14.1.2. The debug environment

A software debugger provides the user interface to the ETM. The debugger enables all the ETM facilities such as the trace port to be configured. The debugger also displays the trace information that has been captured.

The ETM compresses the trace information and outputs it to the AMBA 3 ATB interface. The ETM can then either:

When the trace is captured, the debugger extracts the information from the TPA and decompresses it to provide a full disassembly, with symbols, of the code that was executed. The debugger can also link this back to the original high-level source code, to provide you with a visualization of how the code was executed on the target system.

Figure 14.1 shows how the ETM fits into the CoreSight debug environment. See the CoreSight Architecture Specification for more information.

Figure 14.1. Example CoreSight debug environment

In Figure 14.1, the ETM and the Cross Trigger Interface, are part of a CoreSight system consisting of other cores with their own ETMs, and various other trace sources. The CoreSight components are programmed using the Debug Access Port (DAP) through the APB programming bus, and trace is output over the ATB trace bus. This is then either exported through the Trace Port Interface Unit (TPIU), or stored in the ETB.

See the Embedded Trace Macrocell Architecture Specification for information about the trace protocol, and about controlling tracing using triggering and filtering resources.

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