slow.lib ...how to luk at it ?

[shiv_emf]

Hello guys,

what are parameters listed in library ?? user guide doesnt give any information on structure of library ...

How to calcuate transition time ..?
like
default_max_transition=1.5 is given in slow.lib

now if i apply

set_max_transition 1.2 [curent_design]

after that
report_constraint -max_transition -significant_digits 6 -verbose

1.500000
0.155956
slack---->0.1344044

i want to knw frm whr did 0.155956 came ???

cell used was OAI21XL ...
how to calulate input and output transition time ??
thanks ..
user guide or other manuals r not helping me in this regard !!
thanks
Shiv

 

[gliss]

Have you tried the report_lib command?

 

[shiv_emf]

report_lib lib_name
it will juzz gives ......library loaded into memory

r cell parameters loaded?/
no i dont think so ...
it give default attributes n nominal values n
wire load models etc

but i want transition time ....
thanks for reply
shiv

 

[gliss]

You can check your cell library datasheet. I'm not sure how to do that in DC.
Are you using back annotated information to get accurate transition times based on loading? Or you just want to see default cell library values?

 

[sameer_dlh25]

Hi Shiv,

This transition time is computed by DC depending upon the transition on the input pin (specified by 'related pin' attribute in the lib) and the loadThere are other factor e.g. operating condition which influences the calculation.
For exact calculation you can use report_delay calculation command.
I hope this helped:|

 

[shelby]

Shiv,

I see a few things that are odd ...

1) The default max_transition for the library is 1.5. You applied a new max_transion of 1.2 but it didn't seem to take. Check that the syntax is correct.

2) Decimal places seem off in your report_constraint ...

1.500000 <- max_transition you are checking against
0.155956 <- transition of the cell being reported
slack---->0.1344044 <- how much this transition is passing/failing by

if 0.156 is your actualy transition time your slack should be 1.344 not .1344

as sameer said, do a report_delay_calculation. This will show your cell delay and output transitions, based on your input transition and output load. The .lib has this information also, but it is harder to figure out as it is a 2d array based on input transition and output load which the tool interpolates to get a single value.

 

[shiv_emf]

yep thanks !!......... it helped to some extent ..
n sorry for typo

2d array r difficult to digest ...cant fiqure out wht tool is doing internally ... user guide n other manuals r not helping !!

I hav more query ..
Hold violation in multi-frequency design ...those 2 rules r quite strange ..can any1 explain ?

 

[sameer_dlh25]

"2d array r difficult to digest ...cant fiqure out wht tool is doing internally"

I missed somthing Shiv can you elaborate on what rule you are mentioned here ?

 

[shiv_emf]

2 dimensional Matrix(look up table) not array sorry .....

How is tool assigning values which r not present in look up table..?