Patent ID: 7404128

Claim:
An electrical device comprising: A. a TDI lead, a TDO lead, a TMS lead, and a TCK lead; B. test access port circuitry having a TDI input connected to the TDI lead, a TDO output connected to the TDO lead, a TMS input coupled to the TMS lead, and a TCK input, the test access port circuitry providing an enable serial output signal, an enable serial input signal, and an input/output sync signal; C. an input buffer having an input connected to the TCK lead and an output connected to the TCK input; D. sync circuitry having a first input coupled to the enable serial input signal, another input connected to the input/output sync signal, a clock input coupled to the TMS lead, and an input enable output; and E. serial communication circuitry having an input enable input connected to the input enable output, an output enable input coupled to the enable serial output signal, a clock input coupled to the TMS lead, a serial data input connected to the output of the input buffer and the TCK input, and a serial data output connected to the input of the input buffer and the TCK lead.