Weather and environmental monitoring

The homebuilt weather station

As with all electronic enthusiasts, there comes a a time when you begin to investigate sensors. It might start with a light sensitive resistor, then possibly a temperature sensitive resistor. These two are particularly simple devices. And less than a dollar each.

Imagine both of the resistances pictured were 10k resistors. They form a divider where if each was the same value, they would halve the voltage between them.

Now if we replace one with a resistor that changes slightly then the voltage shall vary either side of that halfway mark. This is one way we can sense light levels and also temperature.

The first time you read a sensor that responds to some sort of stimulus, is the first time you think hey, what can i use those varying values for. Turn on a light when it gets dim? Control a fan when it gets hot? The two simple ones make you think of weather, and before you know it, with your one light sensor and temperature sensor you have yourself a weather station.

There are many other sensors that can be had for only a few dollars each. DHT11 humidity sensor, the bosch pressure sensor etc.

Now the arduino platform lends itself very well to attaching extra chunks of hardware that can transform your sensors into even more powerful ideas. Take for example an sd card shield, not more than $10 and you can start logging all sorts of values to a micro sd card. Save the values to a text file on the card, with the file extension .csv and voila, you can load it straight into an openoffice spreadsheet and graph it!

Add yourself an ethernet shield and all of a sudden you have a web page that displays your weather station data on the internet, for you and anyone else to follow. How did this happen? I have a custom internet connected weather station for an afternoons work and a few tens of dollars? Well lets face it, we can buy good examples of consumer weather stations that have the same and more features for not much more dollars these days, as they are mass produced in volume. The fun of being able to source those same sorts of parts and repurpose them in your own design is such a bonus for the hobbyist. To be able to also quickly and reliably produce some of your own content with systems like arduino, that are so easy to use and understand is awesome. With such modern tools its certainly possible to create something cool and lasting in just an afternoons experimenting.

There is a link to the board in the menus above under ” Weather Station “, yes you are connecting directly to the arduino shield sandwich! Its an Arduino UNO with an Ethernet shield and a breakout shield on the top. It has a temperature sensor or 2, a pressure sensor, a light sensor and a humidity sensor. The web page serves up all the data and even shows the latest skycam photo.

Update!! 27 October 2012

I have decided to commit the design and code to a fixed unit which I have placed right up above the Skycam on my antenna mast.
Its even visible when i pan the camera around, so much so that I can even see if the TX RX leds on the LAN board are working OK.
Here are the pictures of the hardware. I have cabled the sensors directly to the Arduino motherboard via a cable.
The sensors were then place inside an opaque plastic rain cover (an old PET milk bottle!).
I have spliced power into 2 of the spare conductors on the ethernet cable, thereby providing comms and power with only one cable up to the installation.

The sensors all connected to a cable giving GND,5V,3.3V and Analog 0-5 pins

The arduino its ethernet shield and the sensors

Arduino Uno R3 with cable soldered direct

Sensors hot glued inside rain cover

For those of you interested in trying out something similar, i give you my dodgy, multi revision code and may you glean something of value from it..

Ethernet plus power for the board on the one cable

Injecting power over ethernet

Put it in a bag and strap it to the pole


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