用ARM7系列芯片LPC2138作为系统的主控芯片，控制交通灯的循环点亮并显示灯亮时间（采用倒计时显示），当定时时间到的时候控制蜂鸣器响来提醒人们注意红绿灯的状态。-ARM7 series chip LPC2138 as the main chip of the system, the light cycle of the control of traffic lights and display lights in time (the countdown display), when the