Nexus Development Interface (NDI)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 36-83
2. The second pass through the DR then shifts the data in or out of the JTAG port, LSB first.
a) During a read access, data is latched from the selected Nexus register when the JTAG state
machine passes through the CAPTURE-DR state.
b) During a write access, data is latched into the selected Nexus register when the JTAG state
machine passes through the UPDATE-DR state.
36.7.9 Nexus2+ Functional Description
36.7.9.1 Debug Status Messages
Debug Status Messages
NOTE
Debug Status Messages (DSMs) are enabled if the Nexus module is enabled.
Debug status messages report low power mode and debug status. Entering/exiting debug mode as well as
entering a low power mode triggers a debug status message. Debug status information is sent out in the
following format:
Figure 36-60. Debug Status Message Format
36.7.9.2 Ownership Trace
This section details the ownership trace features of the Nexus2+ module.
36.7.9.2.1 Overview
Ownership trace provides a macroscopic view, such as task flow reconstruction, when debugging software
written in a high level (or object-oriented) language. It offers the highest level of abstraction for tracking
operating system software execution. This is especially useful when the developer is not interested in
debugging at lower levels.
Nexus Register Index: Selected from values in Table 36-48
Read/Write (R/W): 0 Read
1Write
STATUS [31:24]
MSB LSB
12
SRC TCODE (000000)
3
6 bits4 bits8 bits
Fixed length = 18 bits
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