●●●●
I was doing a robotics
show and needed a
way to both attract
contestants and display
contest results. I had
seen a couple LED
signs and decided one
would be perfect for
this kind of application.
My only requirement
was that the cost had
to be reasonable and
the sign needed to be
easy to transport and
hook up.
I needed a sign with
an RS232 interface so
I could display real
time contest results.
■ FIGURE 1
CONTROL YOUR
WORLD
PART 3 — Interface Your PC to
an LED Sign
The most prevalent LED sign was
one called the BetaBrite. They
were stocked at most office supply
stores. The best bargain was when I
found them on sale at one of my
local warehouse stores. They cost
me less than $100 each. You can
get more information about these
signs at www.BetaBrite.com.
The signs are manufactured by
a company called Adaptive Micro
Systems, Inc. They manufacture
several signs — everything from
single line indoor signs to multi-line
outdoor signs.
The BetaBrite Sign comes with
an AC adapter for power, IR remote
control, and a CD that contains a
simple program for uploading
messages to the sign from your PC
(see Figure 1).
Being the kind of person I am, I
was compelled to write my own
interface. I figured that once I
learned the protocol, I could interface to the display with microcontrollers, laptops, or my Pocket PC.
Most of these signs come with
an RS232 interface, which is
important if you want to interface
with devices like Pocket PCs or
microcontrollers. If this is your goal,
don’t purchase a USB controlled
sign. The BetaBrite sign comes with
a 25 foot, nine-pin RS232 connector and is set up as a DCE device so
this connector can be plugged
directly into the PC.
If you want to connect it to a
Pocket PC, you will need a null
modem and gender changer or a
Bluetooth RS232 adapter. For
connection to a microcontroller, I
have created an application note
that can be found on the Kronos
Robotics website at www.kronos
robotics.com.
Research the Protocol
I started researching the interface protocol by searching the
Internet. You can find a great deal
of information on various websites,
but the best source is from the
40
September 2006
