A.V. Yakovlev
A.M. Koelmans
L. Lavagno
University of Newcastle upon Tyne. 1994
Asynchronous digital interface circuits exhibit a high degree of concurrency. Self-timed implementation is the most appropriate design discipline for such circuits. Their complexity demands that a formal design methodology, amenable to automation, is used to design them. Existing specification models suffer from severe limitations when it comes to describing the circuit function at a high level, which requires decomposing the specification into intercommunicating sub-modules and synthesizing a logic circuit implementation of that function. We propose a new methodology to design asynchronous circuits that is divided in two stages: abstract synthesis and logic synthesis. The first stage is carried out by refining an abstract model, based on logic predicates describing the correct input-output behaviour of the circuit, into a labelled Petri net and then into a formalization of timing diagrams (the Signal Transition Graph). This refinement involves hierarchical decomposition of the initial implementation until its size can be handled by automated logic synthesis tools, as well as replacing symbolic events occurring on the input-output ports of the labelled Petri net with up and down transitions occurring on the input-output wires of a circuit implementation.