Command Dictionary Setup LFSRs
FastScan and FlexTest Reference Manual, V8.6_4 2-607
Setup LFSRs
Tools Supported: FastScan
Scope: All modes
Usage
SETup LFsrs {-Both | -Serial | -Parallel} {-Out | -In}
Description
Changes the shift_type and tap_type default setting for the Add LFSRs and Add
LFSR Taps commands.
The Setup LFSRs command controls the default setting for the shift_type and
tap_type switches. You specify the LFSR’s shift technique by using one of the
following shift_type switches: -Both, -Serial, or -Parallel. You specify the
placement of the exclusive-OR taps by using one of the following tap_type
switches: -Out or -In. When you change one or both of the default settings, all
future Add LFSRs and Add LFSR Taps commands use the new default.
You use this command primarily for simulating Built-In Self Test (BIST)
circuitry.
Arguments
The following lists the three shift_type switches of which you can choose only
one:
•-Both — A switch specifying that the LFSR shifts both serially and in parallel.
This is the default behavior upon invocation of FastScan.
•-Serial — A switch specifying that a serial shift LFSR shifts a number of times
equal to the length of the longest scan chain for each scan pattern.
•-Parallel — A switch specifying that a parallel shift LFSR shifts once for each
scan pattern.