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DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver
338 of 344
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, as well as all test registers,
remains at their previous states. A rising edge on JTCLK with JTMS HIGH will move the controller to the Exit1-IR
state. A rising edge on JTCLK with JTMS LOW will keep the controller in the Shift-IR state while moving data one
stage thorough the instruction shift register.
Exit1-IR
A rising edge on JTCLK with JTMS LOW will put the controller in the Pause-IR state. If JTMS is HIGH on the rising
edge of JTCLK, the controller will enter the Update-IR state and terminate the scanning process.
Pause-IR
Shifting of the instruction shift register is halted temporarily. With JTMS HIGH, a rising edge on JTCLK will put the
controller in the Exit2-IR state. The controller will remain in the Pause-IR state if JTMS is LOW during a rising
edge on JTCLK.
Exit2-IR
A rising edge on JTCLK with JTMS LOW will put the controller in the Update-IR state. The controller will loop back
to Shift-IR if JTMS is HIGH during a rising edge of JTCLK in this state.
Update-IR
The instruction code shifted into the instruction shift register is latched into the parallel output on the falling edge of
JTCLK as the controller enters this state. Once latched, this instruction becomes the current instruction. A rising
edge on JTCLK with JTMS held low will put the controller in the Run-Test-Idle state. With JTMS HIGH, the
controller will enter the Select-DR-Scan state.