Design Of Ultrahigh Resolution And High Speed Industrial Camera Based On USB3.0 Interface

With the introduction of "Industry 4.0" and "Made in China 2025",machine vision has slowly entered people's field of vision.In the application system of machine vision,the image acquisition module plays an important role,the quality of the image it collects will have a great impact on the subsequent processing and decision-making module.At the same time,the quality of the imaging device and the image capture card in the image acquisition module will also affect the quality of the captured image.In recent years,with the advancement of science,technology and the needs in the industrial production field,higher requirements have been placed on the performance of industrial cameras.Based on this,ultrahigh resolution and high speed industrial cameras based on USB3.0 interface are studied and designed in this paper.The content of industrial cameras studied in this paper includes three parts:image acquisition,image processing and image transmission.In terms of image acquisition,the development status of the existing CMOS image sensor transmission interface is analyzed in this paper.Four CMOS image sensors from Sony,IMX178,IMX334,IMX342 and IMX571,are selected as the front-end of image acquisition.The image sensor transmission interfaces are LVDS,MIPI CSI-2,SLVS and SLVS-EC.In this paper,different interface parsing schemes and hardware schematic diagrams of industrial cameras are designed according to the characteristics of different CMOS image sensor transmission interfaces.Owing to the different transmission protocols and electrical characteristics of different CMOS image sensor transmission interfaces,the main control FPGA chips are different.Xilinx Artix-7 series FPGA chip is used for analysis and processing of the LVDS interface and the SLVS interface.Lattice Crosslink Series FPGA chip is used for analysis of MIPI CSI-2 interface,and Xilinx Artix-7 series FPGA chip is used for processing after completion of analyzing.Microsemi PolarFire series FPGA chip is used for analysis and processing of SLVS-EC interface.In terms of image processing,Hardware ISP on FPGA,including demosaicing,automatic white balance,color matrix correction and gamma correction,is implemented in this paper due to the advantages of FPGA parallel processing.In order to prevent frame dropping during image transmission,a frame buffer module is designed,and a DDR3 chip with a capacity of 4Gbit is selected as an external cache,which can support buffering 8 pictures during image data transmission to make the image transmission more stable.Because it is necessary to implement DDR3 frame buffer on both Xilinx FPGA and Microsemi FPGA,timing of reading and writing of DDR3 on two FPGA chips is analyzed in detail in this paper.In terms of image transmission,USB3.0 interface with mature technology and fast transmission rate is selected for image data transmission in this paper.The USB 3.0 transmission protocol is analyzed and the block transmission method for transmission is selected in this paper,according to the characteristics of industrial camera image data transmission.In the end,The CYUSB3014 is configured as the synchronous Slave FIFO mode,and the high-speed data transmission between FPGA and CYUSB3014 is implemented through asynchronous FIFO.Finally,the system simulation and debugging of industrial cameras based on the four CMOS image sensors are carried out.The simulation and debugging results are in line with expectations.After,system test is performed,the test includes frame rate test,DDR3 cache test and industrial camera shooting test.The cell slice pictures captured by the cameras of four kinds of image sensors are presented,and the cell structure textures are clear.All in all,Comprehensive tests show that the four industrial cameras can be well applied to industrial imaging systems.