12.1.3. Multiple source arbitration

The ITM block outputs trace from two sources, SWIT and timestamp. When multiple sources are trying to emit data, arbitration is performed as shown in Table 12.3. As seen in Overflow packet, overflow is caused by SWIT or timestamp and precedes the source. The synchronization packet has the highest priority and is emitted by the timestamp packet when the synchronization counter reaches zero.

Table 12.3. ITM packet priority levels

PacketPriority
Synchronization Priority level 0, highest priority
Overflow Priority level 1
SWIT Priority level 2
Timestamp Priority level 3, lowest priority

Note

SWIT has a higher priority than timestamp to ensure that SWIT output is always available and that timestamps are emitted after a run.

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