蜂鸣器发声功能。本实验用蜂鸣器播放音乐，“小星星”。为了了解实验的原理，首先介绍了音乐的基本知识，每个音的音乐都有其固定的音高，音乐符号由7个基本辊组成。-The buzzer sound function. This experiment used the buzzer to play music, little star . In order to understand the principle of the experiment, first introduces the basics