Application Dependent FPGA Testing Method

Abstract

Application dependent FPGA testing can reduce time and memory requirements comparing with the tests that exercise complete FPGA structure. This paper describes a methodology of FPGA testing that does not require reconfiguration of the tested hardware and thus it preserves conditions that caused erroneous behavior of the FPGA during its function. We show that the tested part of the FPGA can be efficiently tested by deterministic test patters even in case if we have no precise information about the internal FPGA structure. It is too hardware consuming to store uncompressed deterministic test patterns on the FPGA. From this reason we propose to compress the deterministic test patterns with the help of COMPAS – a compression system that uses scan chains for pattern decompression. COMPAS is well suited for current FPGAs as they can store the scan chain content in the LUT based shift registers. The COMPAS test compression system is based on test pattern overlapping, we propose an improved version of it. Application of overlapped test patterns requires additional shift registers for saving test patterns during test response recording into the internal scan chains. The neighborhood of the tested part of the FPGA can be dynamically reconfigured into shift registers and ORA. The shift registers contain compressed test sequence and allow fast test pattern decompression. Experimental results given in the paper demonstrate efficiency of the proposed FPGA tetste testing method.