On-Line Testing and Reconfiguration of Field Programmable Gate Arrays (FPGAs) for Fault-Tolerant (FT) Applications in Adaptive Computing Systems (ACS)

摘要

Adaptive computing systems (ACS) rely on reconfigurable hardware to adapt the system operation to changes in the external environment, and to extend mission capability by implementing new functions on the same hardware platform. This results in increased functional density and reduced power consumption - features very important in many domains, such as space missions or mobile devices. Field-programmable gate arrays (FPGAs) featuring incremental dynamic runtime reconfiguration (RTR) offer additional benefits by allowing the system to continue to execute uninterrupted, while portions of the FPGA are reconfigured for new logic functions. ACS are often deployed in harsh and/or hostile remote environments, and they are subject to strict high-reliability and high-availability requirements. Cosmic radiation may perturb the operation of a defect-free FPGA, and marginal defects not causing failures in manufacturing testing (such as a short initially having very high resistance) may become active with the aging of the device, or because of environmental factors. Since direct human intervention for maintenance and repair is impossible in such environments, fault-tolerant (FT) techniques resulting in graceful degradation must be used to achieve the desired mission life even in the presence of faults. However, traditional FT design, based on replicated modular redundancy and voting, is extremely expensive given the space, weight, and power constraints of ACS.