Control Your World
sensors will be used in parasite mode.
I found this module to be very accurate, and once
calibrated, tracks the local weather station readings within 2%. Hobby Boards calibrates the module for you when
you place your order but you may need to calibrate the
module again once it is installed into your weather station.
The test program BarometerGauge shown in Figure 21
has a built-in calibration wizard, so calibration is a breeze.
Notice in the test program I am displaying the
DS2438 temperature reading. It runs a bit high due to the
onboard regulator so I don’t recommend using it for
anything but monitoring the board temperature.
In order to predict any kind of weather with a barometer, you need to keep track of your readings over time.
Later in the series, we’ll tie all the sensors to a single
program that will do just that.
■ FIGURE 20
There are myriad sensors you can add to your weather
station. As this series continues, we will look at some of
these. I will also be writing small application notes for them
and placing them on the Kronos weather forum at
your station is built.
As you can
see, there are a lot
of variables and ■ FIGURE 21
no two weather
stations are alike. Don’t worry. Part of the fun is tearing
down the station and rebuilding it in a new and better
configuration to suit your needs.
All the example programs, as well as the source, are
available for download at www.kronosrobotics.com/
Projects/ esensors.shtml. NV
You may have noticed that we only talked about individual sensors and not a weather station as a whole. Many of
the sensors can work together to give us calculated readings
like wind chill and heat index. Near the end of the series we
will look at display systems and ways to plot long term data.
For now, it is important that you get the individual
sensors working. Later, I will show you how to use a
microcontroller to collect and display your data. The display
system you choose and the collection method will dictate
how your weather station is built.
Next month, we are going to put our weather station aside
and look at home automation. I will show you how to interface
to three different X10 controllers. If you decide later to tie the
home automation system into your weather station, the type of
controller you use as your interface will also play a part in how
■ Fascinating Electronics
■ AAG Electronica
■ Kronos Robotics
■ Hobby Boards
March 2007 37