9.2. ITM functional description
The ITM generates trace information as packets. Multiple sources can
generate packets. If multiple sources generate packets at the same
time, the ITM arbitrates the order in which packets are output.
These sources in decreasing order of priority are:
Software trace. Software
can write directly to ITM stimulus registers to generate packets.
Hardware trace. The DWT generates these packets,
and the ITM outputs them.
Time stamping. Timestamps are generated relative
to packets. The ITM contains a 21-bit counter to generate the timestamp.
The Cortex-M3 clock or the bitclock rate of the Serial Wire
Viewer (SWV) output clocks the counter.
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