Background Information: Home Automation

Lower energy costs, improved security of goods and people and enhanced quality of life are the benefits offered by Home automation, a concept that has been familiar for more than twenty years but which has not yet been widely employed. Now, thanks to the convergence of several key factors, Home automation has reached the point of true technical and economic viability.

Home automation will cut energy costs by allowing precise, intelligent control over energy usage. For example, heating and lighting can be dynamically adjusted in every room and appliances such as washing machines and dishwashers can be loaded and left to switch themselves on at a time when electricity is cheapest..

In the security area, Home automation offers much more than conventional smoke and intruder detection; damage to goods such as electrical equipment or freezer contents can be forestalled by monitoring appliances for short-circuit or open-circuit conditions, failsafe security status messages can be transmitted to outside agencies and equipment such as baby monitors or outside video cameras can superimpose messages on TV screens..

Quality of Life enhancements include in-house distribution of audio-visual entertainment, automatic adjustment of ventilation in response to weather changes and voice activation of doors for disabled people..

Most of these features have been technically possible for some years but are either too expensive or would be too complex, in practice, for widespread domestic use. In fact, the two major requirements for the Home automation market to take off are low cost and ease of use..

LOW COST is essential because Home automation is part of the consumer market. The cost of Home automation includes not only the incremental cost (i.e. the price difference between buying a dumb washing machine and a smart one) but also the cost of the infrastructure. Systems that require the installation of a central control terminal or a significant amount of new wiring will not be viable on economic grounds..

EASE OF USE is essential because Home automation users will come from every social and educational background. A smart appliance should involve no special installation procedures and it should not require the user to learn any special programming commands. In addition, there should be maximum flexibility in controlling the appliance e.g. via a home PC, a TV set, a remote telephone and so on..

For the last few years, SGS-THOMSON and a variety of other European companies have been working together within the European Union's Esprit programme to define and develop a standard known as the European Home System (EHS). Initially aimed at purely domestic applications, EHS is now also being aimed at commercial applications such as hotels and office buildings..

A key feature of EHS is the concept of automatic installation or enrolment. An EHS-compatible appliance that is plugged into the EHS bus will immediately identify itself and be able to communicate with other devices on the bus. As far as the actual communications medium is concerned, EHS supports twisted pair, coax cable, infra-red, radio frequency and mains-borne signalling. The ability to communicate over mains wiring is a crucial enabling factor because it means that Home automation systems can use zero-cost wiring. .

In terms of semiconductor devices, Home automation has three essential requirements: local intelligence, power actuation and communications, all of which must be implemented at minimum cost..

Intelligence
Much of the intelligence in Home automation is distributed around the system; typically, lamps, light switches and even the mains sockets themselves will contain embedded microcontrollers (MCU). The intelligence does not usually have to be very great but it must be very, very cheap. .

SGS-THOMSON's solution for the most cost-sensitive applications is the ST62 MCU family that has been used for many years in applications such as domestic food processors and electric drills. ST62 devices are ideal for applications where total cost must be minimised because they need no external ADCs, no external 5V regulators and no external EMI protection. .

Where higher performance is required, we also offer the ST7, ST9 and ST10 MCU families, so that there is an SGS-THOMSON microcontroller to meet every price/performance specification. European Home Systems (EHS) protocol software is available at TRIALOG for the ST9 microcontroller. .

Power Actuation
Many of the applications for Home automation are controlling power ( motors, heaters,light) that must be controlled by low level logic signals. SGS-THOMSON is the world leader in this area, being one of the leading suppliers of discrete power devices such as Triacs and the undisputed champion of smartpower..

Our protected MOSFETs, for example, combine the rugged power handling capability of discrete power MOSFETs with on-board protection circuitry that makes them almost indestructible. In addition, if the power transistor is turned off in response to a fault condition, g diagnostic information can be sent to the local MCU which can, in turn, send this information over the bus to the appropriate control/monitor devices. .

SGS-THOMSON's third generation BCD technology, the most advanced in the world, also has potential applications in Home automation. BCD3 allows a full MCU core plus peripherals to be integrated with multiple DMOS power transistors to form a "supersmart" power IC. .

Communications
One of the early barriers to Home automation was the cost of wiring all the appliances, controllers and sensors together. This is no longer a problem, thanks to the ST7537HS1 power-line modem which uses an inexpensive but very effective frequency-shift keying (FSK) approach to send data over 220V/110V AC power cables in compliance with the European CENELEC EN50065-1 and the US FCC standards. .

The ST7537HS1 sends data at 2400 bits per second in half duplex mode, with a carrier frequency of 132.45kHz. The FSK technique achieves the best tradeoff between performance and cost; simpler amplitude shift keying (ASK) modems do not guarantee sufficient reliability, while more sophisticated spread spectrum solutions are much more expensive without providing a significant improvement in performance. .

A carrier sense circuit on the chip allows multiple devices to operate independently on the same power line with the same carrier frequency. This is an important feature because it allows new appliances or other equipment to be simply plugged into any convenient mains socket without any risk of conflicting with other devices..

Today, many companies are preparing for the Home automation market; although there is much scope for further development in areas such as international standards and cost reduction, the major conditions for commercial success have now been satisfied. In particular, SGS-THOMSON is already able to offer all of the semiconductor components required to make the "intelligent home" a reality..

For further information, please contact :
Simon Loe
Technical Press Relations Manager
SGS-THOMSON Microelectronics
St Genis, France
Tel : +33 4 50402558
Fax : + 33 4 50402860
November 1995/B519H
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