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Viewpoints: Have you unplugged yet?

A few years ago, the future of the 8 and 16bit mcu was being questioned. As embedded applications grew more and more complex, the hardware scene was likely to be dominated by fpgas, asics, cplds and SoCs. Would the traditional general purpose mcu survive?

Today we see that the traditional 8 and 16bit mcu seems healthy and, although seasoned, has been able to find itself a brand new position as the enabler in low cost, low power wireless systems. But let us not forget that there is a new breed of low power 32bit mcu designs aiming to enter the wireless niche.

And the future of wireless systems seems really bright; we are literally surrounded by them already, both at home and at work, so there should be plenty of room for different mcu architectures with different trade offs.

Wireless systems address many of the everyday challenges in modern society. They bring safety and security to our homes, they enable new types of portable systems, they keep track of goods and items, and they support energy saving and control. This article gives an overview of some of the application areas where wireless technology is growing rapidly.

Home automation
A smart house allows you complete control of the home electronics while adding comfort, security and safety. By connecting all home electronics to a central control unit, you can adjust the settings for individual products or groups of products depending on whether you're at home or not, the time of day, weather conditions etc. Wireless technology makes it all feasible; who would want a super connected home with cables everywhere?

There is almost no limit to the possibilities available. Make sure that you have turned on the alarm or switched off the stove and unplugged the iron, as you leave or when you've already left the house. Avoid spending money on HVAC when nobody is at home but set the timer so that the climate is comfortable when you return from work. Add lamps and your favourite music to the system to make you feel welcome home.

Record your patterns of drawing curtains and blinds, switching on and off light, music etc and let the house play those patterns when you're away to keep burglars unsuspicious. Put a keyless lock in your front door and use different levels of locking when you're away, when you're at home in the daytime and at a night. Connect the smoke detectors and flood sensors to the control system and make sure that you get immediate information if an accident should happen.

We see different wireless techniques used in today's home products: rf, ZigBee, and IR.
Considering that many products are intended as install-it-yourself products, who can ensure interoperability between the different devices in your home? Even with a degree in electronics engineering, this could be a hassle.

Manufacturers, both in the US and in Europe, form alliances to promote compatibility and connectivity through remote control standards. In the near future we will most likely see more bundled kits, starter sets and pre-packaged solutions for the home owner.

Healthcare
Wireless technology is already well established in the field of medical applications. With escalating healthcare costs in many countries and a demand for flexible healthcare solutions, wireless systems have a strong potential in the growing field of medical devices.

In pre-hospital care, medical telemetry can save lives by transmitting data from a patient during transport to an emergency clinic and allowing proper preparations while the patient is on the way. With bi-directional communications, hospital staff can also provide instant prescriptions and guidelines to paramedics.

With telemetry solutions, many patients can be monitored simultaneously, which is cost efficient for hospitals and other providers of healthcare. On a cardiac ward, for example, data such as ECG rhythm can be collected from many patients and displayed on handheld devices carried by doctors and nurses.

Patients are no longer necessarily tied to their hospital beds by a lot of wires but can move freely within the ward depending on their condition. A patient can also be monitored continuously with the same system during transportation between wards, which greatly improves the flow of information.

Patients that may otherwise have had to be connected to hospital equipment can now go home earlier, gaining more comfort and mobility while remaining under careful medical monitoring thanks to wireless systems. For example, implantable devices for cardiac monitoring, drug delivery or neuro stimulation may provide Internet access.

Diabetes management products may also include wireless technology that allows a blood glucose monitor to communicate with an insulin pump for continuous control of the blood glucose level.

Smart energy
As energy consumption and environmental issues are in focus in many countries, government requirements on energy management change and the need for flexible metering programs increase.

Submetering, where each household pays for the exact amount of electricity, gas and water that it consumes, gives a perfect incentive to be a conscious consumer. To implement submetering in an existing building, mesh networking communication is required to interconnect nodes for routing data.

The ZigBee wireless protocol allows up to 65,000 nodes on a single network—enough to cover a huge residential area. One such example is the city of Gothenburg, Sweden, where all 270,000 homes will be connected in a wireless ZigBee network for metering services.

Smart energy also means that you can feed any surplus heat generated by for example kitchen appliances into your heating system. This allows you to automatically reduce the amount of electricity used for warming up the house while the dish-washer or washing-machine is running.

Since the demand for electricity varies a lot depending on weather conditions, the time of day and many other conditions, energy demand management is a major challenge for the utilities. Typically demand is high when the energy-supply systems are constrained and vice versa.

One way of addressing this problem is distributed power generation where many sources contribute to a grid energy storage system. For example, with solar panels mounted on the roof and small wind turbines in the garden, you may have more energy available than your household needs. Distributed energy systems where energy is generated close to the point of use and grid-tied electrical systems where excess capacity is fed back to the local mains grid for storage is an environmentally friendly way of balancing demand and supply. This of course requires bi-directional connection and submetering to calculate the contribution and usage of each household for correct billing.

Identification, payment and asset management
Radio-frequency identification (rfid) has distinctly widened the scope of embedded systems. rfid tags are placed inside and on objects that traditionally hardly were considered by the embedded industry.

In its simplest form the rfid tag basically serves the same purpose as a barcode. The tag itself only contains an identification number and all related information are stored in a data base.

The signal is initiated from the reader and can be read only at a very short distance. A more advanced rfid tag has a small but rewritable memory. These types are both passive, they are powered by the reader. An active rfid tag carries its own battery, is bigger and more expensive but can communicate over a longer distance.

Today rfid tags are used for identification, payment and asset management. In many countries rfid tags are included in passports and the technique is used also in security cards and student ID cards for access control. For more than 10 years now, rfid cards are being used all over the world for payment of road tolls, in the public transport systems and at parking lots. The cards are typically charged with money at a local convenience store, at ticket counters in metro and railway stations and at add-value machines.

The cards typically have the size of a credit card and when you show it to a scanner, the scanner display shows how much money is available or how many days the card will remain valid. Tracking of goods, luggage and other assets such as books in a public library or cattle are other areas where rfid tags are already in vast use. rfid technology has been adopted in inventory systems and by logistics and transportation companies all over the world to improve efficiency and business value.

Apart from global standardization issues, there are several security and privacy questions to take into consideration. Illicit tracking of rfid tags and undesired surveillance of consumer habits are some examples. The implantation of rfid tags into humans, does raise a number of ethical concerns.
Summary
The trend in rf communication today is towards really low power, low cost solutions that can form a non-intrusive part of our daily lives. When designing and building wireless devices and applications the usual trade-offs apply; I probably need high performance, low parts cost and low power consumption, all at once, for my application.

What's more, I have a choice of selecting a standard communication protocol like ZigBee to enable easy interoperability with other standards conforming devices intended for the same type of application; or I can trade interoperability for smaller code size (and possibly lower clock frequency) by using a proprietary communication protocol with a smaller API size.

After balancing the various trade-offs it is highly likely that you can select a standard mcu+radio package already on the market as the basis for your design, due to the proliferation of solutions available.

Author
Margareta Eriksson Hoerling, marketing communications manager, IAR Systems

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