stm32 f0 discovery kit gpio without librarry

这是一个基于stm32处理器，用于测量扬声器F0值的程序，没有外部设备，靠芯片内部AD采样，程序仅供参考-This is based on stm32 processor, used to measure the value of F0 speaker program, no external equipment, by AD chip sampling program is only a test