CS 4330/6310
ASSIGNMENT 4 - STATE CHARTS

Pretend that you are a systems analyst for a company that wants to develop and market a garage door opening device. You have identified a potential customer and gathered some requirements.

1. The system should be composed of three devices: a remote control device, a stationary control device, and a mounted motor.
2. The remote control device consists of an activator button and a light. The light goes on when the button is pushed and goes off when the button is released. The remote control device sends a signal to the motor.
3. The motor works in two directions, pulling the door up or pushing it down. It is turned on and off by either of the control devices. If the motor is currently inactive and it receives an activation event notification, it will move in the opposite direction from the last previous motion. Also, if either control device button is pressed while the motor is running in a upward direction, the motor is immediately turned off. However, as a safety precaution, if the motor is running downward and either button is pressed, the motor stops and then immediately starts again, going in the upward direction. The motor is automatically turned off when the door reaches its fully open or fully closed position.
4. Housed with the motor is a work light. Each time the motor is activated, the light comes on and stays on for at least five minutes. It then turns off unless overridden as indicated by requirement 5c. If the motor is re-activated within the five minute period, the five minute time period is reset.
5. The stationary device consists of three button-light pairs. These lights are small telltales indicating system state.

1. One button and light combination works identically with the button and light on the remote control device.
2. Another button enables and disables the remote control device. That is, it acts as a toggle, alternatively enabling and disabling the remote control device. If the remote is deactivated, this button's light is on; otherwise it is off. This is intended as a security feature for disabling remote access.
   
3. The third button-light pair controls the work light on the motor. There are four possibilities, depending on whether the motor has run in the last five minutes or not and whether the button has been pushed an odd or even number of times:

Work Light Behavior

Run within the last five minutes	Pushed an odd or even number of times	Behavior
Yes	Even	Light stays on until time expires
Yes	Odd	Light stays on until the button is re-pressed
No	Even	Light is turned off
No	Odd	Light stays on until the button is re-pressed

The button itself has a small telltale light. This light comes on when the button is first pressed. It goes off the next time the button is pressed. It continues to alternate with each button press.
 
6. You should assume that the door is initially closed, the motor is off, the light is off, the remote is enabled, and the motor has not been run in the last five minutes.

Your assignment is to model the external behavior of this system. Use a UML State Chart to express the model.  Use a drawing tool to prepare your diagram. Turn in the diagram that you generated. You may work in pairs for this problem.