EE 316 Computer Engineering Junior Lab Project 1: Traffic Light Controller

The traffic Light Controller

Specifications EW street is heavily traveled NW street is lightly traveled Pedestrian can halt traffic for crossing but not create traffic jam EW, NS and Pedestrian traffic signals have at least Green and Red lights Each green light is on for 5, 9 and 4 secs, respectively

Remember! The design cycle involves:  Careful planning  Learning  Setting specific goals  Designing  Building  Testing and  Troubleshooting

Design Methodology Study the details in the Specification (read between lines). Partition the design problem into smaller sub-components or parts. Create specifications for each part and their interactions with others. Design and build each of the basic components/parts and test them thoroughly before attempting to combine with or connect to other sub- components. Predict what to expect at each step and decide how would you test your hypothesis with measurements.

Design Methodology (contd.) Test the circuit and verify if your design worked as expected Troubleshoot your circuit if design does not work. Pay attention to power/ground lines, interfaces/ports (pin diagram and wires), fanout, drive currents (TTL vs. CMOS), bad connections, wrong delays etc. Modify the design if needs and repeat the steps. Write every step in the Notebook (legible documentation please). Draw circuit diagrams, pin diagrams chips, test and measurement results, troubleshooting, and design changes etc.

A partial list of subcomponents A state machine (sequential circuit) Counter/timer Clock generator circuit 7-segment displays LEDs to be used as traffic signals Debounced switches

The state machine and the controller State diagram/table and outputs State assignment and K-maps A timer/counter to be used as a controller to trigger transition from one state to the other depending on the inputs

Counter/Timer and clock generation circuit Identify a TTL or CMOS based 7400 series chip that would be appropriate for this project Study the data sheet carefully before using any chip Verify the clock frequency with an oscilloscope. Use the digital logic analyzer to verify design

7-Segment Displays and LEDs You will need appropriate Drivers for the two kinds Of displays. Also, remember LEDs/displays can be destroyed very easily. Use resistors to limit current

More details All switches need to be debounced. You can destroy switches too. Use resistors. Add bypass capacitors between VDD and GND if you cannot explain state skips or strange behaviors.

Project Reports Each project writer is to submit a project report containing: Problem description An executive summary Design objectives Significant details of design process Alternative designs Schematics documenting your hardware design HDL and test bench files (for future reports) Software design, i.e. flowchart or pseudocode Performance Results References