Design And Implementation Of Data Interface For Multi-spectral Note Image Acquisition System

In the day-to-day operation of financial institutions,a large number of notes need to be retained,including checks,notes of exchange,promissory notes and so on.In the traditional financial operations,only the paper notes are retained for references,which lead to many problems such as low efficiency,inconvenient access to the paper notes and false identification without enough objectivity.With the development of intelligence,digital processing,identification,authentication and archiving of notes become an inevitable trend.Digital collection of notes in the financial business can be realized by using a common scanner.But ordinary scanning equipment has large volume which has great inconvenience in operations as they do no have multi-spectral image acquisition function.Therefore,the development of specialized multi-spectral image acquisition device becomes an urgent need for financial institutions.In the multi-spectral notes image acquisition device,CIS(Contact Image sensor)is used to collect the image and transmit it to the computer through USB.The hardware module of this device need data acquisition interface,SDRAM memory interface and USB interface controller of CIS,designed through FPGA,which is the key technical problem of multi-spectral image acquisition device.This paper completed the design and implementation of the relevant technical schemes.Based on FPGA in Altera,this paper designs and realizes a data interface scheme of hardware module in the system of multi-spectral image collection device.The main achievements include the three parts as follows.Firstly,the CIS data collection interface is realized.The interface realizes the analog to digital conversion of image signal and data acquisition in synchronous mode of CIS point clock,row clock and A/D sampling clock.During the process of image acquisition,a total of ten images such as positive and negative light,white light,infrared light and ultraviolet light can be collected only by one time through the progressive,real-time switching of CIS light source,while the original image in the hardware real-time correction processing.Secondly,the SDRAM memory interface is realized.The interface supports 120 MHz clock frequency.The state machine will be used to help the realization of read and write operations on the SDRAM chip.And double slice SDRAM is used to realize ping-pong buffer,which solves the image data overflow problem caused by the instantaneous bandwidth dithering of USB interface.Thirdly,the USB controller interface is realized.The interface and the USB controller carry out high-speed data communication in the synchronous SLAVE FIFO mode to realize the real-time transmission of the image data.Finally,the USB controller driver free software interface is realized.Under the Windows operating system,the device does not rely on third party drivers and dynamic libraries to transmit image data,which meets the requirements of the financial institutions for security.Based on the above accomplishments,a multi-spectral note image acquisition device has been developed.After testing,the average transmission speed of the USB controller is 30MB/s,which meets the requirements of data transmission bandwidth.The whole device functions normal,and it can stably and reliably realize the acquisition of multi-spectral notes images.Functional performance meets expected objectives and meets the requirements of financial institutions for such equipment.