Re: [Linuxptp-users] Hardware PTP clock synchronization

[Keller, J. E <jac...@in...>]

I agree with you.. But the architects here usually just consider
1588/PTP support sort of a "best effort" when designing the hardware.
That tends towards not really properly supporting the feature. At least
early on there weren't many hardware guys here who actually understood
what PTP needed either, so some of the older designs just don't quite do
the right thing.

That is why some of the designs really don't work quite as well as one
would like.

Thanks,
Jake

On Fri, 2013-08-02 at 17:20 -0400, Dale Smith wrote:
> Yeah, that's pretty much what I suspected.
> 
> 
> A reason you want to use something like a vcxo, is so get get a really
> clean clock for driving things like A2D converters.  It's important if
> you are doing signal analysis.  A fixed frequency clock with pulse
> addition/subtraction to get the right number of clocks edges per
> second just doesn't cut it.
> 
> 
> Thanks,
>    -Dale
> 
> 
> 
> 
> 
> 
> On Fri, Aug 2, 2013 at 4:16 PM, Keller, Jacob E
> <jac...@in...> wrote:
>         On Fri, 2013-08-02 at 14:36 -0400, Dale Smith wrote:
>         > On Fri, Aug 2, 2013 at 1:54 PM, Keller, Jacob E
>         > <jac...@in...> wrote:
>         >         Richard suggested the i210, and I also would
>         recommend this
>         >         part.
>         >         Obviously I am somewhat biased as I am an Intel
>         engineer.
>         >         However this
>         >         part definitely is better than the 82576 because it
>         supports
>         >         timestamping all packets (vastly reducing issues)
>         >
>         >
>         > Something I'm unclear on after reading the i210 datasheets,
>         is if it
>         > is possible for it to use an external servoed vcxo or the
>         like for the
>         > 1588 clock, or does it only do the missing pulse / extra
>         pulse thing
>         > to adjust the 1588 clock frequency?
>         >
>         >
>         > Thanks,
>         >    -Dale
>         
>         
>         
>         I do not believe you can use an external servo to create the
>         1588 clock.
>         You may, however, be able to use an external PPS signal and
>         have that
>         timestamped and software tune the onboard 1588 clock
>         frequency.
>         
>         I don't know this for certain though.
>         
>         Thanks,
>         Jake
> 
>