DS26401 Octal T1/E1/J1 Framer
304
Test-Logic-Reset
Upon power up, the TAP Controller will be in the Test-Logic-Reset state. The Instruction register will contain the
IDCODE instruction. All system logic of the device will operate normally.
Run-Test-Idle
The Run-Test-Idle is used between scan operations or during specific tests. The Instruction register and test
registers will remain idle.
Select-DR-Scan
All test registers retain their previous state. With JTMS LOW, a rising edge of JTCLK moves the controller into the
Capture-DR state and will initiate a scan sequence. JTMS HIGH during a rising edge on JTCLK moves the
controller to the Select-IR-Scan state.
Capture-DR
Data may be parallel-loaded into the test data registers selected by the current instruction. If the instruction does not
call for a parallel load or the selected register does not allow parallel loads, the test register will remain at its current
value. On the rising edge of JTCLK, the controller will go to the Shift-DR state if JTMS is LOW or it will go to the
Exit1-DR state if JTMS is HIGH.
Shift-DR
The test data register selected by the current instruction will be connected between JTDI and JTDO and will shift
data one stage towards its serial output on each rising edge of JTCLK. If a test register selected by the current
instruction is not placed in the serial path, it will maintain its previous state.
Exit1-DR
While in this state, a rising edge on JTCLK will put the controller in the Update-DR state, which terminates the
scanning process, if JTMS is HIGH. A rising edge on JTCLK with JTMS LOW will put the controller in the Pause-DR
state.
Pause-DR
Shifting of the test registers is halted while in this state. All test registers selected by the current instruction will
retain their previous state. The controller will remain in this state while JTMS is LOW. A rising edge on JTCLK with
JTMS HIGH will put the controller in the Exit2-DR state.
Exit2-DR
A rising edge on JTCLK with JTMS HIGH while in this state will put the controller in the Update-DR state and
terminate the scanning process. A rising edge on JTCLK with JTMS LOW will enter the Shift-DR state.
Update-DR
A falling edge on JTCLK while in the Update-DR state will latch the data from the shift register path of the test
registers into the data output latches. This prevents changes at the parallel output due to changes in the shift
register.
Select-IR-Scan
All test registers retain their previous state. The instruction register will remain unchanged during this state. With
JTMS LOW, a rising edge on JTCLK moves the controller into the Capture-IR state and will initiate a scan
sequence for the instruction register. JTMS HIGH during a rising edge on JTCLK puts the controller back into the
Test-Logic-Reset state.
Capture-IR
The Capture-IR state is used to load the shift register in the instruction register with a fixed value. This value is
loaded on the rising edge of JTCLK. If JTMS is HIGH on the rising edge of JTCLK, the controller will enter the Exit1-
IR state. If JTMS is LOW on the rising edge of JTCLK, the controller will enter the Shift-IR state.
Shift-IR
In this state, the shift register in the instruction register is connected between JTDI and JTDO and shifts data one
stage for every rising edge of JTCLK towards the serial output. The parallel register and all test registers remain at
their previous states. A rising edge on JTCLK with JTMS HIGH will move the controller to the Exit1-IR state. A