Research And Development Of UXI Virtual Instrumentation Platform

The Universal Serial Bus has the advantages of high speed, flexible configuration and ease of use, which make it not only one of the most popular interface for PC periphery, but also applied by more and more instrumentations. It shows great potential in the area of Virtual Instrumentation (VI).There are two main difficulties in developing USB-based VI. First, the communication protocol of USB is very complicated, so developers have to spend a lot of time and energy studying the specification and debugging the interface circuit. Second, USB works in a semi-duplex style, which makes it unable to realize the syncronization of multiple instrumentations directly.This paper proposes the concept of UXI VI platform to resolve these problems. We realize a whole unified software and hardware development platform, on which designers can concentrate on the functional part of their instruments without being entangled in the complicated USB specification. The platform also provides two methods, one using SOF signal and the other adding a syncronization wire, to realize the syncronized triggering of multiple instruments in an Automated Testing System.The UXI Virtual Instrumentation Platform is made up of two parts, the USB device part which includes the general hardware interface and the controlling firmware, and the USB host part which includes the UXI general device driver and a set of general functional library. The sample device uses the EZ-USB FX2 as the core interface chip. The firmware applies the command-interpreting style to guarentee the transmitting speed and flexibility of the system. On the PC side, this paper researches the WDM driver technique and develops the general device driver, a dynamic link library which provids the function of multi-thread IO, and the VB functional library, to ensure the credibility of data transmission and ease of use.Finally, this paper uses a development example to show the function of the UXI VI platform.