On-Board Computer OS Design For MPC8260-Based Micro-satellite

The development of satellite technologies and the application of modern techniques and materials have made the satellite products miniature, intelligent and of small size. With the realization of high-performance small load and mature application of micro-electronic technology, modern small satellite, with many functions and good performance, has been developed.Small satellites are highly integrated. With the principles of generalization, systematization and modeling, they could constitute an integrated electronic structure of high-performance micro-nano satellites; therefore the share of hardware, software and information could be realized. Micro-satellites often adopt high-performance processors to reduce the number of controled MCU. The hardware can be simplified and the reliability of the satellite system can be improved via high-performance software. In this case, powerful operating system should be applied so as to enhance data processing and managing of peripheral equipments. The special working environment of satellites makes them different from civil equipments in choosing the right operating system. The embedded Linux system has made great success in civil embedded equipments, but in satellites, this system has rarely been applied. Based on the analysis of characteristics of typical on-baord computer operating systems of micro-satellites, this paper discusses the feasibility of applying embedded Linux system into on-baord computer of micro-satellite and designs an operating system for an on-baord computer of MPC8260-based micro-satellite.The design of the operating system includes three parts: transplanting a bootloader, transplanting and cuting a Linux kernel and making a file systems. The bootloader has applied Uboot-1.1.4, and according to the characteristics of hardware platform, the functions of Uboot-1.1.4 have been enhanced and extended. These functions include arrangement of address space, configuration of hardware and improvement of Flash driver. The on-board computer can work with simple functions, but the reliability and security are highly required. Hence the Linux 2.4 kernel has been transplanted and cut. The root file system has used the Ramdisk file system, in the format of ext2 file system. The original functions have been extended, and with the transplanting a JFFS2 file system based on Flash, the later system development and upgrade have been made possible.After testing, the expected targets have been achieved, and this operating system can work with satellite-managing programs stably.