设计一个由一条主干道和一条支干道的汇合点形成的十字交叉路口的交通灯控制系统，具体要求如下：

(1) 主、支干道各设有一个绿、黄、红指示灯，两个显示数码管。

(2) 主、支道交替允许通行，主干道每次放行60 s，支干道每次放行30 s，在每次由亮绿灯变成亮红灯的转换过程中，要亮5 s的黄灯作为过渡，并进行减计时显示。 -The design of traffic lights one formed by a main road and a branch roads converging points of intersection control system, detailed requirements are as follows:

(1) the main trunk road, each of which is equipped with a green, yellow, red lights, two digital tube display.

(2) the main, branch channels alternately to allow passage, each trunk release 60 s, branch trunk release each 30 s, in each time by the green light into red light in the process of transformation, the yellow light to light 5 s as a transition, and to reduce the time display.