A universal test and maintenance controller for modules and boards

The design of a versatile module test and maintenance controller (MMC) is presented. Driven by structures test programs, an MMC is able to test every chip in a module or PCB via a test bus. More than one test bus can be controlled by an MMC, and can support several bus architectures and many modes of testing. The differences between MMCs on different modules are the test programs that they execute, the number of test buses they control, and the expansion units they use. A simple yet novel circuit, called a test channel, is used in an MMC. The MMC processor can control a test channel by reading/writing its internal registers. Once initialized by the MMC processor, a test channel can carry out most of the testing of a chip. Thus the processor need not deal with detailed test-bus control sequences since they are generated by the test channel. This strategy greatly simplifies the development of test programs. The proposed MMC can be implemented as a single-chip ASIC (application-specific integrated circuit) or by off-the-shelf components. Some of its self-test features are presented.<
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