SWV is not selectable because Cortex-M0 and Cortex-M0+ do not contain SWV, as can be read in e.g. KAN-297 from ARM:
Serial Wire Viewer (SWV) is a data trace feature found on many ARM Cortex-M3, M4, M7, M23, and M33 processors. Cortex-M0 and Cortex-M0+ do not have SWV.
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Regards /Peter
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Perhaps an alternative is to write the code for some MCU that has advanced debugging support, and then when it's functional, port the code to the MCU that doesn't have advanced debugging support.
+1 Yes using a proxy would be a possible path. If the problem is more nuanced that might be more difficult. The CM0(+) is distinctly more fussy about memory alignments, and instructions.
Having a good Hard Fault Handler, with diagnostic register, stack and opcode output can be very helpful for both lab and field debugging of issues via a serial terminal.
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