Re: [time-nuts] Beaglebone NTP server
On Sun, Dec 7, 2014 at 12:09 PM, folkert folkert@vanheusden.com wrote:
On my rpi the jitter is between 2 and 10us iirc but it is a while since
I tested it. A quick peak shows me currently 3us jitter. Not bad for a
userspace solution imho.
Really? The PPS to GPIO interface is handles in user space? It is not
interrupt driven?
In the implementations I've seen the critical real time work is done inside
the PPS interrupt handler and then of course ntpd runs in userland and can
take as much time as it needs
--
Chris Albertson
Redondo Beach, California
It can be but suffers from enough jitter to be unusable.
All current BBB out of the box kernels have PPS-gpio. Google PPS gpio DTS
bbb.
Enjoy :-)
On Sunday, December 7, 2014, Chris Albertson albertson.chris@gmail.com
wrote:
On Sun, Dec 7, 2014 at 12:09 PM, folkert <folkert@vanheusden.com
javascript:;> wrote:
On my rpi the jitter is between 2 and 10us iirc but it is a while since
I tested it. A quick peak shows me currently 3us jitter. Not bad for a
userspace solution imho.
Really? The PPS to GPIO interface is handles in user space? It is not
interrupt driven?
In the implementations I've seen the critical real time work is done inside
the PPS interrupt handler and then of course ntpd runs in userland and can
take as much time as it needs
--
Chris Albertson
Redondo Beach, California
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From: Chris Albertson
Really? The PPS to GPIO interface is handles in user space? It is not
interrupt driven?
In the implementations I've seen the critical real time work is done inside
the PPS interrupt handler and then of course ntpd runs in userland and can
take as much time as it needs
---================
Folkert's solution was very helpful, but there is now kernel-mode PPS
support for a GPIO pin the current Raspberry Pi Linux - see:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#easy
I'm running that on a couple of systems here.
Cheers,
David
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions and
everything works beautiful. The PI that is running the PPS timekeeping with NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
On 12/8/14, David J Taylor david-taylor@blueyonder.co.uk wrote:
From: Chris Albertson
Really? The PPS to GPIO interface is handles in user space? It is not
interrupt driven?
In the implementations I've seen the critical real time work is done inside
the PPS interrupt handler and then of course ntpd runs in userland and can
take as much time as it needs
---================
Folkert's solution was very helpful, but there is now kernel-mode PPS
support for a GPIO pin the current Raspberry Pi Linux - see:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#easy
I'm running that on a couple of systems here.
Cheers,
David
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
time-nuts mailing list -- time-nuts@febo.com
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--
vbradio.wordpress.com
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions
and
everything works beautiful. The PI that is running the PPS timekeeping with
NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
---=============
Oh, yes! That's much better, Frits! Delighted to have helped!
(Although it now shows up an hourly periodicity - any idea what might be
causing that?)
73,
David GM8ARV
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Hourly cron jobs, perhaps?
-Bob
On Tue, Dec 9, 2014 at 8:04 AM, David J Taylor <
david-taylor@blueyonder.co.uk> wrote:
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions
and
everything works beautiful. The PI that is running the PPS timekeeping
with NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
---=============
Oh, yes! That's much better, Frits! Delighted to have helped!
(Although it now shows up an hourly periodicity - any idea what might be
causing that?)
73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
time-nuts mailing list -- time-nuts@febo.com
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For those of you that have gotten the BeagleBone Black up and
running as an ntp server with the 1PPS signal input in kernel space,
what gpio input pin is being used?
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.
Thanks,
--- Graham / KE9H
==
On Tue, Dec 9, 2014 at 11:18 AM, Bob Darlington rdarlington@gmail.com
wrote:
Hourly cron jobs, perhaps?
-Bob
On Tue, Dec 9, 2014 at 8:04 AM, David J Taylor <
david-taylor@blueyonder.co.uk> wrote:
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions
and
everything works beautiful. The PI that is running the PPS timekeeping
with NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
---=============
Oh, yes! That's much better, Frits! Delighted to have helped!
(Although it now shows up an hourly periodicity - any idea what might be
causing that?)
73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
time-nuts mailing list -- time-nuts@febo.com
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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
On 12/9/14, David J Taylor david-taylor@blueyonder.co.uk wrote:
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions
and
everything works beautiful. The PI that is running the PPS timekeeping with
NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
---=============
Oh, yes! That's much better, Frits! Delighted to have helped!
(Although it now shows up an hourly periodicity - any idea what might be
causing that?)
73,
David GM8ARV
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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--
vbradio.wordpress.com
If you're using the pps-gpio module, the hardware can support "up to
Two Interrupt Inputs per Bank". So if you're not using the gpio for
anything else, any of the gpio should work.
If you want to use the timer hardware (and pps-dmtimer module), each
timer has an assigned pin.
Quoting Graham / KE9H ke9h.graham@gmail.com:
For those of you that have gotten the BeagleBone Black up and
running as an ntp server with the 1PPS signal input in kernel space,
what gpio input pin is being used?
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.
Thanks,
--- Graham / KE9H
==
On Tue, Dec 9, 2014 at 11:18 AM, Bob Darlington rdarlington@gmail.com
wrote:
Hourly cron jobs, perhaps?
-Bob
On Tue, Dec 9, 2014 at 8:04 AM, David J Taylor <
david-taylor@blueyonder.co.uk> wrote:
Thanks for pointing this out David,
Compiling an new kernel was holding me back. I followed your instructions
and
everything works beautiful. The PI that is running the PPS timekeeping
with NTP
is serving as a VLF receiver as well. Taxing the poor CPU, but with
kernel PPS support
the NTP daemon has become way happier! (see attachment)
73, Frits W1FVB
---=============
Oh, yes! That's much better, Frits! Delighted to have helped!
(Although it now shows up an hourly periodicity - any idea what might be
causing that?)
73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
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.
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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/