Design And Implementation Of The Infrared Image Acquisition System Based On USB2.0

The high altitude reconnaissance aircraft armed with infrared imaging sensors is one of the most efficient tools for varying fields such as wildfire mapping, remote sensing, thermal detection, identification and location of threat targets, etc. Quickly as well as conveniently acquiring the wide area images from the infrared line scanner is very important for data processing thereafter. For this purpose, the USB (Universal Serial Bus) 2.0 standard, whose transfer rate can reach 480Mbps, was adopted in the interface between upper PC and lower infrared line scanner for real-time image transfer based on the character of the infrared image acquisition.The paper firstly analyzes requirements for the interface when online transferring infrared images and studies the theory and the specification of USB2.Then, by accommodating a microcontroller P89C61, a FPGA and a USB2.0 chip ISP1581, the hardware scheme has been designed. The FPGA gets digitalized image signals from the infrared line scanner and then stores all data in a SRAM buffer. The Direct Memory Access (DMA) channel was selected as the highway between FPGA and ISP 1581. ISP1581 serves as the USB2.0 easy connection to upper PC.The paper deals with the developing of an infrared image acquisition system based on USB2.0, focusing on the firmware design, the device driver of usb, the program coding and the way to improve transfer speed .The developed system has worked properly and experiments have shown that the interface's average transfer rate had reached 128Mb/s. Thus it can meet the requirements for real-time bulk transfer of infrared images.