使用STM32的DSP库函数，对AD来的信号进行FFT变换，并显示到LCD屏上。做的是512点fft，显示240个数，且有一定的精度保证。具有很高的实时性。-Use the STM32 DSP library functions, the signal of the AD to the FFT transform, and display to the LCD screen. Do is 512 points fft, show the number 240, and there is a ce
