I purchased a brand new EFM8 kit and I haven't made any hardware changes to it. The Debug Mode of the Kit Manager is stuck on "Off" and cannot be changed to "MCU". What is happening here?


During startup, the kit bootloader checks if both push-buttons are pressed, in which case it halts before starting the application. The device should normally be held in reset during this check, but a firmware bug let the target application run during the check. This affects all EFM8 STKs.


The target application programmed on these devices pulls both push-button lines low, which causes the check above to halt during startup.


Possible workarounds include:

  • Hold the reset button pressed while powering on the kit
  • Switch off target power (set the power switch to "BAT") during startup
  • Modify the target application to not pull both push-button lines (P0.2 and P0.3) low early in the program execution

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