1. The Calendar Alarm Sydney Tang Su-tarn Lim Chen-song Qin

2. Overview Introduction Demo Design Enhancements

3. Key Features View the time and date, including the weekday Program up to eight alarm events Enter data directly

4. Design Overview Top-level view Control Time and Date Keypad Display Resource utilization

5. Top-level view

6. Control Contains 3 state machines –User interface –LCD state –LCD handshaking Manages memory for event programming Keeps track of time and date

7. Time and Date Implemented by cascaded counters Month counter has a variable maximum value Uses Julian Calendar

8. Keypad state machine

9. LCD state machine

10. Resource Utilization Total logic cell usage > 95% Lessons learned: –The cost of UI Data-entry error checking: 6-7% Showing variable text: 14% Formatting the display: 10-20% –The value of modularity

11. Enhancements Upgrade from Julian to Gregorian Calendar Auto-select weekday Add more types of events –once only –yearly –daily Allow user-entered event descriptions

12. Questions?

13. Getting the day of the week Lookup table –400 elements for Gregorian –28 elements for Julian Nasty formula* –W = (k + floor(2.6m - 0.2) - 2C + Y + floor(Y/4) + floor(C/4)) mod 7 Let the user supply it *source: sci.math FAQ

14. Calendar schemes Which of these are leap years? –1900 –1998 –1999 –2000 –2100 –2400 It depends on the Calendar you use