Nexus Development Interface (NDI)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 971
26.7.3 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 26-13 describes the NDI configuration options.
26.7.4 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.
Figure 26-14 shows the MCKO_DIV encodings. In this table, SYS_CLK represents the system clock
frequency. The default value selected if a reserved encoding is programmed is SYS_CLK2.
NOTE
On MPC5606S, the pad type used for the Nexus2+ signals will not support
the default SYSCLK2 and SYSCLKsetting, so the user must change the
MCKO frequency to be not faster than SYSCLK4.
Table 26-13. NDI configuration options
JCOMP Asserted
MCKO_EN bit of the
Port Configuration Register
FPM bit of the
Port Configuration Register
Configuration
No X X Reset
Ye s 0 X Disabled
Ye s 1 1 Full-Port mode
Ye s 1 0 Reduced-Port mode
Table 26-14. MCKO_DIV Values
MCKO_DIV[2:0] MCKO frequency
0b000 SYSCLK1
0b001 SYSCLK2
0b010 Reserved
0b011 SYS_CLK4
0b100 Reserved
0b101 Reserved
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