some questions about Astro!

[seu_noop]

hi all!
when i begin to load my sdc file which is the outputed file of Design Compiler,
what should I pay attention to ?esipically the clock signal.Should I change some setting ? Thank a lot!

 

[hgby2209]

I think you dont need to change setting, but need to know something ...
1. some constraint (command) Astro can't eat, ex: set_max_area,
set_wire_load_mode .... etc.
2. constraint must set to the leaf cell. If You have constraint which doesn't set to
the leaf cell then You can download the get_loads, get_drives
utility from Synopsys web side, and use it in Primetime to write out a
appropriate SDC file.

About Clock you maybe need using Astro command "dbDefineSyncPin" to define the sync pin.

 

[seu_noop]

thanks!
But I read some sdc files, i find that the designer add the set_propagated_clock constraint for every clock. and there is no one in my sdc file. Is the file uncomplete? Will this item affect the clock tress synthesis!

 

[zyphor]

before CTS, the clock is ideal for all flip-flops so that the result is not precise. After CTS you should add set_propagated_clock in the sdc file to specify the real clock network latency for all clocks.

 

[soccer]

by CTS, you can insert set_propagated_clock in the sdc file to specify the real clock network latency for all clocks.

 

[wkong_zhu]

You also can use Astro command to specify the propogated clock. SDC need not be modified.

 

[seu_noop]

Can u tell me whichi command can do that? thanks