4.5.2. Linking with an ECT

The ECT is the structure that enables the correlation of triggers from the various parts of the SoC. It is composed of one or more CTIs that act as the primary matrix between the trigger inputs and outputs and the channel structure that propagates activity to other areas of the SoC.

When you require more than two CTIs, you can link them with CTMs that permit safe linking of channels to and from CTIs.

The CTI and CTM enable you to:

Exporting a channel interface out of your subsystem provides a standard interface for more system-wide communication of debug events.

Tools can identify the programmable interfaces of the CTIs and then flexibly alter the connections of trigger sources and destinations over the various channels to adapt the propagated activity for the required purpose. You can isolate individual CTIs to stop the transmission of activity over the CTM to other CTIs.

Each CTI provides a set number of trigger inputs and outputs on the following styles of sampling:

You can use these sampling schemes to convert to and from other styles of trigger signals, for example:

Conditioned

Keeps the output active for one clock cycle after an acknowledgement is received.

Level/pulse

Used when the trigger destination is level sensitive, the signal is active for only one clock cycle.

Sticky

Keeps the output active until a corresponding clear register clears it.

NoAck

Used when the output follows the input trigger and does not require an acknowledgement.

Software programmable

Used by the application to trigger events under software control. This enables a debugger to force an event using the configuration registers.

Note

Because the ECT safely crosses asynchronous clock domains, it is possible for multi-shot events that occur close to each other to be masked within the cross-trigger structure and only result in a single pulse on a trigger output. You must only use the ECT with single shot events, or multi-shot where safe, where time delay characteristics are not important.

Copyright © 2004, 2007, 2010 ARM Limited. All rights reserved.ARM DGI 0012D
Non-ConfidentialID062610