Nexus
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 25-17
25.7 NPC Functional Description
25.7.1 NPC Reset Configuration
The NPC is placed in disabled mode upon exit of reset. If message transmission via the auxiliary port is
desired, a write to the PCR is then required to enable the NPC and select the mode of operation. Asserting
MCKO_EN places the NPC in enabled mode and enables MCKO. The frequency of MCKO is selected by
writing the MCKO_DIV field. Asserting or negating the FPM bit selects full-port or reduced-port mode,
respectively.
Table 25-12 describes the NPC reset configuration options.
25.7.2 Auxiliary Output Port
The auxiliary output port is shared by each of the Nexus modules on the device. The NPC communicates
with each of the individual modules and arbitrates for access to the port. Additional information about the
auxiliary port is found in Section 25.2, “External Signal Description.”
25.7.2.1 Output Message Protocol
The protocol for transmitting messages via the auxiliary port is accomplished with the MSEO functions.
The MSEO
pins are used to signal the end of variable-length packets and the end of messages. They are
not required to indicate the end of fixed-length packets. MDO and MSEO are sampled on the rising edge
of MCKO.
25–1 Reserved
0
PSTAT_EN
Processor status mode enable. Enables processor status (PSTAT) mode. In PSTAT mode, all auxiliary output
port MDO pins are used to transmit processor status information, and Nexus messaging is unavailable.
0 PSTAT mode disabled
1 PSTAT mode enabled
Note: PSTAT mode is intended for factory processor debug only. The PSTAT_EN bit should be written to
disable PSTAT mode by the customer. No Nexus messages are transmitted under any circumstances
when PSTAT mode is enabled
Table 25-12. NPC Reset Configuration Options
JCOMP
Asserted?
PCR[MCKO_EN] PCR[FPM] Configuration
No X X Reset
Yes 0 X Disabled
Yes 1 1 Full-Port Mode
Yes 1 0 Reduced-Port Mode
Table 25-11. PCR Field Descriptions (continued)
Field Description
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