[SI-LIST] Re: DDR Eye diagrams

I have a Tek TDS7404.

-----Original Message-----
From: Tom Dagostino [mailto:tom@xxxxxxxxxxxxx]
Sent: Tuesday, July 27, 2004 11:13 PM
To: Novak David
Subject: RE: [SI-LIST] DDR Eye diagrams


David

What scope are you using?  Some scopes have word triggers that will =
allow
you to qualify the trigger with the read or write line.

Tom Dagostino
Teraspeed Consulting Group LLC
503-430-1065
tom@xxxxxxxxxxxxx
www.teraspeed.com

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Novak David
Sent: Tuesday, July 27, 2004 8:19 PM
To: si-list
Subject: [SI-LIST] DDR Eye diagrams


For measuring DDR eye diagrams, the best location to measure reads is at =
=3D
the memory controller and the best place to measure writes is at the =3D
DDR. For example, measuring reads at the DDR will show more reflections =
=3D
than actually seen by the memory controller (I should mention that I =3D
have only series termination).

This sounds simple, but I cannot think of a way to make the scope =3D
differentiate between reads and writes. You might suggest that I create =
=3D
a memory test which only does reads or only does writes. However, my =3D
worst case signals are when the entire system is running.

Can anyone tell me how to make the scope trigger only on reads or only =
=3D
on writes?

Thanks,
David
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