The purpose of this module is to illustrate the concept of a finite state machine and its application in the field of digital design. The example being investigated is the design of a pedestrian crossing controller unit. The pedestrian crossing consists of a traffic light and a pedestrian light. When a pedestrian wants to cross, he or she pushes a button and the lights change accordingly. This unit has one input signal: WALKREQUEST (W), which corresponds to a pedestrian pushing the walk button; and five outputs: Red, Yellow, Green, Walk and Don’t Walk.
In the following FSM simulation, the active state is indicated by a shaded circle. Press the "Walk" button and see what happens to the output as the machine changes states.
Begin FSM simulation (Web demo)