OpenSTA_labs

Day 1 :

Lab_1 : About OpenSTA

OpenSTA is a gate level static timing verifier. As a stand-alone executable it can be used to verify the timing of a design using standard file formats like :-

-Verilog netlist

-Liberty library

-SDC timing constraints

-SDF delay annotation

-SPEF parasitics

OpenSTA is architected to be easily bolted on to other tools as a timing engine.

By using a network adapter, OpenSTAcan access the host netlist data structures without duplicating them.

Query based incremental update of delays, arrival and required times & Simulator to propagate constants from constraints and netlist tie high/low

OpenSTA pdf :

Lab_1 : Inputs to OpenSTA

cd lab1
simple.v

Liberty File : Standards Cells Information is present in liberty or .lib file .lib life

Lab_1 : run OpenSTA

Following files shows the steps to read all the above inputs & perform the timing check

sta run.tcl

Following the command use to run OpenSTA

sta run.tcl -exit | tee run1.log

After the execution of above command , all inputs are being read as show in below image :-

Reports the Timing results in below image

Day2 :

Lab_2 : Liberty Files

The .lib file is an ASCII representation of the timing & power parameters associated with any cell in a particular semiconductor technology

It contains the information like :- -I/O delay paths -Timing check values -Interconnect delays

Following the command to read liberty file in OpenSTA :-

read_liberty

Lab_2 : Exercise 1

Find all cells in simple_max.lib Total 211 cells are present

Find all pins of NAND2_X1 All pins w.r.t NAND2_X1 & their direction can be found from lib file as shown below :-

Find Different between NAND2_x1 & NAND3_X1 Difference between NAND2_x1 & NAND3_X1 is highlighted in below image :-

Lab_2 : Exercise 2

Day3 :

Lab_3 : Understanding Slack Compulation

Following the circuit provided to perform the slack compulation calculation

Following snap shows the command & inputs used for slack computation :-

report_checks -from F1/CK

Run run.tcl

This will report slack compulation w.r.t that path as shown in below image :-

report_checks -from F1/CK -endpoint_count 100

Day4 :

Lab_4 : Clock Gating Check

Open s27.v

Lab 4 : Async Pin Check

Day5 :

lab_5 :slack computation

From the above figure we have to analyze the path in the report of the slack

Type cd lab3

• Run sta run.tcl -noexit | tee out.txt

exercise

report_checks –from F1/CK -endpoint_count 100

Commom path pesimism removal('CRPR')

Type cd lab4

• Run

sta run.tcl –exit | out.txt
report_checks –to F2/D

With set sta_crpr_enabled 1 :

set sta_crpr_enabled 1
report_checks -to F2/D

ECO insertion

cd lab5 and run.tcl

Run

sta run.tcl –exit | tee run.log

Difference between s27.v and s27_eco.v