PMC-Sierra, Inc.
PM73488 QSE
L
PMC-980616
Issue 3
5 Gbit/s ATMSwitch Fabric Element
Released
Datasheet
114
instruction register is set to the IDCODE instruction.
10.2.2
Run-Test-Idle:
The run test/idle state is used to execute tests.
10.2.3
Capture-DR:
The capture data register state is used to load parallel data into the test data registers selected by the current
instruction. If the selected register does not allow parallel loads or no loading is required by the current
instruction, the test register maintains its value. Loading occurs on the rising edge of TCK.
10.2.4
Shift-DR:
The shift data register state is used to shift the selected test data registers by one stage. Shifting is from MSB
to LSB and occurs on the rising edge of TCK.
10.2.5
Update-DR:
The update data register state is used to load a test register’s parallel output latch. In general, the output
latches are used to control the device. For example, for the EXTEST instruction, the boundary scan test reg-
ister’s parallel output latches are used to control the device’s outputs. The parallel output latches are updated
on the falling edge of TCK.
10.2.6
Capture-IR:
The capture instruction register state is used to load the instruction register with a fixed instruction. The
load occurs on the rising edge of TCK.
10.2.7
Shift-IR:
The shift instruction register state is used to shift both the instruction register and the selected test data regis-
ters by one stage. Shifting is from MSB to LSB and occurs on the rising edge of TCK.
10.2.8
Update-IR:
The update instruction register state is used to load a new instruction into the instruction register. The new
instruction must be scanned in using the Shift-IR state. The load occurs on the falling edge of TCK.
The Pause-DR and Pause-IR states are provided to allow shifting through the test data and/or instruction reg-
isters to be momentarily paused.
The TDO output is enabled during states Shift-DR and Shift-IR. Otherwise, it is tri-stated.
Boundary Scan Instructions
The following is a description of the standard instructions. Each instruction selects an serial test data register path
between input, TDI, and output, TDO.
10.3
10.3.1
BYPASS
The bypass instruction shifts data from input TDI to output TDO with one TCK clock period delay. The
instruction is used to bypass the device.
10.3.2
EXTEST
The external test instruction allows testing of the interconnection to other devices. When the current instruc-
tion is the EXTEST instruction, the boundary scan register is place between input TDI and output TDO. Pri-
mary device inputs can be sampled by loading the boundary scan register using the Capture-DR state. The
sampled values can then be viewed by shifting the boundary scan register using the Shift-DR state. Primary
device outputs can be controlled by loading patterns shifted in through input TDI into the boundary scan reg-
ister using the Update-DR state.