Feedback Shift Registers Evolutionary Design Using Reverse Polish Notation

Abstract

The paper presents the use of Genetic Algorithm in the design of registers with linear and non-linear feedback. Such registers are used, among others, in the diagnostics of digital circuits as Test Pattern Generators, and Test Response Compactors. Of particular importance are the registers that generate the maximum cycle, and in practice, respectively long. The length of the test generator cycle is important to Fault Coverage. The selection of the register feedback structure to achieve the maximum cycle is a difficult task, especially for the register with a non-linear feedback function. It is a novelty to propose coding solutions by means of Reverse Polish Notation, thanks to which the simple mechanism of a stack with automation, realizing a context-free grammar of logical expressions can be used to evaluate these solutions. This form of representation of the genotype of solutions is a certain generalization and gives greater possibilities to search the space of acceptable solutions. Such solutions must be minimized due to the limitation of area overhead on the silicon implementation of the tester. The obtained results indicate that the proposed approach gives positive solutions.