Design Of Camera Link Image Acquisition Card Based On PCIe Bus

In the field of ocean engineering research, non-contact measurement technology based on visual principles provides an effective solution approach for accurate measurements of offshore platforms and fluid flow states. This technology replaces the traditional touch sensors by using industrial cameras and image acquisition card. It avoids the interference caused by contacting sensors with the object, effectively improves the measurement resolution and accuracy. Due to the large amount of image data, the performance of image acquisition card puts forward very high demand in real-time image processing technology.This paper first introduces the situation and future prospects of the image acquisition card, and then presents the design procedure of an image acquisition card based on PCI Express bus and Camera Link interface, according to the high-speed precision measurement requirements for offshore platforms and fluid motion in the study of marine engineering. The card uses programmable FPGA as the control core, and receives image data through the Camera Link interface and stores it to external memory DDR2, then transfers data to the host computer by PCI Express bus interface.The detailed design procedure of digital image acquisition card is presented in this paper, which includes hardware interface design and software programs. Firstly, the Camera Link image acquisition technology, and PCI Express bus transfer interface and DDR2interface hardware circuit design are introduced. Secondly, the Camera Link image acquisition software module and PCI Express interface program based on embedded PCIe hard IP core of FPGA are designed, which includ the achievement of high-speed DMA data transfer program based on the PCI Express bus. At last, SignalTapII online logic analyzer is used to debug acquisition card modules in the QuartusⅡ11.0development environment, which gives the online debugging timing diagram. According to transmission test, we can see that DMA transfer bandwidth is more than500MB/s while keeps a stable performance. By comparing images collected by the image acquisition card with the actual target image, it is clear to see that accquried images can meet the desired requirements. The experimental results show that the designed Camera Link image acquisition card achieves the expected results in aspects of image transmission speed, the effect of the image display and controls the camera, which provides good support for image processing platform in marine engineering experiments.