PC Software Design For Circuit Fault Diagnosis System Based On JTAG Interface

With the rapid enhancement of the electronic devices manufacturing process, theinternal structure of the chips is more and more complex, and the circuit integration ishigher and higher. As a result, the test point spacing for testers is getting smaller, andthere have been an increasing number of recessive unreachable nodes. Testing andmaintenance of the electronic devices are becoming more and more difficult, andtraditional probe-based circuit test methods can’t meet the new developing requirements.In this context, the JTAG (Joint Test Working Group) proposed the boundary scanprotocol, and formed the IEEE1149.1industry standard in1990. The device andexternal circuit can be tested by adding the boundary scan cells to the peripheral devicepins, which greatly improves the testability of the circuit, so it is necessary to study thetest tools based on the theory of boundary-scan.This paper proposed a general method of reading BSDL files and after getting thefiles’ information, the simulated graphic of the chip and the waveform of pin statuechanges can be drawn, thus displaying the pin statue changes of the chip intuitively.This thesis mainly represents the implement of information extracting and processing ofthe netlist file that generated by PCB design software. After getting the circuitboundary-scan information and components connection information, the circuit boardcan be tested in different test algorithms. For example, real-time display the chip pinstate that supports the boundary scan, set the specified pin state on demands, performthe circuit interlink test, etc. The PC interface is written in the MFC programmingenvironment and the friendly interface provides a convenient for users to test the circuitboard and identify circuit fault.Through joint commissioning of the upper computer and the JTAG controller, theresults show that the designed upper computer software can function as intended; thesystem is of plug-and-play without external power supply; and the software interface issimple and reliable for communication, etc.