Enabling The Etm Interface - ARM ARM966E-S Technical Reference Manual

9.2

Enabling the ETM interface

ARM DDI 0186A
The ETM interface on the ARM966E-S is enabled by the top-level pin ETMEN. When
this input is HIGH, the ETM interface is enabled and the outputs are driven so that an
external ETM can begin code tracing.
When the ETMEN input is driven LOW, the ETM interface outputs are held at their last
value before the interface was disabled. At reset, all ETM interface outputs are reset
LOW.
The ETMEN input is usually driven by the ETM, and driven HIGH once the ETM is
programmed using its TAP controller.
Note
If an ETM is not used in an embedded ARM966E-S design, the ETMEN input must be
tied LOW to save power.
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Embedded Trace Macrocell Interface
9-3