8.10 FUSE - Configuration and User Fuses

Fuses are part of the nonvolatile memory and store the device configuration. The fuses can be read by both the CPU and UPDI, but only UPDI can program or clear them. The configuration values stored in the fuses are written to their respective 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. Modified values in the configuration fuses will take effect only after a Reset.

The fuses are not affected by a chip erase.

Note: When writing the fuses, all reserved bits must be written to ‘0’.