Research Of Aviation Circuit Board Fault Diagnosis Based On Testability Technology

At present,the detection of aviation circuit boards at home and abroad can only be carried out through functional detection,contact detection,infrared thermal imaging detection,etc.These detection methods are all based on the functional direction of the device,the operation process is complicated,the test speed is slow,and it is difficult to achieve accurate fault location.The boundary scan test in testability technology is a method specifically designed to solve complex circuit tests by testing the board from the device design principle.The test platform based on boundary scan technology has convenient operation and fast test speed,and can realize chip pin level fault location.Firstly,the conventional test vector generation algorithm is analyzed.In view of the shortcomings of the unrestricted short-circuit fault model of the interconnected network,based on the short-circuit possibility theory of the circuit board network,a model of limited short-circuit fault is established.Combined with the minimum weight point coverage method,a minimum weight point coverage algorithm based on the limited short-circuit fault model is proposed,the test vector generated by this method has good compactness and completeness compared with the conventional method.Secondly,after the research of IEEE1149.4 standard,the overall design scheme of the test platform based on boundary scan technology is constructed,and then the communication and scan control module in the test control box and the software of the test platform are designed in detail.In the design process,the host interface adopts USB communication mode,and the boundary scan controller is implemented by FPGA.In order to improve the processor utilization,FIFO buffer is introduced into the test data input and output module.In the test platform software,the functions of automatic loading of test files,system self-test,test algorithm and scan link selection are designed to realize automatic generation,execution,test response analysis and fault diagnosis of test information.Finally,the DEMO experiment board was designed and multiple jumpers and fault switches were set to meet the test of different network numbers and fault type tests.The DEMO board is used to comprehensively verify the test platform,and various interconnection faults injected in advance are successfully detected,which can accurately judge the fault type and locate the fault location.The experimental results show that the test platform based on boundary scan technology can quickly and accurately determine the fault type and locate the fault location,which can realize the "second" level test and the "pin" level fault location of the circuit board.It has good test speed and positioning accuracy and achieves the desired results.