BUILD IT YOURSELF
By Matthew Bates
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Those 8 x 8 matrix displays are good for more than just making scrolling
signs. With a little imagination and a whole lot of extra time on your hands, you
can actually use them to create simple yet amazing little action games. No
matter how many or how few pixels you have at your disposal, the theme
remains the same. It is always a matter of destroy or be destroyed, chase or be
chased, or something along these lines. If the game is interesting enough, at some
point you stop noticing that it is taking place on a field of only 64 LEDS. The
only thing that matters is victory.
The most common, simple, and least expensive matrix
display is an organization of 64 single or dual color LEDS
arranged as eight rows by eight columns. The footprint
standards for these displays are typically referred to as
small, medium, and large, ranging in size from 3/4 to
1.5 inches square. These LED displays come in two
distinct polarity types defined as Anode in Row or
Cathode in Row, which denotes how the rows are
connected to the diodes.
This polarity definition is important at a programming
level, by defining whether a low or high command is
issued to light the individual LEDs. The illustration in
Figure 1 shows a common organization in which the rows
are all connected to the common cathode side of the
The 24-pin dual color displays are all pretty standard
as far as pin numbering. I find that the square pattern LED
is a better choice for most game play. The square pattern
display seems to be less common than the traditional
round pattern. Adafruit is a good source for high quality
dual display units but they can be had from various places.
Futurlec sells a less expensive 16-pin single color display.
36 October 2013