Test Generation, Testability and Fault Diagnosis

We propose test generation methods for digital circuits using structural BDDs and focus on the relatively understudied problem of fault-masking due to the presence of multiple simultaneous faults. We show how SSBDDs enable new kinds of views through the graph topology to the interaction of simultaneous faults, potentially leading to fault masking. A novel method of test groups is presented as an extension of the known method of test pairs. We also discuss the testability issues and present algorithms for SSBDD-based signal probability calculation. We propose an Angel’s advocate approach for test generation and fault diagnosis in the general case of multiple faults that avoids fault masking. To carry out multiple-fault diagnosis, we model the diagnostic experiments using Boolean differential equations and find the solutions using SSBDDs.