Jtag Mode Selection - Motorola MPC533 Reference Manual

Table 2-6. MPC533 Development Support Shared Signals
1
Signal
JCOMP/RSTI
TCK/DSCK/MCKI
TDI/DSDI/MDI0
TDO/DSDO/MDO0
TMS/EVTI
1
Only one set of signals are enabled at a time.
Signal
DSCK
DSDI
EVTI
MDI0
JCOMP
2.5.1

JTAG Mode Selection

The MPC533 has five JTAG signals. The test data input (TDI) and test data output (TDO)
scan ports are used to scan instructions as well as data into the various scan registers for
JTAG operations. The scan operation is controlled by the test access port (TAP) controller,
which in turn is controlled by the test mode select (TMS) input sequence. The scan data is
latched at the rising edge of the test clock (TCK).
On the MPC533, JTAG is used for boundary scan only. There is no access to internal
MPC533 circuitry. When JTAG mode is enabled, the READI module will be held inactive.
See Figure 25-5 for JTAG mode selection.
JTAG is entered by the following sequence of events:
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Direction
Input
Input
Input
Output
Input
Table 2-7. MPC533 Mode Selection Options
State
BDM Mode
High
Low
High
Low
Nexus Configuration
High
Low
High
Low
JTAG Selection
Low
High
Chapter 2. Signal Descriptions
MPC533 Development Support Signal Sharing
JTAG BDM
JCOMP —
TCK DSCK
TDI DSDI
TDO DSDO
TMS —
When Sampled
SRESET negation
SRESET negation
8 clocks after SRESET
8 clocks after SRESET
RSTI negation
RSTI negation
EVTI negation
EVTI negation
PORESET
PORESET
READI
RSTI
MCKI
MDI0
MDO0
EVTI
Affect
BDM mode enabled
BDM mode disabled
Synchronous mode
Asynchronous mode
READI module Disabled
READI module Enabled
Full Port mode
Reduced port mode
Nexus or BDM allowed
JTAG Mode Selected
2-25