Nexus Development Interface (NDI)
Freescale Semiconductor
31-5
PXR40 Microcontroller Reference Manual, Rev. 1
31.1.3.1
Nexus Reset Mode
In Nexus reset mode, the following actions occur:
•
Register values default back to their reset values.
•
The message queues are marked as empty.
•
The auxiliary output port pins are negated if the NDI controls the pads.
•
The TDO output buffer is disabled if the NDI has control of the TAP.
•
The TDI, TMS, and TCK inputs are ignored.
•
The NDI block indicates to the MCU that it is not using the auxiliary output port. This indication
can be used to three-state the output pins or use them for another function.
31.1.3.2
Full-Port Mode
In full-port mode, all the available MDO pins are used to transmit messages. All trace features are enabled
or can be enabled by writing the configuration registers via the JTAG port. The number of MDO pins
available is 16.
31.1.3.3
Reduced-Port Mode
In reduced-port mode, a subset of the available MDO pins are used to transmit messages. All trace features
are enabled or can be enabled by writing the configuration registers via the JTAG port. The number of
MDO pins available is 12. Unused MDO pins can be used as GPIO. Details on GPIO functionality
configuration can be found in
Section 7.3.1.13, Pad Configuration Registers (SIU_PCR)
31.1.3.4
Disabled-Port Mode
In disabled-port mode, message transmission is disabled. Any debug feature that generates messages can
not be used. The primary features available are class 1 features and read/write access.
31.1.3.5
Censored Mode
When the device is in censored mode, reading the contents of internal flash externally is not allowed. To
prevent Nexus modules from violating censorship, the NPC is held in reset when in censored mode,
asynchronously holding all other Nexus modules in reset as well. This prevents Nexus read/write to
memory mapped resources and the transmission of Nexus trace messages. See
, for information on Nexus port enabling and disabling regarding censorship.
31.2
External Signal Description
The auxiliary and JTAG pin interfaces provide for the transmission of messages from Nexus modules to
the external development tools and for access to Nexus client registers. The auxiliary/JTAG pin definitions
are outlined in
Summary of Contents for PXR4030
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