Re: XGMII
Hi Roger,
I fully agree with your statement. Why add additional pins to an already
wide interface and add the complication of synchronization when it can be
done with relative ease with a single reference clock? Several companies
that I know of are implementing XGMII as presented and have not had issues
with the proposed timing spec.
If it ain't broke, don't fix it ;-)
Cheers,
Claus
Claus Stetter
Allayer Communications
Tel: +1 408 570 0888 x170
Fax: +1 408 570 0880
Cell: +1 408 221 6461
Email: cstetter@xxxxxxxxxxx
http://www.allayer.com
----- Original Message -----
From: Roger Ronald <rronald@xxxxxxx>
To: Justin Gaither <jgaither@xxxxxxxxxxxxxxx>; 802.3ae
<stds-802-3-hssg@xxxxxxxx>
Sent: Tuesday, July 18, 2000 4:26 AM
Subject: Re: XGMII
>
> This interface does not seem to be any harder than interfacing to DDR RAM
> at the same speed. Every corner garage shop will soon be turning out
> DDR RAM based motherboards soon.
>
> Personally, I'd much rather have relatively tight timing instead of
> complications in the clocking and a whole new chip to chip
> protocol to spec/understand/debate/document/build.
>
> RR
> ----- Original Message -----
> From: "Justin Gaither" <jgaither@xxxxxxxxxxxxxxx>
> To: "802.3ae" <stds-802-3-hssg@xxxxxxxx>
> Sent: Monday, July 17, 2000 3:15 PM
> Subject: XGMII
>
>
> >
> > Everyone,
> >
> > Concerning the XGMII interface, I remember at least one comment
> > during the plenary and I have the same reservation concerning the
> > extreme width and tightness of the setup and hold timing.
> >
> > I would like to suggest separate clocks for each of the 8 bit lanes.
> > This would allow each lane to have a manageable number of tightly
> > coupled signals, and allow for 1 or two clocks skew between lanes. The
> > Bus could easily be spread across the pins of a device enabling
> > distributed reference and less ground bounce. I don't see adding 3 more
> > pins to a 37 pin interface to be excessive. Synchronization of the
> > lanes could be done using the control lines for a sync. (i.e.. 1111
> > followed by 1000 on the control is start of data).
> >
> >
> >
> > --
> > Justin Gaither Phone: 512-306-7292 x529
> > RocketChips, Inc. Fax: 512-306-7293
> > 500 N. Capital of TX Hwy.
> > Bldg 3 email: jgaither@xxxxxxxxxxxxxxx
> > Austin, TX 78746 WWW: www.rocketchips.com
> >
> >
> >