PIC World Clock
Approx construction cost US$96.00
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:
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Simplified World map
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Current UK clock and calendar data
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Clock data for any other time zone, adjustable via switches
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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).
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Marker�s position vertically (latitude) varies with the weeks and months throughout the year, spanning the Tropics of Capricorn and Cancer.
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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)
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Additional city time zones can be readily added by those readers who have PIC Toolkit Mk2 or Mk3 (TK3 V1.2 or higher).
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Accuracy of clock time-keeping adjustable via switches.
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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.
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Runs from a mains-powered 9V battery adaptor, plus standby battery backup.
More details on this construction project can be found in the August 2002 issue of EPE Online, the world's first web-delivered electronics and computing hobbyist magazine.
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