Assessment of bit error detecting and correcting codes for safety-critical embedded fuzing systems

Embedded software systems are increasingly used in safety-critical applications. When developing safety-critical embedded-software systems, stringent requirements must be fulfilled for memory and code execution integrity. The IEC 61508 explicitly asks for the usage and assessment of efficient algorithms that detect and correct bit errors in all types of memories, e.g., flash memories, and processing units that are either part of or interact with safety related systems that implement safety functions in accordance with the required safety integrity level (SIL). This paper shows which as well as how well-known algorithms for bit error detection, e.g., Hamming codes, can be used in a safety-critical generic sample system in the military fuzing domain. Requirements of the IEC 61508 are presented that must be fulfilled for the implementation of the code. The focus is on an overall testing and verification method for the bit error detecting and correcting code within its samp le embedded system environment. We present the tool chain used for the method, including the simulation of the bit error injection and overall error detection assessment. We discuss and determine different measures for integrity, e.g., n-bit error detection and correction, and efficiency, e.g., execution time and memory resources needed for the check routines, for the physical realtime sample system.