可产生矩形脉冲和正弦信号，矩形脉冲的脉宽可以改变，正弦信号则可以改变频率和时宽-Can produce rectangular pulse and sinusoidal signal, the rectangular pulse width can be changed, sinusoidal signal can be changed when the frequency and width

Display fft. A fast Fourier transform (FFT) is an algorithm to compute the discrete Fourier transform (DFT) and its inverse.