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TAP Controller
JTAG Port, Rev. 4
Freescale Semiconductor
17-23
17.8.1.11 Capture Instruction Register (pstate = E)
When the TAP Controller is in this state and a rising edge of TCK occurs, the controller advances
to the Exit1-IR state if TMS is held at a one or the Shift-IR state if TMS is held at a zero.
17.8.1.12 Shift Instruction Register (pstate = A)
In this controller state, the Shift register contained in the Instruction Register (IR) is connected
between TDI and TDO and shifts data one stage towards it’s serial output on each rising edge of
TCK. When the TAP Controller is in this state and a rising edge of TCK occurs, the controller
advances to the Exit1-IR state if TMS is held at a one or remains in the Shift-IR state if TMS is
held at a zero.
17.8.1.13 Exit1 Instruction Register (pstate = 9)
This is a temporary controller state. If TMS is held
high
, and a rising edge is applied to TCK
while in this state causes the controller to advance to the Update-IR state. This terminates the
scanning process. If TMS is held
low
and a rising edge of TCK occurs the controller advances to
the Pause-IR state.
17.8.1.14 Pause Instruction Register (pstate = B)
This controller state allows shifting of the Instruction Register (IR) in the serial path between
TDI and TDO to be temporarily halted. All Test Data registers selected by the current instruction
retain their previous state unchanged. The controller remains in this state while TMS is held
low
.
When TMS goes
high
and a rising edge is applied to TCK, the controller advances to the
Exit2-IR state.
17.8.1.15 Exit2 Instruction Register (pstate = 8)
This is a temporary controller state. If TMS is held
high
, and a rising edge is applied to TCK
while in this state, the scanning process terminates and the TAP Controller advances to the
Update-IR state. If TMS is held
low
and a rising edge of TCK occurs, the controller advances to
the Shift-IR state.
17.8.1.16 Update Instruction Register (pstate = D)
During this state, instruction shifted into the Instruction Register (IR) is latched from the Shift
register path on the falling edge of TCK and into the instruction latch. It becomes the current
instruction. On a rising edge of TCK, the controller advances to the Select_IR state if TMS is
held
high
or the Run-Test-Idle state If TMS is held
low
.