9.8. Triggers

A trigger event is defined as when the Trigger Counter reaches zero, or when the trigger counter is zero, when TRIGIN is HIGH. All trigger indication conditions, TrigEvt, TrigFl, and TrigIn, in the Formatter and Flush Control Register can be enabled simultaneously. This results in multiple triggers appearing in the trace stream.

The trigger counter register controls how many words are written into the Trace RAM after a trigger event. After the formatter is flushed in normal or continuous mode a complete empty frame is generated. This is a data overhead of seven extra words in the worst case. The trigger counter defines the number of 32-bit words remaining to be stored in the ETB Trace RAM. If the formatter is in bypass mode, a maximum of two additional words are stored for the trace capture post-amble. See Formatter and Flush Control Register, 0x304.

Figure 9.18 shows a flowchart defining the conditions for indicating a trigger in the formatted data. This flowchart only applies for the condition when continuous formatting is enabled (EnFCont HIGH) in the Formatter and Flush Control Register.

Figure 9.18. Generation of a trigger request with continuous formatting enabled


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