The Design Of The Virtual Logic Analyzer Based On USB

With the rapid development of the LSI, the programmable logic device, the high-speed signal processor, computer technology and so on, a new class of test equipment emerged-logic analyzer. It is a kind of test instrument to analyse the digital devices, is usually used to analyse the logic relationship of the digital system. It can solve the detection and fault diagnosis of the digital system effectively. The emergence of the logic analyzer solves the test of the digital device, computer and VLSI in R&D, production, repair and maintenance.With the rapid development of the electronics, the widely used of the PC, the virtual instrument based on PC will be a major development trend in the test instrument. USB (Universal Serial Bus) is a mainstream standard computer interface. The USB interface has many features, such as plug and play, hot swap. It allows users to quickly and easily connecting a variety of interface devices of PC. The logic analyzer based on USB makes full use of the computer to breakthrough the limitation of traditional instrumentation in transmission, processing, display and storage, has greatly improved in capability. Therefore, research the logic analyzer based on USB interface is has great economic and practical significance.This paper describes the principles and processes of the logic analyzer based on USB. With the help of the Field-programmable devices-FPGA to design the logic analyzer based on USB, greatly simplifies the peripheral hardware circuit. FPGA-Field-Programmable Gate Array, it is the further development based on PAL, GAL, CPLD and other programmable devices. It is a semi-custom circuit in integrated circuit field. FPGA not only solve the lack of custom circuits, but also has more gates than the old programmable devices. With the USB2.0 interface, the logic analyzer has higher communication speed with PC, transmission stability, very convenient to use and to some extent cost savings. Now, the power of this virtual instrument and greater price advantage makes the development of virtual instrument based on PC become a very promising direction.