Hi Stabsauger,
SW1 is the TARGET RESET AND BOOTLOADER PUSH BUTTON. If you didn't press it and OpenSDA is always in Bootloader-Mode, then the low voltage signal is from RESET_b pin of KE04.


If you don't have an external debugger, I'm afraid you'll need to modify the circuit.
for example:
Remove R35 and use J5 to isolate the low voltage to avoid putting OpenSDA into Bootloader-Mode when powered through J6.
Or remove R11, R12, and make KE04 get power later than OpenSDA through J9.

Best Regards,
Robin
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