具有固定的“红灯—绿灯”转换间隔，并自动切换。它们一般由“通行与禁止时间控制显示、红黄绿三色信号灯和方向指示灯”三部分组成。在交通灯的通行与禁止时间控制显示中，通常要么东西、南北两方向各50秒；要么根据交通规律，东西方向60秒，南北方向40秒，时间控制都是固定的。交通灯的时间控制显示，以固定时间值预先“固化”在单片机中，每次只是以一定周期交替变化。-having fixed the "red light-green light" switch partitions, and automatic switching. They are generally from "prohibiting access and time control, red-yellow-green lights and direction indicator" is composed of three parts. Traffic lights in the passage of time and prohibit control indicates that things are usually either the north-south direction of the two 50 seconds; either on the basis of traffic laws, an east-west direction 60 seconds, 40 seconds north-south direction, the time control are fixed. Traffic lights to the time control, a pre-fixed time value "cured" in SCM, each is a certain cycle alternation.