说明：  通过atmega128实现简单的追光系统，通过自带adc模块并用差分输入模式检测光敏电阻的电压差来向步进电机发出对应信号，实现追光功能。
(Through ATmega128, a simple light tracing system is realized. By using ADC module and differential input mode to detect the voltage difference of photoresist, the corresponding signal is sent to the stepping motor to realize the light tracing function.)