可以对所给正弦信号进行采样，并判断过零点且输出频率和正弦信号一样的方波信号。用ePWM模块来确定采样频率，来一次中断采样一次，确保采样率。并对所采样的数据进行有效值计算(The given sinusoidal signal can be sampled and the zero-crossing point can be determined and the square wave signal with the same frequency as the sinusoidal signal