Multiplexer for tap controller and WSP controller outputs
In a first embodiment a TAP 318 of IEEE standard 1149.1 is allowed to commandeer control from a WSP 202 of IEEE standard P1500 such that the P1500 architecture, normally controlled by the WSP, is rendered controllable by the TAP. In a second embodiment (1) the TAP and WSP based architectures are merged together such that the sharing of the previously described architectural elements are possible, and (2) the TAP and WSP test interfaces are merged into a single optimized test interface that is operable to perform all operations of each separate test interface.
1. A circuit comprising:
A. test access port having:
i. a TDI lead, a TDO lead, a TMS lead, a TCK lead, and a TRST lead; and
ii. a test access port controller having inputs connected to the TMS, TCK and TRST leads and having ClockIR, ShiftIR, CaptureIR, UpdateIR, Reset, Select, ClockDR, ShiftDR, CaptureDR, and UpdateDR output leads;
B. a wrapper serial port having:
i. a clock lead, a capture lead, a shift lead, an update lead, a transfer lead, a reset lead, a select lead, a WSI lead, and a WSO lead; and
ii. a wrapper serial port controller having inputs connected to the clock lead, the capture lead, the shift lead, the update lead, the transfer lead, the reset lead, and the select lead, and having ClockIR, ShiftIR, CaptureIR, UpdateIR, Reset, Select, ClockDR, ShiftDR, CaptureDR, UpdateDR, and TransferDR output leads; and
C. multiplexer circuitry having a first bus input connected to the output leads of the test access port controller and having a TransferDR input, a second bus input connected to the output leads of the wrapper serial port controller, and having an output bus having ClockIR, ShiftIR, CaptureIR, UpdateIR, Reset, Select, ClockDR, ShiftDR, CaptureDR, UpdateDR and TransferDR output leads.
2. The circuit of claim 1 in which the TransferDR input of the first bus input is connected to a fixed voltage.
3. The circuit of claim 1 in which the TransferDR input of the first bus input is connected to the transfer lead of the wrapper serial port.