This is my second
AVR project. I decided to make my own TIX clock using an AVR
controller. The real TIX clock can be bought from places like Thinkgeek . When I first saw them
I had to have one, but the price was a bit too high. And besides,
it's much cooler and more fun to say "I made that!" So I
started upon making my second clock project. Can you read the time in the
picture above? It's 22:19. First thing I did was write a little Visual Basic
simulator program to get a bit of an idea of what sort of code it would
need.
This project had it's own challenges.
Origonally I wanted to have time adjustment done via a pulse encoder. So
one could select the hours or minutes and then tweak them up or down using a
little rotary knob. Unfortunatly, finding components like rotary encoders
in little old New Zealand is a bit difficult, so I had to resort to 3 push
buttons. Secondly the display had to be multiplexed as there is a total of
27 LED's in the display. Having all those LED's on at one time would draw
great amounts of current plus also needing a great number of IO lines. I
ended up multiplexing the display from left to right, so that there is never
more than three LED's on at any time.
Here's a picture of the clock on
the
breadboard. Again
the chips in the bottom right had corner are just there for storage.
Once
I got the basic principle going I tried to make it display the patterns
randomly, but that was a bit beyond my math capabilities :-} So I have
ended up doing the patterns with an array. Each number can have 10
different dot patters for display.
The display is made up out of Vero/strip board
and that silver stuff you see convering flourescent lights in offices. On
top of that I have placed an opaque sheet of plastic film with a clear sheet
of perspex on top to keep it all flat and looking nice.
The controller board is a simple
vero/strip board example as well, and mounted on the back of the
display board. At the top left you can see the three transistors that are
the row drivers, and on the
right
the two transistor array's that are the column drivers. The crystal for the
RTC is mounted underneath the board.
click Here to
download a little video clip of the clock in action (350k .wmv
file)
