Datasheet

673
32133D–11/2011
UC3D
Figure 31-4. AUX+JTAG Based Debugger
31.3.8.1 Trace Operation
Trace features are enabled by writing OCD registers by the debugger. The OCD extracts the
trace information from the CPU, compresses this information and formats it into variable-length
messages according to the Nexus standard. The messages are buffered in a 16-frame transmit
queue, and are output on the AUX port one frame at a time.
The trace features can be configured to be very selective, to reduce the bandwidth on the AUX
port. In case the transmit queue overflows, error messages are produced to indicate loss of
data. The transmit queue module can optionally be configured to halt the CPU when an overflow
occurs, to prevent the loss of messages, at the expense of longer run-time for the program.
31.3.8.2 Program Trace
Program trace allows the debugger to continuously monitor the program execution in the CPU.
Program trace messages are generated for every branch in the program, and contains com-
pressed information, which allows the debugger to correlate the message with the source code
to identify the branch instruction and target address.
31.3.8.3 Data Trace
Data trace outputs a message every time a specific location is read or written. The message
contains information about the type (read/write) and size of the access, as well as the address
and data of the accessed location. The UC3D contains two data trace channels, each of which
AVR32
AUX+JTAG
debug tool
JTAG
AUX
high speed
Mictor38
Trace buffer
PC