State encoding and functional decomposition for self-checking sequential circuit design

In a previous paper, we presented a functional decomposition technique for low cost self-checking realizations of combinational circuits. This technique can be applied directly to the design of the next state logic of FSMs. In this paper, we present a methodology for good state encoding which results in a low cost self-checking realization of the FSM. The state encoding problem for self-checking realizations of FSMs consists of (a) the choice of a code space for state encoding, and (b) the assignment of codewords to individual states. While (b) can be solved using existing state assignment tools, (a) is addressed for the first time in this paper.<>