Re: [time-nuts] Beaglebone NTP server
Dan: Thanks. I don't know where you were quoting from, but it was the
answer I needed.
Paul: I found BB-BONE-GPS-00A0.dts, so I will start editing/hacking from
there.
I plan to run under Debian 7.7 or 8-Testing.
Thanks,
--- Graham
==
On Tue, Dec 9, 2014 at 5:33 PM, Paul tic-toc@bodosom.net wrote:
On Tue, Dec 9, 2014 at 12:59 PM, Graham / KE9H ke9h.graham@gmail.com
wrote:
I guess I am asking if the kernel "pps-gpio" has a specific preferred
pin,
or whether it can be mapped to any available gpio pin.
The provided-with-stock-dtb pin is: <0x40> which is P9 pin 15.
I use the only "free" pin on P8 or P9: <0x7c> which is P8 pin 26
There are various maps/charts/lists around with the pins. Just decompile
/lib/firmware/BB-BONE-GPS-00A0.dtbo and fiddle if you want a different
pin. The Debian relases come with dtc, I don't know about Angstrom.
e.g.
http://www.embedded-things.com/bbb/beaglebone-black-pin-mux-spreadsheet/
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Graham make sure you read up on dtb and fdt. Many if not most distros don't
have what you might call a default.
On Tuesday, December 9, 2014, Graham / KE9H ke9h.graham@gmail.com wrote:
Dan: Thanks. I don't know where you were quoting from, but it was the
answer I needed.
Paul: I found BB-BONE-GPS-00A0.dts, so I will start editing/hacking from
there.
I plan to run under Debian 7.7 or 8-Testing.
Thanks,
--- Graham
==
On Tue, Dec 9, 2014 at 5:33 PM, Paul <tic-toc@bodosom.net javascript:;>
wrote:
On Tue, Dec 9, 2014 at 12:59 PM, Graham / KE9H <ke9h.graham@gmail.com
wrote:
I guess I am asking if the kernel "pps-gpio" has a specific preferred
pin,
or whether it can be mapped to any available gpio pin.
The provided-with-stock-dtb pin is: <0x40> which is P9 pin 15.
I use the only "free" pin on P8 or P9: <0x7c> which is P8 pin 26
There are various maps/charts/lists around with the pins. Just decompile
/lib/firmware/BB-BONE-GPS-00A0.dtbo and fiddle if you want a different
pin. The Debian relases come with dtc, I don't know about Angstrom.
e.g.
<
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Hi David,
Yes, You mean the hourly dips? That is caused by the the VLF receive
software that
is running on the same PI. It makes hourly recordings of DC to 24 Khz
with a USB soundcard. The CPU is running at max capacity most of the
time.
Perhaps it is now time for a dedicated PI, that only has the task of
playing Stratum One.
If anyone is interested:
https://pivlf.wordpress.com/
73, Frits W1FVB
---============
Yes, that is quite interesting, Frits, and of course the hourly dips are
just as you say.
I take it that the spectrum is from a broadband antenna, and that the graphs
below are signal strengths of specific stations? Perhaps you have a
description of the project. Perhaps link that description from the text:
"Raspberry PI Project by W1FVB"
RPi cards have a way of proliferating - I have seven now! At least two are
actually doing something useful (ADS-B receiver with a DVB-T dongle, and a
wall clock driven by NTP).
73,
David GM8ARV
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
On Sun, Dec 7, 2014 at 3:10 PM, folkert folkert@vanheusden.com wrote:
Regarding the fs error
As an aside: this thread is like a zombie. Folkert's reply was to my post
from March
2014
in response to Henry Hallam who was replying to a message from
Gabs Ricalde posted in June 2013.
I suppose I should have waited six months to post this.
Well, I am hoping to get to the point where the path to using the BBB as an
NTP server using the PRU for more precise timing, and using the LTE-lite to
provide the 1pps and time data. Of course, the LTE-lite can also provide
1pps and 10MHz to my workbench. (It's all going to go in a 1U box in the
rack next to my workbench.)
Yes, I know that all the information is out there and much if it can be
gleaned from this list by following several threads back through several
months. But that brings to mind playing Adventure. Has anyone compiled a
how-to for turning a BBB into an NTP server using the PRU for timing? Seems
like a straight-forward and useful turn-key kind of thing.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
Brian,
Sorry about the long post.
I was on a similar path recently. I wanted to create
a nice and simple Stratum 1 server using a beagleboard.
In addition, I wanted to create a nice case for it
so I would enjoy looking at it from my desk.
Since I was already using a GPS Motorola receiver to
create a Linux NTP server, I was pretty sure I had most of
the parts.
Since The Beagleboard is using systemd I figured I would
start by creating a CentOS 7 Stratum 1 machine so I can
figure out all the systemd pieces.
I finished this 5 days ago.
Next, using Cadence Allegro (OrCAD) I designed a
proto cape for the Beagleboard.
This is also done. I figure I will use the proto cape
as a prototype board and also get familiar with
all the pins on the Beagleboard I/O headers.
This is also done (mostly) as of yesterday.
Actually, I was in the middle of documenting this
when this thread caught my eye.
You and everyone on this list are welcome
to the Cadence Project and all the files.
You can use this basic project to design any cape
for the Beagleboard. I am releasing it as free.
Just mention my company: Maxima Physics.
I will finish the documentation for CentOS 7 + NTP
server over the next few days. I have also been fighting
a nasty flu :(
Comments are most welcome.
-George Hrysanthopoulos
On 12/10/2014 04:58 PM, Brian Lloyd wrote:
Well, I am hoping to get to the point where the path to using the BBB as an
NTP server using the PRU for more precise timing, and using the LTE-lite to
provide the 1pps and time data. Of course, the LTE-lite can also provide
1pps and 10MHz to my workbench. (It's all going to go in a 1U box in the
rack next to my workbench.)
Yes, I know that all the information is out there and much if it can be
gleaned from this list by following several threads back through several
months. But that brings to mind playing Adventure. Has anyone compiled a
how-to for turning a BBB into an NTP server using the PRU for timing? Seems
like a straight-forward and useful turn-key kind of thing.
Neil Schroeder wrote:
Graham make sure you read up on dtb and fdt. Many if not most distros
don't
have what you might call a default.
I have done several device tree overlays on the BBB, so I think I can
usually get the
I/O lines and pin-mux to do what I want them to do. It was a total pain
figuring
it out without good documentation. Any distro that I use does contain the
cape manager, so I have a starting point.
==
David wrote:
RPi cards have a way of proliferating - I have seven now! At least two
are actually doing something useful.
When you get 24 of them, you can build a parallel super computing cluster.
:-)
http://www.amazon.com/gp/product/1783989440/
--- Graham
==
On Wed, Dec 10, 2014 at 10:56 AM, Paul tic-toc@bodosom.net wrote:
On Sun, Dec 7, 2014 at 3:10 PM, folkert folkert@vanheusden.com wrote:
Regarding the fs error
As an aside: this thread is like a zombie. Folkert's reply was to my post
from March
2014
in response to Henry Hallam who was replying to a message from
Gabs Ricalde posted in June 2013.
I suppose I should have waited six months to post this.
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.
On Wed, Dec 10, 2014 at 9:58 PM, Brian Lloyd brian@lloyd.aero wrote:
Well, I am hoping to get to the point where the path to using the BBB as an
NTP server using the PRU for more precise timing, and using the LTE-lite to
provide the 1pps and time data. Of course, the LTE-lite can also provide
1pps and 10MHz to my workbench. (It's all going to go in a 1U box in the
rack next to my workbench.)
Yes, I know that all the information is out there and much if it can be
gleaned from this list by following several threads back through several
months. But that brings to mind playing Adventure. Has anyone compiled a
how-to for turning a BBB into an NTP server using the PRU for timing? Seems
like a straight-forward and useful turn-key kind of thing.
Getting a BBB to take 10MHz refclk input (in the fashion of
http://www.febo.com/pages/soekris/)
and being able to timestamp multiple PPS signals via the PRUs would
make for a pretty awesome time-nuts toy.
On Wed, Dec 10, 2014 at 4:58 PM, Brian Lloyd brian@lloyd.aero wrote:
Well, I am hoping to get to the point where the path to using the BBB as an
NTP server using the PRU for more precise timing
Using a PRU seems like overkill if all you want from the BBB is NTP. The
standard pps-gpio should move the system clock precision below
system/network jitter (.5 to 1 microsecond). The next step is using a
timer (TIMER4) which should get you into .1 microsecond offsets.
Naturally if you're doing significant computing (heh) on the BBB you might
want to use a real time unit.
The current portion of this thread is part of the June-2013 hread started
by Gabs Ricalde about using TIMER4 for capture with 10MHz/1PPS input.
https://www.febo.com/pipermail/time-nuts/2013-June/077430.html
Quoting Paul tic-toc@bodosom.net:
Using a PRU seems like overkill if all you want from the BBB is NTP. The
standard pps-gpio should move the system clock precision below
system/network jitter (.5 to 1 microsecond). The next step is using a
timer (TIMER4) which should get you into .1 microsecond offsets.
As a note to people wanting to use the timer hardware on the BBB - I
have a driver for it at https://github.com/ddrown/pps-gmtimer
I wrote up the results in using it at
http://blog.dan.drown.org/beaglebone-black-timer-capture-driver/
The summary of it is:
pps-gpio - 50% of the time local clock offset within +/- 0.07us, 98%
within +/- 0.61us
pps-gmtimer - 50% of the time local clock offset within +/- 0.04us,
98% within +/- 0.43us
Also, if you're using pps-gpio, you might want to disable cpufreq and
force your processor to 1GHz. It'll help with interrupt latency and
jitter.
cpufreq ondemand, 300MHz-1GHz -
http://dan.drown.org/bbb/run9/interrupt-latency.png
98% of interrupts handled 12.92us-23.21us after the event happened.
cpufreq forced 1GHz - http://dan.drown.org/bbb/run8/interrupt-latency.png
98% of interrupts handled 6.04us-8.58us after the event happened.