Designing the Port Interface Unit for the Lutonium Asynchronous Microcontroller

The requirements, features, and implementation of the port interface unit for the Lutonium asynchronous microcontroller are covered in detail. The Lutonium is a new microcontroller that is pin-and software compatible with the Intel 8051 family of microcontrollers, and it is being designed by the Caltech Asynchronous VLSI Group. The port interface unit controls five 8-bit I/O ports, exposing them to the processor as directly accessible registers. The port interface unit also sequences external memory bus access phases using the same I/O ports. The final design allows both backward compatibility with the 8051 series and many advanced power-saving features. It is built around a primary state machine responsible for controlling and sequencing basic operations. The transistor networks for the port unit are complete, and extensive simulations ha ve been done to verify the logical correctness of the design. The layout has not yet been completed, but preliminary performance numbers have been extracted from the transistor-level design.