POV Clock
The POV Clock in Action
Setting the POV Clock
The other aspect I liked about this clock is the
time setting function.  On earlier clocks I used
three pins for setting hours, tens of minutes
and minutes.  On this project I simply ran out of
pins, so I needed to work out something using
a single pin.  The same pin is grounded to
increment each digit in its turn.  I think it's more
elegant than the three-pin solution.  Watch it
(My next clock has a real switch, so you don't
have to touch a wire to the battery.)
This is a project I did to play
around with persistence of vision
or POV.  The four-digit display is
multiplexed, meaning only one
digit is ever illuminated at any
time.  The idea is this is done so
fast that the eye thinks it is looking
at four digits.  
But hey, if you got
it, flaunt it!
 Therefore the display
on this clock will slow down to
demonstrate the one-at-a-time
idea and then speed up until the
digits all seem to stay on.
My aversion to regular construction
techniques continues here.  I
decided to build the clock on a
round dowel since both the
microcontroller and the display
have pins on both sides.  

There were one or two difficult
wirings for which I had to drill some
holes at really awkward angles
through the wood.

The pipe cleaners I've had around
the house, waiting for a creative
impulse to use them.
Originally I was looking for a
domino to use as frame, but it was
surprisingly hard to find a
regular-sized wooden domino.  I
tried using a rubber eraser, but it
got melted and nasty during the
Top View
Bottom View
A useful tool I found during this
project is the website
www.time.gov.  The current time is
shown, accurate to a fraction of a
second.  (Although it's only precise
to the second.  Not sure how your
measurement can be more
accurate than precise.)  Anyway, it's
useful.  I'll set the clock to match
this, then come back days later to
see how many seconds it is off.  
This is used to calculate the
correction factor used in the code.
C Code for POV  Clock
PIC Projects