Figure 50. Swo Pin Configuration With Stm32Cubemx - STMicroelectronics STM32 Application Note

Printf debugging
It has to be used in combination with a Serial Wire Viewer (SWV) on host side which
provides the following features:
•
PC (Program Counter) sampling
•
Event counters that show CPU cycle statistics
•
Exception and Interrupt execution with timing statistics
•
Trace data - data reads and writes used for timing analysis
•
ITM trace information used for simple printf-style debugging
This chapter only addresses the printf-style debugging feature.
In order host debugger can manage flexible pin assignment ensure SWO pin is not used for
other purpose.
In STM32CubeMX:
Select "Trace Asynchronous Sw" in SYS -> Debug selection box as shown in
This secures that the PB3 is not allocated to another use. No specific code is generated.
Other init steps are performed by the SWV integrated in the IDE or in the ST-LINK utility.
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Figure 50. SWO Pin configuration with STM32CubeMX

AN4989 Rev 3
AN4989
Figure 50.