可以通过STM32的AD采集测出正弦波的频率，并在液晶屏上显示出来。（原子的mini板可直接用）-AD can gather through the STM32 measured sine wave frequency, and displayed on the LCD screen. (Atoms mini board can be directly used)

STM32的程序，是在正点原子的mini开发板基础上自己编写的程序，包括超声波测距，PWM波输出，同时进行3路AD采集的程序，对想要学习stm32的同学非常有用-STM32 procedures in mini development board based on punctuality atoms have written procedures, including ultrasonic distance measurement, PWM wave output, simultaneous 3