PXS20RM Datasheet, PDF (1134/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Nexus Port Controller (NPC)
NOTES:
1 _{PSTAT Mode is intended for factory processor debug only. The PSTAT_EN bit should be written to disable PSTAT}
mode if Nexus messaging is desired. No Nexus messages are transmitted under any circumstances when PSTAT
mode is enabled.
Table 34-6. MCKO_DIV Values
MCKO_DIV[2:0]
MCKO Frequency
0
SYS_CLK¹
1
SYS_CLK/2
2
SYS_CLK/3
3
SYS_CLK/4
4
Reserved
5
Reserved
6
Reserved
7
SYS_CLK/8
NOTES:
1 _{The SYS_CLK setting for MCKO frequency should only be used if this setting does not violate the}
maximum operating frequency of the auxiliary port pins.
34.5 Functional description
34.5.1 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 34-7 describes the NPC reset configuration options.
Table 34-7. NPC Reset Configuration Options
JCOMP Equal to
npc_jcomp_plug?
no
yes
yes
yes
MCKO_EN bit of the Port
Configuration Register
X
0
1
1
FPM bit of the Port
Configuration Register
X
X
1
0
Configuration
Reset
Disabled
Full-Port Mode
Reduced-Port Mode
34.5.2 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 Nexus modules and arbitrates for access to the port.
34-10
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor