Computers as Components, 3rd Edition

4.8 Design Example: Alarm Clock

Our first system design example will be an alarm clock. We use a microprocessor to read the clock’s buttons and update the time display. Because we now have an understanding of I/O, we work through the steps of the methodology to go from a concept to a completed and tested system.

4.8.1 Requirements

The basic functions of an alarm clock are well understood and easy to enumerate. Figure 4.32 illustrates the front panel design for the alarm clock. The time is shown as four digits in 12-hour format; we use a light to distinguish between AM and PM. We use several buttons to set the clock time and alarm time. When we press the hour and minute buttons, we advance the hour and minute, respectively, by one. When setting ...