System-Level Design and Modeling

Abstract

The modeling and design of embedded systems can be performed at several abstraction levels. Gajsky [Gaj83] identifies the following abstraction levels in the context of CAD tools for VLSI:

• Circuit level is the lowest level of abstraction. For example, the hardware at this level is seen as transistors, capacitors, resistors, etc., and differential equations are often used to describe their functionality.

• Logic level is next towards higher levels of abstraction. Here, the functionality is represented as boolean logic (hence the name, logic level), implemented in hardware using logic gates and flip-flops.

• At the register-transfer level the functionality is captured in terms of register-transfer operations on ALUs, registers, multiplexers, etc.

• The highest level of abstraction is the system level, where the functionality is described using “system-level specification formalisms” (in the case of VLSI design, these can be description languages like VHDL, Verilog or SystemC) and the architecture is seen as building blocks consisting of processors, memories, etc., interconnected using buses.