PXR40RM Datasheet, PDF (1335/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Nexus Development Interface (NDI)
Table 31-11. PCR Field Descriptions (continued)
Field
Description
6–30 Reserved
31
Processor status mode enable. Enables processor status (PSTAT) mode. In PSTAT mode, all auxiliary output
PSTAT_EN 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 must be written to disable
PSTAT mode by the customer. No Nexus messages are transmitted under any circumstances when
PSTAT mode is enabled
31.7 NPC Functional Description
31.7.1 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 31-6 describes the NPC reset configuration options.
31.7.2 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 31.2, External Signal Description.
31.7.2.1 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.
Figure 31-5 illustrates the state diagram for MSEO transfers. All transitions not included in the figure are
reserved, and must not be used.
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
31-19