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Description / Abstract:
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.