Study On Boundary Scan Fault Diagnosis For Digital Circuit Board And No Aliasing And Anti-confunding Optimistic Algorithm

This thesis introduces design and implementation methods of the circuit board boundary scan fault test diagnostic system, including theoretical study, system hardware formation, algorithm realization, fault diagnosis process design,validation and test platform foundation ect. No aliasing and anti-confunding optimistic algorithm is also researched in detail and applied to the circuit boards fault diagnosis. The algorithm could largely solves symptom confusion problems of the bridge fault and sluggishness fault under insuring no aliasing and constrictive test matrix.At first, this thesis summarizes current status of circuit board fault diagnosis technology, introduces study dynamic of boundary scan technology, then introduces boundary scan technical principle as well as boundary scan standard in detail,which supply methods for studying circuit board fault diagnosis theory. The thesis analyzes and summarizes constant fault models of the circuit board,dicusses optimization problem of boundary scan theory at circuit board fault diagnosis, including test model foundation, test algorithm , test procedure as well as diagnose methods. The basic idea of no aliasing and anti-confunding optimistic algorithm is applied to the fault diagnosis of the circuit boards by analyzing no aliasing and anti-confunding optimistic algorithm during circuit board fault diagnosis. Generated test matrix using no aliasing and anti-confunding optimistic algorithm can ensure no symptom aliasing . At the same time, the algorithm can compress the large test matrix into the small. Every parallel test vector is inequality in the test matrix,but they have the same weight value,which could be preestablished by deviser. While these parallel test vectors are loaded to the circuit board in turns from computer, we could capture corresponding response vectors which can be provided to diagnostic system to analyse,and detect faults. Test show that,generated test matrix using no aliasing and anti-confunding optimistic algorithm have upper fault coverage. At last, the thesis design a fault test diagnostic system, including design and realization of the circuit board and interface, embeding chip of supporingt boundary scan structure, frame of the scan chain categoricalness diagnose scheme. The test system can implement data communication and fault diagnosis with software. It realizes joint between PC parallel ports and circuit board TAP ports. Meanwhile, no aliasing and anti-confunding optimistic algorithm is verified on test diagnostic system . The result shows that test system can largely solve confusion problems between bridge fault and sluggishness fault., even, generated test matrix is smaller and compact,which improves rates of fault detection .