1.6 Fuses

The fuses hold the device configuration and are part of the nonvolatile memory. They are available from device power-up. Their values are maintained through a chip erase. The fuses can be read by the CPU or the programming interface (e.g., UPDI), but can only be programmed or cleared through the program/debug interface. The configuration values stored in the fuses are copied to their respective target registers at the end of the start-up sequence so that the fuse values can be used by the CPU.

The Fuse Summary table can be found in the Memories → Fuses (FUSE) subsection from the device data sheet. An example extracted from the ATmega4808/4809 data sheet is presented below.

Figure 1-7. FUSE Register Summary

A code example is provided in Configuring Fuses.