The custom traffic-light interface

The subject of our main Tcl/Tk lesson is a simple traffic-light controller. The system is comprised of three primary components: a state machine, a pair of traffic lights, and a pair of traffic sensors. The components are described in three VHDL files: traffic.vhd (the state machine), queue.vhd (the traffic arrival queue) and tb_traffic.vhd (the testbench).

You could, of course, simulate this system with ModelSim's familiar interface, but Tcl/Tk provides us the option to try something different. Since we're simulating something most of us have seen and experienced before, we can create an intuitive interface unique to the simulation.

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