The Digital Circuit Fault Diagnosis System Based On FPGA Design And Key Technology Research

This subject comes from the plane repair factory. The digital fault test system is designed for thetesting of the various and complex functional digital circuit. The system is needed to test the digitalcircuit which is made up by TTL and CMOS digital devices. But sometimes it is also used to test somespecial digital circuit which is often working at the high volt. During the testing, different frequency isalso needed and the interface of such digital circuit is very complex.This topic mainly completed the design of digital circuit fault diagnosis system. the system ismainly composed of industrial control computer and digital channel module. Industrial computer isthe control center of the whole system, with ability of establishing testing tasks, editing test vector,the results of data analysis, etc. Digital channel module is constituted by the control circuit, the testsignal transmission circuit and the response signal receiving circuit. Control circuit uses the FPGA+SDRAM plan to improve the flexibility of the digital channel module, storage depth and speed oftesting. Test signal transmission circuit can output voltage which is+9V~-6V test vector.it’scurrent drive capacity is up to100ma, the receiving circuit can realize the voltage range in+9V~-6V signal reception, signals can be high level, low level and high resistance states.It solves thetraditional digital circuit testing system test voltage range is small, driving ability is small, theproblem of poor compatibility. This article also studies the key technology of the performance ofdigital fault diagnosis system. To solve the problem of fault state of the digital channel module can’tbe reflected and data communication is normal judgment problem, this paper presents acommand/response style of communication protocol to improve the reliability of data exchange. Inthis paper,any frequency division is used to provide customers with the highest can amount to50MHZ test frequency, and adjustable frequency, solve the integer frequency division provides lessspecies test frequency This paper also designs the self-check function module of the digital channelmodule such as the implementation of the control circuit, data storage and digital channelself-inspection. In addition on the digital channel module for digital circuit fault diagnosis systems theneed of repair and maintenance, this article also designed the offline detection device to provide theeasy offline testing.