has anyone managed to combine a few big macros with a very s

Question

has anyone managed to combine a few big macros with a very small ~4 number of standard cells mostly to drive constants

aryap · Answer

i can t get floorplanning to work because even tweaking `PL SKIP INITIAL PLACEMENT ` `PL BASIC PLACEMENT` and `PL RANDOM GLB PLACEMENT` the placer seems impossible to tune correctly i tried `PL TARGET DENSITY` down to 0 00000377 so i used a custom script to skip initial placement altogether relying on macro placement and detailed placement but now of course a lot of stuff overlaps

Hanssel Enrique Morales Norato · Answer

I manage to doit by setting the sizing to absolute and setting a fixed area

aryap · Answer

i ve done that confused

aryap · Answer

what density value how many cells did you have

Hanssel Enrique Morales Norato · Answer

Around 100 cells I m trying to run a design that uses 2 DFFRAM but I m getting some overlap even when the floorplanning results show that the design it s oversized

Amr Gouhar · Answer

< aryap> Maybe consider putting these 4 cells in another macro So the top level would only contain macros

aryap · Answer

Hmmmmm ok They re just constants Maybe I can avoid them

Amr Gouhar · Answer

< aryap> From experience it s easier to have conb cells wrapped in a macro rather than have them floating around in the top level and causing routing trouble

aryap · Answer

my solution seems to be to re run the flow until the initial seed places the 4 annoying cells somewhere not problematic

aryap · Answer

but i guess the constant macro is next