鉴于单片机芯片的智能处理功能，本设计采用理论和实验验证相结合的方法，采用以单片机STC89C52芯片为核心的主体电路。各单位电路进行设计并选择合适的元器件。在选择元器件时，要注意所选芯片的性价比。在设计整个电路时需要对各个单元电路进行相应功能的调试仿真。本次设计的研究内容是设计一个基于单片机控制的由测距、感光、定时和测量温度四大功能于一体的多功能视力保护器（可实现实时时钟显示）。它具有以下功能：

1.当使用者脸部距离写字台低于35cm时，“距离”灯闪亮，同时有报警声提醒使用者及时调整座姿。采用超声波反射自检方式测距离。
2．学习环境光线自动检测。当光线照度低于国家教委规定的100lx时，“光线灯”闪亮，同时发出报警声，提醒使用者打开台灯或暂停工作。
3．学习时间自动检测。当学习时间达到45分钟时（可自己设定具体时间），“定时灯”闪亮，提醒使用者休息片刻。
4．正常情况下实时时钟和温度显示（可显示年月日）(In view of the intelligent processing function of MCU chip, the design adopts the method of combining theory with experiment verification, and takes the main circuit of STC89C52 chip as the core. The units of each unit are designed and selected for the appropriate components. When selecting components, pay attention to the cost performance of the selected chip. In the design of the whole circuit, it is necessary to debug and simulate the corresponding functions of each unit circuit. The research content of this design is to design a multifunctional vision protector based on single chip microcomputer, which is composed of four functions of ranging, sensitivity, timing and temperature measurement, which can realize real-time clock display.)