The use of hierarchical information to test large controllers

Gate-level test pattern generators require insertion of scan paths to handle the flat gate-level representation of a large sequential controller. In contrast, we present a testing methodology based on the hierarchical finite state machine model. Such a model is used to specify very complex control devices by means of a top-down design approach. Our approach allows the generation of compact test sets with very high stuck-at fault coverages, without any DfT logic.