DS2155LB Maxim Integrated, DS2155LB Datasheet - Page 201

• Manufacturer Part Number: DS2155LB
• Description: Network Controller & Processor ICs
• Manufacturer: Maxim Integrated

DS2155
Select-IR-Scan
All test registers retain their previous state. The instruction register remains unchanged during this state.
With JTMS LOW, a rising edge on JTCLK moves the controller into the Capture-IR state and initiates 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 enters the Exit1-IR state. If JTMS is LOW on the rising edge of JTCLK, the controller enters
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 toward the serial output. The parallel register and all test
registers remain at their previous states. A rising edge on JTCLK with JTMS HIGH moves the controller
to the Exit1-IR state. A rising edge on JTCLK with JTMS LOW keeps the controller in the Shift-IR state
while moving data one stage through the instruction shift register.
Exit1-IR
A rising edge on JTCLK with JTMS LOW puts the controller in the Pause-IR state. If JTMS is HIGH on
the rising edge of JTCLK, the controller enters the Update-IR state and terminates the scanning process.
Pause-IR
Shifting of the instruction shift register is halted temporarily. With JTMS HIGH, a rising edge on JTCLK
puts the controller in the Exit2-IR state. The controller remains 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 puts the controller in the Update-IR state. The controller loops
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 LOW puts the controller in the Run-Test-Idle
state. With JTMS HIGH, the controller enters the Select-DR-Scan state.
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