1-wire is the other half of ibutton, being just chips that you string together on a shared databus. They also send power down the data line, but we've found that this is much more error prone, and cat5 is cheap. So we just sent a separate gnd and pwr pair. Over long distances you would probably provide the power separately at the destination.
My biggest issues with 1-wire are: proprietary, poor noise immunity, difficulty in obtaining parts. On the other hand, for BA I reckon it's probably the simplest and easiest approach. The aagelectronica bits are good value, and I wonder if there is interest here for us to make a run of ponic specific units/kits. If there is interest I can get short runs of PCBs and get a bulk order of components in.
What sorts of things are people interested in measuring?
I'm interested in:
* CO2 gas (have sensor for $20AU)
* pwm control for fans (PIC based)
* temperature (DS18S20)
* variable valves (I've got a simple low cost, low tech way to drive gate valves from a computer with builtin UPS - explain later)
* 240V relays (2405 or 2408 with ULN2901 or similar and DPDT relay)
* water level (already in pipeline)
* pH, NO3-, NH4+ (sensors for these might be hard to source)
* integrating PAR (suitable choice of LEDs + PIC)
* watthour meter (I have samples of a single chip solution for this, + the 1-wire counter)
Some of these are a single chip solution from maxim, some require a 1-wire chip and a sensor, some will require a combined DS2408 and PIC micro using something like pypicn:
http://mec-symonds.eng.monash.edu.au/tw ... ara/PyPicn
A PIC will make practically anything possible (including closed loop control).
Anything I've missed?
Backyard Aquaponics
