Partially reconfigurable system-on-chips for adaptive fault tolerance

Due to the runtime flexibility of modern dynamically reconfigurable SRAM-based FPGAs, FPGA devices have become an attractive platform for developing system-on-chips (SoCs) for space applications (space SoCs). However, since the FPGA´s SRAM is highly susceptible to space radiation, system reliability is a primary concern for space SoCs. To maintain system reliability and mitigate space radiation effects, space SoCs must be designed with redundant copies of system functionality. Space SoCs must contain enough redundancy to ensure system reliability for the highest anticipated radiation level, which imposes a large area overhead. However, since radiation levels vary based on the system´s orbital position, the system does not always require the highest level of redundancy. Space SoCs that can adapt the system redundancy based on the current radiation level can achieve more effective device utilization. In this paper, we present a flexible, FPGA-based, adaptive SoC for space system development. Our space SoC leverages partial reconfiguration to dynamically adapt the system´s level of redundancy according to varying radiation levels. We present a software algorithm to manage the system´s adaptability, implement the SoC on a Xilinx Virtex-5 device, and evaluate the SoC´s resource utilization using the International Space Station´s orbit.