 When are tests good enough?
by Dave Bonnett
Technical Marketing Manager
Who’s to say when test coverage is good enough? That’s precisely the dilemma confronting many test engineers on a regular basis.
ScanWorks’ test coverage reports can help because they address the fundamental questions of how much boundary-scan test coverage is available and how much of this coverage is being utilized by a particular test or test suite. When a test engineer can answer these questions, he can decide whether his test coverage is good enough or whether he needs to tweak the tests to generate better coverage.
ScanWorks’ fault coverage reports describe exactly what faults a test or a set of tests will detect. A new whitepaper from ASSET, Fault Coverage Reporting, explains the coverage available with various types of tests and how it is reported.
For example, ScanWorks’ interconnect tests will verify whether a circuit board or circuit board assembly has been put together correctly. Interconnect tests determine whether the electrical connections between devices and circuit boards are working properly.
Given the input parameters and other information provided ScanWorks’ Test Pattern Generator (TPG), ScanWorks’ interconnect fault coverage report documents the coverage obtained by the tests that will be applied to the design. Once the engineer knows this, he can decide to improve test coverage by providing the TPG with more information, such as additional models of non-boundary-scan devices. Another way to improve test coverage would be to define certain constraints that are activated during test application.
ScanWorks’ interconnect fault coverage report examines the nets or chip-to-chip interconnections on a circuit board and classifies each one according to the type of test coverage the net provides. Class 1 nets, for example, offer complete test coverage for all opens and shorts. The figure below shows a sample of the summary of an interconnect fault coverage report. Nets that are classified 2 through 6 offer varying degrees of fault coverage. Detailed coverage information is provided in the coverage report. |
