首先从主程序开始，接着初始化变量及LCD接口，然后初始化方波发生器、晶振管，使LCD显示信息，进入开机状态。等待动作——选择按键，包括播放键，暂停键，停止键，当然也可以选择返回；如果选择的是播放键，LCD上会显示歌曲编号，与此同时演奏相应的乐曲，此时，你可以按上一曲或下一曲键，使其演奏上一个或下一个乐曲。-First,　the beginning of the main program, then initialize variables and LCD interfaces, and initialize the square-wave generator, crystal tube, the LCD display information into the boot state. Wait action-　buttons, including play button, pause button, stop button, of course, can choose to return　If you choose the play button, the song number will be displayed on the LCD at the same time play the corresponding song, this time, you can press a button or next song to play on the previous or next song.