Algorithms for VLSI Test Compression.

PATH-FINDER
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Algorithms for VLSI Test compression play vital role in the time to market for any VLSI Chip, often a lot of time is spent on testing the chip, its not always feasible to test for all the possible input vectors for a VLSI Chip because the number of test vectors can grow exponentially with the PI(Primary Inputs), often we its enough to test the chip assuming a fault model (ex: Single Stuck af Fault) and select vectors which can give as high as 100% fault coverage. A test vector set generated (by a Automatic Test pattern Generator) for a given fault coverage will have some 'X' (don't cares) in the test pattern, in this work we propose an efficient way which can qualify a test pattern by the legth of the path (either between any two sequential nodes or between Primary outputs and sequential nodes), selecting such test patterns based on the length of path tested will be very helpful in delay testing. So given a test vector set we want to compress it based on the quality(length of path tested) by a test pattern. See more details in this doc1doc2. Download PathFinder-0.9
** This algorithm is an implementation of work which is still unpublished.
INPUT and OUTPUT:
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Pathfinder takes the following as input
1. A standard cell library (a verilog file of all the standard cells, you have to convert this verilog file into a CFG file, use the make_cfg.pl script shipped with pathfinder ).
2. Netlist file synthesized/technology mapped using the library in (1)
3. Top cell name
4. List of all the stuckat faults (/).
5. Module name of your sequential element.
OUTPUT:
Pathfinder lists all the paths between PI,PO and a sequential block through the list of stuck at faults provided. USAGE:
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1. make clean
1.1 make depend
2. make
3. ./pathfinder GSCLib_3.0.v_new.v s9234_scan.v s9234 s9234.fault.DT SDFFSRX1
OUTPUT:
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Parsing the cell file
PATHFINDER: A total of 145 memory elements found
PATH Between [DFF_189_Q_reg] -> [DFF_88_Q_reg] (SIZE=5):
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U365/A [n397] U586/A [n398] U356/A1 [n393] U355/A [n391] DFF_88_Q_reg/D [g6594] 

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PATH Between [DFF_87_Q_reg] -> [DFF_21_Q_reg] (SIZE=2):
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U250/A0 [n635] DFF_21_Q_reg/D [g6745] 

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PATH Between [DFF_99_Q_reg] -> [DFF_167_Q_reg] (SIZE=4):
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