Subject : Embedded Systems Design

Topic : Embedded Serial Communication

Difficulty level : Medium

i) Zigbee is an IEEE standard 802.15.4 protocol. Its communication latency is 30 ms and protocol stack overhead is 28 kb.

ii) The physical layer radio has a 2.4 GHz band carrier frequency with DSSS. It supports the range up to 70m. The data transfer rate is 250 kbps and supports 16 channels.

iii) Zigbee network –

• A zigbee network is a self-organizing network which detects nearby zigbee devices and establishes communication.
• It supports peer-to-peer (2 devices) and mesh (1 device to multiple devices) networks. Peer-to peer communication means each node at network functions as requesting as well as responding device and mesh communication means each network functions as mesh.
• A node is connected to another node directly or through mutually interconnected nodes.

iv) Zigbee protocol supports large number of sensors, lighting devices, air conditioning and other devices for home and office automation.

v) The components of Zigbee network are-

• Zigbee router: It transfers packets from neighbor source to nearby node.
• Coordinator: It connects zigbee network with another. Also it connects WLAN cellular network with each other.
• End devices: these are the transceivers of data.