PXS20RM Datasheet, PDF (1126/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Nexus Port Controller (NPC)
JCOMP
Reset
Control
Debug
Mode
Control
EVTO
Control
PSTAT
MDO Mux
MDO
MSEO_B
Port
Arbiter
Message
Transmitter
MDO/MSEO
Generation
TCK
TMS
TDI
JTAG
Interface
Register
Control
Miscellaneous
Logic
TDO
Generation
TDO
Figure 34-1. Nexus Port Controller Block Diagram
34.2.1 Overview
On a system-on-a-chip device, there are often multiple blocks that require development support. Each of
these blocks implements a development interface based on the IEEE-ISTO 5001-2003 standard. The
blocks share input and output ports that interface with the development tool. The NPC controls the usage
of the input and output port in a manner that allows all the individual development interface blocks to share
the port, and appear to the development tool to be a single block.
34.2.2 Features
The NPC block performs the following functions:
• Controls arbitration for ownership of the Nexus Auxiliary Output Port
• Nexus Device Identification Register and Messaging
• Generates MCKO enable and frequency division control signals
• Controls sharing of EVTO
• Generates an MCKO clock gating control signal to enable gating of MCKO when the auxiliary
output port is idle
• Control of the device-wide debug mode
• Generates asynchronous reset signal for Nexus blocks based on JCOMP input, censorship status,
and power-on reset status
• System clock locked status indication via MDO[0] following power-on reset
• Provides Nexus support for censorship mode
34-2
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor