5.5.1 ARM Cortex-M4 Processor - Trace and Profiling
For system trace the processor integrates an Instrumentation Trace Macrocell (ITM) alongside data watchpoints and a profiling unit.
To enable simple and cost-effective profiling of the system events these generate, a stream of software-generated messages, data trace, and profiling information is exported over two different ways:
- Output off chip using the TPIU - through a single pin, called Serial Wire Viewer (SWV). Limited to ITM system trace.
- Internally stored in RAM - using the CoreSight ETB. Bandwidth is then optimal but capacity is limited.

SWV trace data are output on the Serial Wire Output (SWO).