help:clock path in Astro

Y

yyqonline

Guest
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing
 
"yyqonline" <yyqonline@gmail.com> a écrit dans le message de news:
1158721773.326316.277650@d34g2000cwd.googlegroups.com...
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing
Click to expand...
Hi,

It seems your clock is still evaluated in ideal mode as oppose to propagated
mode.
It looks like that is switch off "ignore propagated clock", it would use
propagated mode and report real clock tree delays.

Serge
 
Hi YuQing,
Have you set_propagated_clock * after CTS?
Can you post the Astro and PT timing report for the same path?

Best regards,
ABC

yyqonline wrote:
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing
Click to expand...
 
Hi ABC,
I read in a notebook that i should enter "sdc set_propagated_clock
[get_ports clk]" after CTS, but it seems that my Astro version do not
support this command. So i write a "set_propagated_clock [get_ports
clk]" into my .sdc file input.
Can this works the same? Maybe this should be checked, but i do not
know how to.

btw, in my Timing Report, there is no indication about whether the
clock is set to be propagated or still ideal, while it is mentioned in
my notebook that this attribute of clock should be quoted in Timing
Report.

Thanks a lot .

ABC wrote:
Hi YuQing,
Have you set_propagated_clock * after CTS?
Can you post the Astro and PT timing report for the same path?

Best regards,
ABC

yyqonline wrote:
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing
Click to expand...
 
Hi Serge Bédikian,
i agree that it seems a lot that the clock is still evaluated in ideal
mode, but i am sure that i have seitch off "ignore propagated clock"
and switch on "ignore clock uncerntainty".
Thanks a lot for your concern.

YuQing


Serge Bédikian wrote:
"yyqonline" <yyqonline@gmail.com> a écrit dans le message de news:
1158721773.326316.277650@d34g2000cwd.googlegroups.com...
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing


Hi,

It seems your clock is still evaluated in ideal mode as oppose to propagated
mode.
It looks like that is switch off "ignore propagated clock", it would use
propagated mode and report real clock tree delays.

Serge
Click to expand...
 
Hi YuQing,
Don't understand why your scheme mode and load SDC doesn't work.
For scheme mode interactive command, sdc "set_propagated_clock
[get_ports clk]" should work. You need to show the Astro log file when
loading sdc constraint just to double confirm the loading is done
properly and also timing report. The timing report will tell it is
ideal or propagated clock automatically.

Best ergards,
ABC
p/s: Sorry if spamming mail as it is not verilog specific case.

yyqonline wrote:
Hi ABC,
I read in a notebook that i should enter "sdc set_propagated_clock
[get_ports clk]" after CTS, but it seems that my Astro version do not
support this command. So i write a "set_propagated_clock [get_ports
clk]" into my .sdc file input.
Can this works the same? Maybe this should be checked, but i do not
know how to.

btw, in my Timing Report, there is no indication about whether the
clock is set to be propagated or still ideal, while it is mentioned in
my notebook that this attribute of clock should be quoted in Timing
Report.

Thanks a lot .

ABC wrote:
Hi YuQing,
Have you set_propagated_clock * after CTS?
Can you post the Astro and PT timing report for the same path?

Best regards,
ABC

yyqonline wrote:
hi,
everyone
I meet a problem while using Asto to implete my deisgn. After Placement
& Routing, I find the clock path is between about 130ns to 220ns (a
specific, and very very slow lib used in my design) by using
"Timing=>Skew Analysis...", but while I check my timing path, I find
that Astro still consider the "clock network" is 1.000ns which is
specified in my ".sdc" file. In a other word, the clock skew are not
calculated when Astro calculats path timing. I have changed "Timing
Setup" options such as "ignore clock uncertainty", "ignore propagated
clock" after CTS. This results in problems while STA by PrimeTime.
For example, a path having a slack is 90ns in Astro Timing Report can
be negetive in PT which takes the clock skew into account.
Can anybody give some advice?
Thanks.

YuQing
Click to expand...
 
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