Design and Simulation of a Traffic Light Controller Using a Microprocessor Training Kit and Programmable Peripheral Interface

A traffic light controller is a classical application for learning microprocessor interfacing. This paper presents the design of a four-way traffic light controller using a microprocessor training kit and a programmable peripheral interface. The program drives the signal lamps through an output port according to a state table with timing generated by software delay routines. The correctness of the sequence and the timing accuracy of the delays are verified by simulation. In simulation the state table produced the correct sequence with no conflicting greens, the software delay error was at most 3 µs per interval, and the worst-case clock drift of a 20 ppm crystal was 1.7 s per 24 h.