TEST ACCESS PORT SWITCH

摘要

A Test Access Port (TAP) switch provides a centralized serial test interface between an electronic system and a resource external to the electronic system. The electronic system includes the TAP switch and a plurality of electronic circuit components, each electronic circuit component having a TAP coupled to the TAP switch. In one or more embodiments, the TAP switch comprises a first circuit configured to provide a clock signal to a selected one of the TAPs responsive to a selection code included in a serialized instruction, e.g., a code appended or prepended to the instruction. The TAP switch further comprises a second circuit comprising an instruction register (IR) configured to pass serialized instructions received by the TAP switch to the selected TAP and a third circuit configured to forward serialized data received from the selected TAP to an output of the TAP switch responsive to the selection code.