scope:

This standard develops a methodology for access to embedded instrumentation, without defining the instruments or their features themselves, via the IEEE 1149.1™ test access port (TAP) and additional signals that may be required. The elements of the methodology include a description language for the characteristics of the features and for communication with the features, and requirements for interfacing to the features.

Purpose

IEEE Std 1149.1 specifies circuits to be embedded within a semiconductor device to support board test; namely, the TAP, TAP Controller, and a number of internal registers.1 In practice the TAP and TAP Controller are being used for other functions well beyond boundary scan in an ad-hoc manner across the industry to access a wide variety of embedded instruments. The purpose of the IEEE 1687 initiative is to provide an extension to IEEE Std 1149.1 specifically aimed at using the TAP to manage the configuration, operation, and collection of data from this embedded instrumentation circuitry.