Fail-Safe and Fail-Operational Systems safeguarded with Coded Processing

Safety has the highest priority because it helps contribute to customer confidence and thereby ensures further growth of the new markets, like electromobility. Therefore in series production redundant hardware concepts like dual core microcontrollers running in lock-step-mode are used to reach for example ASIL D safety requirements given from the ISO 26262. Coded processing is capable of reducing redundancy in hardware by adding diverse redundancy in software, e. g. by specific coding of data and instructions. A system with two coded processing channels is considered. Both channels are active. When one channel fails, the service can be continued with the other channel. It is imaginable that the two channels with implemented coded processing are running with time redundancy on a single core or on a multi core system where for example different ASIL levels are partitioned on different cores. In this paper a redundancy concept based on coded processing will be taken into account. The improvement of the Mean Time To Failure by safeguarding the system with coded processing will be computed for fail-safe as well as for fail-operational systems. The use of the coded processing approach in safeguarding fail-safe systems is proved.