Circuit Cellar (April 2007)

100 Pages·2007·17.43 MB·English

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#201 April 2007
CIRCUIT
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THE MAGAZINE FOR COMPUTER APPLICATIONS
EMBEDDED PROGRAMMING
MCU-Based Keyboard Interface
Reverse-Engineered
ECP Bus
Create a Modbus Master
Embedded RF
Communication
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7 25274 75349 9
$4.95 U.S. ($5.95 Canada)
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201_Task_Masthead.qxp 3/6/2007 9:30 AM Page 4
TASK MANAGER
The Cruelest Month?
FOUNDER/EDITORIAL DIRECTOR CHIEF FINANCIAL OFFICER
E Steve Ciarcia Jeannette Ciarcia
ven if you spent your college years working with circuit boards and MANAGING EDITOR MEDIA CONSULTANT
writing code, you’re probably familiar with the famous first sentence of C.J.Abate Dan Rodrigues
the poet T.S.Eliot’s modernist masterpiece, The Waste Land(1922): WEST COAST EDITOR CUSTOMER SERVICE
Tom Cantrell Debbie Lavoie
“April is the cruelest month—”
CONTRIBUTING EDITORS CONTROLLER
You may have heard a few exhausted bookkeepers and accountants Jeff Bachiochi Jeff Yanco
Ingo Cyliax
mumble that line a few times too.Tax season, right? ART DIRECTOR
Fred Eady
Well, we here at Circuit Cellarhave a different take on April.It’s a George Martin KC Prescott
great month.Not only are we now past the days of sleet, snow, and Ed Nisley GRAPHIC DESIGNER
Mary (Turek) Sobuta
dark commutes to and from the office, we have a lot of exciting things NEWPRODUCTSEDITOR
on our plate—which is your plate too, of course. John Gorsky STAFF ENGINEER
John Gorsky
This month we’re off to the Embedded Systems Conference in San PROJECT EDITORS
Steve Bedford
Jose, where we plan to spend the entire week talking everything
Ken Davidson
embedded with our readers and advertisers.Look for our booth.We David Tweed
hope to see you there!
ASSOCIATE EDITOR
The Microchip 16-Bit Embedded Control Design Contest also kicks Jesse Smolin
off this month.As you know, we’ve brought you a lot of amazing con-
tests over the years.This one is sure to create a lot of buzz in the design
ADVERTISING
community.With a handful of amazing eligible parts to choose from, this 860.875.2199 • Fax:[phone] (cid:129) www.circuitcellar.com/advertise
contest is going to get competitive quick.Ready to hit the workbench?
PUBLISHER
On the editorial front, we’re excited about the articles in this issue. Sean Donnelly
On page 12, we begin with an article about Steven Savage’s award-win- Direct:860.872.3064, Cell:860.930.4326, E-mail:[email protected]
ning ATir keyboard interface design.This project won him First Prize in ADVERTISINGREPRESENTATIVE
the Atmel AVR Design Contest 2006.If you’re preparing a project for the Shannon Barraclough
Direct:860.872.3064, E-mail:[email protected]
new Microchip contest, be sure to check out this article.Steven shows
ADVERTISINGCOORDINATOR
what it takes to put together a winning project.
Valerie Luster
Another project-inspiring design is Tom Kibalo’s Java-based 1-Wire E-mail:[email protected]
distributed watering system (p.20).Tom used his hardware and soft-
ware skills to build a handy system to water plants in six EarthBoxes.
Cover photography by Chris Rakoczy—Rakoczy Photography
Even if gardening isn’t your thing, you can use the principles he covers www.rakoczyphoto.com
to design and program a multiple-module system for other purposes. PRINTED IN THE UNITED STATES
At the end of his article about the watering system, Tom writes that
CONTACTS
he plans to use ZigBee technology to extend the system’s range SUBSCRIPTIONS
beyond its 1-Wire limitations.Well, you don’t need to wait until Tom Information:www.circuitcellar.com/subscribe, E-mail:[email protected]
Subscribe:800.269.6301, www.circuitcellar.com/subscribe, Circuit Cellar Subscriptions, P.O.Box 5650,
upgrades his system and writes another article.Why not take Fred Hanover, NH 03755-5650
Address Changes/Problems:E-mail:[email protected]
Eady’s advice and implement the technology in a system of your own?
GENERAL INFORMATION
In“Uncomplicated RF Communication”(p.45), Fred shows you how to 860.875.2199, Fax:[phone], E-mail:[email protected]
EditorialOffice:Editor, Circuit Cellar, 4 Park St., Vernon, CT 06066, E-mail:[email protected]
get your system on the air. NewProducts:New Products, Circuit Cellar, 4 Park St., Vernon, CT 06066, E-mail:[email protected]
On page 28, Gordon Dick describes how he designed and built a three- AUTHORIZED REPRINTSINFORMATION
860.875.2199, E-mail:[email protected]
axis CNC mill machine.The easy-to-move machine is a great project for AUTHORS
Authors’e-mail addresses (when available) are included at the end of each article.
anyone who loves design and woodworking.It features an old laptop, an
intelligent motion controller, and an old X-ray machine.
CIRCUIT CELLAR®, THE MAGAZINE FOR COMPUTER APPLICATIONS (ISSN 1528-0608) is published monthly by Circuit Cellar
Have you tried Visual Basic 2005 yet? As you know, Aubrey has been
Incorporated, 4 Park Street, Vernon, CT 06066.Periodical rates paid at Vernon, CT and additional offices.One-year (12 issues)
putting it to use for some time now.This month, he finishes up his series subscription rate USA and possessions $23.95,Canada/Mexico $34.95,all other countries $49.95.Two-year (24 issues) sub-
scription rate USA and possessions $43.95,Canada/Mexico $59.95,all other countries $85.All subscription orders payable in
about a generic Modbus simulator (p.60).To put you on the right track, 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 5650,Hanover,NH 03755-5650 or call
he explains how he created the generic interface to gain access to any 800.269.6301.
Modbus slave via an Excel workbook.As Aubrey explains, the application Postmaster:Send address changes to Circuit Cellar, Circulation Dept., P.O.Box 5650, Hanover, NH 03755-5650.
simply pulls the information from Excel, presents it on the UI, formats it,
Circuit Cellar® makes no warranties and assumes no responsibility or liability of any kind for errors in these programs or schematics or for the
and sends and receives Modbus messages. ceor-nassesqeumebnlceeds p orof jaencyts s, uCcihrc ueirtr oCres.llaFru®rt hdeisrcmlaoimres, baencya ruessep oonf spiobsilistyib lfeo rv tahreia stiaofne iann tdh ep rqoupaelirt yfu anncdti ocno nodf irtieoand oefr -masasteermiablsle adn pdr owjeocrktsm baanssehdip u opfo rne aodr-
from plans, descriptions, or information published by Circuit Cellar®.
With projects like these to keep you occupied, it’s going to be a pro-
The information provided by Circuit Cellar® is for educational purposes.Circuit Cellar® makes no claims or warrants that readers have a right to
ductive month. bcounilds trthuicntg osr boapseerda teu paonny tohfe tshee i ddeeavsic eusn ddeers pcraibteendt hoer roetihne ur nredleerv athnet irnetleelvleacnttu paal tpernotp oerr toyt hlaewr iinnt ethlleeicrt ujuarli spdriocptieornt,y olar wth aotf rtheea dreerasd hear’vse j uar isridgihctt ioton.
The reader assumes any risk of infringement liability for constructing or operating such devices.
[email protected] Entire contents copyright © 2007 by Circuit Cellar, Incorporated.All rights reserved.Circuit Cellar is a registered trademark of Circuit Cellar, Inc.
Reproduction of this publication in whole or in part without written consent from Circuit Cellar Inc.is prohibited.
4 Issue 201 April 2007 CIRCUIT CELLAR® www.circuitcellar.com
5.qxp 3/2/2007 11:54 AM Page 1
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201_toc.qxp 3/5/2007 3:53 PM Page 6
April 2007: Embedded Programming
FEATURES
12 ATir Keyboard Interface 38 Reverse-Engineered ECP Bus
Steven Savage Miguel Sanchez
First Prize Atmel AVR Design Contest 2006
45 Uncomplicated RF Communication
20 Java-Based EarthBox Watering System Fred Eady
Tom Kibalo
60 Generic Modbus Simulator (Part 2)
28 Build a Three-Axis CNC Mill Machine Create a Modbus Master Using Visual Basic 2005
Gordon Dick Aubrey Kagan
ATtiny45-Based Keyboard Electronic Watering System (p.20) Computer-Controlled Mill
Interface (p.12) Machine (p.28)
COLUMNS
56 ABOVETHEGROUNDPLANE
Battery Capacity
Charge USBUnplugged? (p.78)
Ed Nisley
70 FROMTHEBENCH
Local Interconnect Network
Jeff Bachiochi
78 SILICON UPDATE What’s on the LIN Bus? (p.70)
USB:(Wire)Less is More
Tom Cantrell
DEPARTMENTS
4 TASK MANAGER 94 INDEX OF ADVERTISERS
The Cruelest Month? May Preview
C.J.Abate
96 PRIORITY INTERRUPT
8 NEW PRODUCT NEWS Only Real Events Lead to Real Trends
edited by John Gorsky Steve Ciarcia
93 CROSSWORD
6 Issue 201 April 2007 CIRCUIT CELLAR® www.circuitcellar.com
7.qxp 10/4/2006 1:48 PM Page 1
Dream of Darkness,
Wasteman!
What can AVR picoPower • True 1.8V supply voltage enabling operation of all features and core down to 1.8V
do for your design? • Minimized leakage current enabling 100 nA Power Down sleep consumption
• Sleeping brown-out detector enabling full protection with no power penalty
• Ultra low power 32 kHz crystal oscillator enabling operation at only 650 nA
npn.qxp 3/5/2007 3:55 PM Page 8
NEW PRODUCT NEWS Edited by John Gorsky
RS08 C COMPILER
The C6808 Code Development Systemthat supports Freescale
Semiconductor’s advanced 8-bit RS08 microcontroller architecture
is now shipping. The C6808 is one of the first C compilers for
RS08. It allows easy migration of programs written for Freescale
Semiconductor’s HC05 and HC08 to the high-volume 8-bit micro-
controller platform. The C6808 supports all HC08, HCS08, and
now RS08 parts in its optimizing C compiler and tools.
The C6808 Code Development System includes an optimizing C
cross-compiler with an inline macro-assembler, support libraries,
full program optimization with the BClink optimizing linker, and
the BCLIDE. The compiler produces industry-standard executables
and code files, including the Byte Craft Limited .COD file format
and ELF/DWARF. The .COD file and ELF/DWARF contain every-
thing an emulator needs for C-source-level debugging.
The C6808 supports ISO TR 18037 named address spaces and
fixed-point math. It implements the full C language within the tion than conventional asynchronous program-
limits of the hardware: Any potential application can be imple- ming.
mented in C with greater ease and optimization than in assembly. The C6808 costs $1,750.
Thread support in C complements the RS08 interrupt architecture
and threads can model hardware interrupt arbitration in software. Byte Craft Limited
They typically allow faster, smaller code and less RAM consump- www.bytecraft.com
MODULAR KICKSTART KIT TARGETS R8C,M16C,AND M32C VGA CONTROLLERS FOR EMBEDDED APPLICATIONS
The new IAR0018 KickStart kit contains all the necessary The ezVGA Graphics Controllerand ezVGA Serial
tools for initial evaluation and prototyping on the Moduleare two new display controllers from Multilabs.
R8C/M16C/M32C microcontroller range, giving developers The ezVGA Graphics Controller is an embedded graph-
the opportunity to test 8-, 16-, and 32-bit microcontrollers ics controller
within the same core family. It also provides the flexibility to that can be
change the microcontroller during the course of the evalua- interfaced to
tion. Using the same fully featured tools, which will be used any design via
when real product development starts, makes it possible to an 8-bit data
avoid the delays and errors that can be caused by changing bus and four
tools and the development environment after the evaluation addressable
proof-of-concept milestone is reached. control lines.
The kit includes code-limited versions of the Embedded Through the
Workbench for the M16C, the M32C, and the R8C. An applica- ezVGA Graph-
tion baseboard fitted with a microcontroller from one of seven ics Controller,
available device families such as the R8C, the M16C, or the your embedded
M32C is also included. The board is fitted with three serial controller or
interfaces: two MAX232s and one TTL along with a USB-to- processor will easily generate color VGA graphics. It
serial interface, CAN with a transceiver, user LEDs, a 16 × 2 provides all the circuitry necessary for a host interface,
character LCD module with an LED backlight, an LDR and video memory control, and generating color VGA
potentiometer connected to the A/D-channel, an encoder graphics with high screen resolution.
switch with a push button, a MMC/SD card interface, and The ezVGA Serial Module takes it one step further.
other features. With the ezVGA Graphics Controller and an on-board
The kit also includes microcontroller, it scales high-resolution color VGA
a Renesas Technology graphics down to two serial communication lines and
E8-USB debugger, with a handful of graphics and text commands. This makes
all the necessary cables the ezVGA Serial Module a ready-to-use serial-con-
and documentation. It trolled VGA video card that will deliver VGA func-
works for all the rele- tionality to your design. The nine easy-to-learn com-
vant microcontrollers mands give any embedded controller or processor the
and can be driven from ability to draw high-resolution color, VGA text, and
within an IAR Embed- graphics.
ded Workbench. The The ezVGA starts at $24.95and the ezVGA Serial
IAR0018 costs $495. Module is $64.95.
IAR Systems Multilabs
www.iar.com www.multilabs.net
8 Issue 201 April 2007 CIRCUIT CELLAR® www.circuitcellar.com