Fuse Bytes

Fuse Bytes (AVR® MCU Targets)

When doing drag-and-drop programming, the debugger masks out any fuse bits attempting to disable Unified Program and Debug Interface (UPDI), meaning that the UPDI pin cannot be used in its Reset or GPIO modes; selecting one of the alternative functions on the UPDI pin will render the device inaccessible without using an external debugger capable of high-voltage UPDI activation.