Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[Frank Wayne]

Thank you. I have not had time to revisit this lately and now school has 
started again, but I will try it as soon as I have the chance.

If you work at Schloss Laxenburg, I am very jealous. :)

From: MAYER Hans [hans.ma...@iiasa.ac.at]
Sent: Tuesday, January 02, 2018 05:45
To: Frank Wayne; questions@lists.ntp.org
Subject: RE: More than one PPS source on Raspberry Pi?

Hi Frank,

Sorry for late answer.
Yes, I compiled a driver to use it twice.
Here a link of my rubidium stratum-1 project 
http://blog.mayer.tv/2017/06/11/stratum-0-server.html
Inside there are several links. One is for a second driver which you can find 
here: https://github.com/hans-mayer/pps2gpio

Kind regards
Hans




-Original Message-
From: questions [mailto:questions-bounces+hans.mayer=iiasa.ac...@lists.ntp.org] 
On Behalf Of Frank Wayne
Sent: Monday, December 4, 2017 5:35 PM
To: questions@lists.ntp.org
Subject: [ntp:questions] More than one PPS source on Raspberry Pi?

Has anyone tried to use more than one PPS source at the same time on a 
Raspberry Pi? The device tree overlay pps-gpio does not seem to support more 
than one instance. That is, if my config.txt specifies two instances of 
pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi 
forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian 
or another OS that will run on a Pi?

Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[MAYER Hans]

Hi Frank,

Sorry for late answer. 
Yes, I compiled a driver to use it twice.
Here a link of my rubidium stratum-1 project 
http://blog.mayer.tv/2017/06/11/stratum-0-server.html 
Inside there are several links. One is for a second driver which you can find 
here: https://github.com/hans-mayer/pps2gpio

Kind regards 
Hans




-Original Message-
From: questions [mailto:questions-bounces+hans.mayer=iiasa.ac...@lists.ntp.org] 
On Behalf Of Frank Wayne
Sent: Monday, December 4, 2017 5:35 PM
To: questions@lists.ntp.org
Subject: [ntp:questions] More than one PPS source on Raspberry Pi?

Has anyone tried to use more than one PPS source at the same time on a 
Raspberry Pi? The device tree overlay pps-gpio does not seem to support more 
than one instance. That is, if my config.txt specifies two instances of 
pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi 
forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian 
or another OS that will run on a Pi?

Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[Miroslav Lichvar]

On Mon, Dec 04, 2017 at 04:25:26PM -0500, Brian Utterback wrote:
> Doesn't adding a second PPS signal mean that the accuracy can only go down?
> If the two PPS signals are really in sync then they will be clocking
> essentially simultaneously. They won't get serviced simultaneously so one
> will either be ignored or will be serviced after a delay.

I think some GPS units can be configured to shift the PPS edge by a
specified offset to avoid two PPS signals triggering an interrupt at
the same time.

-- 
Miroslav Lichvar
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[Link, Ken]

I've always thought having multiple PPS sources on a single machine wouldn't 
work because the PPS interrupts would occur at the same time, causing random 
offsets and jitter to show up on the PPS sources since the interrupts would be 
queued in an essentially random order and processed sequentially.

Is it different for the Raspberry Pi?



Open Systems International, Inc.

Ken Link
Supervisor
Software Development

4101 Arrowhead Drive
Medina, Minnesota 55340-9457
Phone: 763 551 0559
Fax: 763 551 0750
Email: ken.l...@osii.com
Website: www.osii.com

-Original Message-
From: questions [mailto:questions-bounces+klink=osii@lists.ntp.org] On 
Behalf Of Frank Wayne
Sent: Monday, December 04, 2017 10:35 AM
To: questions@lists.ntp.org
Subject: [ntp:questions] More than one PPS source on Raspberry Pi?

Has anyone tried to use more than one PPS source at the same time on a 
Raspberry Pi? The device tree overlay pps-gpio does not seem to support more 
than one instance. That is, if my config.txt specifies two instances of 
pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi 
forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian 
or another OS that will run on a Pi?

Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[Brian Utterback]

Doesn't adding a second PPS signal mean that the accuracy can only go 
down? If the two PPS signals are really in sync then they will be 
clocking essentially simultaneously. They won't get serviced 
simultaneously so one will either be ignored or will be serviced after a 
delay.


On 12/4/2017 12:02 PM, Paul J R wrote:

The answer is no and yes (and also maybe)..

no because the current pps-gpio driver only loads a single pin (though 
it could be extended to load more than one, but i dont think anyones 
done that).


yes because the other way it could be achieved is to create a second 
module called pps-gpio2 and then init that with a different pin 
config, and that wouldn't be overly hard and possibly easier than 
trying to extend the existing driver (depending on knowledge of kernel 
drivers).


Lastly, maybe because im unaware of what hardware limits the rpi might 
have which might get in the way of doing something like that (from 
what i've read, every pin is capable of being configured for 
interrupts, so it sounds like it should be possible)


On 05/12/17 03:35, Frank Wayne wrote:
Has anyone tried to use more than one PPS source at the same time on 
a Raspberry Pi? The device tree overlay pps-gpio does not seem to 
support more than one instance. That is, if my config.txt specifies 
two instances of pps-gpio for different GPIO pins, only /dev/pps0 is 
created.


The documentation for pps_gpio is limited or missing, and the 
Raspberry Pi forum and the LinuxPPS list have not helped.


If pps-gpio cannot do it, is there another way to get PPS devices for 
Raspbian or another OS that will run on a Pi?


Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions




___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions



--
Oracle 
Brian Utterback | Principal Software Engineer
Phone: +1 6038973049 
Oracle Systems Server & Cloud Engineering
1 Oracle Dr. | Nashua, NH 03062

All working systems eventually show their own agendas.

Green Oracle  Oracle is committed to 
developing practices and products that help protect the environment

___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

Re: [ntp:questions] More than one PPS source on Raspberry Pi?

[Paul J R]

The answer is no and yes (and also maybe)..

no because the current pps-gpio driver only loads a single pin (though 
it could be extended to load more than one, but i dont think anyones 
done that).


yes because the other way it could be achieved is to create a second 
module called pps-gpio2 and then init that with a different pin config, 
and that wouldn't be overly hard and possibly easier than trying to 
extend the existing driver (depending on knowledge of kernel drivers).


Lastly, maybe because im unaware of what hardware limits the rpi might 
have which might get in the way of doing something like that (from what 
i've read, every pin is capable of being configured for interrupts, so 
it sounds like it should be possible)


On 05/12/17 03:35, Frank Wayne wrote:

Has anyone tried to use more than one PPS source at the same time on a 
Raspberry Pi? The device tree overlay pps-gpio does not seem to support more 
than one instance. That is, if my config.txt specifies two instances of 
pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi 
forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian 
or another OS that will run on a Pi?

Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions




___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions

[ntp:questions] More than one PPS source on Raspberry Pi?

[Frank Wayne]

Has anyone tried to use more than one PPS source at the same time on a 
Raspberry Pi? The device tree overlay pps-gpio does not seem to support more 
than one instance. That is, if my config.txt specifies two instances of 
pps-gpio for different GPIO pins, only /dev/pps0 is created.

The documentation for pps_gpio is limited or missing, and the Raspberry Pi 
forum and the LinuxPPS list have not helped.

If pps-gpio cannot do it, is there another way to get PPS devices for Raspbian 
or another OS that will run on a Pi?

Frank Wayne
___
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions