( ESNUG 381 Item 3 ) -------------------------------------------- [11/08/01]
Subject: ( ESNUG 380 #9 ) Users On The New DFT/PhysOpt Flow For 2001.08
> I want to alert your readers to the recent changes in the DFT Compiler /
> PhysOpt flow in the new 2001.08 release.
>
> - Vandana Kaul
> Synopsys, Inc. Mountain View, CA
From: Mark Wroblewski <markwrob@colorado.cirrus.com>
Hi John,
I read with great interest Vandana's pointers on the differing flows for
DFT/PhysOpt in ESNUG this morning. Send her my thanks as a Synopsys
customer.
- Mark Wroblewski
Cirrus Logic Broomfield, CO
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> Adding A Lockup Latch To The End Of Scan Chains
> -----------------------------------------------
> The "set_scan_configuration" command has a new option in 2001.08 which
> allows customers to add a lockup latch to the end of the scan chain.
> The command syntax to enable this capability is:
>
> "set_scan_configuration -insert_end_of_chain_lockup_latch true"
>
> The default value for this option is false.
From: Paul Schnizlein <paul@agere.com>
Hi, John,
For us, the end of a scan chain is a flop that is also a primary Output,
so we don't need a MUX. Why would one want a lockup latch at the end of a
scan chain? Well, we know what those things are used for, shifting reliably
across different clock domains. But I associated the "end of the chain" as
the primary scan out, and where's the other domain after that?
- Paul Schnizlein
Agere Systems Austin, TX
---- ---- ---- ---- ---- ---- ----
From: Paul Fletcher <paul.fletcher@motorola.com>
Hi, John,
I read Vandana's entry in ESNUG 380 #9. It was very good. ESNUG is one
of the best things that Synopsys has going for it and it is great when
the Synopsys AEs contribute.
I have a question on a small section of Vandana's entry:
"When starting with a design that has the scan chains stitched, use the
command "set_scan_state scan_existing" instead of "set_scan_state
test_ready" to indicate the design is scan chain stitched, not just
scan replaced.
The command "report_test -state" can also be used when starting with an
existing scan replaced .db file to verify the scan state of the design."
If you are starting with a scan stitched design and you set the scan state
to scan_existing, will PhysOpt know to ignore the scan chain connections in
it's placement? This seems a very important issue; if PhysOpt does not
ignore these connections then the placement will be non-optimal. PhysOpt
should be able to do this because it has all the information it needs. It
knows the scan chains are stitched and it knows what nets are involved.
However if PhysOpt does not use this information when it does the placement
it is not doing as good of a job as it could.
I would be interested in knowing what PhysOpt does in this case.
- Paul Fletcher
Motorola Chandler, AZ
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