Operating in the 2.4 GHz frequency that can be used almost anywhere, the ZigBee wireless protocol provides a low-cost, low-power mesh network ideal for green and global embedded applications such as smart energy and smart home initiatives. Øyvind shares an overview of ZigBee specifications and implementation requirements for ensuring device interoperability.
ECD: Give us a technical overview of how ZigBee technology fits with embedded applications.
STRØM: ZigBee is a wireless protocol that is a mesh network designed from the ground up for device connectivity. Controlled by the ZigBee Alliance, ZigBee executes on top of the IEEE 802.15.4 standard that was finalized in 2006. ZigBee provides a networking solution for small devices and wireless remote monitoring of sensors and simple input devices such as light switches. These devices typically have very low bandwidth and power requirements and are deployed in the 2.4 GHz frequency worldwide. ZigBee has a defined rate of 250 Kbps best suited for periodic or intermittent data or a single signal transmission from a sensor or input device.
The ZigBee Alliance focuses on the Smart Energy 2.0 profile, which is mandated in the United States for smart metering implementation. The Alliance also focuses on smart lighting, Radio Frequency for Consumer Electronics (RF4CE), and smart home automation.
ECD: What types of embedded products can benefit from ZigBee?
STRØM: A number of embedded products can benefit from ZigBee, including smart metering systems that allow utility companies to track meters wirelessly through a central station. The standard is best suited for embedded applications in wireless consumer devices such as remote controls and human interface devices like keyboards and mice. The protocol can be embedded directly into various applications to allow wireless connectivity at the 2.4 GHz frequency.
ECD: Will ZigBee replace or coexist with current communications standards?
STRØM: ZigBee will coexist with different wireless and wired protocols, including Wi-Fi, power line communications, and Bluetooth low energy. Wireless is continuing to grow rapidly, and many products are moving to wireless protocols. For instance, the wireless 802.15.4 ZigBee RF4CE standard is replacing infrared applications such as remote controls. In addition, many applications in the smart energy and lighting areas are moving to wireless protocols including ZigBee and Wi-Fi. All these standards will definitely coexist in the future.
ECD: What test and product certifications are required to implement ZigBee?
STRØM: To become ZigBee certified as a semiconductor company, vendors must ensure their applications are interoperable. Periodic interoperability events verify that devices work with other certified devices.
The ZigBee PRO and ZigBee RF4CE specifications serve as the base networking system to facilitate ZigBee’s interoperable market standards. Both feature sets define how the ZigBee mesh networks must operate and pass interoperability testing through a ZigBee test facility. ZigBee PRO, the most widely used specification, is optimized for low power consumption and supports large networks with thousands of devices. The ZigBee RF4CE specification was designed for simple, two-way, device-to-device control applications that don’t require the full-featured mesh networking capabilities offered by ZigBee 2007. ZigBee RF4CE has lower memory size requirements and enables lower-cost implementations.
Atmel offers ZigBee-certified wireless microcontrollers that are certified to both specifications using the Atmel ATmega128RFA family of devices or the RF231 transceiver together with one of the Atmel AVR- or ARM-based standard microcontrollers (see Figure 1).
ECD: What other challenges complicate ZigBee implementation, and how can designers overcome them?
STRØM: There are many software debugging and interoperability design challenges when implementing new software protocol stacks. With ZigBee implementation, the primary challenge is debugging larger networks and ensuring interoperability within the system. Specifically for ZigBee, the challenge comes down to the high node count in the mesh network, which is hard to debug. Atmel solutions make this challenge easier by providing a complete suite of software and hardware tools in addition to the appropriate support required to implement these networks.
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