Robust ACCESS: Verification, Test, and Diagnosis of Advanced Scan Infrastructures

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Complex integrated systems contain an increasing part of non-functional infrastructure hardware, which support or even facilitate bring-up, maintenance, debug, test and diagnosis. So-called reconfigurable scan networks (RSNs) have meanwhile been standardized and are more and more widespread. While originally this type of infrastructure was dedicated for offline operation, this project renewal will investigate their reuse at runtime to support fault tolerance and robustness in safety critical systems. The first phase of the project came up with innovative methods for verification, test, and diagnosis of RSNs. These techniques will now be the basis to employ RSNs transparently at runtime and satisfy the strict temporal requirements set by the safety standards for fault detection and fault correction.For example, in the automotive area safety critical systems contain cores which are already self-testable or at least use error detecting mechanisms. Since self-test procedures should put a minimum of additional workload to the entire system, methods are needed to collect error indicators by the non-functional infrastructure in the background and to transport them to some fault management subsystem. This subsystem may be implemented as dedicated hardware, as a special coprocessor or just by some software, and it is responsible for the immediate reaction on some fault indication. For further appropriate actions upon a fault message, usually more detailed diagnostic information about the affected core is required. The additional information should not be obtained by putting additional workload on the remaining functional paths, instead methods will be investigated to use the already present non-functional infrastructure for exchanging diagnostic information in the background.The non-functional infrastructure can only be used for implementing fault tolerance in safety critical systems, if the infrastructure itself is fault tolerant. The offline test of RSNs developed in the first project phase will be extended to a periodical self-test following given time limits. Self-diagnostic features will be added to allow the continuing use of the infrastructure even in the case of faults. Methods for synthesizing robust RSNs will be investigated which allow the online reconfiguration of the RSNs in the faulty case to guarantee the accessibility of all critical components.