IEEE 1149.1 Test Access Port (JTAG)
32-3
Freescale Semiconductor
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
When one module is selected, the inputs into the other module are disabled or forced to a known logic
level, as shown in
, to disable the corresponding module.
NOTE
The JTAG_EN does not support dynamic switching between JTAG and
BDM modes.
32.2.2
Test Clock Input (TCLK)
The TCLK pin is a dedicated JTAG clock input to synchronize the test logic. Pulses on TCLK shift data
and instructions into the TDI pin on the rising edge and out of the TDO pin on the falling edge. TCLK is
independent of the processor clock. The TCLK pin has an internal pull-up resistor, and holding TCLK high
or low for an indefinite period does not cause JTAG test logic to lose state information.
32.2.3
Test Mode Select/Breakpoint (TMS/BKPT)
The TMS pin is the test mode select input that sequences the TAP state machine. TMS is sampled on the
rising edge of TCLK. The TMS pin has an internal pull-up resistor.
The BKPT pin is used to request an external breakpoint. Assertion of BKPT puts the processor into a halted
state after the current instruction completes.
32.2.4
Test Data Input/Development Serial Input (TDI/DSI)
The TDI pin receives serial test and data, which is sampled on the rising edge of TCLK. Register values
are shifted in least significant bit (lsb) first. The TDI pin has an internal pull-up resistor.
The DSI pin provides data input for the debug module serial communication port.
Table 32-2. Pin Function Selected
JTAG_EN = 0
JTAG_EN = 1
Pin Name
Module selected
BDM
JTAG
—
Pin Function
—
BKPT
DSI
DSO
DSCLK
TCLK
TMS
TDI
TDO
TRST
TCLK
BKPT
DSI
DSO
DSCLK
Table 32-3. Signal State to the Disable Module
JTAG_EN = 0
JTAG_EN = 1
Disabling JTAG
TRST = 0
TMS = 1
—
Disabling BDM
—
Disable DSCLK
DSI = 0
BKPT = 1
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60
