The digital home control systems industry is still in its novelty stage, despite holding the promise of ubiquity for the last two decades. Zensys, a Fremont, California wireless technology company, believes that it has the answer to getting the industry off the ground, with realistic solutions that are affordable, easy to install and reliable.
The chip-based Z-Wave technology developed by Zensys is a home control system that uses mesh networking over two-way wireless RF communication. Its RF transmissions are based on a robust, low-cost FSK radio platform operating in the 915 MHz band (868 MHz in Europe). The small 5 mm x 5 mm ZW0201 chip includes a fully-featured FSK radio receiver, accelerated 8051 CPU, 32 kB of Flash memory and SDRAM. It also has a comprehensive set of peripherals for home automation, including a Triac controller, 8/12-bit ADC and UART. Finally, it features a high-quality radio front-end, and displays an input sensitivity of -104 dBm with very low power consumption.
A home control network is typically characterized by relatively few nodes - typically 20 to 200 - located within a 1500 to 6000 square foot area. Each node communicates relatively infrequently, usually every 5 to 15 minutes. A typical application message consists of 4 to 6 bytes of payload information: these are instructions to a device to turn on, set a dimness level, read the temperature, query door status and so forth. Relatively new applications in home controls, such as the support of universal remote controls and metadata increase this data demand. Z-Wave supports 10 kbit/s and 40 kbit/s transfer rates in any network topology, and is fully backward compatible.
A home control network typically consists of a complex mix of nodes powered by A/C and battery power, and ones that are both fixed and mobile. All nodes need to be able to communicate with each other seamlessly.
In the Z-Wave technology, nodes are differentiated as being in one of three fundamental node types: controllers, routing slaves and slaves. All node types work together and can be mixed in any combination:
Z-Wave supports battery-powered devices such as handheld remotes and moving sensors within each node type. Also, the full support of portable nodes - such as remote controls - is critical for the success of any wireless home control solution, and so is provided by Z-Wave.