tegy is an unnecessary overhead. An example would be a security system, with a mains powered controller and (hopefully) very infrequent security alerts. Three device types are recognised in the IEEE 802.15.4 MAC specification; full function devices, the network co-ordinator that is a special type of full function device, and reduced function devices. These device types are described in Table 10-13. Devices use either full 64-bit or short 16-bit addresses, and transmitted frames can include both destination and source addresses. This is necessary for peer-to-peer connections and is also important in mesh topologies, to provide robustness to single point failures in the network. Chapter Ten Table 10-13: ZigBee Device Types Device type Description Full function device (FFD) FFDs carry all features specified by the IEEE 802.15.4 standard. They have additional memory and computing power to perform network routing functions and can be used as edge devices where the network interacts with external devices. Network co-ordinator The PAN co-ordinator is the most complex of the device types with the largest memory and computing power. It is a full function device that maintains overall control of the network. Reduced function device RFDs have limited functionality in order to reduce (RFD) complexity and cost. They can only communicate with FFDs and will generally be used as network edge devices. ZigBee in Practice ZigBee networks will cover a variety of short-range, low data rate applications from PC peripheral interfacing to industrial control, as shown in Table 10-14. A typical ZigBee home automation network might cover the first three of these application areas, bringing together control of lighting, security, home entertainment and a variety of PC peripherals into a single network. Table 10-14: ZigBee Application Areas Application area Application examples PC peripherals Mouse, keyboard and joystick interfaces Consumer electronics Home entertainment system (TV, VCR, DVD, audio system) remote control Residential and othe