Lessons learned using boundary scan and built-in test for integration and diagnostic test of the U.S. Navy joint standoff weapon

The integration of the various hardware and software components of a newly developed system can be a difficult and time consuming task. In many cases, the factory test equipment and test programs are not normally available for testing of the first few printed wiring boards (PWBs)/subsystems/systems built. The time taken to diagnose encountered problems can mean the difference between meeting or failing to meet product delivery schedules. Well planned design for test (DFT) and test development can significantly reduce the risk and overall cycle time of the integration and testing of these early PWBs/subsystems/systems. On a recent DoD program at Texas Instruments the Built-in Test (BIT) designed for field support of the weapon system, and the boundary scan intended for factory test support, were utilized to provide improved accuracy and reduced cycle time for processor board acceptance test (AT), hardware/software integration, environmental stress screening (ESS), and for the diagnosis of problems encountered during PWB/subsystem/system Integration. This paper briefly describes the weapon system, the diagnostic requirements, and the functionality of the BIT, boundary scan and DFT implemented. These details are followed by a discussion of problems encountered and lessons learned in utilizing these field and factory test capabilities as integration and diagnostic tools in a development environment.