Browse Prior Art Database

Self-Test Diagnostic Data Reduction

IP.com Disclosure Number: IPCOM000099470D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 3 page(s) / 90K

Publishing Venue

IBM

Related People

Douskey, SM: AUTHOR

Abstract

Described is a technique for reducing stored diagnostic data and diagnostic test time in a standard random pattern self-test environment. A common self-test hardware design involves sharing a pseudo-random pattern generator (PRPG) and multiple input signature register (MISR) test hardware across multiple entities (chips, modules, etc.). The developed technique applies directly to this configuration, although it may be adaptable to others. The technique minimizes the data required for diagnosis by reducing the previously required signatures for each entity under test to signatures that are combinations of entities. There is no loss of isolation capabilities for single entity failures, and there is minimal added complexity for multiple ones.

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Self-Test Diagnostic Data Reduction

       Described is a technique for reducing stored diagnostic
data and diagnostic test time in a standard random pattern self-test
environment.  A common self-test hardware design involves sharing a
pseudo-random pattern generator (PRPG) and multiple input signature
register (MISR) test hardware across multiple entities (chips,
modules, etc.).  The developed technique applies directly to this
configuration, although it may be adaptable to others.  The technique
minimizes the data required for diagnosis by reducing the previously
required signatures for each entity under test to signatures that are
combinations of entities.  There is no loss of isolation capabilities
for single entity failures, and there is minimal added complexity for
multiple ones.  A shared hardware self-test design involving six
entities is used to illustrate this method.

      Six entities require seven signatures.  One global signature
tests all logic and six individual signatures for isolation.  Normal
good machine test time takes one signature and time "t," while a
failing card takes "7t" to test and diagnose.  This method reduces
the seven signatures to four, and it reduces the diagnostic test time
from "7t" to "4t."  This reduction is accomplished by creating test
signatures involving multiple entities.  The resulting pattern of
failures of these new diagnostic signatures is then analyzed to
determine the failing entity.

      Fig. 1 shows the arrangement of the four new signatures
required for the six-entity design.  Note that all six entities are
tested in the global signature, while signature A tests...