Instructables
Picture of The Arduino Weather Station / Thermostat
UPDATE: http://www.instructables.com/id/Temperature-and-Humidity-on-a-Graphical-LCD/

UPDATE: Add dew point calculations

I've always been interested in monitoring my local weather, and noticed the difference between what weather.com and accuweather.com think my local weather is, and what I see out the window. I also wanted better control over my heating and A/C system. As a computer and electronics nut, I've been playing with the Arduino Microcontroller, and decided to to meld my interests. So here goes the documentation on my home built solar powered weather station (always being modified, and expanded) with HVAC Control.

 
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Step 1: The Arduino

Picture of The Arduino
pico.jpg
The first step was obtaining a Arduino board. We purchased ours from hacktronics.com. After working through the tutorials on their site, I felt confident that I understood the simple scripting and connection concepts, and moved forward.

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments. - http://arduino.cc/

The Arduino requires 5v to run, and we supply this with our Pico Solar PV / Lithium battery pack.
Robotix_au8 days ago

Couple of quick questions, is it impossible to use the Arduino to keep time.... (I was thinking of using pulseIn function at the start/end of the loop to keep time...)

So if the RTC is essential can you just plug it into 5 consecutive Arduino pins instead of dealing with so much wiring?

sspence (author)  Robotix_au8 days ago
the rtc uses two datalines (a4 and a5) in addition to power and ground. you can't just plug the rtc into the arduino, as the pin connections will not line up.

Hmm... I think you can, instead of GND you just digiWrite(pin LOW) and instead of 5V you digiWrite(Pin HIGH)... I know its not best practice but it does seem to work seamlessly

Have a look at an example with an Ultrasonic sensor:

https://www.youtube.com/watch?v=pdIUNHps-5s

sspence (author)  Robotix_au8 days ago

sda and scl are reversed on this module, so you can't. you'll need to find another module. do you really want to waste your analnog ports defining them as power and ground?

Good point, I guess that depends on what the circuit needs, I really like what you built... especially that its self powered. I just bought some 1W panels + lipo batteries to see if I can build similar circuits.

oukolova2 years ago
Hi! We launched a new project of weather map layer for OpenStreetMap http://openweathermap.org/. It public project that collects data from more than 20,000 meteorological and weather stations around the world. The more weather stations connect the more precise weather data we provide to people. All collected weather data are provided under CC-BY-SA 2.0.You can connect your weather station to the service http://openweathermap.org/connect
schuguy2 years ago
I'm wondering if you ever added the relays and the outdoor temp and humidity.
sspence (author)  schuguy2 years ago
I added the SSR's, directly addresses by an output pin. This allows control of ac devices, up to 660v and 150 amps, depending on the SSR, with an optically isolated 5v input.

I also added the outdoor temp and humidity.
bkik4 years ago
Does/Can this setup also log data for an extended period of time (say three months)? I'd love to be able to drop this in an off-grid spot and have it continuously working for me; just check on it every few weeks and dump data to a laptop. Or even better, find a way to dump the data to a server so I can visit it and dl it from anywhere. Would this work?
the naP bkik2 years ago
You can use Gobetwino (http://www.mikmo.dk/gobetwino.html) to log the serial output to a file on a computer connected to the Arduino. If you have a machine that is always on, this is a pretty good way to go, as it doesn't require any additional hardware.

If not, one of the listed options is pretty nice, especially the storage shields.
sspence (author)  bkik4 years ago
This is very cool. When you are ready to integrate forecasted weather for your location to make your HVAC controls predictive, let me know, as we can provide and even integrate your sensor data if we can get at the output.
roland9853 years ago
What OS are you using? I am using Xubuntu 11.04
sspence (author)  roland9853 years ago
Ubuntu 11.04 and Windows Vista.
cprocjr4 years ago
I was thinking about doing something like this, but with wind speed and rainfall as well. Thanks for the instructable! It'll probably help a lot when I finally get around to building mine.
sspence (author)  cprocjr4 years ago
I'll eventually get those functions in there, probably by sniffing the wireless feed from a lacrosse weather station. easier than making a anemometer and rain gauge.
cprocjr sspence4 years ago
I thought about making a anemometer and rain gauge, and I've even planned them out, but I don't want to take the time to actually make them. So instead, I just bought them from sparkfun: http://www.sparkfun.com/commerce/product_info.php?products_id=8942

I'll post an instructable once they arrive at my house and I've programed my arduino!
frenzy4 years ago
I said to myself 6 months ago how i should do this project, good job getting to it first!
sspence (author)  frenzy4 years ago
Wait till I get the relays installed and it turns on my a/c and furnace when necessary :-) Should have barometric pressure and time / date functions (for setback thermostat capability) working next weekend. Running out of IO lines, will need a expander. http://www.embedds.com/arduino-i2c-expansion-io/
Yea, I have a heat pump, and one of the efficiency tweaks is to not turn on the auxiliary heating when the outside weather is above 0 degF

I might reuse some of this to add that feature to my "dumb" digital thermostat, which will do a call for "aux heat" if it kicks on and the room temp is 2 degF below the set point.
renegade4284 years ago
nice job! how much did it cost you about?
sspence (author)  renegade4284 years ago
About $70 or so.
odiekokee4 years ago
That is awesom. Now if i can figure out how to make it send signals back over morse code or something without RF i'll be set.
sspence (author)  odiekokee4 years ago
We both remember the modulated lightbeam kits of the late 70's.
kikiclint4 years ago
I think one of your wires on your lcd is loose in that first picture. Mine does the funny wierd symbols if a wire temporarily becomes disconnected.
sspence (author)  kikiclint4 years ago
naw, it was a errant carriage return (println instead of print), carried over from the serial output of the original code snippet.