Using offline and online BIST to improve system dependability - the TTPC-C example

Fault-tolerant distributed real-time systems are facing many new challenges. Although many techniques provide effective masking of node failures on the architectural level, several trends are aggravating the reliability demands on the node level. Starting with a brief presentation of the fault tolerance properties of the time-triggered architecture TTA the corresponding support by the time-triggered protocol controller (TTPC-C) is discussed. We propose a strategy for improving these properties with respect to the anticipated new fault scenarios. It turns out that the application of BIST during node startup and before node reintegration improves system fault tolerance. Additionally a combined strategy of online BIST and error correction can efficiently protect memory. We illustrate the implementation of the proposed mechanisms. Our implementation experiences on an FPGA platform show that the involved overheads are moderate.