| Virtual Instrument represents the trend of the ATS(automatic test system) development. The USB-bus technology provides the Virtual Instrument with new space to develop. The Virtual Instrument based on the USB-bus coincides with the new bus standard and the trend of instrument development. Since there is no Virtual Instrument based on USB-bus, the research of this paper focus on the application of USB-bus in Virtual Instrument.Based on deep analysis of USB protocol and WDM (Windows Driver Model), the driver program of USB is developed with DriverStudio and compiled with VC++, then the driver program is encapsulated to DLL (Dynamic Link Lib). On the basis of that, the hardware is designed and the fireware is programmed with TMS320VC5402 in CCS. The application program based on the LabWindo-ws/CVI is developed and the flow chart is presented. At last, the debug method and conclusion are also put forward.This design has main four advantages described as follows:1. The USB driver program based on WDM, which supports PnP (plug and play) and power management, meets the requirement of driver program in the future.2. The fireware design in language C has the high ablity of code naturalization. The USB fireware structure makes it convenient that the system is upgraded and maintained3. The advantages of USB and RS-232 reinforce each other. Therefore the devices with RS-232 could be grafted on devices with USB, which makes USB-bus technology popular.4. It is creative that USB device is constructed with DSP in the hardware design. The USB real-time communication can be guaranteed, considering such points as the fast DSP speed and the special DSP instructions with high performance. |
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