Zigbee Stack, Profile and Application Development

Raycomm are a UK based, leading developer of custom software and electronic design solutions for innovative technological products and systems.

Zigbee is wireless protocol aimed at low to medium data rate applications typically with low power requirements operating in license free bands. It has the following general characteristics:

• Data rates of 250 kbps and 20 kbps
• Star topology, peer to peer possible
• 255 devices per network
• CSMA-CA channel access
• Optional Guaranteed Time Slot
• Fully handshaked protocol for transfer reliability
• Low power (battery life multi-month to nearly infinite)
• Dual PHY (2.4GHz and 868/915 MHz)
• Extremely low duty-cycle (<0.1%)
• Range: 10m nominal (1-100m based on settings)
• Location Aware: Yes, but optional

ZigBee-compliant products operate in the unlicensed bands worldwide, including 2.4GHz (global), 915Mhz (Americas) and 868Mhz (Europe). Raw data throughput rates of 250Kbs can be achieved at 2.4GHz (10 channels), 40Kbs at 915Mhz (6 channels) and 20Kbs at 868Mhz (1 channel). Transmission distance is expected to range from 10 to 75 meters, depending on power output and environmental characteristics.

The logical size of a ZigBee network ultimately depends on which frequency is selected, how often each device on the network needs to retransmissions can be tolerated by the application. ZigBee's addressing scheme supports 255 active nodes per 'network coordinator', and multiple network coordinators can be linked together to support extremely large networks.With support for 16 channels in the 2.4GHz band, and 255 nodes per network coordinator, ZigBee networks can contain over 4,000 unique nodes in a single network with high system reliability.

How does Zigbee relate to Bluetooth

• The ZigBee stack is small (28Kbytes) compared to the Bluetooth stack (250K). This relates to lower cost and lower power consumption.
• Ultra-low power consumption is a key system design aspect of the ZigBee technology to allow long lifetime non-rechargeable battery powered devices versus rechargeable devices for Bluetooth. As an example the transition from sleep mode to data transition is much faster in ZigBee than for Bluetooth.
• ZigBee networking capabilities include 255 devices per network, compared to 8 for Bluetooth networks.
• The data rate for ZigBee technology is 250kbps compared to 1 Mbps for Bluetooth wireless technology.
• Range for ZigBee products is expected to be ~30 meters in a typical home, compared to ~10 meters for Bluetooth products (without power amplifier).

We can assist in the development of complete new products using Zigbee technology or help to integrate Zigbee into your existing products. We can also undertake a feasibility study to assess the suitability of Zigbee for your needs.