Digital Home Opportunity for OEMs

Digital Home Devices to Offer Increased Opportunities for Embedded OEMs

The much touted digital home may have started off with lighting and thermostat controls, but it is rapidly expanding to more advanced security, energy management and lifestyle enhancement applications and beyond as the ecosystem grows.


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With embedded systems spreading well beyond industrial environments, they have become pervasive in peoples’ everyday lives. The trick has been to design such systems so that the user is dealing with the external functionality and is relatively unaware that behind it lies complex electronics, microprocessors and software. So the gas pump is still the gas pump even though the display is digital and it automatically reads the credit card, prints a receipt and offers a discount on a car wash—while simultaneously displaying advertising on a screen while the vehicle is being filled.

The line between what was once considered “consumer electronics,” such as TVs and stereos, has long since been breached by the invasion of microprocessors and microcontrollers into everything from toasters, toys, cash registers and tablets up to automobiles and the signs in stores. The list is endless. Small wonder then that the march of embedded has been defining what is increasingly being called “the digital home.” Since most homes now already have multiple personal computers, smartphones, tablets and, increasingly, Wi-Fi networks, the idea of adding digital control to such things as light switches, appliances, window shades, thermostats and more is almost a no-brainer.

But beyond mere convenience of controlling normal devices with a controller similar to a TV remote, there are some very compelling motivations for moving toward the digital home. These include security, entertainment control, energy management and lifestyle enhancement, especially in the areas of home health for an aging population. And now the existence of a mature ecosystem of products is making it possible for consumers as well as utilities and service organizations to offer custom solutions from the very simple to quite complex and sophisticated (Figure 1). 

Figure 1
While individual home control devices may be relatively simple and single function, they can be configured in ways to behave and interact that can result in very sophisticated applications. In addition, these devices may not remain so simple for long.

The Z-Wave Alliance is a consortium of over 160 companies that have collaborated to build wireless home control products that conform to the Z-Wave standard, which specifies a mesh network topology and a protocol stack that is compatible and interoperable all the way up to the application layer. The alliance certifies members’ products so that they are completely interoperable. While the devices are individually relatively simple and single-function, there is a great variety and they can be combined in almost endless combinations. These can then be configured with software into sets of coordinated, purpose-directed functions, which can then be invoked by a button on a remote, a smartphone or tablet app or a remote computer over the Internet.

A Z-Wave Home Network

For the vast majority of Z-Wave implementations, the basis is a gateway (sometimes called a bridge) that connects to the Internet via Wi-Fi and also communicates with the various devices via the Z-Wave radio mesh network. Then, of course, there is a selection of devices from simple switches to motion sensors, energy monitors, IP cameras and so on. In addition, there will be a remote-style handheld controller for convenience. Gateways come with some version of control panel software that lets the user set up and configure devices for the type of behavior that is desired. Some services like Verizon require an online subscription while others supply a basic control and setup panel and offer apps for sale to control different devices and their interactive behavior.

Not surprisingly, some Z-Wave offerings are from telecom companies such as Verizon and AT&T, some can be acquired as additional services from security alarm companies, and still others are available as do-it-yourself products from companies such as Loews, Home Depot and Fry’s Electronics. In addition, there are entrepreneurs starting to form service companies that specifically do comprehensive home setup services for applications that, as mentioned before, can become quite sophisticated.

For example, when combined with an alarm system, the Z-Wave devices can be configured for an “away” mode that can be invoked at the push of a button on a remote or a key fob. Such a mode could set the locks, set the lights to turn on and off at times and in sequences to look like people were at home, activate indoor or outdoor cameras, turn off AC or heating, and also activate the alarm functions with communications both to security services and to the user’s smartphone or tablet. Alternate modes can be programmed for use while people really are at home such as having motion sensors turn lights on and off.

Combined with such scenarios, the possibilities of energy management are becoming increasingly attractive. Devices for monitoring power consumption are available for application to the whole house or to individual devices or appliances. A number of them are able to respond to alerts from electrical utilities for load shedding or thermostat adjustment in accordance with demand response arrangements as well as to respond to time of day pricing for optimum power usage. Of course, applications are also available and can be set up to give users an analysis of their home power consumption in order to help optimize their consumption.

A very promising and rapidly growing area for the application of digital home control is to assist “aging in place” desires of seniors who want to continue to live independently as long as possible yet be assured that assistance is available if needed. This is separate from applications in telemedicine where the data from blood pressure meters, oxymeters, heart monitors and the like are transmitted to medical centers via the Internet. It can, of course, be used in conjunction with such devices, which generally communicate with a computer gateway via Bluetooth and an Internet connection.

By configuring standard home control devices in specific ways, it is possible to set up systems that can monitor a home situation and issue alerts if necessary. For example, if an elderly person gets up to use the bathroom at night, it is dangerous to do so in the dark. Therefore, motion sensors can be programmed to detect someone getting out of bed and turn on selected lights in a dimmed condition so as not to blind the person with glare. It then waits a given amount of time to detect motion that would indicate a return to bed.

Should, as often happens, a person slip and fall in the bathroom, they could be trapped there for days. But if motion is not detected after a certain amount of time, the system could send an email, or if more urgency is desired, place a phone call or even alert 911. All this and even more creative scenarios can be set up with just the basic Z-Wave devices and the gateway configuration software, which is designed to be intuitive for the nontechnical user.

Of course, developing such software and devices, which despite their current relative simplicity will become increasingly sophisticated as well, requires effort and skill on the part of OEMs. Currently there are well over 700 Z-Wave-compatible devices on the market with more on the way. In addition, the latest generation of Z-Wave silicon is moving to support IP while retaining backward compatibility with existing and future devices.

Z-Wave technology is built around a low-power SoC design (sleep current 3.2 μA) that itself is based on an integrated 8051 microcontroller core and a radio transciever. Successive generations include increasing amounts of program memory, radio frequency selections and I/O pins. All are compatible. Further power savings is due to the mesh network technology, which automatically routs the RF signal from node to node using a Tx/Rx current of 34/28 mA in the fourth generation chips. The silicon is also offered on a series of modules for easier development and integration (Figure 2).

Figure 2
Block diagram of a Z-Wave module with a third generation chip based on an 8051 microcontroller core. Various interfaces are available for controlling and interacting with selected devices along with a low-power radio transceiver. Bit rates of 9.6, 40 and 100 Kbit/s are available.

Also available to OEMs is the Z-Wave Home Control Development Kit produced by Sigma Designs. The programmer/development kit includes a reference design module, cables, antenna and other hardware needed to get started. Kits are available in different regional versions to accommodate the radio frequencies that have been allocated in different geographical regions.

A software development kit (SDK) is also available via download, which includes the Z-Wave protocol stack, documentation, data sheets, protocol libraries and sample applications. Not included but also required for application development is the PK51 8051 compiler from Keil Embedded Development Tools. As Z-Wave moves toward IP support in its fifth generation and builds momentum, it is clear that devices will become more complex as will their internal application code. That will mean even more opportunities for advanced configuration of different devices in increasingly diverse and specialized application scenarios.  

Z-Wave Alliance

Keil Embedded Development Tools
Plano, TX.
(972) 312-1107.
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Sigma Designs
Milpitas, CA.
(408) 262-9003.