An adaptive self-test routine for in-field diagnosis of permanent faults in simple RISC cores

The localization of permanent faults in a processor is a precondition for applying (self-)repair functions to that processor core. This paper presents a software-based self-test technique that can be used in the field for test and fault localization, there-by providing a high diagnostic resolution. It is shown how the self-test routine is adapted in the field to already detected faults in the processor, such that these faults do not affect the test- and diagnostic capability of the self-test routine. By this it becomes reasonable to localize multiple permanent faults in the processor. The proposed self-test is software-based, but it requires a few modifications of the processor. The feasibility of the technique is presented by an example; limitations are discussed, too.