3. On-line Check Technology for Processor Components

Abstract

Production test cannot ensure the level of dependability needed in safety-critical systems or systems in hostile environment. The reason is that transient effects or changed system parameters are not detectable in advance by production test techniques.

The time diagram outlined in Fig. 16 explains the stages from an effective fault to a system failure. This diagram is based on a figure from Clark and Pradhan in [50]. It shows that an early fault detection may avoid a system failure if the time for a faulttolerance mechanism is sufficient. Therefore, on-line error detection in digital circuits is a must to fulfill the demands for the dependability in current and future embedded systems.

Sections 3.1 and 4.1 give a brief overview of on-line test or check techniques in digital circuits. Sections 3.2 to 3.3 and 4.2 to 4.3 present extended and new on-line techniques for the observation of components and the according control signal flow for data operations in embedded processors.