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What causes the TPIU to generate "trigger packet"

Applies to: TPIU

Answer

A trigger signal coming into the TPIU, or a flush completion will cause the TPIU to generate a "trigger" output. The TPIU TRM also defines a "trigger packet" (tracedata[1:0] = 2'b00, tracectl=1).

The complication with the "trigger packet" output is that it requires a precise alignment of data on the Trace Port which is impossible when it is in a CoreSight world because the data output is independent of the data generation (for example, you may not even be running with a Trace Port that is a multiple of 8 bits wide!).

So the TPIU will only output:

If your ETM (or other source) generates a trigger packet which is received by the TPIU, it is treated as raw data - the TPIU will not change this trigger packet into its own trigger packet type.

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