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CHAPTER 8 JTAG BOUNDARY SCAN
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(15) Exit2-IR
Exit2-IR is a state that the controller enters temporarily. In this state, at the rising edge of the signal being
input to the JCK pin, if the level of the signal being input to the JMS pin is held high, the TAP controller
enters the Update-IR state. In this way, scan processing is terminated.
On the contrary, at the rising edge of the signal being input to the JCK pin, if the level of the signal being
input to the JMS pin is held low, the TAP controller enters the Shift-IR state.
Both the bypass register and boundary scan register, selected with the current instruction, maintain their
previous states.
While the TAP controller is in this state, or while the instruction register remains in the same state,
instruction conversion is not performed.
(16) Update-IR
While the TAP controller is in the Update-IR state, at the falling edge of the signal being input to the JCK
pin, the instruction shifted into the instruction register is latched from the shift register path to the parallel
output of this register. A new instruction, once latched, becomes the current instruction.
Both the bypass register and boundary scan register, selected with the current instruction, maintain their
previous states.
While the TAP controller is in this state, at the rising edge of the signal being input to the JCK pin,
provided the level of the JMS signal is held high, the TAP controller enters the Select-DR-Scan state.
On the contrary, at the rising edge of the signal being input to the JCK pin, if the level of the JMS signal is
held low, the TAP controller enters the Run-Test/Idle state.
In both the Pause-DR state explained in (8) and the Pause-IR state explained in (14), data shift in the
bypass register, boundary scan register, and instruction register is temporarily halted.