[asterisk-dev] Alternative Clock Source

[Oron Peled]

On Tuesday, 10 בJuly 2007 23:38, Paulo Garcia wrote:
> Is it possible to do exactly the opposite? Instead of providing my own clock
> source, is it possible the get this clock from the zaptel layer. I'm
> thinking on using our software layers with another vendor cards like Digium
> and Sangoma. We don't use zaptel so I'm wondering to know if it is some kind
> of way to get this clock .

Look at the thread starting with:
  http://lists.digium.com/pipermail/asterisk-dev/2007-May/027437.html
It points to a very small patch to zaptel that achieve this goal.
[basically have zaptel call back interested spans every tick].

If you have the proper hardware, you can use this solution to sync
your hardware from other cards (We currently use it in our Astribank
drivers).

Matthew Fredrickson correctly pointed out later in the same thread that
for synchronizing a PLL based clock we can use far less than 1000 ticks/sec
Therefore we held back this patch and were checking other options for sync.

What about your application? Can you leave with less frequent updates (like
once per second) or are 1000 ticks/sec updates are a must for your case?

> On 7/10/07, Tzafrir Cohen <tzafrir.cohen at xorcom.com> wrote:
> >
> > On Tue, Jul 10, 2007 at 02:52:32PM -0300, Paulo Garcia wrote:
> > > Hi All,
> > >
> > > After some research I decided to patch the ztdummy to provide the clock
> > > source for Asterisk.
> >
> > Please help test
> >
> >   http://bugs.digium.com/8896
> >
> > It is essentially qhat you describe.
> >
> > >
> > > Now, I'm wondering with a scenario where I have my card and another
> > vendor
> > > card (e.g. Digium or Sangoma). How the clock will work in this
> > situation?
> > > The true-zaptel-card (Digium or Sangoma) will "overwrite" my patched
> > ztdummy
> > > and use its own clock? Is there a way to my clock have high priority in
> > this
> > > case?
> >
> > The patch there also adds the option 'prefmaster' to ztdummy. This will
> > make ztdummy try to take the sync mastership "by force" when it loads.
> >
> > However a digital span can still take timing on certain circumstnaces if
> > it is configured as a timing source. But then again, in setups where
> > you're supposed to provide timing, no other device should be a timing
> > source (a value other that '0' for the 'timing' parameter in the span=
> > line in ztcfg).
> >
> > --
> >                Tzafrir Cohen
> > icq#16849755                    jabber:tzafrir at jabber.org
> > +972-50-7952406           mailto:tzafrir.cohen at xorcom.com
> > http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir
> >
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> 
> 
> 
> -- 
> --------------
> Paulo Garcia
> Pika Technologies Inc
> 

-- 
Oron Peled                             Voice/Fax: +972-4-8228492
oron at actcom.co.il                  http://www.actcom.co.il/~oron
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