Symbolic hazardfree minimization and encoding of asynchronous finite state machines

Abstract — This paper presents an automated method for the synthesis of multiple-input-change (MIC) asynchronousstate ma-chines. Asynchronousstate machine design is subtle since, unlike synchronous synthesis, logic must be implemented without haz-ards, and state codes must be chosen carefully to avoid critical races. We formulate and solve an optimal hazard-freeand critical race-free encoding problem for a class of MIC asynchronousstate machines called burst-mode. Analogous to a paradigm success-fully used for the optimal encoding of synchronous machines, the problem is formulated as an input encoding problem. Implementa-tions are targeted to sum-of-product realizations. We believe this is the first general method for the optimal encoding of hazard-free MIC asynchronousstate machines under a generalized fundamen-tal mode of operation. Results indicate that improved solutions are produced, ranging up to 17 % improvement.