Configuring The Ndi For Nexus Messaging - Freescale Semiconductor MPC5604B Reference Manual

33.7.3

Configuring the NDI for Nexus Messaging

The NDI is placed in disabled mode upon exit of reset. If message transmission via the auxiliary port is
desired, a write to the port configuration register (PCR) located in the NPC is then required to enable the
NDI and select the mode of operation. Asserting MCKO_EN in the PCR places the NDI 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. When writing to the PCR, the
PCR LSB must be written to a logic zero. Setting the LSB of the PCR enables factory debug mode and
prevents the transmission of Nexus messages.
Table 33-13 describes the NDI configuration options.
MCKO_EN bit of PCR
33.7.4 Programmable MCKO Frequency
MCKO is an output clock to the development tools used for the timing of MSEO and MDO pin functions.
MCKO is derived from the system clock, and its frequency is determined by the value of the MCKO_DIV
field in the port configuration register (PCR) located in the NPC. Possible operating frequencies include
one-quarter and one-eighth system clock speed.
Refer to the MCKO_DIV [2:0] field description in
SYS_CLK represents the system clock frequency. The default value selected if a reserved encoding is
programmed is SYS_CLK2.
33.7.5 Nexus Messaging
Most of the messages transmitted by the NDI include an SRC field. This field is used to identify which
source generated the message.
on the MPC5604B. These values are specific to the MPC5604B. The size of the SRC field in transmitted
messages is 4 bits. This value is also specific to the MPC5604B.
All other combinations
33.7.6 EVTO Sharing
The NPC block controls sharing of the EVTO output between all Nexus clients that generate an EVTO
signal. The sharing mechanism is a logical AND of all incoming EVTO signals from Nexus blocks,
Freescale Semiconductor
Table 33-13. NDI configuration options
0
1
1
Table 33-14 shows the values used for the SRC field by the different clients
Table 33-14. SRC Packet Encodings
SRC[3:0]
0b0000
MPC5604B/C Microcontroller Reference Manual, Rev. 8
FPM bit of PCR
X
1
0
Table 33-4 for the MCKO_DIV encodings, where
MPC5604B Client
e200z0
Reserved
Configuration
Disabled
Full-Port Mode
Reduced Port Mode
817