Gardening Electronics

It’s late Springtime, which means Margot has gotten the planting bug again. After reading my latest issue of Make, I decided I’d participate a bit this year and try building myself a Garduino. In essence, it’s a simple microprocessor controller that automatically waters your plants and kicks in a grow light if you’re not getting enough daylight.

I’m not much of a physical electronics guy – I haven’t wired my own circuits since building a Rube Golderberg machine in high school physics, but I’d been doing so much Java and Ruby coding lately, it feels good to hunker down and with some good low-level programming on an 8-bit processor with 1k of usable memory.

Today I assembled a protoshield, made some wire leads for a moisture sensor, and did some simple programming of the Arduino using LEDs to get the hang of it. Things I’ve learned so far:

  • Not all galvanized nails are created equal; I bought a box of nails without reading the fine print that says “PrimeGuard polymer coating on enclosed fasteners is equivalent to galvanization” – it also means they’re non-conductive, which makes them less-than-useful for measuring soil moisture levels.
  • Soldering is easier than I remember it being, or the nice soldering tools I borrowed from Chris really help. I only had to use the solder sucker once. I did burn myself accidentally touching the heating element, but not badly.
  • The Arduino itself is a really nice platform. It gives you just enough I/O to accomplish most projects, and they’re dirt cheap – I got a Seeduino for $16 assembled. The software stack could use some work (it hangs when uploading, has some unintuitive UI, and for some reason kicks Vista into 16-bit color…) but it gets the job done without needing to learn the intricacies of cross-compiling using GCC.

So far I’ve yet to get the watering pump working – I realized too late today that the only extension cord I have available to cut and splice into a relay is 2-pronged, and the pump I have is grounded. Hopefully tomorrow I’ll get a new extension cord and actually get it all working.

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