[SI-LIST] Re: How to select signals for DDR2 eye diagram measurement in point to point topology
- From: "Michael Rose" <mrose@xxxxxxxxxxxx>
- To: "Hermann Ruckerbauer" <hermann.ruckerbauer@xxxxxxxxxxxxx>, "yardala" <yardala@xxxxxxxxx>
- Date: Thu, 8 Jul 2010 11:45:05 -0400
Yardala,
Or you can write a simple loop on the host processor to perform
consectutive writes or reads (remember to disable cache).
Mike
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Hermann Ruckerbauer
Sent: Thursday, July 08, 2010 11:39 AM
To: yardala
Cc: si-list@xxxxxxxxxxxxx; Daniel Mysliwitz
Subject: [SI-LIST] Re: How to select signals for DDR2 eye diagram
measurement in point to point topology
Hello Yardala,
guess you want to seperate Reads and writes ...
Some scopes to have features to do so quite comfortable.
There are several methods that can be used on other scopes:
If you utilize ODT you might can arm the trigger by a DQ level setting,
and trigger on the next DQS.
Last time I armed the trigger on a Glitch from a Reflection on an
unterminated system and triggered on the next DQS.
Theoretically you could trigger on the DQ/DQS setup condition as Writes
are edge aligned while reads are Center aligned. But due to tristate
conditions this can be quite difficult.
When having to do this I usually check the signal shape by a single
shot and compare write to reads to figure out what is the best way to
arm my trigger. Each system can have it's unique best way of doing so.
If you have a good memory test available you might be able to set this
in read / Write only mode. The one on www.memory-test.de should be able
to do so, although i have not used the feature so far.
Regards
Hermann
EKH - EyeKnowHow
Hermann Ruckerbauer
www.EyeKnowHow.de
Hermann.Ruckerbauer@xxxxxxxxxxxxx
Veilchenstrasse 1
94554 Moos
Tel.: +49 (0)9938 / 902 083
Mobile: +49 (0)176 / 787 787 77
Fax: +49 (0)3212 / 121 9008
schrieb yardala:
> Hi, All
> I would like to do DDR2 eye diagram measurement by a 4 channels scope
(Tek
> 5104). My system is a point to point
> topology in DDR2 memory, in DRAM side, I can combine DQM and DQS as
a
> trigger condition to accumulate
> eye diagram, but in controller side, I cann't find a good combination
to do
> it.
>
> Could any one can tell me which signals can form a good trigger
condition to
> measure eye diagram ( DQ vs DQS)?
>
> Thank you !
>
> Yardala
>
>
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