Graphically displays calendar, clock, and global time-zone data.

Returning from holiday, Editor Mike commented to the author that he had seen an interesting world clock display at his hotel. It consisted of a world map across which was a series of light emitting diodes whose brilliance portrayed local time-zone daylight conditions. Could the author design one?

In EPE Feb '01, the author’s article Using Graphics L.C.D.s had been presented. Could this l.c.d. (liquid crystal display) be used to portray a world map? The author knew that, in principle, it was possible to produce a screen dump of any image and process it for loading into a PIC microprocessor for output to a graphics l.c.d.

Based on this, the end result of this project is a PIC16F877-based circuit whose graphics l.c.d. shows the following:

• Simplified World map
• Current UK clock and calendar data
• Clock data for any other time zone, adjustable via switches
• Flashing marker for sun's current highest position, i.e. true noon at that longitude (angle in relation to 0°, GMT, Greenwich Mean Time, London).
• Marker's position vertically (latitude) varies with the weeks and months throughout the year, spanning the Tropics of Capricorn and Cancer.
• Multi-paged text display of 150 major cities and their time zone displacements in relation to GMT (e.g. New York -5 hours, Sydney +11 hours)
• Additional city time zones can be readily added by those readers who have PIC Toolkit Mk2 or Mk3 (TK3 V1.2 or higher).
• Accuracy of clock time-keeping adjustable via switches.
• Principal clock and calendar data stored in the PIC's non-volatile EEPROM (electrically erasable programmable read-only memory) for recall in the event of power failure.
• Runs from a mains-powered 9V battery adaptor, plus standby battery backup.