Design and Simulation of Virtual Reconfigurable Circuit for a Fault Tolerant System

Evolvable Hardware (EHW) refers to hardware that can change its architecture and behavior dynamically and autonomously by interacting with its environment. This paper presents a new approach to on-line fault tolerance via reconfiguration of the Programmable Elements (PE) mapped onto field programmable gate arrays (FPGAs). A grid of PE is programmed on the FPGA structure. A complete hardware implementation of an evolvable combinational unit for FPGAs is then performed. The proposed combinational PE grid on FPGA is used as virtual reconfigurable circuit (VRC). Cartesian Genetic Programming (CGP), genetic operators are described in Verilog - HDL and used to reprogram the VRC. In all the cases the unit is able to evolve (i.e. to design) the required function automatically and autonomously, with a maximum delay of 22.82ns (when logic level is 16) which is 40% lower than previous attempts. The design parameters of the proposed architecture are also discussed. The fault detection, based on self-checking technique can detect the faults of PEs and routing interconnections in the FPGAs concurrently with the normal system work. After locating the faulty PE, the VRC will be reconfigured using reserved PEs.