ETB

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The Embedded Trace Buffer (ETB) is a small, circular on-chip memory area where trace information is stored during capture. It contains the data which is normally exported via trace pins, immediately after it has been captured from the ETM. The buffer can be read out through regular debug interface device once capture has been completed. No additional special trace port is required, so that the ETB can be read via a normal J-Link. The trace functionality via J-Link is limited by the size of the ETB. While capturing runs, the trace information in the buffer will be overwritten every time the buffer size has been reached. The result of the limited buffer size is that not more data can be traced than the buffer can hold. Because of this limitation, an ETB is not a fully alternative to the direct access to an ETM via J-Trace.