Research On Internal Thread Detection System And Its USB Interface Circuit

The parameter measurement of threaded parts is a basic measurement technique in the machinery industry, and the non-contact measurement technology is a new measurement technology which combined with electromechanical, optical measurement and computer image processing technology. In this paper, the detection system of internal thread measurement and the USB interface circuit are researched, and then the detection system model framework and data acquisition hardware and software systems are established.The principle and structure of internal thread detection system are introduced, and the whole system diagram is given. The optical subsystem based on the principle of laser triangulation, precision machinery platform subsystem used in axial feed displacement and data acquisition and transmission subsystem are established.A system with high-speed data acquisition, storage and transmission is designed, according to the non-contact thread detection system features of high-speed and miniaturization. Sequential circuits generated by CPLD driver CCD output signal, while controlling the AD sampling and conversion, subsequently, the digital signal is got into the FIFO,which is connected with USB through GPIF moden when the GPIF waveform is triggered, the data is got into the high-speed USB endpoint buffer and waits for the host to read into memory buffer for further storage display;In hardware design, a general scheme of the data acquisition system is proposed and its work principle is given. The main chip CCD and USB using in the acquisition system are introduced, furthermore, the main modules of hardware circuit and the CPLD logic are designed.In software design, USB firmware framework is established with the analysis of the USB bus system, communication protocols and WDM driver model. The system of firmware, USB device drivers and host applications are designed. The entire USB communication design and interface display functions are completed.