本代码适用于89c51单片机，可以实现将模拟电压转换为数字电压后显示在七段数码管上。可以通过按键设置电压的最低和最高门限。超过门限会有报警信号-The code for 89c51 microcontroller, analog voltage can be converted to a digital voltage display on the seven segment. Button to set the voltage by the minimum and maximum thresh