A comparison of software-based techniques intended to increase the reliability of embedded applications in the presence of EMI

Corruption of the instruction pointer in an embedded computer system has be en shown to be a common failure mode in the presence of electromagnetic int erference, and previous investigators have suggested that the use of techni ques such as 'Function Tokens' (FT) and 'NOP Fills' (NF) can reduce the imp act of such failures. In this paper, both a statistical analysis and empiri cal tests of code from an embedded application are used to assess and compa re these techniques. Two main results are presented. First,it is demonstrat ed that claims about the effectiveness of FT may neither be well founded no r generally applicable; specifically, it is concluded that rather than incr easing system reliability, the use of FT will have the opposite effect. Sec ond, it is demonstrated that NF may be easily applied in most embedded appl ications, and that the use of this approach can have a positive impact on s ystem reliability. (C) 2001 Elsevier Science B.V. All rights reserved.