CC_1995_i0055.pdf

CIRCUIT

THE COMPUTER APPLICATIONS JOURNAL

lthough convenGonal wisdom holds that

embedded applications require special embedded

controllers and interfaces, we’re starting to see that

wisdom challenged. When cost, not size, is the primary

concern, off-the-shelf solutions from the desktop arena often offer a better

price/performance ratio than their semicustom cousins.

A good example is Ed’s embedded ‘386SX series. He’s been able to

show that by using inexpensive, “jelly-bean” motherboards instead of tiny,

specialized controllers, costs stay down without sacrificing performance.

I had occasion in the past few weeks to come across another example,

though with a much smaller market. Caller ID, a service provided by the local

phone companies across the U.S., provides the called party with the caller’s

phone number (and sometimes name) before answering the phone. Caller

ID boxes that display and record the data are available from many

electronics suppliers in a price range of $3C-$90. Most of these units are

stand-alone devices, though. Interfacing them with a computer to make

further use of the information is a costly and kludgy proposition.

Some of these boxes do have a serial port tacked on the side, but it

drives the price up well over $100 for the unit. There is a better alternative.

If you can do without the fancy display (e.g., your application uses a

voice to notify you who’s calling), many modems on the market today offer

Caller ID as an additional feature to the normal data and fax capabilities.

Why pay over $100 for a box that does nothing but Caller ID when you can

get a modem to do the whole deal for under $130?

Another good example of reusing other solutions can be found in one

of our articles this month. Infrared-based printers intended for use with

intelligent calculators are inexpensive and readily available. Using them in

an embedded application is a simple matter of knowing what IR codes to

send. Why pay triple the price for a special-function, battery-operated printer

when a low-cost, canned solution exists?

Such economies of scale helped put a virtual end to build-your-own

PCs (though no amount of monetary savings could match the pleasure many

of our readers derive from making their own). This trend is now moving into

the embedded peripheral market where A/D converter boards, Caller ID

boxes, and tiny printers have so many features included that it doesn’t make

sense to roil your own. The functional& is already there! And who has the

time or money, anyway?

There will always be a place for custom and semicustom solutions,

especially with constraints on size, weight, power usage, and so forth. Such

engineering is our lifeblood. We just have to be sure to keep an open mind

when design specs aren’t tight.

FOlJNDEWEDlTORlAL DIRECTOR

PUBLISHER

Steve Ciarcia

Daniel Rodrigues

EDITOR-IN-CHIEF

PUBLISHER’S ASSISTANT

Sue Hodge

TECHNICAL EDITOR

CIRCULATION COORDINATOR

Janice Marinelli

Rose Mansella

ENGINEERING STAFF

CIRCULATION ASSISTANT

Jeff Bachiochi & Ed Nisley

Barbara Maleski

WEST COAST EDITOR

CIRCULATION CONSULTANT

Tom Cantrell

Gregory Spitzfaden

CONTRIBUTING EDITOR

BUSINESS MANAGER

NEW PRODUCTS EDITOR

ADVERTISING COORDINATOR

Harv Weiner

Dan Gorsky

ART DIRECTOR

CIRCUIT CELLAR INK, THE COMPUTER APPLICA-

Lisa Ferry

TIONS JOURNAL (ISSN 0696-6985) IS published

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Issue #55 February 1995

Circuit Cellar INK

Ken Davidson

John Dybowski

Jeannette Walters

Pellervo Kaskinen

Interfacing Flow Meters to High-speed Counters

by Bill Payne

Use Infrared to Make Embedded Printing Easy

by leff Fisher

It’s Not Just for Memory Anymore

An Introduction to PCMCIA

by Lalo J. Gastriani

Speeding and Slimming Your Port Access

A Different Way of Reading from the PC Parallel Port

by Tracey Lee e9 Kok-Leong Ong

Battery-operated Power Supplies

Selecting the Right Battery and Supply for Your Application

by David Prutchi

¦ Firmware Furnace

Journey to the Protected Land: Infrastructure Improvement

Ed Nisley

¦ From the Bench

Fitting 10 oz. into a 5-0~. Package

An Application for Highway Safety

/eff Bachiochi

¦ Silicon Update

I Sync, Therefore I DRAM

Tom Can trell

¦ Embedded Techniques

Downsizing

Atmel’s AT89C205 1 Flash-based Microcontroller

[ohn Dybowski

Letters to the Editor

New Product News

edited by Harv Weiner

Circuit Cellar INK

Issue #55 February 1995

NEW COVER-A STEP UP

I got the latest INK today-very professional

looking. It reminds me of PopuIur Science or such. Of

course, the contents are much better than those other

magazines!

Hope y’all have a great ‘95

P.S.: Thanks for sending a replacement for the issue

that the postal service mangled.

Editor’s Note: The March issue features fuzzy logic and

will be offering two fuzzy-pong designs. Be sure to pick

up a copy so you can compare Tom’s technique with a

fuzzy approach.

Russ Reiss

Bolton, CT

PRAISE AND FIXES

I really enjoy Ed Nisley’s series on protected-mode

programming. At the moment, my only application is

writing assembly language subprograms to run under

Lahey FORTRAN F77L EM/32, which runs under the

Pharlap DOS extender. Even so, I’ve found several

helpful nuggets of information. If Ed wants to explain

how to write an interrupt service routine for IRQ2

(vertical retrace) running in protected mode under

Pharlap, I wouldn’t mind at all.

As an ancient controls engineer (MIT ‘57), I noticed

that Tom Cantrell’s PID-pong control loop has the

gains set wrong. The response shown in Figure 5 (INK

50) is much too oscillatory. You can see, not quite

hidden by the noise, a slowly decaying sine wave in the

fan plot starting after each change in the position

setpoint.

The frequency of the sine wave is the natural

frequency of the entire system; it shouldn’t be so

prominent in the responses. In a well-designed system,

it would damp out in a couple of cycles or less after a

change in setpoint. With this design, the motor has to

work too hard and there is little stability margin. A few

decibels gain increase (temperature or whatever) could

make the design unstable.

To improve the response, set the gain to zero. Try

reducing the P gain or increasing the D gain. Up to a

point, increasing the D gain allows for higher values of

the P gain without making the response too oscillatory.

Once you get good values for the P and D gains,

increase the I gain as far as possible without spoiling

the transient response. Small test inputs should be used

in this stage. Finally, adjust the nonlinear parameters

for the largest inputs you expect.

FOR YOUR INFORMATION

Thank you for featuring fuzzyTECH-MP, Microchip

Technology Inc.‘s new fuzzy logic development tool, in

your December ‘94 issue. Several readers have asked us

how to obtain more information about Inform Software

Corporation, Evanston, Ill., who developed the fuzzy

logic tool suites for this device. Inform Software can be

reached at (800) 929-28 15. The fuzzyTECH-MP product

is available only through any Microchip worldwide sales

office and authorized dealer or by calling (602) 786-7668.

Eric Sells

Public Relations Manager

Microchip Technology, Inc.

Contacting Circuit Cellar

We at Circuit Cellar INKencourage communication between

our readers and our staff, so have made every effort to make

contacting us easy. We prefer electronic communications, but

feel free to use any of the following:

Mail: Letters to the Editor may be sent to: Editor, Circuit Cellar INK,

4 Park St., Vernon, CT 06066.

Phone: Direct all subscription inquiries to (800) 269-6301.

Contact our editorial offices at (203) 875-2199.

Fax: All faxes may be sent to (203) 872-2204.

BBS: All of our editors and regular authors frequent the Circuit

Cellar BBS and are available to answer questions. Call

(203) 871-1988 with your modem (300-14.4k bps, 8Nl).

Internet: Electronic mail may also be sent to our editors and

regular authors via the Internet. To determine a particular

person’s Internet address, use their name as it appears in

the masthead or by-line, insert a period between their first

and last names, and append ‘Qcircellarcom” to the end.

For example, to send Internet E-mail to Jeff Bachiochi,

address it to jeff.bachiochi@circeIlar.com. For more

information, send E-mail to info@circellar.com.

James C. Wilcox

Palos Verdes Estates CA

Issue #55 February 1995

Circuit Cellar INK

IN-J ~BI~(NEW~

B B

Edited by Harv Weiner

MINIATURE CCD CAMERA

A miniature breadboard-type CCD black & white camera (1.26” x 1.26”

x 0.75”) is available from Edmund Scientific. The camera can be used for

home and office security, robotics, machine vision, and instrumentation

applications.

The unit produces video output with an automatic electronic shutter

and features a 3.7-mm pinhole lens built into the breadboard assembly. The

field of view is 45” vertical x 60” horizontal with 32-mm x 32-mm dimen-

sions. Miniature details can be observed on a TV monitor from a range of

only inches up to 15’ with a 0.3-1~~ minimum illumination. Resolution is

380 TV lines horizontal by 350 lines vertical. The unit uses 9-VDC input.

Edmund Scientific Co.

Dept. 14B1, N999 Edscorp Bldg. Barrington, NJ 08007

(609) 573-6259 Fax: (609) 573-6295

#500

EMBEDDED SYSTEM DEVELOPMENT TOOLS

Phar Lap’s new TNT Embedded ToolSuite delivers a total solution for 32.bit embedded-systems development on

the Intel 386/486 family of microprocessors. The suite offers an easy and cost-effective, one-stop solution for building

embedded applications using popular DOS and Windows compilers. Supported compilers include 32-bit C/C++

products from Borland, Microsoft, and MetaWare.

The ToolSuite’s components include the TNT Embedded Kernel, Visual System Builder, LinkLoc (a 32.bit linker

and locator), and CVEMB and TDEMB shells for embedded cross-debugging. Full support for C/C++ run-time librar-

ies, an MS-DOS-compatible file system, and a floating-point-emulation library are also included.

The TNT Embedded Kernel provides a simple operating system for running embedded programs. Its two main

functions are to initialize 32.bit protected mode and provide the foundation for running a C/C++ run-time library.

These functions can save development time since developers don’t have to set up their own protected-mode environ-

ment or learn new run-time libraries. The Kernel can be loaded from ROM or diskette. The Kernel also includes a

floating-point emulator, native MS-DOS file system, and a remote file system.

The Visual System Builder enables developers to configure and customize the TNT Kernel to match their

hardware setup through an easy-to-use Windows utility. Developers can specify where memory is located in the

target, how the kernel is loaded into memory, and how the target system communicates with the debugger.

As a sophisticated one-step linker/locator,

LinkLoc builds embedded applications that run

on the TNT Embedded Kernel. LinkLoc includes

a rich set of command switches to control the

entire link process. It can provide full symbolic

information for C/C++ source-level debugging

with CodeView or Turbo Debugger. In addition,

it can output files for an in-circuit emulator or

PROM programmer.

The TNT Embedded ToolSuite sells for

$2995. Requirements include a PC-compatible

host computer running DOS and Windows 3.1.

Phar Lap Software, Inc.

60 Aberdeen Ave. Cambridge, MA 02138

(617) 661-l 510 Fax: (617) 876-2972

#I501

Issue #55 February 1995

Circuit Cellar INK

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