乐曲硬件演奏电路设计 功能要求：仿照课本P263的实验9-1，设计一乐曲演奏电路，演奏的曲目不限，但起码要有两首歌曲，演奏的歌曲分手动选择和自动循环两种模式。-Playing music hardware circuit design functional requirements: P263 experiment along the lines of books 9-1, the circuit design of a music concert, repertoire limitati