Aim

This assignment is designed to apply your knowledge on microcontroller to build a traffic light system. You are asked to solve problems related to software programming, hardware connection scheme, timing diagrams, system testing and evaluation of the whole design.

Mini-Traffic Lights for T-Junction

Your task is to build traffic lights for a T-junction (Fig. 1(a)). The traffic lights you will design are going to be evaluated against the task of controlling the normal flow of cars as well as giving due permission to pedestrians who are waiting to cross the road.

For this proof-of-concept design, use LEDs (red, amber, green) to represent the red, amber and green traffic lights.

Main functions of the system are described as follows:

When there is no pedestrian:

1) Cars coming from any direction have the same priority levels;

2) When a green light is given to a car, the car can go to any other directions of the T-junction except making a U-turn;

3) The maximum waiting time for any front car is 1 minute;

4) Once lighted, the duration time for the green light is 10 seconds;

5) Change the lighting from red to amber smoothly and vice versa;

6) Change the lighting from amber to green smoothly and vice versa;

7) Green and red lights shall not be on at the same time;

8) Avoid crashes;

9) The red lights for pedestrians shall be on;

When there are pedestrians:

1) Pedestrians might press the button on the puffin crossing (Fig. 1(c)) to indicate that they wish to cross the road;

2) When button pressed, turn on one amber LED on the puffin crossing immediately to indicate the acceptance of the pedestrian's request;

3) If possible, switch on the green light on the puffin crossing to give pedestrians permission to cross the road;

4) Once lighted, the duration time for the green light is 5 seconds;

5) When a green light is on, switch on the buzzer; when the green light is off, switch off the buzzer;

6) For safety reasons, when pedestrians are crossing the road, there shall be no car-traffic.

To start the design, one route is to decompose the project into several steps:

1) Design one RAG (red/amber/green) unit (cars only);

2) Design one puffin crossing unit (pedestrians only) ;

3) Combine one RAG unit and one puffin crossing unit;

4) Build the whole system with 3 RAG units and three puffin crossing units.

To work on this project, one needs a STM32 development board, bread-boards, LEDs, resistors and many jump wires. All materials can be obtained from the store of the school, including video cameras to film your brief demonstration.

You can work on this project by yourself, or you can team up with another student of this module. But you can only have one team and every team can only have 2 members, i.e., you can't have a team with 3 members or more. For every team, there is one team-leader and one member.

If you decide to build a team to work on this mini-project, be careful in selecting your team member. Because you both have to sign an agreement contract (attached) and you two will get the same marks for this assignment, including the main report and the lab demonstration/test.