Let me start this column with a confession—I'm lazy. Basically, I suspect we all are a little. We like our remote controls, our automatic garage door openers, and our coffee makers that have that cup of java ready by the time our feet touch the bedroom floor.
What do I have to thank for allowing me to indulge this tendency? A tiny 8- or 16-bit microcontroller embedded in my appliances.
"The main advantage of microcontrollers is twofold," says Richard Steele, Product Marketing Engineer for STMicroelectronics (New York, NY). "First, additional features and conveniences can be added without any extra cost because it is a programmable device. Second, one can achieve better precision by intelligently controlling these functions."
Also, with a little bit of engineering, one can write programs that replace existing hardware, says Maxime Teissier, Field Application Engineer for the company.
STMicroelectronics developed a microcontroller specifically for meeting today's refrigerator challenges, such as energy savings and efficiency. The device handles two tasks that had previously been accomplished mechanically: driving the motor and regulating the thermostat.
A microcontroller can control the motor more efficiently and precisely than a mechanical device, because it can constantly monitor motor current, rpm, and other parameters to keep it operating at its most efficient range. This means the motor requires less energy while doing a better job, says Teissier.
In the STMicroelectronics model, the same microcontroller also regulates the temperature. By coordinating the on-off cycle of the thermostat with the operation of the motor, a user will see substantial gains in energy savings because the motor ramp-up, speed, and runtime are controlled more precisely.
A microcontroller is a pretty powerful compute engine, says Steele. It can process as many tasks as needed for most appliance applications.
Another advantage of microcontrollers is improved product performance. Because the previous thermostat operated by a mechanical switch, it was either on or off. With a microcontroller, one can input different settings. "Consumers get better efficiency in terms of their ability to maintain a constant temperature," says Steele, "keeping the food fresher and in better condition. With less deviation in temperature, your lettuce won't freeze."
Battery chargers are another good example, says Teissier. A microprocessor matches the charging rate with the battery's chemical characteristics. By measuring the exact amount of current the battery is drawing, it can automatically determine whether to pull back the current so the battery doesn't over-charge, or ramp up the current so the battery charges faster.
Mark Zeinstra, business manager from Johnson Controls (Plymouth, MI), is a believer. Johnson Controls makes the HomeLink® Universal Transceiver. With HomeLink, a homeowner can remotely activate garage doors, entry door locks, lights, and security systems, and even check tire pressure.
In 2001, more than 4 million vehicles will feature the HomeLink, including models manufactured by Acura, Audi, BMW, DaimlerChrysler, Ford, General Motors, Honda, Infiniti, Jaguar, Lexus, Land Rover, Mitsubishi, Nissan, Shelby, Toyota, Saab, and Volvo.
This next-generation HomeLink system boasts Microchip's KEELOQ technology implemented on the company's PIC16C76 RISC microcontroller, with 8K of OTP program memory to control and interface with the various HomeLink subsystems. "We wouldn't be able to create HomeLink without microcontrollers," says Zeinstra.
"Microprocessors add flexibility through the design process," he says. "A developer can make a device to do things that it normally wouldn't be able to do because writing software is easier than redesigning circuits."
HomeLink is a perfect example of this. "By changing our software and algorithms, we were able to add a feature to sense low tire pressure," Zeinstra says. This feature adds value to the product, allowing the company to charge more, and perhaps increase its profit.
A microcontroller consists of a microprocessor that serves as the central processing unit (or brain), memory, and peripherals like serial, parallel, and USB ports.
A typical microcontroller costs anywhere from 50 cents to $5. More expensive ones can run as much as $20 or $30. But typically, a $1 micro and a power supply can replace an entire mechanical system, engineers say.
Although embedding microcontrollers may cost about the same as a mechanical system, the value of the resulting product is much higher, says STMicroelectronics' Steele.
"Value is money and margin," he says. "With a microcontroller, you add convenience features. It doesn't add to the cost of goods, but you suddenly have features that are of value to the consumer. Because it has more functions, you can charge more."
That holds true for almost all high-end appliances available today, including automobiles, washing machines, clothes driers, dishwashers, electronic toothbrushes, and power tools.
And let's face it, customers are willing to pay for convenience…just look at me! I'm willing to pay $75 for my electric toothbrush with its two-minute warning signal, instead of $2.99 for a hand-operated model, just so I don't feel guilty the next time I visit the dentist!
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