Design Example: Automobile Lock
The automobile theft rate in Muldavia is so high that CyclesPerSecond rental car agency has decided to add a new security device to their cars. The initial system design has been completed and our consulting firm has been retained to implement the device. The agency designers hand us the following description:
"Please build us a small black box (2"x3"x0.5") we can attach to the dash that consists of a keypad (keys 0-9) and two LEDs, one green and one red. It should perform as follows:
- When the ignition is turned on, the red LED should light up and the keypad is activated. However, the car will not start.
- If the driver enters a correct four-digit code, the green LED goes on as well and the car can now be started by turning the ignition switch further clockwise to the start position.
- If the code is not correct, the green light will not go on and the car will not start."