Single-chip microcomputer with application specific integrated circuit

摘要

A single-chip microcomputer is constituted by a single-chip microcomputer core (4), an external bus interface circuit (1), an external bus, a logic circuit (3) and a bus interface (2). For asynchronously accessing to an exterior from the single-chip microcomputer core, the external bus interface circuit produces an asynchronous access control signal to the exterior based on an access control signal from the single-chip microcomputer core. The internal bus interconnects the single-chip microcomputer core and the external bus interface circuit, and the logic circuit is asynchronously accessible to and from the single-chip microcomputer core. The bus interface circuit is connected to the internal bus and produces an asynchronous access control signal to the logic circuit based on an access control signal inputted through the internal bus. Even when the user logic unit is designed with operating clocks independent from the operating clocks of the single-chip microcomputer, the function of the user logic unit is not bound by any significant limitations, and the number of steps involved in preparing the user logic test pattern is reduced.