Computing Seeds for LFSR-Based Test Generation From Nontest Cubes

Abstract

In test data compression methods that are based on the use of a linear-feedback shift register (LFSR), a seed that produces a test for a target fault is computed based on a test cube for the fault. With a given LFSR, a seed may not exist for a given test cube, even though a seed may exist for a different test cube that detects the same fault. This issue is addressed in this brief by computing seeds for LFSR-based test generation without using test cubes. Instead, the procedure described in this brief is based on the use of nontest cubes. A nontest cube for a fault must be avoided in any test or test cube for the fault in order to allow the fault to be detected. Therefore, nontest cubes do not limit the ability of the procedure to compute seeds with a given LFSR. Experimental results demonstrate the advantages that the use of nontest cubes provides, and the associated computational cost.