The Design And Implement Of The Space-born Computer With Fault Tolerance

Synthetic Aperture Radar(SAR) is a kind of high-resolution microwave imaging radar. Research on Space-born Real-time SAR system is important for the defense system of our country. As the control module, the Space-born computer plays an indispensable part in the Real-time SAR system. In this thesis, we discuss the hardware design of the space-born computer and the implement of the boot loader with the ability of fault tolerance against Single Event Upset(SEU).Today the dependability of the computers used in many fields gains increasingly attention. Various fault tolerant techniques are applied to improve it. Traditional hardware redundancy, such as TMR and Mixed TMR, still exists in many system designs. FPGA has gradually replaced DSP to do signal processing in many aviatic and space applications and it is also used to implement the fault tolerance design. And the software fault tolerance, such as NVP and block recovery, can be used in the system that is cost-sensitive and not time critical. Especially, software-implemented EDAC have taken good effect when used in the memory system of space-born computers.In the design of the space-born computer, we use two different kinds of programable logic device to guarantee the reliability. CPLD to complete functions such as POST, initializing the watchdog and the link with main computer, SRAM-based FPGA to set up the embedded system. We implement the boot loader on the develop board. This boot loader is based on MircoBlaze CPU in the FPGA and has the following characteristics as built-in test routine, full-function interrupt system, easy-use command shell and reliable file transfer with ZMODEM. The structure of boot loader is well organized so that it is convenient to add new functions.To alleviating the effect caused by SEU, we use software based EDAC to guarantee the integrity of the memory system. According to the property of the system, we introduce two fundamental primitives using the (12, 8) hamming code. And we add some functions such as variable protection, stack protection and scrubber based on the two fundamental primitives. The experiment results show that the system is equipped with fault tolerance against SEU effect when using these means.