十字路口车辆穿梭，行人熙攘，车行车道，人行人道，有条不紊。那么靠什么来实现这井然秩序呢？靠的是交通信号灯的自动指挥系统。交通信号灯控制方式很多。本设计主要分为五大模块输入控制电路、时钟控制电路、片内外程序切换控制、显示电路。以MSC-51系列单片机IntelAT89C51为中心器件来设计交通灯控制器，实现了AT89C51芯片的P0口设置红、绿灯、黄灯燃亮时间的功能；为了系统稳定可靠采用了74LS14施密特触发器芯片的消抖电路，避免了系统因输入信号抖动产生误操作；显示时间直接通过AT89C51的P2口输出，由CD4511驱动LED数码管显示红灯燃亮时间。(Crossroads shuttle vehicles, pedestrians bustling, car lanes, walkways, everything in good order and well arranged. So what can we do to achieve this orderly order? It depends on the automatic command system of traffic lights. There are many ways to control traffic lights. This design is mainly divided into five modules, input control circuit, clock control circuit, chip internal and external program switching control, display circuit. MSC-51 series microcontroller IntelAT89C51 centric devices to design the traffic light controller, the AT89C51 chip P0 port set of red, green, yellow light to kindle the function of time; the system is stable and reliable with shake eliminating circuit 74LS14 Schmidt trigger chip, avoids the system for input signal jitter generation misoperation; direct display time AT89C51 through the P2 port output, driven by CD4511 LED digital tube display lights burning time.)