Enhancing legacy General Purpose Interfaces

Modern Automatic Test Equipment (ATE) systems are expected to provide a platform for existing Test Program Sets (TPS), as well as enable testing of new much more advanced Units Under Test (UUT). There are many methods to provide an interface to the UUT including reusing the existing interface or the new CTI interface. Each choice made has advantages and disadvantages to the interface. One approach is to enhance the existing interface so that there is minimal or no impact to the existing TPS hardware and still allow for additional capabilities to be provided. By creating an active chassis behind the General Purpose Interface (GPI) one can enhance the interface and allow for additional capability. In addition, this approach provides a reliable and maintainable system to the end user. This paper will discuss one such approach to provide modern capabilities to a legacy General Purpose Interface. When system engineers begin the design of an automated test equipment (ATE) system, they must take into consideration whether or not there is a requirement to replace the functionality of an existing platform. Architecting a system capable of testing legacy as well as newly introduced products presents challenges that are not normally encountered in ´ground-up´ designs. The desire to maintain existing test program sets with minimal or no change often conflicts with the need to insert advanced technology into the system. In these cases, the legacy system typically drives the instrumentation input/output (I/O) interface to the Units Under Test (UUT) in order to preserve the significant investment in TPS development. However, a legacy I/O pinmap will more than likely prove inadequate for newer product requirements which demand a new mix of instrumentation and I/O types. There are a few different approaches to interface design that can be pursued in order to maintain existing TPS compatibility while planning for future requirements. One approach would be to architect a new layout - - of I/O for future requirements, and utilize a transition adapter that maps to the legacy interface. However, this method introduces risk to the existing program sets by adding connections and therefore different characteristics that may alter test results. This paper will present a solution that enhances an existing interface with little impact to the existing TPS, while introducing multi-purpose capabilities to the I/O map through the use of an active General Purpose Interface.