2.11.4. Consequences of parallel execution on the sequencer

If the sequencer receives multiple transition requests in the same cycle, no transitions take place and the sequencer remains in the original state. The ETM might have multiple transition requests in a cycle where instructions are executed in parallel. You must be aware of this behavior when programming the sequencer. There is a work-around for simple events, as Example 2.3 shows.

Example 2.3. Programming for parallel events

Consider the following transitions:

  • transition from state 1 to state 2 based on event A

  • transition from state 2 to state 3 based on event B.

To effect these transitions where A and B can occur in the same cycle, you must program the sequencer as follows:

  • Program the transition from state 1 to state 2 (register 0x060) to occur on event (A & !B).

  • Program the transition from state 2 to state 3 (register 0x062) to occur on event B.

  • Program the transition from state 1 to state 3 (register 0x065) to occur on event (A & B).

Programming the ETM sequencer in this way ensures the correct handling of simultaneous occurrences of event A and event B.


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