The Weather Station II

by Michael Shaw, June 2012

Front panel of the Weather Station II

 

This article describes a weather station I designed to provide a way of monitoring and recording daily local weather activity. I call it the Weather Station II, or WSII. It utilizes the Dallas Semiconductors 1-Wireâ Interface that supports a variety of sensors that can be used to accurately measure atmospheric phenomena. Multiple devices can be connected to the WS II using a single standard phone cable.

A list of the WSII features:

* Uses Dallas Semiconductor 1-Wireâ Interface

* Supports multiple devices using a single cable

* Measures Rain in .01” resolution

* Menu driven operation using a 5 Button input Panel

* Real Time Clock Calendar (RTCC)

* Measure temperatures in Centigrade or Fahrenheit

* Display time in 12 or 24 hour format

* Temperature range from -55 to 68°C (–67 to +180 ° F)

* Sensors accurate to +/- 1 degree C

* Connects using standard telephone cable

The weather instruments are mounted on PVC pipe that is attached to the house or roof.

Weather Station II sensors mounted on house

The WSII is powered from a 12VDC wall wart and provides a built-in 9V battery backup which will keep the unit powered for about 1 hour in case power is interrupted. A year’s worth of daily records data (wind, rain and temperature) is stored in non-volatile Read Only Memory (ROM) and will be retained even if the power is shut-off and the backup battery is removed from the unit.

Daily Recorded Data 

The unit utilizes a Dallas DS18S20 Temperature Sensor and DS2334 Dual Counter modules. These modules are available from a company called Hobby Boards (www.hobby-boards.com). PVC pipe is used to mount and house the modules and weather instruments. The dual counter module is used to collect wind and rain data. The rain collector was purchased from a company called Davis Instruments (www.Davis.com) and the anemometer was purchased from a company called Fascinating Electronics Inc. (www.fascinatingelectronics.com).

The Weather Station controller is an ATMega128 development board from Sparkfun Electronics (www.sparkfun.com). It has a 2 line, 16 character LCD screen, 5 push buttons, RS232 interface circuit, Dallas iButton port, Relay with 10A/250VAC contacts, Buzzer and Status LED.

The controller functions are all written in C code. I developed the Dallas 1wire interface after researching the protocol specifications on their website (www.dallas.com). This code was originally developed for a PIC processor (the WSI), and later developed for the Atmel Atmega128 processor.

The WS II unit features are accessed from a system of menus using the front panel buttons. The weather data display items are accessed using the MAIN menu and the configuration of the weather station options are accessed through the SETUP menu. The menu hierarchy is as follows:

WSII Menu Hierarchy

The WSII has been successfully deployed in 2 locations, one in Sunrise, Fl and the other in Atlantic Beach, Fl. The units have been used to gather data for a couple of years. This data is used to keep track of monthly temperature and rain totals.

The WSII was a project to measure weather data in realtime and save the data for later analysis. The project has been a success and future projects are planned. Some of the desired features for a future weather station are adding barometer and wind direction sensors. These should give me the ability to provide weather prediction to the weather station in the future.