T-238+ Assembly Manual
Rev. 3 March 2006
Page 1 of 11
Tucson Amateur Packet Radio
Internet: [email protected] www.tapr.org
Non-Profit Research and Development
Corporation
T-
238+
Main Board (Rev B)
T-238+ Assembly Manual
This document was originally written April 2005. © 2005 Tucson Amateur Packet Radio Corp.
Reproduction or translation of any part of this work beyond that
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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
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Introduction ......................................................................1
Acknowledgments ............................................................2
Parts list...........................................................................2
Construction notes ...........................................................3
Construction.....................................................................3
Button Board Construction ...............................................7
Power-up and initial testing ..............................................6
Assembly drawings ........................................................11
Board layout...................................................................12
Schematic diagram ........................................................13
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 dev ice that needs a serial connection. Four push-
button switches and a Liquid Crystal Display (LCD)
module prov ide 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, to a computer for processing and/or logging, or
directly to a radio using the MX-614-based modem. There
is nothing about this board that makes it solely a weather
station. This just happens to be what the software for it
does.
The T238+ is a successor to the TAPR T238. Software
releases will work with both projects. The software will
determine at startup which project it is running on and
configure itself as needed.
For the most current information on weather sensors,
software downloads, dev elopment tools, and related
information, v isit
http://www.tapr.org
and follow the links
to the T238+ project, or v isit
http://www.beals5.com/wx
.
The TAPR T-238+ is a ready-made kit with the weather
application pre-programmed into the microcontroller. It is
possible to dev elop your own applications on the T238+ as
well. A debug header is prov ided that with a small adapter
circuit can enable a fully functional dev elopment system.
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 prov ides 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
positiv e. Unlike the original T238, the T238+ contains
analog circuitry that is much more susceptible to RFI,
making the need for a metal case much greater.
As T-238 programs are dev eloped they will be displayed
or linked from the TAPR Weather web site. Go to
http://www.tapr.org and follow the T238 links. If you’v e
created a project and would like to display or link to it,
contact TAPR at [email protected].
The T238+ is discussed on the Weather Special Interest
Group (WXSIG). You can join WXSIG v ia the web at
http://www.tapr.org/cgi-bin/lyris.pl?join=wxsig.
