AMD-K6-2E Datasheet, PDF (247/332 Pages) Advanced Micro Devices – AMD-K6™-2E Embedded Processor

22529B/0—January 2000
Preliminary Information
AMD-K6™-2E Processor Data Sheet
12.3
Boundary-Scan Test Access Port (TAP)
Test Access Port
The boundary-scan Test Access Port (TAP) is an IEEE standard
that defines synchronous scanning test methods for complex
logic circuits, such as boards containing a processor. The
AMD-K6-2E processor supports the TAP standard defined in
the IEEE Standard Test Access Port and Boundary-Scan
Architecture (IEEE 1149.1-1990) specification.
Boundary scan testing uses a shift register consisting of the
serial interconnection of boundary-scan cells that correspond to
each I/O buffer of the processor. This non-inverting register
chain, called a Boundary Scan register (BSR), can be used to
capture the state of every processor pin and to drive every
processor output and bidirectional pin to a known state.
Each BSR of every component on a board that implements the
boundary-scan architecture can be serially interconnected to
enable component interconnect testing.
The Test Access Port (TAP) consists of the following:
s Test Access Port (TAP) Controller—The TAP controller is a
synchronous, finite state machine that uses the TMS and
TDI input signals to control a sequence of test operations.
See “TAP Controller State Machine” on page 236 for a list
of TAP states and their definition.
s Instruction Register (IR)—The IR contains the instructions
that select the test operation to be performed and the Test
Data Register (TDR) to be selected. See “TAP Registers” on
page 231 for more details on the IR.
s Test Data Registers (TDR)—The three TDRs are used to
process the test data. Each TDR is selected by an
instruction in the Instruction Register (IR). See “TAP
Registers” on page 231 for a list of these registers and their
functions.
Chapter 12
Test and Debug
229