
MOTOROLA
Chapter 8. Signal Descriptions
8-49
Signal Descriptions
8.3.12.3 JTAG Test Data Output (core_tdo)—Output
The JTAG test data output signal is an output on the G2 core. Following are the state
meaning and timing comments for the core_tdo output signal.
State Meaning
Asserted/Negated—The contents of the selected internal instruction
or data register are shifted out onto this signal on the falling edge of
core_tck. The core_tdo signal remains in a high-impedance state
except when scanning of data is in progress.
Timing Comments
Assertion/Negation—core_tdo should not be used for normal
operation and is only valid when core_tdo_oe is asserted.
8.3.12.3.1 JTAG Test Data Output Enable (core_tdo_oe)—Output
The JTAG test data output enable signal is an output on the G2 core. Following are the state
meaning and timing comments for the core_tdo_oe output signal.
State Meaning
Asserted—Indicates that the G2 core is driving a valid core_tdo
during the shiftDR or shiftID state of the TAP controller.
Negated—Indicates that the core is not driving a valid core_tdo
value.
Timing Comments
Assertion/Negation—The core_tdo signal is always driven,
regardless of the state of core_tdo_oe. Also, core_tdo is always
driven when core_lssd_mode
is asserted and scanned.
8.3.12.4 JTAG Test Mode Select (core_tms)—Input
The test mode select (core_tms) signal is an input on the G2 core. Following are the state
meaning for the core_tms input signal.
State Meaning
Asserted/Negated—This signal is decoded by the internal JTAG
TAP controller to distinguish the primary operation of the test
support circuitry.
Timing Comments
Assertion/Negation—core_tms should not be used during normal
operation and always must be set to either a high or low logic state.
Note that this input contains an internal pull-up resistor to ensure that
an unterminated input appears as a high signal level to the test logic.
8.3.12.5 JTAG Test Reset (core_trst)—Input
The test reset (core_trst) signal is an input on the G2 core. Following are the state meaning
and timing comments for the core_trst input signal.
State Meaning
Asserted—This input causes asynchronous initialization of the
internal JTAG test access port controller. Note that the signal must be
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.