Formal specification and preliminary design of an asynchronous traffic light controller

An exercise in formal specification and design of an asynchronous controller that leads to the CMOS implementation is presented. In this paper we focus on the formal specification of the controller by using communication sequential process, a tool based on Hoare's CSP. We also present the procedure, based on Martin's synthesis method, used to formally derive the preliminary design of the asynchronous traffic light controller. The formal specification and circuit implementation are formally verified with a verification tool package STTools, capable of model checking and simulating programs.