The Hardware Design Of In-Circuit Tester(ICT) Based On FPGA

The In-Circuit Test(ICT) for the printed circuit board(pcb) that has been welded the components is a very important aspect in the process of production,which related to the quality of the electronic product.The paper is based on the study of auto-testing of pcb technology home and aboard,uses the advanced electronic technolog,designs a high-performance,low-cost,small size,easy to carry and operate ICT equipment.In this paper,the ICT system includes controller circuit,signal circuit,signal acquisition circuit,components test circuit,USB communication circuit and switch matrix circuit.The controller circuit uses the FPGA chip as the core,which is used to control all the other circuit to work normally and completes communication with the host.Testing of analog components,the paper discusses the quarantine principle of analog components on the pcb first, then,elaborates the testing mehtods forresistance,capacitance(inductance),diodes,transistors ,amplifier,and designs the testing circuit for them.Because the necessary for the test,in the paper,there has designed a signal circuit,which could output a DC voltage source signal or DC current source signal that amplitude adjustable and a AC signal that amplitude and frequency adujstable.Testing of digital devices,the paper divides into two types for digital devices,one is the boundary-scan device and another is the non-boundary scan device. and elaborates the testing principles respectively for the two types of digital devices,the paper has given the hardware test circuit.In this paper, because all the test results are DC voltage signal,so the paperdesigns a universal acquisition circuit to sample the test results. The paper also designs a switch circuit,which uses to access the components of pcb to the test circuit. For the design of communication circuit,there uses a usb chip to complete the circuit design for the communication with the host computer.On the software design,this paper adopts the Nios II C language to complete it to assist the hardware to realize the test work.This paper has completed the test of every circuit part and the gang tuning of the system.The test results prove that the designs meet the requirement of the project.