Design Of A Portable Data Acquisition Instrument's USB Transmission And Noise Analysis Modules

The paper is concerned with the improvement of old portable data acquisition instrument, which contains the program migration, the design of USB transmission and noise analysis modules.The paper introduces the USB 1.1 specification at first, especially focusing on the electrical and mechanical characteristics, the data flow model, and the communication protocol of USB at first, then discusses the design of the USB module.The design of USB module includes four segments: hardware design, firm design, driver design and application design. In the hardware design segment, the performance of PDIUSBD12 and the reasons of selecting it are firstly introduced, then the hardware scheme is given in detail. At the beginning of firmware, it is need to initialize the USB interface, so the controller can detect it, whenever the data acquisition instrument is connected with the controller, then the firmware finish the task that the controller tells. In the driver program segment, the paper presents WDM model, how it works, the selection of development tools, the functions of several importment routines, and the process of compiling and debugging. In the application segment, how to find the USB device, and how tocomplete the communication by using the API functions are firstly introduced, the interface of the USB module on computer is given at last.The noise analysis module can complete the measurement and analysis of environmental noise, etc. Physical quantities and evaluation methods of noise are firstly introduced, the performances of TMS320C31 are secondly introduced, and the design of module is given in detail at last. The data acquisition instrument has two CPUs, each of them can finish the different task. The singlechip allow us which parameters we select and display the overall sound pressure lever and the graphs on LCD; DSP can sample data, design the Butterworth Filter, finish the data filtering, weighting and so on.The paper has finished the program migration, the design and debuging of USB transmission and the noise analysis modules.