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With large scale integrated circuit and computer technology are popularizing and developing, data domain measuring instrument for digital system come into existence as the situation requires. Logic analyzer is the mostly used universal testing instrument of all data domain testing instruments, which makes great help for developing and maintaining digital system.Virtual logic analyzer has some merits such as easy price, easy control, could set complicated trig condition, easy to dispose and display captive data and so on. Based on detailed analysis and research work principle of logic analyzer, virtual instrument technology, EDA technology, USB communication principle and some relative information, design a logic analyzer which is based on virtual instrument technology, has USB2.0 communication interface, use FPGA chip for the core of hardware system.This paper adopts one high integration level FPGA chip in hardware system to realize all of logic functions. This FPGA chip realizes trig judgment and data storage function. It contains trig module, memory module, selecting frequency module and some relevant logic circuits; has word trig, path trig, out trig, burr trig, serial trig, composing trig six kinds of trig manners in total, 32 paths×8Kb memory volume and so on capabilities.According as the design plan of system, use EZ-USB FX2 SCM for HOST. Design peripheral circuit, firmware program and firmware download drive program for SCM. It realizes communication between host computer and hardware circuit.Design upper computer’s application software with VC++ software development platform, realizes overall control for system. Including control instrument and set parameter module, gather data module, display data module and manage database module total four modules. And put forward communication protocol between upper computer and lower computer.This virtual logic analyzer’s hardware circuit is highly integration and modularize; system has some merits such as higher data transmission speed, easy to use, user oriented, low cost, easy to upgrade and so on.
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