NXP Semiconductors PXN2020, Reference Manual, Page: 1168 / 1376

Nexus Development Interface (NDI)
PXN20 Microcontroller Reference Manual, Rev. 1
36-18 Freescale Semiconductor
36.5.5 NPC Functional Description
36.5.5.1 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.
Table 36-4 describes the NPC reset configuration options.
36.5.5.2 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 individual modules and arbitrates for access to the port. Additional information about the
auxiliary port is found in
Section 35.1.1.1, Individual and Multi-Core Debug.
36.5.5.2.1 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 36-8 illustrates the state diagram for MSEO transfers. All transitions not included in the figure are
reserved, and must not be used.
Figure 36-8. MSEO Transfers
MSEO = 00
MSEO = 11
MSEO = 01
MSEO = 00
Normal
Transfer
End
Packet
Start
Message
End
Message
Idle
MSEO = 00 MSEO = 01 MSEO = 11
M
SEO
=
0
1
M
SEO
= 1
1
M
SE
O =
00 M
SE
O
=
10
M
SE
O
=
11
MSEO = 01 MSEO = 00
MSEO = 10
MSEO = 01
MSEO = 11
MDO:
Invalid
MDO:
Invalid
MSEO = 10