CC_1999_i0112.pdf

(1197 KB) Pobierz
T H E M A G A Z I N E F O R C O M P U T E R A P P L I C AT I O N S
ANALOG TECHNIQUES
Dual-Slope ADC Techniques
#112 NOVEMBER 1999
CIRCUIT
CELLAR
®
Build an Autoranging Frequency Counter
HDTV—HD Formats and
Signal Transportation
Protocol Implementation
Using IrDA Solutions
www.circuitcellar.com
Double your technical pleasure each month. After you read
Circuit Cellar
magazine, get a
second shot of engineering adrenaline with
Circuit Cellar Online,
hosted by ChipCenter.
— FEATURES —
A Switcher for Many Reasons
Lawrence Foltzer
Need a quick solution for a variable high-voltage applica-
tion? Lawrence shows us that the answer may be as
simple as making a variable burst length, fixed duty-
cycle switching power supply driven by an RC-clocked
PIC microcontroller.
— COLUMNS —
Considering the Details
I/O for Embedded Controllers—Part 2: Analog I/O
Bob Perrin
Embedded systems are used in so many different applications,
it’s impossible to cover all possible analog I/O requirements.
In Part 2 of this series on I/O, Bob offers a few circuits and
components that have proven adequate for many applications
in the past.
Embedded Systems
n-Formation
Implementing an
n-Tiered
Client-Server Architecture
Mark Taylor
In corporate environments, who knows what depends on
who knows who, and who knows who depends on who who
is. As Mark shows us, the
n-tiered
architecture was de-
signed to make sure the right people have access to the
information they need.
Lessons from the Trenches
Timing is Everything
George Martin
If you’ve ever wanted to choke the person who made up a
project design schedule, or if you are the one responsible for
making the schedules, you might want to listen to what
George has to say about the importance and benefits of mak-
ing a realistic, achievable, and practical plan for bringing
your design to completion.
Testing 1, 2
Part 4: Immunity—Not for Circuitry
George Novacek
Your design needs to be rock solid regardless of what
frequency is thrown at it—and that’s a lot these days with
the proliferation of cellular phones, radar, and microwave
technology. And, your design needs to keep its radiation of
frequency to itself as well. Check in with George to find
out what tests the lab will throw at your design to make
sure it’s ready for the real world.
Silicon Update Online
16-Bits or Bust
Tom Cantrell
If 8-bit chips are the compact pickup truck and 32-bit
chips are the Corvettes, what does that make the
16-bit chips? Tom does some homework
and hopes to find out exactly
where 16-bit chips fit
in the MCU
market.
Resource Links
• The 80186
•
RS-485 Multidrop Networking
Benjamin Day
W
.
C
WW
CU
IR
CE
IT
OM
R
.
e
C
LLA
abl
T
ctob
rO
s fo
t
nten
o
of C
/
O
E
IN
er 1999
NL
Connect Your PIC to the Internet
• Fuel Cells and Radioisotope Heater Units
• Joint Test Action Group (JTAG) IEEE 1149.1 and IEEE 1149.4
Bob Paddock
Test Your EQ
8 Additional Questions
NOW, GETTING CONNECTED TO THE
INTERNET CAN EARN YOU CASH
www.circuitcellar.com/pic2000
www.circuitcellar.com
Internet
000
PIC
2
contest
®
2
Issue 112
November 1999
CIRCUIT CELLAR
®
12
20
26
36
60
66
74
78
Build a MIDI Sustain Pedal
Bill Dudley
Working with a Dual-Slope ADC
Richard Lao
Embedded Living
Tuning into the HA Channel
Mike Baptiste
What’s the Count?
Build an AVR-Controlled Frequency Counter
Stuart Ball
IrDA Technology
Part 2: Protocol Layers
Hari Ramachandran
I
MicroSeries
High-Definition TV
Part 1: Video Formats and Transport
Mark Balch
From the Bench
Without Acceleration
Part 1: All We Have Left is Velocity
Jeff Bachiochi
Silicon Update
LPC—The Little Processor that Could
Tom Cantrell
I
Task Manager
Elizabeth Laurençot
Household Variable =
Steady Work
New Product News
edited by Harv Weiner
Test Your EQ
Advertiser’s Index
December Preview
Priority Interrupt
Steve Ciarcia
Another Typical Trip
6
8
83
95
96
I
ISSU
44
Nouveau PC
edited by Harv Weiner
INS
46
RPC
52
APC
IDE
E
Real-Time PC
Serial Port Interfacing
Ingo Cyliax
Applied PCs
Sending a DOS Stamp Airmail
Fred Eady
11
2
Issue 112
www.circuitcellar.com
CIRCUIT CELLAR
®
November 1999
3
TASK
MANAGER
Household Variable = Steady Work
he theme of this issue—analog techniques—
should bring to mind projects that have to do
with measuring a continuous physical variable.
Think voltage. Think pressure. Think TV.
Huh? One “continuous physical variable,” in my household at least, is
the television—although as far as we’re concerned, the primary variable
concerns who has control of the remote and which channel is currently
being broadcast into our living room.
And as for how this variable may change over time, I imagine that a
decade from now, we’ll still spend some of our time watching the tube. But
of course, now we’re being told that it’s not going to be the same old TV
after all. As our MicroSeries columnist this month, Mark Balch, tells us,
there’s no doubt that high-definition television is coming to stay.
There’s a bit of time before the FCC-mandated curtain falls in 2006, and
to tell the truth, I haven’t been all that interested in high-definition technol-
ogy so far. In fact, I’ve been wondering, what’s all the fuss? So we get a
wider view of the TV—so what? Just what my family needs: more screen to
stare at, right?
However, I decided to investigate a bit further what else HDTV has in
store for us. After reviewing some of the information in one of the online
newsletters devoted to HDTV, I’m starting to get a clearer picture of the
benefits of the technology. I visited http://web-star.com/hdtv, but a quick
Internet search will show you how
many
of these newsletters are out there!
One exciting area is the high-quality imaging necessary for flight simula-
tors. Apparently, top-end flight simulators have to deal with compatibility of
line rates and aspect ratio, the overlaying/compositing of multiple images to
obtain realistic effects, and splitting the output of image generators to feed
several display devices simultaneously.
On the educational and cultural fronts, you’ll find high-definition devices
at museums and schools as well. For example, museums will offer wall-size
video displays and kiosks showing slide-quality images of various artworks.
As might concern you more personally, if you have a health issue to
resolve, consider the impact of high-resolution systems on medical imaging.
According to Dr. Robert Brecht at the University of Texas Department of
Biomedical Communications, “Subjects that make NTSC an insufficient
visual medium are pathology, radiology (they don’t like anything under 1000
lines), microanatomy, telediagnosis, and CAD-CAM.”
It sure looks like a lot of these high-definition imaging systems are part
of various embedded systems. So, after you get more HDTV info from
Mark’s series, I hope you’ll be motivated to hit the power-off switch on your
own remote control and spend your time designing some cost-effective,
viable, high-resolution devices for our everyday lives.
t
THE MAGAZINE FOR COMPUTER APPLICATIONS
EDITORIAL DIRECTOR/PUBLISHER
Steve Ciarcia
MANAGING EDITOR
Elizabeth Laurençot
SENIOR TECHNICAL EDITORS
Steve Meyst
TECHNICAL EDITORS
Michael Palumbo
Rob Walker
WEST COAST EDITOR
Tom Cantrell
CONTRIBUTING EDITORS
Mike Baptiste Ingo Cyliax
George Martin Bob Perrin
NEW PRODUCTS EDITOR
Harv Weiner
PROJECT EDITOR
Janice Hughes
Ingo Cyliax
Fred Eady
ASSOCIATE PUBLISHER
Sue Skolnick
CIRCULATION MANAGER
Rose Mansella
CHIEF FINANCIAL OFFICER
Jeannette Ciarcia
CUSTOMER SERVICE
Elaine Johnston
ART DIRECTOR
KC Zienka
GRAPHIC DESIGNER
Jessica Nutt
ENGINEERING STAFF
Jeff Bachiochi
Steve Bedford
Ken Davidson
John Gorsky
EDITORIAL ADVISORY BOARD
Norman Jackson
David Prutchi
Cover photograph Ron Meadows—Meadows Marketing
PRINTED IN THE UNITED STATES
ADVERTISING
ADVERTISING SALES MANAGER
Bobbi Yush
Fax: (860) 871-0411
(860) 872-3064
E-mail: bobbi.yush@circuitcellar.com
ADVERTISING COORDINATOR
Valerie Luster
(860) 875-2199
ADVERTISING CLERK
Fax: (860) 871-0411
E-mail: val.luster@circuitcellar.com
Sally Collins
CONTACTING CIRCUIT CELLAR
SUBSCRIPTIONS:
INFORMATION: www.circuitcellar.com or subscribe@circuitcellar.com
TO SUBSCRIBE: (800) 269-6301 or via our editorial offices: (860) 875-2199
GENERAL INFORMATION:
TELEPHONE: (860) 875-2199
FAX: (860) 871-0411
INTERNET: info@circuitcellar.com, editor@circuitcellar.com, or www.circuitcellar.com
EDITORIAL OFFICES: Editor, Circuit Cellar, 4 Park St., Vernon, CT 06066
AUTHOR CONTACT:
E-MAIL: Author addresses (when available) included at the end of each article.
ARTICLE FILES: ftp.circuitcellar.com
For information on authorized reprints of articles,
contact Jeannette Ciarcia (860) 875-2199 or e-mail jciarcia@circuitcellar.com.
CIRCUIT CELLAR
®
, THE COMPUTER APPLICATIONS JOURNAL (ISSN 0896-8985) is published monthly by Circuit Cellar
Incorporated, 4 Park Street, Suite 20, Vernon, CT 06066 (860) 875-2751. Periodical rates paid at Vernon, CT and additional offices.
One-year (12 issues) subscription rate USA and possessions $21.95, Canada/Mexico $31.95, all other countries $49.95.
Two-year (24 issues) subscription rate USA and possessions $39, Canada/Mexico $55, all other countries $85.
All
subscription orders payable in U.S. funds only via VISA, MasterCard, international postal money order, or check drawn on U.S. bank.
Direct subscription orders and subscription-related questions to Circuit Cellar Subscriptions, P.O. Box 698, Holmes, PA
19043-9613 or call (800) 269-6301.
Postmaster:
Send address changes to Circuit Cellar, Circulation Dept., P.O. Box 698, Holmes, PA 19043-9613.
elizabeth.laurencot@circuitcellar.com
6
Issue 112 November 1999
Circuit Cellar
®
makes no warranties and assumes no responsibility or liability of any kind for errors in these programs or schematics
or for the consequences of any such errors. Furthermore, because of possible variation in the quality and condition of materials and
workmanship of reader-assembled projects,
Circuit Cellar
®
disclaims any responsiblity for the safe and proper function of reader-
assembled projects based upon or from plans, descriptions, or information published in
Circuit Cellar
®
.
Entire contents copyright © 1999 by Circuit Cellar Incorporated. All rights reserved. Circuit Cellar and
Circuit Cellar INK
are registered
trademarks of Circuit Cellar Inc. Reproduction of this publication in whole or in part without written consent from Circuit Cellar Inc.
is prohibited.
CIRCUIT CELLAR
®
www.circuitcellar.com
NEW PRODUCT
NEWS
Edited by Harv Weiner
DIFFERENTIAL AMPLIFIER
The
DFA 5
is a low-voltage differential amplifier
for test and measurement applications. Gain settings
from 1 to 1000 are switch selectable and have an ac-
curacy of 1%. The unit may be used as either a differ-
ential mode or a single-ended mode amplifier. With
common-mode noise rejection that exceeds 100 dB,
the DFA 5 makes low-voltage measurements straight-
forward. The unit is suitable for use with oscillo-
scopes and other common test equipment.
The DFA 5 is designed to amplify differential sig-
nals ranging from several volts down to microvolts.
Maximum frequency depends on the gain setting, and
ranges from 20 kHz at a gain of 1000 to over 1 MHz at
unity gain. The unit allows for both AC and DC cou-
pling, with an AC mode low-frequency cutoff of
10 Hz using nonattenuating probes.
The unit is small, lightweight, and low in cost. It
can run for days on its internal battery or be powered
by an external power source.
The DFA 5 sells for
$129.
EVALUATION KIT FOR GPS RECEIVER MODULES
The
SGM5600EK
is a kit for evaluating GPS
receiver modules. It includes the SiGEM SGM3900
low-noise GPS active antenna, 9-V AC adapter,
automobile power plug, 7.5′ serial cable, CD mapping
software, and SiGEM’s SGM5606PS GPS receiver.
There is an NMEA serial port, a DGPS serial port, a
satellite lock indicator (LED), and a hardware reset
button on the front panel. A switchable 3.3- or 5-V
DC feed to an active antenna is also included. The
antenna has a noise figure of less than 1 dB and
consumes less than 20 mW.
DGPS corrections can also be provided to the GPS
receiver internally, by mounting a suitable DGPS
card, or externally, by connecting to the serial port
through an RS-232 interface. Extra internal board
space permits customization. An 8–15-V input
supply range is available.
The GPS receiver module communicates with
computers via NMEA 0183-formatted messages.
MapSite software is bundled with the evaluation kit
and provides an accurate picture of GPS position,
track, waypoints, and the route between them. It can
also create maps from compatible scanned maps and
works well with commercially available digital raster
maps. The software can be used to record real-time
position information and track from the SiGEM GPS
receiver. Sentences are in GCA, GSA, GSV, and VTG
NMEA formats. The SiGEM modules also support
RTCA-SC159, WAAS, and EGNOS DGPS data
formats. ToolKit software is also provided for inte-
grating GPS functions into Visual Basic applications.
The SGM5600EK evaluation kit sells for
$299, or
for
$379 including MapSite and ToolKit.
Allison Technology Corp.
(281) 239-8500
Fax: (281) 239-8006
www.atcweb.com
SiGEM, Inc.
(613) 271-1601 • Fax: (613) 271-1896
www.sigem.ca
8
Issue 112 November 1999
CIRCUIT CELLAR
®
www.circuitcellar.com

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika:

Zgłoś jeśli naruszono regulamin