A UUT-centric test specification simplifies digital functional test development

Abstract

Open-architecture test systems were supposed to simplify test program set (TPS) development while using the latest instrumentation. The promise was that choosing best-in-class tools to integrate instrument-specific drivers would create efficiency in the TPS development process. Unfortunately, TPS development is as complex as ever. In most cases, the cost for the TPS development is much higher than the test instrument itself. This paper postulates a reason why: while test requirements are specified with a UUT (unit under test)-centric view, the available instrument drivers and tools force test developers to take an instrument-oriented view during test development. A UUT-centric TPS describes tests in terms of the behavior of the I/O, while an instrument-oriented TPS describes tests in terms of instrument setup (such as when using an instrument-specific driver). This paper describes a UUT-centric digital test development approach using the iStudio Digital Test Editor associated with Teradyne's new generation of digital test instruments. This integrated graphical toolset combines test development, debugging, and code-generation capabilities under one environment, and works in conjunction with the user's existing applications development environment. Instead of the traditional instrument orientation, the toolset enables the test developer to specify tests in terms of user test data; e.g. DC characteristics for UUT signals, bus cycle definitions, and vector-based timing data. The ability to generate readable, properly-constructed source code and the UUT-centric interface make the toolset a major training tool for test engineers. More importantly, even when the tool generates source code, developers can still use the same UUT-centric environment to debug the tests that they used to develop them