Testing micropipelines

Micropipelines, self-timed event-driven pipelines, are an attractive way of structuring asynchronous systems that exhibit many of the advantages of general asynchronous systems, but enough structure to make the design of significant systems practical. As with any design method, testing is critical. We present a technique for testing self-timed micropipelines for stuck-at faults and for delay faults in the bundled data paths by modifying the latch and control elements to include a built-in scan path for testing. This scan path allows the processing logic in the micropipeline, as well as the control of the micropipeline, to be fully tested with only a small overhead an the latch and control circuits. The test method is very similar to scan testing in synchronous systems, but the micropipeline retains its self-timed behavior during normal operation.