8.8 FUSE - Configuration and User Fuses
Fuses are part of the nonvolatile memory and hold factory calibration and device configuration. The fuses can be read by the CPU or the UPDI, but can only be programmed or cleared by the UPDI. 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 can be altered by the user. Altered values in the configuration fuse will be effective only after a Reset.
The fuses are not affected by a Chip erase.
Note: All reserved bits must be written to
‘0’ when writing the fuses.