●●●●
16X16 TRI-COLORED LED
MATRIX - REAL TIME
CLOCK FOR THE
PARALLAX
SX52
BY TIMOTHY D. GILMORE
In my second year of college, some
students programmed a huge light
display standing about 12 feet high
in 8085 assembly language. It was
round with colored light bulbs and
reminded me of the lights on a Ferris
wheel. As an electrical engineering
student, I was captured by the
coolness of being able to control
something as beautiful as this
display. A couple of years ago, I
walked into a Brookstone store in
the Atlanta airport and saw a floating
display clock. I had just started
getting involved with Parallax
microcontrollers, beginning with a
year worth of experience with their
BASIC Stamp 2 microcontroller and
then moving into SX chips.
Internet that used a PIC chip. I converted the PIC Basic
code over to work on an SX28. It used a 20x7 LED matrix
display that I hand-soldered point-to-point. It was my first
microcontroller LED persistence of vision (PoV) project.
I liked the SX chips as they could also be programmed
in an easy SX/B Basic like language, as well as assembly
language if required. I studied as much as I could find on
PoV and LED matrix theory as I knew this would not be
easy to immediately learn. I was new to SX chips but it
was a huge step up in capability as compared to the
BASIC Stamp 2 microcontrollers. I was and still am a
very active member of the Parallax user forums (http://
forums.parallax.com/forums/) and have received a great
deal of help from all of the moderators and forum users
such as JonnyMac, Bean, JDOhio, Sparks-R-Fun, and
others. It is from their help that this project is possible.
Three Colors From Two
Iwanted to create a similar light emitting diode (LED)
display project but found very little on the Internet at the
time that was related to moving LED displays. There were
some Microchip PIC and Atmel AVR LED display projects
but nothing really for the SX chips. The SX chips at the
time were relatively new but also powerful, inexpensive,
and very fast. I found one LED display project on the
40 January 2009
This project allows the user to display the time and
date not only using one color, but three color LEDs.
Actually, the LEDs are bi-colored 8x8 LED matrix modules I
originally purchased inexpensively on eBay from a company
in Hong Kong named Sure Electronics (www.sureelectronics.
net/ goods.php?id=230). Later this year, their website was
available and I now purchase directly through that.
I used the trick of turning on both LEDs at the same
