Usb-based Logic Analyzer Hardware Design

Logic analyzer is one of the most important data domain test instruments. Withthe accelerating advancement of the digitization process, logical analyzer is gettingwidely used. As its functions and capabilities raised, there are new demands foroperational convenience and easy portability. Portable logic analyzer based on USB islight and handy, which is easy to carry and operate. With utilization of computer, thelogic analyzer based on USB enhances data transmission, process, display and storage,which improves the performance of data analyzing, and in another aspect, it can alsogreatly lower the cost of the instrument.This paper expatiates the principle of the hardware design of a logic analyzerbased on USB and brings forward a scheme. The principle and design of the dataacquisition section and the USB interface section are emphasized in this paperaccording to the difficulties of the hardware design. The software, which is closelyrelated with the hardware, is also mentioned in the paper.The first chapter describes the logic analyzer's application and developmenttends in the field of data domain test. The work and the specified specs of thisinstrument are also introduced in this chapter. Chapter 2 specifies the scheme andpower supply mode of the logic analyzer based on USB according to the design target,also mentions that the data acquisition circuit and the USB interface circuit are thecritical parts of the design.The principle and design of the circuits in data acquisition section are expatiatedin chapter 3, which introduces the designs of the trigger word distinguished circuitand the storing control circuit in detail. A design of increasing storing capability isalso introduced in this chapter. Chapter 4 describes the USB protocol and a design ofUSB interface circuit. The signals connection between the data acquisition section andthe FX2 is described in this chapter.The firmware for the EZ-USB FX2 and the realization of USB bulk transfer areexpatiated in chapter 5. The design and flow chart of the data acquisition program aredissertated in chapter 6. Chapter 7 introduces a test methodology for this logicanalyzer and discusses the data transfer speed of the USB interface. The hardwaredesign of this logic analyzer is summarized in chapter 8.Testing shows that the logic analyzer is provided with powerful data analyzingability, as well as rapid data transfer speed of USB interface, which ensure theinstrument to be competent for analyzing high speed signals.