Hair brained plans galore! I am planning on flooding my house with environmental sensors. Temperature for starters. All over the place. And of course I want my readings to be gathered on a central machine. Live. So, no data logging on separate memory chips. I need some sort of network. With wires and stuff, because I do not trust the airwaves for this sort of thing. Also, I am a cheap skate.
So my list of requirement looks a bit like this:
- thin two-wire cable(s) running through my house
- multiple sensor units hooked up to this cable (parallel)
- each sensor sends digital data over the cable to a central master unit
My wild idea so far extends to this:
- one little MCU on each remote sensor unit
- very little power consumption by sensor units
- power comes through cable from central unit
- sensor unit stores power, in super capacitor, I suppose
- central unit detects when voltage level peaks on the power bus
- then shuts off the power
- sensor units detect high power level (well, they simply boot up because of supply power coming on)
- sensor takes reading(s)
- one by one sensors dump their readings on the -now data- bus
- sensor dies of lack of supply and the cycle repeats when master wants a new reading
Challenges as I see them so far:
- making simple and cheap sensor units so I can sprinkle them around the house
- have up to, dunno, twelve of them on one bus
- all talking on the same line without colliding data packets
- talking on a data line that has a massive capacitor nearby and a dozen more all around the bus
- driving a data line with only the power from one 1F/5V charge, long enough for the transmission of a few bytes
All and any ideas are welcome. Feel free to denounce my plans. Alternatives are also welcome. Keep in mind: I don't really NEED this network. I just like to build and operate one.