We present new algorithms for embedding test functions into the state diagram of a finite state machine. We first identify the cases where test functions can be embedded into the state diagram of the given object machine without using an extra input line. When such embedding is possible, our method finds it. In other cases, an extra input line must be added to the object machine to make the embedding possible. For the extra input case, we use partition theory and state variable dependencies in the object machine 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 our method yields augmented machine implementations that have lower area than corresponding full scan designs. The test generation complexity for the augmented machine implementation is the same as that for a full scan design. We further consider the embedding of test functions into machines specified as an interconnection of finite state machines. We incorporate test functions into each component finite state machine such that the augmented interconnected machine has the same testability properties as the product machine with test function.>

We present a new area-efficient procedure for embedding test function into the gate-level implementation of a sequential circuit. First, we develop a test machine embedding technique for a given gate-level implementation of a finite state machine. The test machine states are mapped onto the states of the given circuit such that a minimum number of new state variable dependencies are introduced. The composite function is optimized. Experimental results show that our method yields testable machine implementations that have lower area than the corresponding full scan designs. The test generation complexity for our machine implementation is the same as that for a full scan design. To apply the method to large gate-level designs, we partition the circuit into interconnected finite-state machines. Each component state machine can be specified either as its gate-level implementation or as the extracted state diagram. We incorporate test functions into each component finite state machine such that the entire interconnection of the augmented components has the same testability properties as the product machine with a single test function. ISCAS '89 benchmark circuits are partitioned into component finite state machines using a new testability-directed partitioning algorithm. Again, our embedding procedure results in testable circuits that have lower area than the corresponding full scan designs.>

We present a new area-efficient procedure for embedding test function into the gate-level implementation of a sequential circuit. We use partition theory and a state variable dependency minimization criterion to map the test function states onto the states of the given circuit. The test generation complexity for our implementation is the same as that for a full scan design. To apply the method to large gate-level designs, we partition the circuit into interconnected finite-state machines. We incorporate test functions into each component machine such that the augmented interconnected machine has the same testability properties as the product machine with test function. Several ISCAS 89 benchmark circuits are partitioned into component finite state machines using a testability-directed partitioned into component finite state machines using a testability-directed partitioning algorithm. Our embedding procedure results in testable circuits that have smaller area than the corresponding full scan designs.>