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23.1 Features
23.2 Applications
As the microcontroller has significant amounts of on-chip memories, it is not possible to
determine how the processor core is operating simply by observing the external pins. The
ETM provides real-time trace capability for deeply embedded processor cores. It outputs
information about processor execution to a trace port. A software debugger allows
configuration of the ETM using a JTAG interface and displays the trace information that
has been captured, in a format that a user can easily understand.
23.3 Description
The ETM is connected directly to the ARM core and not to the main AMBA system bus. It
compresses the trace information and exports it through a narrow trace port. An external
Trace Port Analyzer captures the trace information under software debugger control. Trace
port can broadcast the Instruction trace information. Instruction trace (or PC trace) shows
the flow of execution of the processor and provides a list of all the instructions that were
executed. Instruction trace is significantly compressed by only broadcasting branch
addresses as well as a set of status signals that indicate the pipeline status on a cycle by
cycle basis. Trace information generation can be controlled by selecting the trigger
resource. Trigger resources include address comparators, counters and sequencers.
Since trace information is compressed the software debugger requires a static image of
the code being executed. Self-modifying code can not be traced because of this
restriction.
23.3.1 ETM configuration
The following standard configuration is selected for the ETM macrocell.
Table 317: ETM configuration
Resource number/type
Pairs of address comparators
Data Comparators
Memory Map Decoders
Counters
Sequencer Present
User manual
UM10139
Chapter 23: Embedded Trace Macrocell (ETM)
Rev. 01 — 15 August 2005
•
Closely track the instructions that the ARM core is executing.
•
1 External trigger input
•
10 pin interface
•
All registers are programmed through JTAG interface.
•
Does not consume power when trace is not being used.
•
THUMB instruction set support
Rev. 01 — 15 August 2005
User manual
[1]
Small
1
0 (Data tracing is not supported)
4
1
No
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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