![](http://datasheet.mmic.net.cn/100000/IF180C52TXXX-20R_datasheet_3493957/IF180C52TXXX-20R_719.png)
719
32099I–01/2012
AT32UC3L016/32/64
31.3
On-Chip Debug
Rev: 2.1.0.0
31.3.1
Features
Debug interface in compliance with IEEE-ISTO 5001-2003 (Nexus 2.0) Class 2+
JTAG or aWire access to all on-chip debug functions
Advanced Program, Data, Ownership, and Watchpoint trace supported
NanoTrace aWire- or JTAG-based trace access
Auxiliary port for high-speed trace information
Hardware support for 6 Program and 2 Data breakpoints
Unlimited number of software breakpoints supported
Automatic CRC check of memory regions
31.3.2
Overview
Debugging on the AT32UC3L016/32/64 is facilitated by a powerful On-Chip Debug (OCD) sys-
tem. The user accesses this through an external debug tool which connects to the JTAG or
aWire port and the Auxiliary (AUX) port if implemented. The AUX port is primarily used for trace
functions, and an aWire- or JTAG-based debugger is sufficient for basic debugging.
The debug system is based on the Nexus 2.0 standard, class 2+, which includes:
Basic run-time control
Program breakpoints
Data breakpoints
Program trace
Ownership trace
Data trace
In addition to the mandatory Nexus debug features, the AT32UC3L016/32/64 implements sev-
eral useful OCD features, such as:
Debug Communication Channel between CPU and debugger
Run-time PC monitoring
CRC checking
NanoTrace
Software Quality Assurance (SQA) support
The OCD features are controlled by OCD registers, which can be accessed by the debugger, for
instance when the NEXUS_ACCESS JTAG instruction is loaded. The CPU can also access
OCD registers directly using mtdr/mfdr instructions in any privileged mode. The OCD registers
are implemented based on the recommendations in the Nexus 2.0 standard, and are detailed in
the AVR32UC Technical Reference Manual.
31.3.3
I/O Lines Description
These are multiplexed with I/O Controller lines, and must explicitly be enabled by writing OCD
registers before the debug session starts. The AUX port is mapped to two different locations,