9.1. About the ETM interface

The full ARM968E-S debug implementation supports the connection of an external Embedded Trace Module (ETM) to provide real time code tracing of the processor in an embedded system. See the ETM9 Technical Reference Manual for more information.

The ETM interface is primarily one way. To provide code tracing, the ETM block must be able to monitor various ARM9E-S inputs and outputs. The ETM interface drives the required ARM9E-S inputs and outputs out from the processor through the ETM interface registers, as Figure 9.1 shows.

Figure 9.1. ETM interface

The pipelined outputs of the ETM interface provide early output timing and isolate any ETM input load from the critical processor signals. Because all outputs have the same delay, the latency of the pipelined outputs does not affect ETM trace behavior.

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