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CHAPTER 6 JTAG BOUNDARY SCAN
User’s Manual S14054EJ4V0UM
117
(4) Select-IR-Scan
This is a temporary boundary scan state. The boundary scan register and bypass register selected by the
current instruction hold the previous state.
If the TMS pin signal is held low at the rising edge of the TCK pin signal while the TAP controller is in this state,
the controller enters the Capture-IR state, and scan sequence to the selected registers is started.
If the TMS pin signal is held high at the rising edge of the TCK pin signal, the TAP controller enters the Test-
Logic-Reset state. While the controller is in this state, the instruction does not change.
(5) Capture-DR
In this controller state, data is loaded to the boundary scan register selected by the current instruction in parallel
at the rising edge of the TCK pin signal. (In this case, load the data from the input pin of each device to the
corresponding boundary scan register at the same time.) While the TAP controller is in this state, the instruction
does not change.
If the TAP controller is in this state at the rising edge of the TCK pin signal, the controller enters the following
state:
•
If the TMS pin signal is held high : Exit1-DR state
•
If the TMS pin signal is held low : Shift-DR state
(6) Shift-DR
In this controller state, TDI and TDO are connected (at either of the boundary scan register of bypass register) by
the current instruction. The shift data is shifted one state at a time toward the serial output direction at each
rising edge of the TCK pin signal.
The boundary scan register or bypass register selected by the current instruction holds the previous status
without change if the controller is not on the serial bus (not in the Shift-DR state). While the controller is in this
state, the instruction does not change.
If the TAP controller is in this state at the rising edge of the TCK pin signal, the controller enters the following
state:
•
If the TMS pin signal is held high : Exit1-DR state
•
If the TMS pin signal is held low : Shift-DR state
(7) Exit1-DR
This is a temporary controller state. If the TMS pin signal is held high at the rising edge of the TCK pin signal
with the TAP controller in this state, the controller enters the Update-DR state. This ends the scan process.
If the TMS pin signal is held low at the rising edge of the TCK pin signal, the TAP controller enters the Pause-DR
state.
Both the bypass register and boundary scan register selected by the current instruction hold the previous status
without change. While the TAP controller is in this state, the instruction does not change.
(8) Pause-DR
In this controller state, shifting between TDI and TDO connected by either the bypass register or boundary scan
register is temporarily stopped. These registers selected by the current instruction hold the previous state
without change.
The TAP controller remains in this state while the TMS pin signal is low. If the TMS pin signal is held high at the
rising edge of the TCK pin signal, the TAP controller enters the Exit2-DR state. While the TAP controller is in this
state, the instruction does not change.