Motorola Offers Industry's First Integrated Circuit for Three-Dimensional Electric Field Imaging

(Photo: http://www.newscom.com/cgi-bin/prnh/20030127/CGM054 )

Now, design engineers creating embedded systems that require non-contact sensing and three-dimensional (3D) electric field (e-field) imaging may reduce system components and costs by employing the MC33794. This IC integrates support for a microcontroller and up to nine simple electrodes, which can be used independently to provide information on the size or location of an object in a weak electric field.

The MC33794 is designed to replace numerous discrete devices previously needed to achieve the same functionality. Target applications of the IC include appliances, machine tools, automotive safety systems, and virtually any product or system that uses touch panel inputs as a user interface.

"We chose Motorola's low-level e-field imaging IC because it is the first to offer such a high level of integration, which has allowed us to replace numerous ICs and discrete transistors and more than 70 passive components with one device. This has helped us to significantly reduce system size and increase reliability," said Phil Rittmueller, vice president of Elesys North America, Inc., a leading producer of automotive electronic safety systems.

Elesys is now using the MC33794 in its SeatSentry(TM) occupant sensing system to stop an airbag from deploying on a child. The system generates low- level electric fields from multiple antennas mounted in the seat's back cushion. The system can identify a child or small adult when the field detects and interprets a change in the current. By analyzing the changes in the various currents and by combining that information, the height of the passenger and his proximity to the side airbag is detected. If SeatSentry determines the occupant is a child or small adult, the airbag will not deploy. Currently, the occupant sensing system is in use on some Honda vehicles.

The electric field imaging IC was developed through a collaborative effort between Motorola's Analog Products Division, Motorola's DigitalDNA(TM) Laboratory at the Massachusetts Institute of Technology's (MIT) Media Lab and Elesys North America (formerly NEC Technologies Automotive Electronics Division).

"While simple capacitance measurement is one of the most mature kinds of sensing, working with Motorola and Elesys we found that tiny arrays of charging currents can be used to determine real three-dimensional geometries," said Professor Neil Gershenfeld, director of the MIT Media Lab's Center for Bits and Atoms. "Motorola and Elesys have brought this exciting capability to the market in a form that could help save lives today, and that promises to enable many new kinds of unobtrusive and responsive computer interfaces tomorrow."

Target Applications

The MC33794 together with simple electrodes and an MCU can help designers readily implement 3D imaging and sensing. The ability of this combination to detect touch can be used to easily implement automatic on/off features in a wide variety of products. Other applications that may be simple to implement include; liquid level detection, spill detection or moisture sensing. For example, stoves with flat tops could be programmed such that when liquids boil over, the heat would be automatically reduced or turned off.

More sophisticated applications include touch panel inputs. Here, an array of electrodes embedded in glass or behind a non-metallic surface could be sensed in a matrix fashion similar to contact switch inputs. This method eliminates membrane switches or expensive multi-layer resistive touch pads. Because the input is sensed without requiring a contact mechanism, problems of wear, dirt, and corrosion are virtually eliminated. This is especially beneficial in harsh environments.

Another possibility is a virtual computer touch pad that acts as a mouse. With electrodes built in or under the desk, it could sense hand or finger positions on or above a desktop.

  The MC33794 includes:
  -- High-purity tunable sine wave generator optimized for 120 kHz;
  -- Supports up to nine electrodes and two reference capacitors;
  -- Shield driver -- reduces capacitance effects caused by using coaxial
     cables connected to remote electrodes;
  -- Lamp driver to show when a touch pad area is activated;
  -- MCU support -- includes watchdog and power-on-reset timers, a voltage
     regulator, and ISO 9141 physical layer communication interface.

Manufactured with Motorola's SMARTMOS(TM) process, the MC33794 device combines high-density, high-speed logic with precision analog and high- voltage, high-current power circuitry.

Price and Availability

The MC33794 e-field imaging IC, housed in a 44-lead HSOP (heat sink outline package), is currently available in sample and production quantities. Unit pricing starts at $3.09 USD (suggested list price) for 10,000-piece quantities.

Motorola offers an evaluation module to help reduce customers' system development cycle times. The module includes a pre-programmed MCU and necessary software for out-of-the-box measurements. The kit contains an MC33794, a Motorola 68HC908GR8 8-bit MCU, supporting components and RS232 communications port. The kit also includes documentation and software (on a CD-ROM) to assist in design evaluation. The evaluation module (part number KIT33794DHEVM) is available now for $70.00 USD (suggested list price).

About Elesys

Elesys North America Inc. designs and develops the most durable and best-engineered automotive safety systems for the world's vehicles. Elesys North America Inc. is headquartered near Atlanta, GA with sales out of Detroit, MI.

About Motorola Semiconductors

As the world's #1 producer of embedded processors, Motorola's Semiconductor Products Sector creates DigitalDNA system-on-chip solutions for a connected world. Our strong focus on wireless communications and networking enables customers to develop smarter, simpler, safer and synchronized products for the person, work team, home and automobile. Motorola's worldwide semiconductor sales were $4.8 billion (USD) in 2002. For more information please visit http://www.motorola.com/semiconductors

About Motorola

Motorola, Inc. (NYSE: MOT) is a global leader in providing integrated communications and embedded electronic solutions. Sales in 2002 were $26.7 billion. Motorola is a global corporate citizen dedicated to ethical business practices and pioneering important technologies that make things smarter and life better for people, honored traditions that began when the company was founded 75 years ago this year. For more information, please visit: www.motorola.com .

MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners.

Except for historical information, all of the expectations and assumptions, contained in the foregoing are forward-looking statements involving risk and uncertainties. Important factors that could cause actual results to differ materially from such forward-looking statements, include, but are not limited to, the competitive environment for our products, changes of rates of all related services, and legislation that may affect the industry. For additional information regarding these and other risks associated with Company's business refer to the Company's reports with the SEC.

General Backgrounder: Electric Field Imaging IC, the MC33794

Electric field (e-field) sensing provides a means for tracking electric current that can then be imaged to determine what is changing the current. It builds on the strengths of many alternative technologies, such as optical and acoustic sensing, while avoiding several of their weaknesses, such as not being able to detect objects that are not in the line of sight. The applications of low-level electric field imaging are vast, but, until recently, have been restricted by the difficulty in implementing practical electric field systems.

Evolution of E-Field Sensing and Imaging

Dr. Neil Gershenfeld is the director of the MIT Media Lab's Center for Bits and Atoms. From sensor development he originally did for a project with the cellist Yo-Yo Ma, Dr. Gershenfeld's research group studied ways to measure charges on the human body. The resulting instrumentation and algorithms were then used by magicians Penn & Teller in a "sensor chair" that channeled fields from the body and transformed them into sounds. Phil Rittmueller, vice president of Elesys North America, saw this capability demonstrated, and quickly launched a joint project with the MIT Media Lab to develop and bring to market the low-level e-field imaging technique in order to meet an urgent industry need for "smart" airbags. Elesys is a leading provider of automotive electronic safety systems.

Motorola was already a sponsor of Dr. Gershenfield's research through its DigitalDNA(TM) Laboratory at the MIT Media Lab. Engineers at Motorola realized that the 3D (three dimensional) electric charge measurement and inversion technique could be integrated onto a single chip that could enable a wide range of measurements that are contact-less, non-line-of-sight, fast, reliable and cost-effective. Elesys consequently worked with Motorola during the development of its MC33794 and is now using the chip in its occupant detection systems.

Motorola's MC33794

The MC33794 generates a high purity sign wave, steers it to one of nine electrodes and measures the resultant field coupled onto the non-driven electrode(s). A microcontroller (MCU) can be programmed to interpret the resulting data and make a determination of an object interfering in that field.

The MC33794, currently available in production quantities, features the following:

  -- High-purity tunable sine wave generator optimized for 120 kHz (not
     affected by outside noise);
  -- Supports up to nine electrodes and two reference capacitors (electrodes
     can be simple conductive material like wire, special paint, or aluminum
     foil);
  -- Shield driver (reduces capacitance effects caused by using coaxial
     cables connected to remote electrodes);
  -- Lamp driver (to show when a touch pad area is activated);
  -- MCU support (for powering of and communication with a microcontroller
     found in many electronic products)-includes watchdog and power-on-reset
     timers, a voltage regulator, and ISO 9141 physical layer interface.

The MC33794 complements Motorola's line of microcontrollers, integrated microprocessors and digital signal processors with on-chip analog-to-digital converters, such as those found in the 68HC08, HCS12, 56800/E, MPC500, MPC5500 and ColdFire(TM) families. Motorola, according to analyst firm Gartner Dataquest, is the world's leading supplier of microcontrollers (June, 2002).

Example Target Applications

The MC33794 together with electrodes and a MCU can help designers readily implement 3D imaging and sensing. The ability of this combination to detect touch can be used in a wide range of applications from automotive to consumer electronics. For example, an automatic on/off feature can easily be implemented in home appliances. A few electrodes embedded in the body a hair dryer would allow the device to turn on when picked up and turn off when set down. A few more electrodes would allow the user to control the temperature or speed by merely touching a defined location on the barrel of the dryer.

Other applications that could be simple to implement include; liquid level detection, spill detection or moisture sensing. For example, stoves with flat tops could be programmed such that when liquids boil over, the heat would be automatically reduced or tuned off.

More sophisticated applications include touch panel inputs. Here, an array of electrodes embedded in glass or behind a non-metallic surface could be sensed in a matrix fashion similar to contact switch inputs. This method eliminates membrane switches or expensive multi-layer resistive touch pads. Because the input is sensed without requiring a contact mechanism, problems of wear, dirt, and corrosion are eliminated. This is especially beneficial in harsh environments.

Another possibility is a virtual computer touch pad that acts as a mouse. With electrodes built in or under the desk, it could sense hand or finger positions on or above a desktop. With advanced software techniques, the position of an object in 3D space can be determined. An example of this is the occupant detection system, such as the one offered by Elesys.

Elesys is now using the MC33794 in its SeatSentry(TM) occupant sensing system to stop an airbag from deploying on a child. The system generates low- level electric fields from multiple antennas mounted in the seat's back cushion. The system can identify a child or small adult when the field detects and interprets a change in the current. By analyzing the changes in the various currents and by combining that information, the height of the passenger and his proximity to the side airbag is detected. If SeatSentry determines the occupant is a child or small adult, the airbag will not deploy. Currently, the occupant sensing system is in use on some Honda vehicles. For more information: http://www.motorola.com/analog

CONTACT: North America, Brian Thorsen of Motorola, +1-480-413-5209,
brian.thorsen@motorola.com , or Emilie Harris of Lois Paul & Partners,
+1-512-638-5321, emilie_harris@lpp.com ; Europe, Middle East, Africa, Regina
Cirmonova, +41-22-799-1258, regina.cirmonova@motorola.com ; Asia-Pacific,
Gloria Shiu, +852 2666 8237, gloria.shiu@motorola.com ; or Latin America, Jill
Partridge, +1-602-952-3078, jill.partridge@motorola.com , all of Motorola; or
Reader Inquiry Response: Motorola SPS, P.O. Box 17927, Denver, CO 80217 USA

Web site: http://www.motorola.com/analog

Web site: http://www.motorola.com/semiconductors

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