Design And Implementation Of Video Transmission System Of CMOS Image Sensor Based On USB2.0

With the digital product being popularized, application range of the camera shooting is gradually expanded , the quantity in demand for image sensors in main component of the camera shooting is also increasing gradually, however, because of the limit of cost for CCD image sensor , the demand of CMOS image sensor is steeply rising in the past few years. The large number of producers for camera shooting has selected the CMOS image sensor, especially; camera shooting used for mobile phones and other digital products has used the CMOS image sensor. Based on the above background, the thesis plans to design the video transmission system of CMOS image sensor based on USB2.0. It can be widely applied to the system, which can detect camera shooting and capture image. And it has characteristics of high speed of transmission , circuit simplicity, low cost and facility of linking installation and so on.Based on the USB2.0 video transmission system, this thesis discusses its basic components, hardware, software design methods and a detailed description of the principle of the USB 2.0 interface and video display on PC, and it presents the program design process and part of the source code and also takes a comprehensive test.The components adopted in the system mainly include CY7C68013 of FX2 series manufactured by Cypress Semiconductor, camera shooting of CMOS sensor and so on. As for the framework of the thesis, firstly, the systematic hardware circuit are designed according to actual need and make the PCB boards. And then based on the hardware circuit, I programme the firmware procedure of system. Firmware procedure mainly includes several parts of the following: (1) USB2.0 interface's initialization. The procedure sets the registers for CPUCS, USBCS, IFCONFIG of the CY7C68013, and makes it work in the scheduled mode. (2) Image chip's initialization programming. (3) General Programmable Interface(GPIF) programming. First,GPIF designer are made use of to design waveform descriptors of FIFO Read(GPIF waveform ), and then it will be started up FIFO Read waveform descriptors by the firmware. So, FIFO Read waveform descriptors can control the time sequence of CMOS camera shooting and collect image data from CMOS camera shooting. (4) USB2.0 bulk transfer programming. (5) Main framework programming. The function of main program can't only accomplish the function of the (1)～(4) interruption, but give out firmware responsion of USB control transfers and corresponding procedures of interruption initialization and interruption service. Finally, applied procedure is programmed. Its main function includes: detecting USB device, setting up USB data transmission pipe, collecting data from USB interface, displaying the video data on PC and capturing video image at any moment, so based on the system, the applied procedure lays the foundation of analyzing and processing image data later.The system design takes full advantage of the current IC resources. It controls the time sequences of CMOS sensor efficiently by using GPIF, and reads the data into the given buffer, so that the whole system is designed without FIFO and CPLD which are indispensable to the normal solutions. In conclusion, the scheme proposed in this paper has the prominent performance on optimization, which can both reduce the cost and save the resource of the system. Further more, the product development will also be very easy. The experimental results show that the transmission of the system data is stable and the image is sharp. The system has been applied in the quality detection system of the camera shooting of CMOS digital image sensor.