Design And Implementation Of Fault Diagnosis System Based On Boundary Scan Technology

Because of strong anti-jamming capability, convenient for computer processing, digital signal circuit has widely used in television, radar, communications, computers, automatic control, aerospace, and other areas of the science and technology. Digital circuits are the important constituent of all kinds of electronic information system, play an important role in social production and living. Influenced by many factors, the fault of electronic equipment in the operation process is inevitable. Fault leads to equipment failure, even serious accidents. In order to ensure the reliable operation of electronic information system, the research of digital circuit’fault testing and diagnosis has important practical significance for the construction and maintenance of the electronic information system.Taking the research on a12th Five-Year Project of th6general armament department as background, this thesis studies fault diagnosis method of digital circuit based on boundary scan technology. According to the characteristics of digital circuit fault, the fault diagnosis system is developed based on boundary scan technology.Major contributions and innovations of this thesis are as follows:1. The symptom confounding problems of rapid test algorithm which is in boundary scan testing exists. In order to solve these problems, based on in-depth analysis of various test algorithms, an optimization adaptive test algorithm is proposed. First, an improved scheme of walking algorithm was given, based on the analysis of characteristics of the walking algorithm. In the case of the same algorithm completeness, this scheme can improve algorithms compact index. On this basis, combined with improved counting sequence algorithm, a anti-aliasing adaptive testing algorithm is proposed. This algorithm can solve the aliasing of the modified counting sequence algorithm, and improve the completeness indicators greatly, while compact index is good.2. The coverage of test is low, while the circuit board has both boundary scan devices and non-boundary scan devices on it. Based on modeling and classification, a test method for the Non-Boundary Scan devices is proposed to solve this problem. Based on measurable attributes, the on-board-device is modeled and classifed. Abstracting devices and wire as a digraph, a kind of reachability test model of the circuit board is established based on the Dijkstra algorithm and breadth-first search algorithm. A formal definition of method to generate reachable test models and cluster test model is conducted, along with the test program. Experimental results show that this method improves the test coverage of circuit board which has non-Boundary Scan devices, and can be well applied to automated testing. 3. The flexibility of Boundary-Scan Test system which developed by compiled language is poor and it is difficult to reuse the core logic. In order to solve these problems, First, the features and extended methods of tool command language (Tcl) are analysed thoroughly. Then, a feasible method is proposed, which is used to implement Boundary-Scan Test by Tcl scripting language. By defining operation of Boundary-Scan Test as extended commands of Tcl, the goal to control Boundary-Scan Test device by using script command was realized. On the basis of this method, a prototype of Boundary-Scan Test system developed by Tcl has been designed and implemented. Finally, the feasibility of this method was verified by experiental results.4. Based on the above techniques, the fault diagnosis system based on boundary scan technology was realized. The system can test the boundary scan devices, cluster devices and reachable devices. The system has been applied to the12th Five-Year project. The actual operation results show that the proposed fault diagnosis method based on boundary scan technology is correct and effective, and the fault coverage is high.