7.10.2. NonPeriodic synchronization
When the Programming bit is cleared or the OS Lock is cleared,
the ETM must generate the A-sync and I-sync packets before generating
any other trace. It does this by performing the following sequence:
The ETM first generates an A-sync packet.
Next the ETM generates a nonperiodic I-sync packet.
This is generated when trace is turned on, unless a trigger occurs
before trace is turned on.
If data tracing is enabled, the ETM generates a
D-Sync packet on the next data packet.
In ETMv3.5, if Timestamping is enabled, a T-Sync packet must
be generated after stage 2. The T-Sync packet might not be output
immediately after the I-Sync packet.
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