FastScan and FlexTest Reference Manual, V8.6_4
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Compress Patterns Command Dictionary
FlexTest Self-Initialized Specifics
You may only use the Compress Patterns command for combinational circuits or
scan circuits. For scan circuits, FlexTest assumes all the non-scan cells will not
hold their values during loading. By default, FlexTest does not allow pattern
compression for scan circuits that contain any non-scan cells having Hold
capability during scan operation. This is because the results may change due to the
reordering of the test patterns causing reduced fault coverage. You can override
the default by using the -Force option to compress these patterns, but the results
may change. You should understand the impact of this option when deciding
whether or not to use this option.
The Compress Patterns command has a residual memory effect. The initial mode
(reverse/random) is not fixed. Instead, it toggles back and forth, starting with the
mode last used in the same run. You must quit and restart FlexTest to begin with
the same compaction mode.
Arguments
•passes_integer
An optional integer that specifies the number of pattern compression passes.
The default is 1 (perform a single compression pass only).
•-Reset_au (FastScan Only)
An optional switch that specifies fault simulation of AU faults.
•-Force (FlexTest Only)
An optional switch that specifies pattern compression for scan circuits which
contain any non-scan cells that have Hold capability during scan operation.
•-MAx_useless_passes integer
An optional switch and integer pair that specifies the maximum number of
consecutive useless (no eliminated patterns) passes the tool allows before
terminating the pattern compression process. This command option has no
effect on the pattern set if the number of passes (passes_integer argument) is
smaller than the integer value of this switch. The default is the passes_integer
value.