
TAP Controller
MOTOROLA
JTAG Port
17-23
Preliminary
17
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 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 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 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 Selector state
if TMS is held high or the Run-Test-Idle state If TMS is held low.