A High-Speed Data Acquisition System Based On USB2.0

USB interface has been widely used in the measuring instruments due to such advantages as flexible expandablity and HotPlugIn. A portable high speed data acquisition system is developed based on USB2.0 high speed transmission in this paper. The two problem, how to increase the data transmission speed of the system and the development of the USB device driver, are also well studied.Firstly, a USB data acquisition system with the kernel controller LPC2888 is designed. The DMA transmission from data cache to USB bus is realized by LPC2888's USB high speed device controller. The DMA transmission from the data acquisition module to data cache is realized by LPC2888's GPDMA controller. The two DMA process are corresponded by data cache's full complete and half complete interrupt. The testments show that the system has a correct work flow, but the data transmission speed from LPC2888's external I/O to internal data cache is so low that the data acquisition speed of the system is limited no more than 2Msps.In order to increase the data transmission speed of the whole system, a second system is designed by FPGA and CY7C68013 USB2.0 interface chip. The testments show that the system has a correct work flow and a stable performance, the data acquisition speed of the system is up to 10Msps.Based on the two systems above, the data transmission speed of the USB interface is tested and analyzed. Through optimization, the data transmission speed of the two system achieve 14.0MB/s and 37.4MB/s, solving the problem that the data transmission speed of the USB interface application system is commonly low. At last, the factors influencing the data transmission speed of the USB interface are analyzed.About the development of the USB device driver, VISA is applied successfully in the two systems above, proving that VISA is a universal method to develop USB interface application system. The driver made by VISA and the driver supplied by the producer of CY7C68013 are compared. The two drivers operate correct and stable, the efficiency of the VISA driver is a little lower than that of the producer's driver. The max bandwidth of CY7C68013 using the two drivers can reach 21.9MB/s and 37.4MB/s respectively.