CC_1993_i0036.pdf

CIRCUIT CELLAR F] ~~~~ ~

THE COMPUTER

APPLICATIONS

JOURNAL

FOUNDER/EDITORIAL DIRECTOR

Steve Ciarcia

PUBLISHER

Daniel Rodrigues

EDITOR-IN-CHIEF

I(en Davidson

PUBLISHER’S ASSISTANT

Susan McGill

TECHNICAL EDITOR

Michael Swartzendruber

CIRCULATION COORDINATOR

Rose Mansella

the art of writing programs that must deal with real-world

situations and must react in real time to a variety of external stimuli.

I then twisted the topic around and wondered, what about “program-

ming in real time?” An interesting idea to toss around. When you think about

the traditional programming process, you conjure thoughts of Twinkie-driven

late-night sessions banging at the keyboard (and banging your head against

the wall) trying to find an elusive bug that only affects one small facet of your

code. A short program run typically represents hours of effort.

My new idea elicits visions of a super programmer, hands poised over

the keyboard, ready to spit out reams of code in response to some real-

world stimuli to control a reaction as the action takes place.

Ludicrous? Perhaps not. Take the example of training a robot. You

manually direct it to perform some action and the robot dutifully records all

your actions. When you play back the “program,” the robot repeats the task

exactly as you trained it. In the strictest sense of the phrase, you just

programmed the robot in real time.

Moving back to reality, our first feature article this month delves into

one of the latest crazes in programming circles: object-oriented program-

ming. If you thought OOP’s usefulness was limited to windowing environ-

ments, think again. OOP is simply a methodology that is equally helpful in

generating solid embedded programs that run in real time.

Another misnomer in programming circles is that you can’t do

multitasking under MS-DOS. Using the parent-child technique described in

our second article, you can manage those pesky interrupts that often crash a

machine attempting to do two things at once.

Following up on last month’s modem introduction, Technical Editor

Michael Swattzendruber finished his Gemini modem with some actual

hardware.

In our columns, Ed adds some nonvolatile memory to the embedded

‘386SX project; Jeff looks at an old friend and breathes new life into its

limited existence; Tom explores a nifty new technology that directly stores

analog data without the digital middleman; John starts a pair of articles on

the mysteries of recharging batteries; and Russ pulls up patents covering

topics such as in-seat aircraft passenger flight information, encoding

information on a video signal, and an electronic still-video camera.

RSSOCIATE EDITOR

Robert Rojas

CIRCULATION ASSISTANT

Barbara Maleski

ENGtNEERlNG STAFF

Jeff Bachiochi & Ed Nisley

CIRCULATION CONSULTANT

Gregory Spitzfaden

WEST COAST EDITOR

Tom Cantrell

BUSINESS MANAGER

JeannetIe Walters

CONTRIBUTING EDITORS

John Dybowski & Russ Reiss

ADVERTISING COORDINATOR

Dan Gorsky

MEW PRODUCTS EDITOR

iarv Weiner

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Issue #36 July 1993

The Computer Applications Journal

14 Object-oriented Programming in

Embedded Systems

by Mike Podanoffsky

26 PC Parent-Child Programming: A Path to

Multitasking Under DOS

by H. Bradford Thompson

38 High-speed Modem Basics: The Working Hardware

by Michael Swartzendruber

46 ¦ Firmware Furnace

Memories are Made of This: The ‘386SX

Project Goes Nonvolatile

Ed Nisley

56 ¦ From the Bench

Breathing Life into an Old Friend:

Revisiting the 28

Teff Bach&hi

62 ¦ Silicon Update

Talking Chips

Tom Can trell

70 ¦ Embedded Techniques

The Art of Battery Management

Tohn Dybowski

Ken Davidson

Code on the Fly

the Circuit Cellar BBS

conducted by

Ken Davidson

Reader’s INK

~ Letters to the Editor

Steve’s Own INK

Steve Ciarcia

PC Clone $5,000

New Product News

, edited by Harv Weiner

~ Patent Talk

The Computer Applications Journal

lssue#36 July1993 3

TEMPERATURE MONITORING week, and year; weather conditions; forecasted weather

Your article on Temperature Monitoring in the conditions; and knowledge of any special events pro-

February ‘93 issue of The Computer Applications Journal grammed

was outstanding. For a person like me who has spent *control operation of all heat/cooling systems on

many hours considering the same subject, the informa- site including monitoring and recording time active,

tion you presented was well received. heating/cooling fluid output and input temperatures,

Since you have helped me, let me try to make you rate of fluid flow, energy source, and rate of energy

see your project in a different light. The thoughts I am absorption

about to present are not solely about heating a solarium .compute heat transfer for each room, each wall (or

but about home automation. I am a member of EIA’s ceiling), and the building

CEBus Working Group putting the standard together. I *determine the heat/cooling supplied to the building

personally do not believe automating devices is what and compute power plant efficiencies

home automation is about. I doubt that such products *control ceiling fans and motorized window blinds

will ever sell to the American public. The reasons are so to support attaining the desired thermal profile

numerous and so subjective that it would really waste I have carefully left the definition of the Thermal

my time to list them and yours to read them. This letter Profile to your imagination. It can get as sophisticated as

is on home automation: a different viewpoint. one wishes. However, information on heat transfer,

The task you have undertaken is not stated as a goal. power plant efficiencies, and solar heating capability are

I have not read your prior articles but I surmise that, at numbers that every automated home should have. These

least initially, you wanted to add a solarium to your are valuable byproducts of the system described. They

home to enjoy a few of the benefits of Mother Nature indicate how well your systems are functioning, their

such as solar heating and unobstructed views of outdoor deficiencies, your home’s deficiencies, and also give

life in Connecticut. I’ve gone through the same thinking clear indication when they are failing. It is one form of

process but I haven’t had the guts to go as far as you. Integrated Diagnostics.

Like a living room, your apparent thinking has I am what Jeff Fisher referred to as an OOZ: an

focused on keeping the temperature at a constant 72” F. Object Oriented Zealot. He clearly pointed out that

This is as expected, but let me list some other require- CEBus was not completely object oriented. The type of

ments you could have added. They represent system- system I have described requires the application of

level requirements for a home automation system. object-oriented technology. I have built a model of a

The home has to be looked at as an entity. When hotel building in Las Vegas to demonstrate the ease of

initially designed by an architect, a complete thermal computing heat transfer. The model could be attached to

analysis was made to assure that the structure would building HVAC systems to provide control and history

provide a comfortable environment over the four seasons. information. That is the basis of my approach to home

Consideration was given to orientations on the building automation. All control of hardware originates in

site, shading, wall thickness, insulation, HVAC sizing, software models that capture the hardware functionality

window locations, colors of roof coverings, and so forth. and “know” how the hardware should respond to

The number of building parameters that come into play current operational conditions-and does just that.

is extensive. If a builder or an architect can do this, why CEBus is needed to send messages from node to

can’t that information be placed in a computer and that node in the home environment. These messages are seen

machine be used to manage the complete thermal by most as moving from device to device; from the

situation for the household? controller to the controlled. In the system that I visual-

This is what I want my Thermal Manager to do: ize, the messages move from software structure to

*know the thermal profile I wish for each room in software structure; from object to object. Control

the house software in the node determines how a node should

*continuously compute heat transfer to and from the function and does so.

room based on physical characteristics of the room, the

I wish you well on your solarium project. There are

heat supplied or removed from the room by in-house

more people out there trying to do the same type of

heat/cooling sources, and the heat transferred to or from

thing than you probably realize.

the room due to condition of the outside environment

*follow the thermal profile based on sensor data that

Frank Edden

provides actual temperatures; occupancy; time of day,

The Workhouse, Huntington, N.Y.

Issue #36 July 1993

The Computer Applications Journal

EMBEDDED DEVELOPMENT ON A MAC

would prefer to use their Macintosh to develop software

I just read “Steve’s Own INK” in the March issue. I

controllers?

agree most vigorously with his article “PC Trials,” about

what a pain the PC is to set up and make run in the

Fred Johnson

Windows environment. I have watched the pain of one

Knoxville, III.

friend who tries to keep a dozen ‘386s running Windows

limping along in the local junior college. These comput-

We, too, have noticed a distinct lack of microcontroller

development tools designed to run on the Mac. Perhaps

ers are only used for instructing classes on DOS, word

one of our readers has more information that they’d be

processing, databases, and spreadsheets.

willing to share with us.-Editor

I have another friend in the same college who keeps

the Macintosh computer lab running. His Mac network

has a larger number of computers of tremendous variety.

We Want to Hear from You

The interesting thing is, just like in the commercial

Steve cites, the Mac users have few problems.

We encourage our readers to write letters of praise,

Now for my question: I use Macintoshes for every-

the Computer Applications Journal. Send them to:

thing I can in my business, but I have noticed a real lack

run on my Mac II. Much of the hardware that I would The Computer Applications Journal

like to use is designed for the PC parallel port, not a nice letters to the Editor

serial port that I could use. How about an article on

what software and hardware is available for people who

4 Park Street

Vernon, CT 06066

stops her;

And the headaches, cold sweats and other symptoms associated

with debugging real-time embedded applications. Paradigm

DEBUG offers you choices: Intel or NEC microprocessors

Remote target or in-circuit emulator support C, C++ and

assembler debugging Borland, Microsoft and Intel compatibility.

Kickstart vour embedded system with the onlv debugger familv

to have it all. Give us a

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fbven ~OhdiOfU for Embedded c/c++ ~eVe@?rS

PARADIGM: (607) 748-5966

FAX: (607) 748-5968

HO3

The Computer Applications Journal

Issue #36 July 1993

condemnation, or suggestion to the editors of

of cross-compilers and development systems that will

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