( ESNUG 301 Item 7 ) --------------------------------------------- [10/15/98]
Subject: ( ESNUG 300 #5 ) Experiences, New Scripts, & Benchmarks with DC'98
> Conversely, if you are running a hold check, the source clock is
> propagated with min conditions and delays, and the destination clock
> is propagated with max conditions and delays.
>
> This is almost certainly *not* what you want. So:
>
> 1. If you are using the min/max timing feature, do *not* propagate
> your clocks
>
> or
>
> 2. When you back-annotate timing and propagate your clocks, make sure
> the same values are annotated onto max and min delays. Use the
> read_timing examples I gave earlier, and use the perl script if
> necessary.
>
> I haven't tried it, but there is a hidden variable to workaround this
> problem:
>
> remove_min_max_pessimism = "true"
>
> Be sure and do an update_timing after you set this variable. See
> Solvit article Synthesis-304 for more information.
>
> - Steve Golson
> Trilobyte
From: Scott Evans <scott@NPLab.Com>
Steve,
I have used the remove_min_max_pessimism variable and it works as
advertised. In 9808, they have gone back to using only one condition at a
time, unless you specify otherwise. Also, I believe this was fixed in
PrimeTime 9802-PT2.1 as well as 9808.
- Scott Evans
NeoParadigm Labs San Jose, CA
---- ---- ---- ---- ---- ---- ----
From: sgolson@trilobyte.com (Steve Golson)
Scott,
If you have separate min and max delays back-annotated, does it use
propagated max delays for *both* the start and end clocks when doing
setup checks?
I think they may do max delays for the start clock, and min delays for
the end clock. This is not what I want.
- Steve Golson
Trilobyte
---- ---- ---- ---- ---- ---- ----
From: Scott Evans <scott@NPLab.Com>
Steve,
From what I have seen, it uses either min or max depending on what you are
reporting on (setup or hold) and does not mix them when you use that
variable. The tool keeps both sets of numbers in the data structures to
calculate whichever is needed.
- Scott Evans
NeoParadigm Labs San Jose, CA
---- ---- ---- ---- ---- ---- ----
---- ---- ---- ---- ---- ---- ----
From: ryan@dogbert.fsd.com (Ken Ryan)
Hi, John,
I would like to express my sincere appreciation to Steve Golson for his very
informative posting (especially his perl script). I have two designs which I
am working on re-characterizing from SDF files made under revised conditions.
I recently "upgraded" to DC'98, and since my scripts ran with no errors or
warnings I thought nothing of it. It turns out Steve's heads-up saved me a
lot of head-scratching (and possibly in-system failures) later on.
Thank you, Steve, for your time in putting together such a useful message
(and to you, John, for bringing it to me on ESNUG)!
- Ken Ryan
Orbital Sciences Corp. / Fairchild Defense Germantown, MD
|
|
