Test function embedding algorithms with application to interconnected finite state machines

The authors present new algorithms for embedding a test function in the state diagram of a finite state machine. When possible, the test function is embedded in the given object machine without using an extra input line. When such embedding is not possible, an extra input line is added to the object machine to make the embedding possible. For the extra input case, partition theory and the state variable dependencies of the object machine are used to obtain a mapping of the test machine states onto the object machine states. This mapping introduces a minimum number of extra state variable dependencies in the augmented machine as compared to the dependencies in the object machine. Experimental results on several MCNC benchmarks show that the method yields augmented machine implementations that have smaller areas than the corresponding full scan designs. The test generation complexity for the augmented machine implementation is the same as that for a full scan design. The embedding of test functions in machines specified as interconnection of finite state machines is also considered