Weather station update!

It has been quite a while since I last posted here, it was a busy year! I became a father, and that took a lot of the time available to report - I still get quite some time to do the things, only no time to spend here reporting :) , but I hope to revive it now!

So here is an update on the weather station!

Finally, after 11 and a half months the thing died! in the coldest night of the year, after sending a packet indicating -8.1C outside at 3 in the morning...

funnily enough, the FS20 switch that turns the boiler on and off died (stopped receiving) at approximately the same time...can't explain it, it wasn't cold in the room where that one is located...

It sent 51273 messages on a set of 3AA GP branded units, which were not new when it was put outside. Since for each packet I measured the wind for 1 second, this means the JeeNode was in full power mode for a bit over 14 hours.

Anyway, I opened it, days later, and when the temperature outside was up to -1 and the batteries read about 1.9V, or about 0.6V per cell.

I wonder if the fact that the Atmega runs at 16MHz, which is out of the specs at 3.3V (let alone 1.9V), contributed to it failing at low temperature/very low voltage as well, or if it could have been pushed any harder! It is out now with a new set of batteries, since 8/12/2010, but I need to redo the anemometer, so I don't think these batteries will be out until they die!

I think this was a victory for a JeeNode in low power mode!

As for the FS20 switch, I still do not know what happened...It just would not receive, until I moved it to a different place, where reception is fine. I wonder if all the snow on the roof created some effect, which prevented it from working properly. Maybe i should try now that the snow melted. However, if that is the case, then I definitely can not leave it there, as it is precisely when it is cold and snowy outside that I need it the most!
Plans are on the making anyway for a JeeNode OpenThem controler, which should be comming soon. I already developed the control loop (PI) which determines the desired water temperature, now I just need to adjust the PI coeficients and implement the hardware, for which most components are already in the house!

I hope to report before the new year again on another project!

Weather station

Finally, I decided to progress in the weather station front! mainly due to having received my JeeLink, and having successfully gotten it to work with the JeeNode!

So, the plan was to get a wind speed and amount of light measurement so that I could automate the sunscreens at my place. Of course, I didn't want to buy a commercial weather station, because the ones that do interface with the PC are expensive and you do not have much control, not to talk about Linux, which they probably won't support. So i had decided to take it in my own hands and build it myself!

Some time ago I got a light meter to work, and temperature I had already mastered, so all I needed was wind speed, and maybe direction, and a way to send data around, which was solve by the JeeStuff!

I have built the anemometer before the holidays, but did not have the opportunity to blog about it, so here goes a picture:



It was just a check of whether it moved in the wind, and if you look carefully you can even notice that it is rotating!

And today I bought a weather proof electrical box, and started the process.

First, the JeeNode did not fit inside, by an estimate 0.5 millimeters, so i had to get the dremel tool out and get a some of it sanded into dust, in order to fit.



Then I devised a transparent lid for the light sensor, which I will show you in a future post, when I get a decent picture of it. I did it by warming up some rigid package plastic and forcing it into the hole with a rounded end of a spoon. Then I cut it and inserted it, screwed it and it looks great! (in my opinion!)

I also made some sort of plugs/shield, but I am not yet 100% sure of how it should be.

I did decided to change all the electronics for the sensors to work with 3.3V.

The initial plan was to run it from 5V, but since the JeeNode has a 3.3 LDO regulator, it would be a waste of energy to have say 6V, converted to 5V for the sensors, converted to 3.3V for the jeeNode. And since soon this will all run from a battery and solar panel, the less power the better!

So tomorrow (or today, since it is pretty late) I'll have to redo the detection of rotations for the annemometer, and install the whole thing temporarily to see if all is functional!

I still have to figure out the temperature measurement, but I'll probably end up going with one of those temperature/relative humidity digital combined sensors, instead of the good old LM35.

Daylight measurements

The next project, now that the door bell growls in the mac and the power orb is orbing like mad, is to make a small weather station, with a wind speed meter and a daylight meter in order to control the sun shade in the kitchen.

In the late afternoon the kitchen gets a lot of direct sun, and while that is a good thing in the winter months, it is not as nice in the summer, as it makes it very hot and the refrigerator has to work overtime.

I have an electric sun shade, of the extending type, which is connected to an ELV device making it controllable from the server. However, I cannot lower it automatically, since if it is raining or windy or simply cloudy, it is not a very wise thing to do. I do raise it automatically every day at 20:30, which should cover it most of the year, and in case I need to go out of the house and don't come back till late while the shades are off.

So I started the weather station by getting an LDR and connecting it to the arduino. Using the standalone temperature logger I made a few months back I could leave the arduino in the kitchen the whole day logging the amount of light.


The results are great I think! with the steep rise around 14:00 which is when the sun comes around the bend, and a clear difference between the times when the sun shines and when it doesn't. I think a threshold at around 800 will do the trick.
Furthermore I am quite happy with the excursion of the sensor, going from 0 to 916 at least, which is a 89% coverage of the 5V conversion range!
Now, off to the wind speed! Already spent the night disassembling an old VCR, and got some promising parts out of there!

One more note. I thought a lot about how to make a rain sensor. Not necessarily measuring it, but just to detect if it is raining or not, but concluded that if it is rainy, the sky will be overcast, so it won't be necessary to lower the shades!