Traffic Light Project - Coursework Example

This report covers discussions on the design of three types of traffic light controllers for a simple North/ South and East/ West road crossing.  The first two are basic traffic light controllers with slightly different light red, amber and green light sequences.  For these two types of controller, Johnson decade counters (IC 4017) are used in conjunction with astable multivibrators using timers (IC 555).  Diodes and logic gates are connected at the output of the counter to come up with the required patterns and durations of the light sequences.

  The third type of traffic light controller is for Ambulance Safe Pass Traffic Lights to allow safe passage of ambulances in both North/ South and East/ West directions.  For this type of traffic light controller, a FAB intelligent micro controller unit is used to program the desired traffic light sequence that includes the ambulance safe pass sequence. The building blocks inside Johnson decade counters, astable multi-vibrator timers and the FAB micro controller such as logic circuits, flip flops, Karnaugh maps, truth tables and Boolean expressions are also presented in the Appendix section of the report.

Traffic lights are an essential part of modern life, especially with the increasing number of vehicles that coincides with the increasing number of population.  Traffic lights not only regulate traffic flow in the streets but more importantly prevent the occurrence of vehicular accidents.  Roads without traffic lights are unimaginable.  The traffic light controller is a sequential device that needs to be designed and programmed through multiple step procedures.  A proper traffic light requires accurate timing, correct cycling through the states, and responds to outside outputs such as walk signals or ambulance safe passage.

The objective of this report is to design and implement traffic light controllers for a simple North/ South and East/ West road crossing as shown in figure below.  Three types will be presented and all three will be built and tested to simulate actual traffic lights.  The design procedures will be discussed, which involve finding out the number of states required for a given traffic light sequence and coming out with the simplest design with the minimum number of electronic components.