MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 25-5
asynchronously holding all other Nexus modules in reset as well. This prevents Nexus read/write to
memory mapped resources and the transmission of Nexus trace messages. Refer to Table 13-17 for
information on Nexus port enabling and disabling regarding censorship.
25.2 External Signal Description
The auxiliary and JTAG pin interfaces provide for the transmission of messages from Nexus modules to
the external development tools and for access to Nexus client registers. The auxiliary/JTAG pin definitions
are outlined in Table 25-1.
25.2.1 Detailed Signal Descriptions
This section describes each of the signals listed in Table 25-1 in more detail.
25.2.1.1 Event Out (EVTO)
EVTO is an output pin that is asserted upon breakpoint occurrence to provide breakpoint status indication
or to signify that an event has occurred. The EVTO output of the NPC is generated based on the values of
the individual EVTO signals from all Nexus modules that implement the signal.
25.2.1.2 Event In (EVTI)
EVTI is used to initiate program and data trace synchronization messages or to generate a breakpoint.
EVTI is edge-sensitive for synchronization and breakpoint generation.
Table 25-1. Signal Properties
Name Port Function Reset State
EVTO
Auxiliary Event Out pin Negated
EVTI Auxiliary Event In pin Pulled Up
MCKO Auxiliary Message Clock Out pin (from NPC) Enabled
MDO[3:0] or
MDO[11:0]
Auxiliary Message Data Out pins Driven Low
1
1
Following a power-on reset, MDO0 remains asserted until power-on reset is exited and the system
clock achieves lock.
MSEO
[1:0] Auxiliary Message Start/End Out pins Negated
RDY Auxiliary Ready Out pin Negated
JCOMP JTAG JTAG Compliancy and TAP Sharing Control Pulled Down
TCK JTAG Test Clock Input Pulled Down
TDI JTAG Test Data Input Pulled Up
TDO JTAG Test Data Output Pulled Up
TMS JTAG Test Mode Select Input Pulled Up
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