[vlovich123]

I’ve worked with many M3s and M4s and some Cypress microchips and the JTAG debuggers always worked fine as far as I recall. There were some vendors that liked to force you to buy really expensive ancillary HW but a) there was plenty of OSS that worked fairly well b) you could pick which vendor you went with.

[bsder]

All of those chips you mentioned will turn on all the units at full power when you connect a debugger to them.

And the OSS stuff never works correctly. I wind up debugging the OSS stuff more than my own hardware. And I've used a LOT of OSS (to the point that I wrote software to use a Beaglebone as my SWD debugger to work around all the idiocies--both commercial and OSS).