IEEE P1687.1: Extending the Network Boundaries for Test

Modern integrated circuits used in automotive, industrial, consumer, and IoT (Internet of Things) applications often have limited pin counts. Despite this, these devices can be complex, with significant digital and analog content. These features require rigorous testing to address the quality and reliability requirements of these applications. Because of their limited pin count, a TAP controller interface is often not an option or the TAP controller interface itself may not be an option for other reasons, such as die area. Further, the increasing number of IP based designs, along with the increasing availability of IP cores can result in an IP being integrated deep inside a design. Designers, DfT engineers, and test engineers are facing increasing challenges with the integration and testability of IP in their chips. They also have the task of having to test through interfaces that may change depending on the needs of the customers. IEEE P1687.1 is working on processes that will provide a means for automating communications through non-TAP interfaces, making these types of products ideally suited for the techniques currently under consideration for standardization. This paper, reviews the latest topics being discussed by the working group, including the framework for communicating through these interfaces. It discusses how proto buffers (protobufs) can be used to help bridge the gap between a host controller, like an ATE, and an IJTAG network. The approach leverages the concept of Remote Procedural Calls (RPCs) from the IT space and the integer bit vector (intbv) concept from myHDL to support communications through interfaces and between subroutines handling retargeting and handling control of the interface. A model is presented for evaluating the options and various criteria are reviewed with respect to the framework. The paper also explores debug concerns and potential security issues and how those can be addressed.