[SI-LIST] Re: Displaying eye pattern in an oscilloscope?
- From: Ihsan Erdin <erdinih@xxxxxxxxx>
- To: steve weir <weirsi@xxxxxxxxxx>
- Date: Sun, 23 Oct 2005 11:13:16 -0400
Hi Steve,
I think a simulation vs. measurement comparison is the motivation behind the
eye diagram capturing. I don't know what kind of post-processing filter you
can apply to the captured waveform in order to eliminate one of the
90-degree apart strobe signals on a bi-directional bus but even if this were
possible it would only work on a single memory interface. In order to
understand which memory device is driving you still need to observe (trigger
on) the /CS signal. All in all, I'm not convinced an eye-diagram scope
capture is possible to form a reference to the simulation results. But if
the idea is timing verification as you put it, yes, you can do that by
probing (and logic triggering on) all the control signals but without an
eyediagram pattern on the scope.
Ihsan
On 10/23/05, steve weir <weirsi@xxxxxxxxxx> wrote:
>
> Ishan, I do agree with you that just triggering on DQS and running
> infinite persistence will just make an ugly mess on the screen. And if what
> one wants to do is detailed characterizations by: target/source DIMM,
> interleaved/non-interleaved bursts etc, what I suggest is inadequate.
>
> However, for the very same reason that infinite persistence without a
> cycle type trigger doesn't work well, we can extract reads and writes using
> only DQS and DQ. The trick is to use the 90 / 0 DQS to DQ phase offset of
> write versus read as a post-process filter to separate out the reads from
> the writes in .wfm captures. If the idea is to verify that system level
> timing works, that should be enough for the data path. If the skew moves
> around by more than 90 degrees such that reads can't be distinguished from
> writes, then the channel is broken anyway.
>
> Regards,
>
>
> Steve.
>
> At 11:14 PM 10/22/2005 -0400, Ihsan Erdin wrote:
>
> I'm not sure if it's possible at all. To capture a read or write cycle,
> you'll need a logic triggering setup for data and control signals (/WE, /CS)
> as Chris describes. For an eye diagram pattern, on the other hand, you'll
> need an edge trigger setup either at the clock or the data itself with a
> delay (one or two periods) A logic triggering with an infinite persistence
> display setting will not result an eye diagram.
>
> Ihsan Erdin
>
> On 10/22/05, *Chris Cheng* <Chris.Cheng@xxxxxxxxxxxx> wrote:
>
> Not that simple.
> You will most like need some advanced triggering to trigger on CAS, WE so
> that you can tell if it is a read or write. Then you probably need some
> software to limit the hit to certain address to be sure you get the right
> DIMM. Good luck if you need to see the effect of interleave vs.
> non-interleave.
> ________________________________
>
> From: si-list-bounce@xxxxxxxxxxxxx on behalf of steve weir
> Sent: Fri 10/21/2005 10:59 PM
> To: rrepollo@xxxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Displaying eye pattern in an oscilloscope?
>
>
>
> Don't you have access to both clock and data?
>
>
> Steve
> At 09:17 AM 10/22/2005 +0800, Rep wrote:
> >Good day!
> >
> >I simulated a data signal from SH4 processor to SDRAM, displaying it in
> an
> >eye pattern.
> >I need to verify the signal by actual board evaluation.
> >Could please someone tell me how I could measure the
> >signal in eye pattern through the use of an oscilloscope (TEK)?
> >
> >I would really appreciated any help I could get.
> >
> >Thank you.
> >
> >------------------------------------------------------------------
> >To unsubscribe from si-list:
> >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
> >
> >or to administer your membership from a web page, go to:
> >//www.freelists.org/webpage/si-list
> >
> >For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> >
> >List FAQ wiki page is located at:
> > http://si-list.org/wiki/wiki.pl?Si-List_FAQ
> >
> >List technical documents are available at:
> > http://www.si-list.org
> >
> >List archives are viewable at:
> > //www.freelists.org/archives/si-list
> >or at our remote archives:
> > http://groups.yahoo.com/group/si-list/messages
> >Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
