“This project introduces ATmega328P fuse bits and shows how to set them to use an external 16 MHz crystal oscillator. Fuse bits, also known as fuses or configuration bits, are settings made in microcontrollers to control certain operations that are not normally changed during the execution of the program code. This article will explain what these operations are in the ATmega328P, and how to set them in general. The fuse bits for selecting the clock source will be dealt with in more depth, including the how and why of a 16 MHz external crystal oscillator.”