Design And Implementation Of CPCI Dedicated Test System

Along with the modernization of objects under test,automatic test system is facing increasing challenges.In particular,the signal amount,signal density and signal types under test become increasingly complex.How to accomplish a whole set of complex measurement tasks in a quick,comprehensive,accurate,and flexible way before equipment is put into use is the key for equipment maintenance.A dedicated automatic test system based on CPCI bus was designed to meet the automatic test requirements of multi-channel,high-density,and multi-class complex signals of a certain type of equipment.Firstly,measurement requirements of the objects to be measured,which are in groups were analyzed and classified.Based on the classification,a combinable measurement mechanism for decoupling of signal pretreatment and signal measurement was proposed.According to the requirements of c ompactness,densification,and real-time measurement,an overall plan for a 3U-size CPCI test system was designed.The whole plan includes a customized CPCI backplane,a Loogson system slot computer,a DC regulating board,an AC regulating board,a busbar regulating board and a data acquisition board,whichwas implemented in hardware,firmware,and software levels.For hardware,based on CPCI specification,a CPCI backplane was designed to meet the requirement of input under-test signals and internal conditioning signal transmission.Three dedicated regulating boards were designed for DC,AC,and busbar signals respectively.Through isolation,attenuation/amplification,filtering,conversion,swithcing and other phases,the original signals were pretreated as two types of signals including voltage and frequency to be measured.A time-division-multiplexed data acquisition board was designed under the consideration of the requirements of sampling rate,resolution,measurement accuracy and data caching.In addition,nonvolatile memory was designed for each board to store calibration information.For logic firmware,regarding to the adaptive control of the measured signal and test circuits,a set of combination regulation control code was proposed.The code analysis and regulation control was performed through the FPGA logic on the data acquisition board.It enables the real-time configurability of the hardware circuit.For common measurement requirements,voltage measurement control logic,which is based on multi-channel successive approximation ADC,equal-precision frequency measurement logic,on-board memory interface logic and PCI bus interface logic were developed.Regarding to the user interface,a set of control,configuration,and status registers were designed for software access.In addition,the loop measurement function was realized by configurating the ADC and swiching the measurement channel through logic.As for software,for the real-time measurement requirement,driver programs were developed for the test system hardware on the Loongson 2H system slot computer with VxWorks real-time operating system.For calibration and measurement tasks,interface functions together with single-channel measurement,loop measurement and auto-calibration applications were developed based on as defined register set.After the design and implementation of the architecture,hardware,logic,and software of the entire test system,all the input channels of the system were calibrated in full-scale range.A test environment under laboratory condition was set up,with the calibrated system tested and verified.The test results meet the performance requirements for application.The system has already been put into practice,which verifies the correctness and reliability of the design.This dissertation provides a combinable test scheme and entire implementation method for automatic test of complex objects with dedicated-pretreatment and multiplexed-measurement,showing prospect for similar test systems designing and developing.