Patent ID: 8065578
Filing Date: 2011-11-22
Classification: G01R

Abstract:
1. An integrated circuit comprising: A. a TDI input lead, TMS input lead, TCK input lead, and TDO output lead; B. a first access port having an input connected to the TDI input lead, an input connected to the TMS input lead, an input connected to the TCK input lead, an enable input, and a data output coupled to the TDO output lead; C. a second access port having an input connected to the TDI input lead, an input connected to the TMS input lead, an input connected to the TCK input lead, an enable input, and a data output coupled to the TDO output lead; D. an inverter having an input connected to the TCK input lead and an output; and E. an access port selector having a port select register and a state machine controller, the port select register having an input coupled to the TDI input lead, control inputs, a first enable output connected to the enable input of the first access port, and a second enable output connected to the enable input of the second access port, the state machine controller having an input coupled to the TMS input lead, an input coupled to the output of the inverter, and control outputs connected to the control inputs of the port select register.