AMD AMD-K6-2/400 User Guide - Page 276

TAP Signals, The Test Clock for all TAP operations. The rising

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Preliminary Information AMD-K6™-2E+ Embedded Processor Data Sheet 23542A/0-September 2000 TAP Signals The test signals associated with the TAP controller are as follows: s TCK-The Test Clock for all TAP operations. The rising edge of TCK is used for sampling TAP signals, and the falling edge of TCK is used for asserting TAP signals. The state of the TMS signal sampled on the rising edge of TCK causes the state transitions of the TAP controller to occur. TCK can be stopped in the logic 0 or 1 state. s TDI-The Test Data Input represents the input to the most significant bit of all TAP registers, including the IR and all test data registers. Test data and instructions are serially shifted by one bit into their respective registers on the rising edge of TCK. s TDO-The Test Data Output represents the output of the least significant bit of all TAP registers, including the IR and all test data registers. Test data and instructions are serially shifted by one bit out of their respective registers on the falling edge of TCK. s TMS-The Test Mode Select input specifies the test function and sequence of state changes for boundary-scan testing. If TMS is sampled High for five or more consecutive clocks, the TAP controller enters its reset state. s TRST#-The Test Reset signal is an asynchronous reset that unconditionally causes the TAP controller to enter its reset state. Refer to "Electrical Data" on page 285 and "Signal Switching Characteristics" on page 295 to obtain the electrical specifications of the test signals. 254 Test and Debug Chapter 13

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254
Test and Debug
Chapter 13
AMD-K6™-2E+ Embedded Processor Data Sheet
23542A/0—September 2000
Preliminary Information
TAP Signals
The test signals associated with the TAP controller are as
follows:
TCK
—The Test Clock for all TAP operations. The rising
edge of TCK is used for sampling TAP signals, and the
falling edge of TCK is used for asserting TAP signals. The
state of the TMS signal sampled on the rising edge of TCK
causes the state transitions of the TAP controller to occur.
TCK can be stopped in the logic 0 or 1 state.
TDI
—The Test Data Input represents the input to the most
significant bit of all TAP registers, including the IR and all
test data registers. Test data and instructions are serially
shifted by one bit into their respective registers on the rising
edge of TCK.
TDO
—The Test Data Output represents the output of the
least significant bit of all TAP registers, including the IR and
all test data registers. Test data and instructions are serially
shifted by one bit out of their respective registers on the
falling edge of TCK.
TMS
—The Test Mode Select input specifies the test
function and sequence of state changes for boundary-scan
testing. If TMS is sampled High for five or more consecutive
clocks, the TAP controller enters its reset state.
TRST#
—The Test Reset signal is an asynchronous reset that
unconditionally causes the TAP controller to enter its reset
state.
Refer to “Electrical Data” on page 285 and “Signal Switching
Characteristics” on page 295 to obtain the electrical
specifications of the test signals.