
32 CHAPTER 1 Embedded Computing
■ There shall be an inertia control that shall allow the user to adjust the respon-
siveness of the train to commanded changes in speed. Higher inertia means
that the train responds more slowly to a change in the throttle,simulating the
inertia of a large train. The inertia control will provide at least eight dif ferent
levels.
■ There shall be an emergency stop button.
■ An error detection scheme will be used to transmit messages.
We can put the requirements into our chart format:
Name Model train controller
Purpose Control speed of up to eight model trains
Inputs Throttle, inertia setting, emergency stop, train number ...