The Research And Implementation Of Self-Feedback Test Sequence Searching Algorithm Based On SOPC

Along with the chip design to the deep submicron, the nanometer processing technology's advancement, the very large scale integrated circuit (VLSI) design technique level is getting higher and higher, its characteristic size is getting smaller and smaller, the integration density and the order of complexity are getting bigger and bigger, the circuits testing becomes more and more difficult. Test is the highest expense and most difficulty stage in the VLSI design. In order to reduce the test cost, the design for testability (DFT) becomes the important component in the VLSI design. The core ideology of DFT is which considers the design for test from the beginning in the circuit design, and solves thorny test question on the design stage.Built-in self test (BIST) is an important method of Design for Testability. The Self-feedback test which generates test vectors by the circuit under test is a new BIST method. In this approach, the internal nodes of CUT are a sort of available resources.The test structure of self-feedback captures the responses of some internal nodes through the registers, which feedback to the original inputs and form the next test vector. It makes that the CUT can automatically generate a complete test set after the seed vectors applied.The method researchs how to find a best feedback way in a short period of time, which makes a set of test vectors generated by CUT to reach higher fault coverage in a relatively short length of test. vectors.This paper researches the test sequence search algorithm for self-feedback test method. In this paper, given the test set, it finds such a feedback way, which makes the test vector generated by the CUT itself as much as possible included in the test set after the seed vectors applied. If it can find a set of longest test vector sequence in the test, the corresponding feedback way is able to be found. In this paper, it uses exhaustion and backtracking algorithms to search all of the test pattern combinations for finding the best feedback way.As implemented self-feedback test generation method with software, it will be affected by computer which is essentially serial at speed, and can not obtain all of the feedback way for the larger circuit in a relatively short period of time. Therefore, the use of hardware design is of great significance.This paper designs a slef-feedback test sequence search system based on SOPC. The system implements the test sequence search method based on exhaustion and backtracking, using embedded development technology on XUP Xilinx Virtex-ⅡPro Development System. The system implements the functional verification for test sequence search algorithm on the XC2VP30 FPGA chip, and tests the four standard circuits of the ISCAS85 Benchmark. The experimental results indicate that the test sequence search algorithm is able to find all longest test vector sequence after traversal all test vector combination, as well as all best feedback way. The design achieves a better balance about utilization of resources and speed, and reduces the run time. It also achieves the expectant aim of design.