In PART 1 last month, we described how to build and test a
pair of wireless data communications nodes based on AXE210 project boards
and XBee modules from MaxStream. This month, we look at some of the more
advanced features of the XBee modules.
By way of example, we then learn about some of these features
during the construction of a wireless light and temperature sensor, based on one
of the AXE210 boards. As part of the project, we also see how to receive and log
the data from the wireless sensor to disk with the aid of the second AXE210
board and a PC.
Finally, we dispense with the PC altogether and see how easy it
is to get a PICAXE-to-PICAXE wireless link up and running!
Fig.1: here's a screen shot of the XBee Setup wizard, showing the correct settings for board #1. Remember to swap the DL and MY values around when programming board #2!
As demonstrated last month, sending and receiving data between
two XBee modules is quite straightforward. In those examples, we relied on the
XBee’s default settings.
However, consider the case where more than one module is within
receiving range. Unless we specifically want to send a "broadcast" message to
all modules, then some means of addressing the data to the intended recipient is
This is where the XBee’s intelligent networking features come
into play. For a start, each module is factory programmed with a unique serial
number, allowing it to be explicitly addressed. In addition, each XBee module
can be identified with a programmable "nickname" for ease of use.
Other powerful networking features include the ability to
arrange modules into groups, or "private area networks" (PANs). By assigning a
common group ID to all members, modules not part of that group are automatically
So how do you set an XBee module’s nickname or group ID? Well
for modules connected to a PC, it’s quite straightforward; you’d use the
Programming Editor’s "XBee Setup" wizard. We’ll investigate this method in more