Embedded DSP + flash = motor control

Norwood, MA -Analog Devices has developed an embedded digital signal processor with flash memory, the first in a new family of devices dedicated to the motor control market. White goods manufacturer Electrolux and motor maker Emerson drove the creation of the new DashDSP chip, which was originally developed for integration into a new speed controller in a refrigerator compressor application. The chip is now in high volume production.

"The trick was to design an IC which would enable the motor to operate at peak efficiency, yet keep the refrigerator cool, and do it at a price point which was half that of the existing solution," says Phil Davies, product line director for Analog Devices. "We met those targets by integrating all the analog and control electronics onto one 28-pin package." The high level of integration cut cost and improved performance, thanks to DSP technology and new algorithms developed to control the compressor speed.

The DashDSP chip is designed for sensor or sensorless control of multi-phase motors. The chip offers a digital motor control solution for washers, air conditioners, fans, and pumps, along with variable speed drives for the industrial, consumer, and automotive markets. "We think this is a 250 million unit market by 2004/2005," says Davies. The company plans to extend the device into other digital control areas such as power supplies and ac-to-dc converters. In the near future, a family of more general flash-based DSP products from Analog Devices will go after the handheld Internet appliances, consumer goods, and communications markets.

"The DashDSP family delivers a common platform for a large segment of our variable speed motor control products," says Eric Wildi, vice president of technology for Emerson Corporation. "This commonality enables us to leverage developed code and apply it in totally different applications."

DashDSP is aimed at a segment of the consumer goods OEM marketplace moving up from microcontrollers to DSP for higher signal processing capabilities. "We made the product easy to use by integrating so much precision analog on the chip with the DSP and the flash memory, and by putting it in a 28-pin package," says Davies.

A $395 development tool kit includes DashDSP processor boards, connector boards, cables, and Windows-based programming software. The unit contains a built in monitor and debugger program, which eliminates the need for in-circuit emulation. A design engineer can link directly into the chip via laptop or PC. On Analog Devices'motor control site (www.analog.com/industry/motor_control/), over 60 application code modules are provided for download into the development environment.

"The perception is that DSP is high priced and the development tools and programming is more difficult than for a microcontroller. The first barrier is to get over that mindset," says Davies.

As smart appliances hook into the internet (or with RF communications integrated with those products for wireless communications), DSP can provide control functions and a communications interface.

"White goods companies are interested in communicating with appliances to determine if they are performing within specifications for proactive maintenance," says Davies. "This will be a big push in the future."

Why DashDSP

- Targets 8-bit microcontroller users considering 16-bit step up

- Features easy to use development system

- ADSP-21xx programmable DSP

- Field programmable flash

- Precision analog interface