[time-nuts] Using a frequency synthesizer replacement for motherboard oscillator

Eric Garner garnere at gmail.com
Mon Dec 3 18:44:33 UTC 2012


I'm an applications engineer for a company that makes Ethernet controllers
and PHYs. Some of our customers use crystals (more often oscillators) that
they selected based on price rather than performance. when i'm debugging a
customer issue replacing the clock source with a synthesizer is a good
troubleshooting aid. I's also useful when trying to prove that a low
quality clock source (or clock distribution network) in a link partner is
producing a poor (usually jittery) output that makes it hard for our parts
to achieve link.



On Fri, Nov 30, 2012 at 5:06 PM, Jim Welch <welch20 at comcast.net> wrote:

> OK, I'll bite.  Why?
>
> Jim
>
> >>>I've never done it using to the RTC crystal, but I  do it quite
> frequently in my Day Job to >>>Ethernet controllers on those same pc mother
> boards.
> >>>
> >>>-Eric
>
> On Fri, Nov 30, 2012 at 4:10 PM, Sarah White <kuzetsa at gmail.com> wrote:
>
> > On 11/30/2012 6:30 PM, Eric Garner wrote:
> > > the actual RTC on modern (Intel based) PC's is driven from a
> > > standard
> > > 32,768 Hz crystal attached to the PCH. some of them are in
> > > incredibly
> > small
> > > packages now instead of the old tuning fork-in-a-can ones. peeling
> > > off
> > the
> > > load caps and crystal from the board would allow you plenty of
> > > spaces to tack down a lead from an external synthesizer.
> >
> > Yeah, the one on the (Soekis) example was pretty small. So far none of
> > of the replies have indicated that anyone on here has experience
> > beyond an embedded system.
> >
> > Mostly I started this thread because there have been a few with people
> > discussing implementing NTP on embedded microcontrollers, arduino, etc.
> > and I was thinking of doing it from the other side (turning a nice-ish
> > server into a rock-solid timekeeper)
> >
> > Thanks so far everyone. Really impressed that I already managed to get
> > 4x replies so quickly :)
> >
> >
> >
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> >
>
>
>
> --
> --Eric
> _________________________________________
> Eric Garner
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-- 
--Eric
_________________________________________
Eric Garner


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