Patent ID: 7877653
Filing Date: 2011-01-25
Classification: G01R

Abstract:
1. A TAP access arrangement comprising, A. a TAP controller having a TDI output lead, a TMS output lead, a TCK output lead, and a TDO input lead, B. plural devices, each device having a TDI input lead connected to the TDI output lead of the TAP controller, a TMS input lead connected to the TMS output lead of the TAP controller, a TCK input lead connected to the TCK output lead of the TAP controller, and a TDO output lead connected to the TDO input lead of the TAP controller, C. a test access port control circuit in each device, the control circuit including state machine circuitry, and the control circuit having a TCK input coupled with the TCK input lead and a TMS input coupled with the TMS input lead; D. addressing circuitry in each device, the addressing circuitry having a TDI input coupled to the device TDI input lead, a TMS input couple to the device TMS input lead, and a TCK input coupled to the device TCK input lead; E. detection circuitry within the address circuitry for detecting a control signal on the TDI input lead when the TAP controller inputs control on the TMS and TCK input leads for the state machine circuitry to transition into one of the Run Test/Idle, Pause-DR and Pause-IR TAP states, the detection circuitry having an enable output; and F. gating circuitry within the address circuitry coupling the TMS input lead to the TMS input of the control circuit, the gating circuitry having one input connected to the TMS input lead, another input connected to the enable output, and an output connected to the TMS input of the control circuit.