Research And Design Of Automatic Grating Detector Based On USB2.0

The automatic grating detector is used to check the quality of the fixed position grating in the graph plotter. The image of grating is gathered by the CCD image sensor, and after be processed ,it is transferred to host to estimate the uniformity of black and white grating bar as well as the flaw in the bars. Comparing the technology of external device interface of PC, this thesis put forward the scheme of using USB to complete the image data transfer.The thesis introduces the realization principle of the grating image gathering and USB interface, and expatiates the design of hardware and software of the automatic grating detection system. In the design of hardware, LM9812, a CCD sensor processor, is selected to deal with the CCD output signal. The image data are transferred to the console in PC by the USB chip of CY7C68013A, and FIFO is used as a data buffer. Microstep driver of stepper is programmed to reduce the noises and to make the motor run more steadily. The software is composed of firmware program, driver and application program. In the development part of the Firmware, it introduces the idea and the hierarchy of program design, the program design in detail, some key code and flow chart. In the development part of the driver, it describes the structure of WDM driver and its developing process, depicts the communication method between the driver and application program. In the development part of the host application program, it introduces the function and realization way of the application program.