The intelligent traffic light controller this paper
provides can be applied both in common intersections and multiple branches intersections. It needs to design external
input pins on the controller in order to realize the aim of
adjusting multi-phase based on actual traffic flow. 2-phase,
3-phase and 4-phase play important roles in practical
traffic control, therefore, this system provides their
operation modes as shown in Figure 1.
Both master and slave branches have green, red,
yellow and left-hand turn lights. When it comes to 2-phase
operation mode, green, red and yellow lights work both on
master and slave branches. In 3-phase operation mode,
green, red, yellow and left-hand turn lights work on master
branch, but only green, red and yellow lights work in slave
branch. In 4-phase operation mode, all the lights work in
master and slave branches. The durations of all kinds of
lights are variable, the specific times are set by external
input pins. Both master and slave branches have the LEDs
to display the countdown of running light. This controller
has reset and hold input signals. When the reset signal is
valid, all lights extinguish and all the LEDs show noting
both in master and slave branches. Meanwhile, the
controller receives the settings of running time and phase
number. When the reset signal is invalid, the controller
began to run with the new settings. When the hold signal is
effective, all the LEDs remain unchanged and all the red
lights work both on master and slave branches. When the
hold signal is ineffective, the controller continue to run
with former state.