Configurable Fault-Tolerant Processor (CFTP) for Space Based Applications

Abstract

The harsh radiation environment of space, the propensity for SEUs to perturb the operations of silicon based electronics, the rapid development of microprocessor capabilities and hence software applications, and the high cost (dollars and time) to develop and prove a system, require flexible, reliable, low cost, rapidly developed system solutions. Consequently, a reconfigurable Triple Modular Redundant (TMR) System-on-a-Chip (SOC) utilizing Field Programmable Gate Arrays (FPGAs) provides a viable solution for space based systems. The Configurable Fault Tolerant Processor (CFTP) is such a system, designed specifically for the purpose of testing and evaluating, on orbit, the reliability of instantiated TMR soft-core microprocessors, as well as the ability to reconfigure the system to support any onboard processor function. The CFTP maximizes the use of Commercial Off-The-Shelf (COTS) technology to investigate a low-cost, flexible alternative to processor hardware architecture, with a Total Ionizing Dose (TID) tolerant FPGA as the basis for a SOC. The flexibility of a configurable processor, based on FPGA technology, will enable on-orbit upgrades, reconfigurations, and modifications to the architecture in order to support dynamic mission requirements. The CFTP payload consists of a Printed Circuit Board (PCB) of 5.3 inches x 7.3 inches utilizing a slightly modified PC/104 bus interface. The initial FPGA configuration will be an instantiation of a TMR processor, with included Error Detection and Correction (EDAC) and memory controller circuitry. The PCB is designed with requisite supporting circuitry including a configuration controller FPGA, SDRAM, and Flash memory in order to allow the greatest variety of possible configurations. The CFTP is currently manifested as a Space Test Program (STP) experimental payload on the Naval Postgraduate School’s NPSAT1 and the United States Naval Academy’s MidSTAR-1 satellites.