7.2. Enabling and disabling the ETM interface

The ARM7EJ-S processor ETM interface has one input, ETMPWRDOWN, which is used by the ETM to switch the ARM7EJ-S processor ETM interface on and off.

When ETMPWRDOWN is LOW, the ETM interface is enabled and the outputs are driven so that an external ETM can begin code tracing.

When ETMPWRDOWN is driven HIGH, the ETM interface outputs are held at their last value before the interface was disabled.

Note

If an ETM is not used in an embedded ARM7EJ-S processor design then the ETMPWRDOWN input must be tied HIGH to save power.

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