Using autofix in DFT for resolving violations during insert_dft

Hello.

I have several violation during insert_dft. Mostly C6 - trailing edge port captured data affected by new capture and C26- Clock data different from capture clock for stable cell.

How to fix them? Is it possible too to fix them with autofix?

Rgds

tetramax problem with reset

Hi,

U can use Autofix capability of DC to fix clock violations. Follow the commands as I mentioned below. Change them according to your port names in your design.

These commands should be part of your setting of dft configuration.
declare dft signals

specify scan configuration

#Define the signals for Autofix
set_dft_signal -type TestData -port scanclk
set_dft_signal -type TestData -port reset
set_dft_signal -type TestData -port preset
set_dft_signal -type TestMode -port testmode -active_state 1

#Enabling the Autofix for Clock, Reset and Set
set_dft_configuration -fix_clock enable -fix_reset enable -fix_set enable

#Specifying the Autofix settings
# this information is used for the set and reset and clock fixing.
set_autofix_configuration -type set -method mux -test_data preset -control testmode
set_autofix_configuration -type reset -method mux -test_data reset -control testmode
set_autofix_configuration -type clock -method mux -test_data scanclk -control testmode

# this will tell the tool that optimation was already done so u dont disturbe the optimisation.by doing it again.
set_dft_insertion_configuration -synthesis_optimization none -preserve_design_name true

create_test_protocol

preview_dft

dft_drc

insert_dft
.
.
and so on

thx

snr_vlsi

clock autofix

hi,

Please note that you can not fix C6 or C26 with autofix. These are capture violation and not scan shift violations. Autofix will help only in case where you have shifting problems.

You need to find the coverage hit by these violations. Do "set rule ignore C6 and C26 "in Tetramax and see what is the coverage and the coverage with these violations. It could be that there is not much difference beacuse Tetramax does intelligent pattern generation to get valid patterns. If the difference is huge then you need to do some manual fixing.


...vlsi_eda_guy

how to deal with c6 violation in tetramax

hi,

can the C4 violations be cleared with autofix if not C6 and C26.

b'cause I have tried to autofix the C4 violation, but still i have the same problem.

any solution to overcome the C4 violation other than autofix... like modifying the .spf file etc...,

Added after 4 minutes:

hi vlsi_eda_guy,

Is the C4 violation fixable by using autofix feature in DC, b'cause I have tried to fix the same C4 violation with autofix, but i still get the same violation.

If not autofix, can we modify the .spf file for clearing this C4 violation. If so what is the modification required.

thx

S.Nikhil

c4 violation dft

Hi Nikhil,

I have replied your question in another thread as well,

If you are sure that reset cannot capture value with other clocks off, then declare the reset pin as a constant and get rid of C4.

-vls_eda_guy