A number of years ago when I was enjoying
the hobby of RC Airplane construction and flying, I came upon an idea of developing an inexpensive weather reporting device
that would report the wind and temperature conditions over the telephone. This
all came about after I made one of many trips out to the club flying site only to find that the winds were too strong or blowing
across the runway making it impossible to fly that day. I got tired of loading
the planes and flight gear into my truck only to end up driving home never taking them out
My first idea was to use a modem connection
but that would require the users to have a computer and modem. This idea came
about over 10 years ago so not many modelers had computers and of course there was no such thing as the internet as we know
it today. So after deciding that the modem connection was not going to work,
I came on the idea of using a voice interface. The first design used 28 ICs including
the microcontroller, RAM and EPROM, A/D converter, voice playback IC, and lots of glue logic all on a hand wired board. To the best of my knowledge, it is still running back in Livermore, reporting the
wind conditions at the ‘Livermore Flying Electrons’ flying site.
At one point on time I thought about marketing
the device, so I shrunk the design down to 5 ICs added a solar charge system, low current switching power supply, and a custom
2 layer PCB. As life is, I ran out of time, energy, or interest in the project
so I never brought it to market. I added a 2x20 character LCD to the design so
the weather station could be used locally with out the need of calling it. Additionally,
I added a FCC type approved telephone interface making it leagle to attach it to the public phone lines.
The anemometer and wind direction vane
used in the final design is different in the way that it signals the wind conditions back to the electronics. The anemometer is made by Peet Bros., and it is a real work of engineering.
It only has 4 wires, connected to 2 reed switches. The wind direction
is represented by an out of phase switch closure in relationship to the switch closures of the wind speed sensor. The most difficult part of this project was developing the firmware to calculate wind direction and wind
speed from these 2 switches using 8-bit assembly. In this design I used an I2C
interface to communicate to the temperature probe, removing the A/D converter and its support circuits, I also had to develope
a library of functions to support the I2C interface as it is not directly supported in the microcontroller.
To program the voice playback IC, I developed
a microcontroller circuit that could program the individual words used to make up the messages, edit the recorded words, and
then duplicate the voice message from a master to a copy IC. Once the programmer
was working, I recorded my wife’s voice into the system, right now it is calm
and 90 degrees in my back yard.