Build low cost consumer appliances & smart meters with low pin count 8 bit MCUs

With the widespread adoption of powerful small-form-factor microcontrollers, the cost-per-cycle has dropped low enough that it's now economical to use 16-bit and even 32-bit devices in many embedded applications. Why is it then, even as 16-bit and 32-bit MCUs deliver low-cost processing power, that 8-bit architectures remain so popular?

There are several reasons, including the advent of new consumer and medical applications that benefit from the dramatically improved feature sets and performance of the 8-bit MCU.

As designs continue to move into smaller, more compact applications with limited power resources, low-pin-count (LPC) microcontrollers with complex peripherals and power-saving features become increasingly desirable.

The capabilities available in LPC 8-bit MCUs make them excellent design choices for home appliances such as water heaters, electric pots, de-humidifiers and hair dryers.

A gradual change in control systems design, particularly for products that require sensor inputs such as medical and healthcare equipment, home appliances, automation and process control, also is providing applications for these MCUs.

As a result, 8-bit MCUs dominate the global controller market because of their relatively low prices, improved performance, and new applications. According to recent Gartner-Dataquest reports, the 8-bit MCU market totaled about $5 billion in 2008 and will continue to lead in revenue and unit shipments, contributing almost 30 percent to the total MCU market.

Demand is strong, particularly in China, because of several factors, including de-facto standard architectures, configurable implementations and licensable silicon IP.

Household appliances like air conditioners, washing machines, refrigerators, TVs, home theater systems and radio broadcast receivers, combined with sound recording and reproducing systems, are driving growth for 8-bit MCUs.

Also, the market for household appliances such as dust collectors, smart electric rice cookers, fans and remote controls will continue to grow rapidly. The emerging applications for 8-bit MCUs include the following:

Smart and Utility Metering: A smart meter can identify consumption in more detail than a conventional meter and communicate that information to the local utility for monitoring and billing purposes.

Designed specifically for the demands of utility metering/smart metering applications, 8-bit microcontrollers are the perfect combination of ultra-low-power and high-performance analog integration (for example, 16-bit to 21-bit Delta-Sigma ADC, comparators).

8-bit MCU devices can offer one- to three-phase electricity, water and gas metering, as well as radio frequency wireless interfaces for automated meter reading (AMR).

Smart Sensor Applications: LPC MCUs also help conserve energy. Battery-operated or low-power security systems such as smoke detectors, thermostats and glass breakage systems are ideal for the ultra-low-power consumption and integrated high-performance analog features these MCUs offer.

Integrated wireless networking features are being added to smart sensor applications to strengthen home automation, remote monitoring and control features. Also, 8-bit MCUs fit into 95 percent of all devices used to access the Internet.

Portable Consumer Products: New generations of portable medical products encourage manufacturers to use technologies that reduce the design complexity and time required to develop products. Manufacturers also want to provide built-in LCD controllers and touch sensor controller capabilities. Again, the 8-bit MCU is an ideal choice.

As shown in Figure 1 below Appliances benefit from the energy-saving characteristics of advanced motor control technology. Consumers want to save energy costs and reduce the environmental impact of electricity-generating facilities.

Figure 1: Example block diagrams of household appliance applications

Since the refrigerator is always on, it can consume up to 50 percent of the home energy budget; virtually all that electricity is used to run the compressor motor. Most refrigerators still use constant-speed on/off compressors.

However, variable-speed compressors enable more efficient cooling with precise temperature control, reducing overall energy use. In addition, manufacturers are employing more efficient brushless motors, which also reduce energy consumption.

Replacing low-end universal triac-driven motors with permanent magnet or brushless DC (BLDC) motors in washing machines increases performance and efficiency. Advanced control techniques enable shorter washing cycles, saving energy and water.

Complex systems also can incorporate an 8-bit MCU for basic functions. For instance, LPC 8-bit MCUs are easy to configure and less expensive than stocking the required discrete components. So engineers can use 6- or 8-pin MCUs to control reset circuits that need a configurable time delay in different applications or for electric lighting ballast applications. Battery chargers, electric toothbrushes, toasters, coffee machines, and toys now contain low-cost, 8-bit MCUs.