For the purpose of the project, we required wireless communication between the server and the microcontroller. This communication was achieved by using two XBee wireless devices and one XBee USB-Explorer.

XBee and USB-Explorer

                  XBee is a radio communication module, built by Digi, to the 802.15.4 standard. XBee devices allow us to create a point-to-point or a point-to-many network, depending on usage. Table 6 shows the specs for the XBee devices used and Figure 51 shows the Xbee block diagram.

Table 6: XBee Specs

Figure 51: XBee Block Diagram

           The XBee arduino shield is used to plug in the XBee module into the arduino, shown in figure 52. The module interfaces over the serial line; hence, any data transmitted to and from the arduino can be captured and transmitted. For the XBee module that connects to the server a USB-Explorer board is required, shown in Figure 53.

Figure 52: XBee module plugged into Xbee Shield on the arduino

Figure 53: USB Explorer and XBee Module plugged into USB Explorer

          In order to use the XBee module, it needs to be programmed. The XBee module plugs directly into the USB-Explorer allowing direct access to program the settings on the XBee module. Software called Hyper-Terminal was used to program each of the two XBee modules with the following information: