RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
The boundary scan architecture consists of a TAP controller, an instruction
register with instruction decode, a bypass register, a device identification register
and a boundary scan register. The TAP controller interprets the TMS input and
generates control signals to load the instruction and data registers. The
instruction register with instruction decode block is used to select the test to be
executed and/or the register to be accessed. The bypass register offers a single-
bit delay from primary input, TDI to primary output, TDO. The device
identification register contains the device identification code.
The boundary scan register allows testing of board inter-connectivity. The
boundary scan register consists of a shift register place in series with device
inputs and outputs. Using the boundary scan register, all digital inputs can be
sampled and shifted out on primary output, TDO. In addition, patterns can be
shifted in on primary input, TDI and forced onto all digital outputs.
12.5.1 TAP Controller
The TAP controller is a synchronous finite state machine clocked by the rising
edge of primary input, TCK. All state transitions are controlled using primary
input, TMS. The finite state machine is described below.
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