May
2004, Issue 166
Radio
Roundup
INITIUM
No,
I haven’t forgotten my ABCs. The Initium Promi-SD202
is a Bluetooth product, and I didn’t want to mix the
bulls with the broncos. I’ve been experimenting with
some Bluetooth nodes and have used them to replace RS-232
cables between gadgets in the Florida room.
The
Promi-SD202 is a class 1 Bluetooth transceiver powered
by a 5-VDC power source that can be attained from a
PC USB port, an optional wall wart, or a direct connection
to the host power subsystem using a supplied DC power
cable. It can operate at data rates ranging from 1200
to 230,400 bps, and it connects to the host via an integral
nine-pin RS-232 DCE interface. The effective range is
approximately 100 m.
Getting
on the air with the Promi-SD202 modules was a breeze.
A configuration program is included with the module
pair that permits you to select data rate, connection,
and security options. There are four modes of operation
defined in the configuration program. Mode 0 is used
to initially set up the SD202 modules, which involves
selecting over the air data rates and discovering other
Bluetooth modules that are connectable and within range.
I
wanted the SD202 module pair to always connect at power-up,
so I used the mode 0 functions to allow the modules
to learn about each other (device address, device name,
class of device, etc.) and establish an initial connection.
Both SD202 modules automatically store the Bluetooth
device address of its latest counterpart, which allowed
me to set one module to mode 1 and the other to mode
2.
Mode
1 instructs the SD202 to connect only to the last connected
device, while mode 2 tells the companion module to accept
only a connection from the last device it was connected
to. After the initial connection is complete and the
modes are set, the Promi-SD202 modules can be used as
100-m virtual data cables between machines and various
RS-232-equipped gadgets in the Florida room.
I’m
always testing the RS-232 interfaces on the Easy Ethernet
devices that I ship. Using Bluetooth instead of a cable
removes the distance restriction when a unit goes back
to the bench for testing. I Bluetooth-enabled an EDTP Easy Ethernet ASIX
using the black male-to-male null modem adapter from
the 9XStream evaluation kit (see Photo 6).
|
(Click
here to enlarge)
|
Photo
6—The SD-202 gets it power from the EDTP Easy Ethernet
ASIX via a DC power cable assembly that comes with
the Bluetooth radios. Mark, the machinist that fabricates
all of my weird metal and plastic stuff for my Circuit
Cellar articles, is also using Bluetooth modules
in his machine shop to communicate with a prototype
project he is working on. |
GIT
ALONG LITTLE DOOGIES
We’ve
ridden and roped every data radio that we’ve brought
with us. Now it’s time to gather all the livestock and
move on. If every segment of technology worked as hard
to make its products as easy to use and assimilate as
the embedded data radio folks do, we would already have
a colony on Mars.
All
of the embedded data radio units I mentioned are designed
to be dropped into your final product with a minimum
of wand swinging. Visit each manufacturer’s web site,
and you’ll find lots of additional information to help
you incorporate wireless into your next design. Using
them in your projects allows you to wear your pointy
RF wizard hat to anybody’s rodeo with pride because
you will have helped to prove that RF doesn’t have to
be complicated to be embedded.
