Intrinsic Evolvable Hardware Structures

Introduction

The reconfigurable hardware area, with one of its branches, evolvable hardware, is very dynamic and has experienced great developments in recent years. With 10 years ago from the time of writing the paper (2009) implementation of a logic circuit with a high degree of complexity on a programmable logic involves a series of problems caused by the limitation of existing technology. The market was dominated by complex programmable logic circuits and logic gates for areas of low resolution. Main problem was the number of available logic cells on the chip and response time. Extremely rapid evolution of technology has made at present on an area of programmable gate can be implemented a core processor for high speed, comparable in performance with versions of dedicated integrated circuits. Meanwhile the price of production has decreased very much what makes a modern configurable logic circuit to be available on the market. Therefore, it is necessary to have an evolution in design techniques, synthesis and implementation of logic circuits, techniques, still rely on classical logic programmable array. In those circumstances arise and develop areas of dynamic reconfigurable hardware with its new branch evolvable hardware. This tries to answer the question: in the context of current development of configurable logic circuits, it is not possible to print a new direction in design, synthesis and implementation of logic circuits, so that performance is improved compared to classical methods? As in any new field, lines of research are multiple. One of the objectives of this work is to try to synthesis the assumptions made in a single theory concerning the evolutionary synthesis of logical circuits.

The starting point for this chapter is the intrinsic evolvable hardware structure (configurable through its own resources) illustrated in Figure 1.

Figure 1.

Intrinsic evolvable hardware structure

It is composed of several modules, each allocate the sections in this chapter. A reconfigurable circuit is a circuit which can change their behavior according to a map of configurations that is generated.

The process of generating the map of connections, from a structural or functional description of the new behavior is called logic synthesis of the circuit. There are several classical methods for synthesis of logic circuits, but in principle the synthesis is a laborious process, requiring a high volume of operations (performed with the DeMorgan rules, minimization).

The evolutionary algorithms are search algorithms in an expanded space of multiple objective solutions. They are used in several areas in which other search methods are not effective. The use of evolutionary algorithms (EA) to solve multi objective problem has be motivated mainly because of the nature of the solution based on population which allow generation of several optimal set in a single run (Coello 2002). In the evolvable hardware structures, EA are used to found a map of configurations in a search space that exceed limits imposed by classical methods of synthesis of logic circuits. The complexity of the electronic design search space has encouraged the use of Evolutionary Electronic Design (Ali 2004). This would mean that the solution to be found more quickly and possibly be better than with classical methods of synthesis.

On the other hand, evolutionary algorithms are meant to run on computers (software implementations). This means a limitation on the running speed due to the sequential characteristic of the computers.

A first objective we propose it in the following, is to increase the speed of convergence of evolutionary algorithm by parallel implementation in hardware structures. Hardware implementation of genetic algorithms has another major advantage. They can be integrated in the circuits of which can then be run for the search of solutions. Thus, the intrinsic evolvable hardware structure, shown in Figure 1, can have all the components in the same chip!