7.9 FUSE - Configuration and User Fuses

Fuses are part of the nonvolatile memory and hold factory calibration and device configuration. Both CPU and UPDI can read fuses, but they can only be programmed or cleared by the UPDI. The fuses are not affected by chip erase. The configuration values stored in the fuses are written to their target registers at the end of the start-up sequence.

The fuses for peripheral configuration (FUSE) are preprogrammed, but the user can alter them. Altered values in the configuration fuse will be applicable only after a Reset.

Note: All reserved bits must be written to ‘0’ when writing the fuses.