System on Chip approach for Onboard Computer

This paper deals with the design and development of a System on chip [SoC] based Onboard Computer [OBC] for future onboard space applications of Indian Space Research Organization [ISRO]. The System on Chip approach shall integrate processor core with associated peripherals, other standard cores like MIL-STD-1553B core, application specific low power digital and analog circuits on a monolithic mixed-signal radiation hardened Application Specific Integrated Circuit [ASIC]. The open source LEON3 Processor core has been chosen for the central processing unit of the SoC after a detailed comparative study. The LEON3 processor has been configured modified, integrated with in-house designed OBC logics and implemented on a Xilinx Virtex 5 FPGA. The SoC can easily interface to other satellite subsystems since a interface for the Mil-Std 1553 Bus has also been designed and implemented. A Floating Point unit has been integrated with the LEON3 pipeline to accelerate the computation of complex floating point algorithms. A closed loop design of the onboard software was executed on the LEON3 processor to obtain a performance gain of nearly 50 when compared to presently used MAR31750 processor.