很好用 因为本设计是交通灯的控制，所以要先了解实际交通灯的变化规律。假设一个十字路口为东西南北走向。初始状态0为东西红灯，南北红灯。然后转状态1南北绿灯通车，东西红灯。过一段时间转状态2，南北绿灯闪几次转亮黄灯，延时几秒，东西仍然红灯。再转状态3，东西绿灯通车，南北红灯。过一段时间转状态4，东西绿灯闪几次转亮黄灯，延时几秒，南北依然红灯。最后循环至状态1。 2. 双色LED是由一个红色LED管芯和一个绿色管芯封装在一起，公用负端。当红色正端加高电平，绿色正端加低电平，红灯亮；红色正端加低电平，绿色正端加高电平，绿灯亮；两端都加高电平，黄灯亮。 急救车和交通灯： 中断服务程序的关键是：1. 保护进入中断时的状态-is useful because the design is the control of traffic lights, first understand the traffic lights change. Assuming a crossroads for the east-west north-south. Initial state of things 0 red light, red light north-south. Then the state opening of a north-south green, red things. For a period of time to state 2-green flashing yellow light switch several times, a few seconds delay, things are still red. Three sub-state, opening things green, red light north-south. For a period of time to state four, several things turn green blinking yellow light, a few seconds delay, the North and the South is still red. The last cycle to a state. 2. Two-color LED is a red LED tube core and a core package of green together, the common negative side. When the red is added to I-Greenpeace-Canada is low-level,