The Development Of Data Acquisition Module Based On USB

The users consume lots of time to configure the plugged data acquisition card, which doesn't have the capabilities of hot plugged and portable. As a late-model interface technology, USB is well accepted by vast clients because of its hot plugged and portable capabilities, simplicity and high speed. USB based data acquisition module is a perfect mobile data acquisition device. They are more adapt to the field test and measurement environment. This paper is mainly concerned with the design process of data acquisition system based on USB. The design scheme as well as the developing method and developing process of USB data acquisition system are expatiated. In addition, some working examples of the system are provided.At first, the paper introduces the protocol of USB bus in brief, and then discusses the design of data acquisition system, which includes four segments, hardware design, firmware design, device' driver and application program. In hardware design segment, the features of CY7C68013 are described firstly, and then the schemes of communication module, sampling control module, analog signal sampling module and digital I/O extension module are described in detail. The key points of the design which should be paid attention to are also explained. Firmware design is the most important project of the system. First, the paper presents the idea and the structure of the program, and then introduces the firmware design and the flow chart of the firmware code in detail. In device' driver segment, the principle of windows drivers module and the developing process of USB devices' drivers are briefly described. In the last part, host application program segment, there are user interface program and client's functions with dynamic link library (DLL) encapsulation which are developed with Microsoft' Visual C++6.0.With good understanding of signal acquisition system, USB protocol and CPLD theory, this article has finished the design of data acquisition module based on USB technology. The capabilities it reaches have been tested. It's sampling frequency, sampling accuracy, analog input range and digital I/O capability are on a par with our required.In the end, the paper make a conclusion of the project, and the foreground of USB application is explored.