Design setup for PNR

[ramesh28]

Hello all,

input files required for PNR flow are as : .lef (layout exchange format), .lib (liberty format), .sdc (synopsis design constraints file), .ptf (process technology file) , .def (design exchange format)

i just want to know that who can genetrate those files and at what steps, these file files gets generated.?

As a pnr engineer can we responsible for generating those files? and as a PNR engineer can we make changes to those files?

please give some useful guidance.

Thank you.

 

[rca]

.lef, .lib, .ptf should be provided by the IP & technology providers.
.sdc from the synthesis. You forgot the netlist, which should generate from synthesis tool.
I don't know why you need a def file. The PnR job include the floorplan, and this step will generate a DEF.

 

[ramesh28]

Hi rca,
thanx for reply..

As a PNR engineer can we make changes to .sdc file? or we have to follow constraint file as it is as provided by synthesis guys.

changes in the sense in max capacitance, max transition, etc

i wanted to know about setup margin. means what margin normally be there before placement or after placement? and which constraints decides this setup margin? how can we change it after placement?

thanx.

 

[rca]

Well, for me the sdc provided by the synthesis guy is correct, or could nbe change via the synthesis engineer.
If you want to apply max_trans/cap rule, you could only reduce the values, and you are not able to relax the value if the max trans/cap are already defined by the .lib file or by the sdc.
The tool use by default the most constrainable values.