Additional Exercise
Your task is to design a control unit for a set of traffic lights. The entire set is built of two
traffic lights which signals can be controlled independently over the controlling signal r1 ,
y1, g1 and r2, y2, g2.
r1
r2
y1
y2
g1
g2
Traffic lights #1
Traffic lights #2
The individual signals will be switched on and off according to a dual-counter that works
as a clock generator here.
The counter is represented by the variables x3,... , x0. (Binary)
At the time 0 the counter is set to 0 and traffic light #1 is red, traffic light #2 is green.
The red/ green phase lasts 6 clock pulses. Red and Yellow are on together for 1clock
pulse. Yellow alone for another 1 clock pulse.
a) Please construct a truth table for that traffic light control unit.
b) Find the minimal distributive form for r1, using a KV diagram.
a)
Truth table of the set of traffic lights
b)
1
1
1
1
1
1
1
1
0
0
1
0
0
0
0
0
r1 = x3Úx0 x1 x2