Designing an asynchronous microcontroller using Pipefitter

This paper discusses how Pipefitter, a tool chain that implements a fully automated synthesis flow for asynchronous circuits, can be used to design a simple asynchronous microcontroller. The use of register transfer level (RTL)-like Verilog hardware description languages (HDL) as the input format makes the first steps of the design flow (i.e., specification and simulation) very easy for the designer. Pipefitter directly synthesizes the control unit as a hazard-free standard cell netlist, uses a genetic algorithm to perform binding and multiplexer optimization for the datapath and allows the user to manually specify the binding. It also produces a synthesizable Verilog specification for the datapath, as well as a set of scripts driving both its synthesis and timing analysis by state-of-the-art commercial synchronous RTL and logic synthesis tools. The automated insertion of matched delays completes the logic design, and hands off the netlist to the standard cell-based layout tools. The example presented in this brief, shows how Pipefitter can be effectively used for the design of asynchronous application specific integrated circuits.