7.10 Configuration and User Fuses (FUSE)

Fuses are part of the nonvolatile memory and hold factory calibration data and device configuration. The fuses are available from device power-up. The fuses can be read by the CPU or the UPDI, but can only be programmed or cleared by the UPDI. The configuration and calibration values stored in the fuses are written to their respective target registers at the end of the start-up sequence.

The content of the Signature Row fuses (SIGROW) is pre-programmed and cannot be altered. SIGROW holds information such as device ID, serial number, and calibration values.

The fuses for peripheral configuration (FUSE) are pre-programmed but can be altered by the user. Altered values in the configuration fuse will be effective only after a Reset.
Note: When writing the fuses write all reserved bits to ‘1’.

This device provides a User Row fuse area (USERROW) that can hold application data. The USERROW can be programmed on a locked device by the UPDI. This can be used for final configuration without having programming or debugging capabilities enabled.