone-black/ HTH Attila Kinali I'm also using PPS with the BBB - you even commented on my Web page! http://www.satsignal.eu/ntp/BBB-vs-RPi.html David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
On Thu, 31 Dec 2015 17:27:40 -0800 jimlux wrote: > Has anyone fooled with using NTP on a beaglebone black running Debian > (the beagleboard.org image)? > > I assume it's just a matter of turning on ntpd (which I'm not sure is > even installed) and/or running ntpdate (I'm not looking for super > accuracy.. it's for a sprinkler timer) A couple of people have. If you look at the archives you'll find a few of those. Dan Drown sticks out a bit here, as he is AFAIK the only one who used a GPIO as a PPS input on the BBB: (last mail seen around december 2014) http://blog.dan.drown.org/beaglebone-black-timer-capture-driver/ http://blog.dan.drown.org/tcxo-beaglebone-black/ HTH Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
Has anyone fooled with using NTP on a beaglebone black running Debian (the beagleboard.org image)? I assume it's just a matter of turning on ntpd (which I'm not sure is even installed) and/or running ntpdate (I'm not looking for super accuracy.. it's for a sprinkler timer) Yes, please see: http://www.satsignal.eu/ntp/BBB-vs-RPi.html Happy New Year! David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
Me. It's pretty straight forward. "apt-get install ntp" -Bob On Thu, Dec 31, 2015 at 6:27 PM, jimlux wrote: > Has anyone fooled with using NTP on a beaglebone black running Debian (the > beagleboard.org image)? > > > I assume it's just a matter of turning on ntpd (which I'm not sure is even > installed) and/or running ntpdate (I'm not looking for super accuracy.. > it's for a sprinkler timer) > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
The Debian 8.x (jessie) releases for the BeagleBone run systemd-timesyncd, which is installed and on by default. As long as the Beaglebone is hooked to the internet, it has correct time to +/- 10 milliseconds or so. Probably good enough for a time-nut lawn sprinkler. systemd-timesyncd is a simplified system that corrects the system clock in the computer using NTP, but only as a client. The Beaglebone does not participate as a peer. For Debian 7 (wheesie), I think you need to install and enable ntpd. On Thu, Dec 31, 2015 at 7:27 PM, jimlux wrote: > Has anyone fooled with using NTP on a beaglebone black running Debian (the > beagleboard.org image)? > > > I assume it's just a matter of turning on ntpd (which I'm not sure is even > installed) and/or running ntpdate (I'm not looking for super accuracy.. > it's for a sprinkler timer) > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
On Thu, Dec 31, 2015 at 8:27 PM, jimlux wrote: > Has anyone fooled with using NTP > You can apt-get (in alphabetic order) chrony, ntp (sntp) or openntpd. You can also build ntimed-client. As I recall the obvious installation assumes a RTC. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebone black, debian, NTP client
jim...@earthlink.net said: > Has anyone fooled with using NTP on a beaglebone black running Debian (the > beagleboard.org image)? Works fine for me. I'm building from source to help test the latest bits rather than running the binary packages they provide. I don't remember anything interesting. Poke me off-list if you have any troubles. Works on Raspberry Pi too. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] beaglebone black, debian, NTP client
Has anyone fooled with using NTP on a beaglebone black running Debian (the beagleboard.org image)? I assume it's just a matter of turning on ntpd (which I'm not sure is even installed) and/or running ntpdate (I'm not looking for super accuracy.. it's for a sprinkler timer) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
