Design Example

1
Design Example

• Alarm Clock

2
Features???

• Include
• standard functions
• battery operated?
• 120/240 volts AC
• both
• accuracy?

3
(No Transcript)
4
(No Transcript)
5
Specification

• Classes - top level
• Mechanism - for the device operation
• Buttons - device buttons
• Speaker - buzzer
• Lights - AM/PM, Alarm Ready, Time Digits
• Display - digit scanning etc.

6
Initial Class Diagram
7
Class Refinements
8
Mechanism Class

• Track current time
• Track current alarm time
• Track current alarm on/off status
• Use a time display resolution of one minute

9
Mechanism Class
10
Update Time() Behavior
11
Scan keyboard() behavior
12
Two major software components

• An interrupt-driven routine can update the
  current time
• A timer can be used to interrupt periodically
  and update the time

13
Two major software components

• A foreground program can poll the buttons and
  execute their commands
• foreground program will read the button values
  and then use simple conditional tests to
  implement the commands

14
Two major software components

• Commands
• setting the current time
• setting alarm time
• setting the alarm
• turning off the alarm
• Another routine called by the foreground program
  will turn the buzzer on and off based on the
  alarm time

15
Foreground Code