Wrapper leads gating TAP instruction and data registers
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. An integrated circuit comprising:
A. a test access port having:\
i. a TDI lead, a TDO lead, a TMS lead, and a TCK lead;
ii. a test access port controller having inputs connected to the TMS and TCK leads and having an instruction register and data register control bus output;
iii. a test access port instruction register having a TDI input connected to the TDI lead, control inputs connected to the instruction register and data register control bus output of the test access port controller, a first gating control lead, and a second gating control lead;
iv. a data register having a TDI input connected to the TDI lead, control inputs coupled to the instruction register and data register control bus output of the test access port controller, and a TDO output selectively coupled to the TDO lead; and
v. first gating circuitry having first inputs connected with the instruction register and data register control bus output, having second inputs, outputs connected with the control inputs of the data register, and a control input connected with the first gating control lead;
B. an auxiliary test control bus of leads separate from the TDI lead, the TDO lead, the TMS lead, and the TCK lead; and
C. second gating circuitry having a first set of inputs connected with at least part of the instruction register and data register control bus output, a second set of inputs connected with the auxiliary test control bus of leads, outputs connected to the second inputs of the first gating circuitry, and a control input connected with the second gating control lead.
2. The integrated circuit of claim 1 in which the auxiliary test control bus of leads includes 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.
3. The integrated circuit of claim 1 in which the test access port includes multiplexing circuitry selectively coupling the TDO output of the data register to the TDO lead.
4. The integrated circuit of claim 1 including an additional data register connected with the outputs of the first gating circuitry