monitor the weather at Cloudbait with a simple weather
station developed by Dallas
Semiconductor. The station is based around a series of Dallas
chips that communicate over a simple one-wire network. It was developed
as a promotional product to showcase the 1-wire product line, and
is no longer available from Dallas. It is currently available from
Texas Weather Instruments
and TAI, although
at a rather higher price than the original promotion.
The system works very well,
but requires a dedicated computer to read and record the station
data. It became inconvenient for me to maintain a dedicated serial
port, so I decided to build a standalone controller. Originally,
I was going to have this controller read and log the data, which
could be periodically read and added to a master log. In the meantime,
however, NetMedia came out with a spiffy little Ethernet
Web Server module, the SitePlayer. This postage stamp sized coprocessor
makes it easy and cheap to get data onto a network. In addition
to serving web pages, it is also capable of sending and receiving
UDP data packets, and will soon feature telnet capabilities. Since
I always have my server running, it provides a perfect interface
to my weather station.
system is now in place, and has been operating continuously since
May 2001 with no problems. It consists of the Dallas weather station,
a Motorola 68HC705C8A microcontroller, and a SitePlayer module.
The processor interrogates the station about once a second, calculates
raw values for temperature, wind speed, wind direction, humidity,
and a second temperature at the humidity detector. These values
are placed on a web page and also broadcast system wide via UDP.
A client application running on my server (and optionally on any
other machines on the network) receives these data packets and calculates
average values for display and logging.
In the future, I plan on
adding sensors for barometric pressure, moisture/dew, and cloud
cover. Rainfall measurement devices are available, but I don't plan
on adding one since we don't really have enough precipitation to
make it worthwhile.
Here are all the technical
details of the project. You are free to use any or all of this information
in any way you wish. I'm happy to answer
any questions, though I don't guarantee the world's fastest