Introduction

The 1-Wire® indoor sensor/interface kit was designed to be used with the TAPR T-238/T-238+ APRS Weather Station or N4XI's Linux based WXN weather server over APRS. The humidity and barometric pressure sensors, as well as the rain gauge interface, should work with any other 1-Wire® based software as the design is based on the original Dallas Semiconductor 1-Wire® Weather station.

Board features are as follows:

Feature
Description
Barometric Pressure Sensor Utilizes the Motorola MPX4115AP pressure transducer. Full design specs are available for anyone wishing to write code to support the sensor.
Indoor Temperature Sensor The same 1-Wire® DS18S20 sensor used in the outdoor kit.
Rain Gauge Interface This interface may be installed on the outside board, if desired. It can optionally be configured to support the Aware Electronics RM60/RM70 background radiation monitors. This is primarily for those users running N4XI's WXN server who wish to use/add a background radiation monitor.
EMP (Lightning) Detector Interface There are several devices that can be connected to this interface that will detect EMP pulses. The X1W-4 EMP Sensor kit was designed to work with the interface. However, there is a variety of ready-made and home-brew sensors that will work with the interface.
Aspirator Control Open-drain output to control the X1W-2 aspirator. Used to turn the aspirator off when it is not really needed (e.g., high winds or RH falls below 70%). Helps extend the bearing life of the fan motor.
Rain Gauge Heater Control Open-drain output to turn on a heater in the base of a tipping bucket rain-gauge when the outside temperature falls below 34 degrees. This will allow collecting precipitation totals in sub-freezing weather.
RS-232 Interface Required for barometer calibration program. Can also be used to trouble-shoot 1-Wire® sensors. Also required if running N4XI's WXN server to add the additional sensors.
1-Wire® iButton Clip Allows using any of the available iButtons for the 1-Wire bus. Code in the T-238/T-238+ firmware supports the DS1994 real-time clock iButton. Note that the clip itself is not included with the kit. The end-user must purchase this from Maxim along with any iButtons required.
1-Wire® Loop-Through Permits connecting the T-238/T-238+, this board, and the X1W-1 together.

Current firmware/software support is as follows:

  T-238
T-238+
WXN
Server
Pressure
Transducer
Y Y
Aspirator
Control
n Y
Inside Temp Y Y
Rain Gauge Y n/a
Rain Gauge
Heater Control
n Y
EMP
(Lightning)
n Y
Radiation
Monitor
n Y
RTC
iButton
Y n

A picture of the completed kit can be seen by clicking the camera icon below.

Latest changes and other information on the X1W-1 is available at either of the following two sites:

http://www.tapr.org/
http://n4xi.home.insightbb.com/

The T-238, T-238+, X1W-1, X1W-2 and X1W-4 are discussed on the Weather Special Interest Group (WXSIG). You can join WXSIG via the web by clicking here.

Acknowledgments

The Tucson Amateur Packet Radio X1W-1 kit was made possible by the efforts of:

John Bennett, N4XI – Conceptual and PCB Design
John Koester, W9DDD – Project Manager
Steve Bible, N7HPR – Assistant Project Manager
Joe Borovetz, WA5VMS – Parts Liaison
 
Dwight Hazen, WB9TLH – Beta Tester
Will Beals, N0XGA – Beta Tester

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