T-238 Assembly Manual
Rev. 1 February 2001
Page 1 of 11
Tucson Amateur Packet Radio
8987-309 E. Tanque Verde Rd #337
Tucson, Arizona 85749-9399
Office: (940) 383-0000 Fax: (940) 566-2544
Internet: [email protected] www.tapr.org
Non-Profit Research and Development Corporation
T-
238
T-238 Assembly Manual
This document was written July 2000.
Revision 1 February 2001
© 2000-2001 Tucson Amateur Packet Radio Corp.
Reproduction or translation of any part of this work beyond that
permitted by sections 107 or 108 of the 1976 United States
Copyright Act (or its legal successor) without the express written
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or for further information should be addressed to Tucson
Amateur Packet Radio Corporation. Except as noted above,
permission is hereby granted to any non-profit group or individual
to reproduce any portion of this document provided that: the
reproduction is not sold for profit, the intent of the reproduction is
to further disseminate information on Amateur Packet Radio, the
reproduction is not used for advertising or otherwise promoting
any specific commercial product, full credit is given to Tucson
Amateur Packet Radio Corporation (including address) as the
original source of information, and Tucson Amateur Packet
Radio Corporation is notified in writing of the reproduction.
The information contained in this document has been carefully checked and is believed to be entirely reliable. However, no
responsibility is assumed for inaccuracies. Tucson Amateur Packet Radio Corporation (TAPR) reserves the right to make
changes in any products to improve reliability, function or design without obligation to purchasers of previous equipment.
TAPR does not assume any liability arising out of the application or use of any product or circuit described herein; neither
does it convey license under its patent rights or the rights of others.
Introduction .........................................................................1
Acknowledgments...............................................................2
Parts list ..............................................................................2
Construction notes ..............................................................3
Construction........................................................................3
Power-up and initial testing .................................................6
Board layout ......................................................................10
Schematic diagram ...........................................................11
Introduction
The TAPR T-238 is a general-purpose Motorola
MC68HC908GP32 microcontroller-based board intended
for use with the Dallas Semiconductor 1-Wire™ bus and
any device that needs a serial connection. Four push-
button switches and a Liquid Crystal Display (LCD) provide
the user interface. The initial application for the T-238 is a
controller that accepts data from a Dallas Semiconductor
weather sensor unit, processes it, and formats it for
sending either directly to a Terminal Node Controller (TNC)
for broadcasting in APRS™ format or to a computer for
further processing and/or logging. There is nothing about
this board that makes it solely a weather station. This is
just the first application.
Dallas Semiconductor announced on July 7, 2000 that they
will no long supply the 1-Wire™ Weather Sensor unit.
Tecnologia Aplicada http://www.aag.com.mx now supplies
the 1-Wire(tm) Weather Instrument Kit V2.0. See
http://www.aag.com.mx/weather.html for ordering
information.
The TAPR T-238 is a ready-made kit with the weather
application pre-programmed into the microcontroller. All
the necessary hardware is provided for the more
adventurous people to develop their own applications. A
list of available development tools for the MC68HC908 is
available at http://mcu.motsps.com/dev_tools/index.html.
Development tools are available from P&E Microsystems
at http://www.pemicro.com/ics08/. Download the file
“ICS08GP Software for 68HC908GP20/GP32” which
contains the following programs:
WINIDE08 - Integrated Development Environment w/
Assembler
PROG08SZ - MON08 Flash/EEPROM Programmer
ICS08Z - In-Circuit Simulator
ICD08SZ - Real Time In-Circuit Debugger
More information on how to use the T238 debugging
functions is available in the T238 Operations Manual at
http://www.beals5.com/wx or
http://www.tapr.org/taprf/html/Ft238.html
The T238 kit does not come with an enclosure or power
supply. It is left up to the builder to find an enclosure that
is suitable. For power, the user can use an ordinary wall
transformer (“wall wart”) that provides 8-12 Volts DC at 300
milliamps. The T238 is fitted with a 2.1mm power coaxial
connector arranged so that the center conductor is
positive.
As T-238 programs are developed they will be displayed or
linked from the TAPR Weather web site located at
http://www.tapr.org/taprf/html/Ft238.html. If you’ve created
a project and would like to display or link to it, contact
TAPR at [email protected].
Updated documentation can be found at
http://www.beals5.com/wx or
http://www.tapr.org/taprf/html/Ft238.html.