On-line sensing for healthier FPGA systems

Electronic systems increasingly suffer from component variation, thermal hotspots, uneven wearout, and other subtle physical phenomena. Systems based on FPGAs have unique opportunities for adapting to such effects. Required, however, is a low-cost, fine-grained method for sensing physical parameters. This paper presents an approach to on-line sensing that includes a compact multi-use sensor implemented in reconfigurable logic, methods for instrumenting an application, and enhanced measurement procedures. The sensor utilizes a highly-efficient counter and improved ring oscillator, and requires just 8 LUTs. We describe how to measure variations in delay, static power, dynamic power, and temperature. We demonstrate the proposed approach with an experimental system based on a Virtex-5. The system is instrumented with over 100 sensors with a total overhead of only 1.3%. Results from thermally-controlled experiments provide some surprising insights and illustrate the power of the approach. On-line sensing can help open the door to physically-adaptive computing, including fine-grained power, reliability, and health management schemes for FPGA-based systems.