Homebrewing one-wire stuff is remarkably easy, and since I haven't had a good one-wire rant in a while I thought that the world might benefit from another one. It's that or another Lord Wyleu yarn so take your pick.
Thwe ability to accurately measure parameters like temperature is a real miracle. For anyone who has spent time building analogue measuring kit and the difficulties of getting a simple op-amp to actually hold a consistent gain over 25 degrees or so, probably understands this but for the rest of us it's a problem we don't even have to deal with.
One wire is a product of Dallas/Maxim where a range of devices connect to a common couple of wires ( at least two, the one-wire stuff is marketing hype) and by joining this to a simple USB device you can read the values of temperature to half a degree or so over thirty or more metres with thirty or so devices. I've buried 28 of the chips into our underfloor heating system and I have twenty or more scattered around the solar system and the domestic heating. With these I can view temperatures at any time with just a few lines of code. Python in my case, but as marke says Perl works just as well, and there are lumps of code for Visual Basic, Java and C. in fact in this open age there probably isn't a programming language you could cludge this all onto.
All very useful, but so what?
Well there are several approaches to design, and whilst if I were designing a space probe I would be reasonably sure that thing work pretty well before the launch because the maintenance call is a beans, in the domestic environment a certain amount of redesign is normally required. With the one wire sensors connected to my solar system it was pretty obvious that the one way valve was leaky because the panel temperature tended to track the temperature at the bottom of the tank at night rather than remaining independent. A quick bit of pipe re-routing will solve that particular little issue, Wonderful initself but will the change lead to lower temperatures in the array? I'll know and can react accordingly. Quite fantastic and all without any scrabbeling round in the loft or on the roof at 2.00 in the morning to find out.
Combined with a bit of database knowledge ( Postgres via Django in my particular case) the possibilities of comparative analysis can make a most suitable replacement for a social life, and for most it probably ends about there. But there is a bit more that can be done if several people think along the same sort of lines.
One of the most difficult aspects of resource management is predicting what will happen, so knowing that it's a cold night is of great value, because you can provide that most useful energy saving mechanism control. Here in Cheshire knowing which way the wind blows tells you a fair bit about what weather to expect so if a one-wire rig in Liverpool could tell me what the temperature and solar performance is ther then with a westerly wind I'm going to get the same thing pretty soon. Very handy if you have undrfloor because it allows you to tailor the response to be ready. If Ian in Macclesfield publishes the same sort of data then Easterly winds give me an hour or so of pre warning. Just right for shifting the emphasis from water heating to underfloor and a couple more lumps of gas saved.
A similar system used by the turbine folks would probably lead to a few less photos of bent shafts and such like which begins to become an incalculable saving. Ask the people in Gloucestershire if monitoring water level in such a fashion would be appreciated and you probably would get a pretty definite yes. Ask the likes of Windsave if they would be willing to put these devices on their teapots and publish the results would probably produce a response that would tell you far more about the devices than any number of eco jumping politicians could.
So how would this all be possible? Well technically it just means an agreed method of publishing the results that people agree on and a decent security mechanism to prevent evil individuals like myself deciding to turn your hot water pump on just for the hell of it. The way to do this is actually incredibly simple, you don't let it happen. You measure temperatures, voltage, wind speed, depth of water, volume of kids, litres of weasel liquid effluent, or whatever but you provide no mechanism to control devices. Your hot water pump is controlled by separate software ( separate in a operating system safe fashion rather than mechanical seperation, althou' that is probably preferable) which reads the published data of your measurements in exactly the same way as anyone else on the system would view it.
No hideous security model to protect equipment required because there is no actual way of controlling devices. Slightly more expensive to implement, but as with most community special interest networks, the more join the more powerful it becomes. Monitor internet bandwidth across the Navitorn community? just a couple of software modules away, Gas usage of the community? not difficult even if it involves pointing a camera at the gas meter and using character recognition. Resolving the great plate versus tube debate, well actually lot's more info but probably no definite answer
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Such a system in flood and storm situations would be of great value just to see who was still on-line, and for a installer putting just a few one-wire sensors into a system allows remote monitoring of customers site. Excuse me sir but I think your solar system has boiled dry< would you like me to come round and fix it for you?.
There is one other aspect of community that is required and that is the social aspect. Would you really be willing to reveal to the world that your solar installation might not be optimal? Would you like everyone to know your electricity usage? ( and hence whether or not you are at home). The rogues wouldn't but we are really talking about trust here and comparative methods would quickly expose the devious types who were adding values to fake results and would suffer the loss of trust that would defeat any benefit of their devious ways? Ideal pie in the sky dreaming? Not really. I've done this sort of thing before in the film and video industry, building a collaborative network between competing video companies and the result was incredible in that we discovered how much we had in common on a technical standpoint. BT hated it and spent some considerable time trying to destroy it and control it, but the model was so simple and so beneficial that they gave up. It's still transfered a massive amount of data around and it's still based around the same collaborative approach. It started with seven companies sticking about 10 grand in the pot it's now quite big
www.sohonet.co.uk. Strangely the bandwidth we used then is now available for next to nothing as most of us have it already.
Care to give it a try?
