( ESNUG 430 Item 1 ) --------------------------------------------- [06/16/04]
From: Jan Tofte <jan_tofte=user domain=mentor got calm>
Subject: Net Naming Tricky When Using Calibre with TestKompress Diagnostics
Hi John,
We've seen a few problems with net naming on some customer designs when they
use our Calibre LVS and RVE link to TestKompress diagnostics. The link
between two tools shows the location of the fault candidate in your design
environment (whether it's Astro, BlastFusion, SoCEncounter, ICStation,
Virtuoso, or Calibre DESIGNrev.) The layout viewing is dependent on Calibre
LVS to tie your schematic to your physical data base. It's important that
your net naming is consistent between the different databases! If not, then
the direct link between TestKompress diagnostics report and Calibre may not
work. This can happen if internal tools are used for Verilog/SPICE
conversion. Since Calibre LVS correlates a SPICE netlist to schematic data,
if your netlist naming was changed during Verilog-to-SPICE conversion,
Calibre RVE can not flag the data from TestKompress which uses Verilog as
schematic data. Our ideal flow is as follows:
1.) create TestKompress patterns and save them in a tester format
$testkompress ...
atpg> create patterns
atpg> save patterns mypats.stil -stil
2.) read mismatching patterns from the tester back into TestKompress
for diagnostics (format is: pattern, chain, scan cell position)
$testkompress ... -logfile diags_log.txt
read in original patterns
atpg> set pattern source external mypats.stil
diagnose fail file from tester
atpg> diagnose failures fail_file.log
The result will be a transcript of specific fault candidate(s) that
caused the failures. They are identified by Verilog pin_pathnames.
3.) run Calibre LVS to get a correlation of SPICE models to Verilog
pin_pathnames
4.) If using DesignREV set the following variable (will not be needed in
future Calibre releases):
setenv MGC_RVE_VIEW_FASTSCAN_REPORT 1
5.) load the layout database into your layout viewer/editor or place and
route environment. The steps to execute in Calibre DESIGNrev are:
$calibredrv
a.) open "file" pull-down menu, select "open layout", load the GDSII
b.) open "tools" pull-down menu, select "Calibre Interactive", and
select RVE and multi-layer highlights, and open the path to the
database. The RVE panel will open.
c.) select LVS in the Calibre RVE panel.
6.) View TestKompress fault candidates in RVE
a.) open "file" pull-down menu, select "FastScan Report", browse
and select the TestKompress logfile from the diagnostics
run (diags_log.txt in this example)
b.) the logfile will display and any fault candidate can be selected
and highlighted links for viewing in the physical environment.
The instance or net can be displayed for any of the fault
candidates reported.
FastScan's diagnostics link with Calibre is exactly the same since both it
and TestKompress take the failing data from the tester and report the defect
candidates directly. Neither tool requires additional patterns or
diagnostic modes.
Our flow above may have a problem if Calibre LVS is not used to create a
cross-reference database between SPICE and Verilog. If you're using
internal tools, then the net naming in the cross-reference may not be
consistent with your Verilog net list. The workaround is to use the Calibre
supplied Verilog-to-SPICE converter (v2lvs) to avoid this problem.
- Jan Tofte
Mentor Graphics, Inc. San Jose, CA
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