msp430单片机产生两类声音频率信号，根据实际每类信号的单个周期内包含两种不同频率的方波信号。并且可以通过机械按键切换两类音频信号。(The MSP430 singlechip produces two kinds of sound frequency signals, including two square wave signals of different frequencies in a single period of each class of signals.)