Patent ID: 8621125

Claim:
Electrical circuitry, comprising: a TCK input communicably coupleable to a TCK signal of a serial bus; a TMS input communicably coupleable to a TMS signal of the serial bus; a state-machine operative to follow at least four states of a serial protocol, the four states including a Test-Logic-Reset State, a Run-Test/IDLE state, a SELECT-DR state, and a SELECT-IR state; at least one state counter operative to count a number of times the state-machine follows the serial protocol from the Test-Logic-Reset state through the Run-Test/IDLE state, the SELECT-DR state, the SELECT-IR state, and back to the Test-Logic-Reset state; at least one first logic circuit operative to reset the state counter whenever the state-machine is in the SELECT-DR state, a logical-low is observed on the TMS input, and a logical-low to logical-high transition is observed on the TCK input; and at least one second logic circuit operative to reset the state counter whenever the state-machine is in the SELECT-IR state and a logical-low is observed on the TMS input and a logical-low to logical-high transition is observed on the TCK input.