Hey there!

I'd like to write a bit about the docking the modules and connectors used today.

I've chosen 30cm as the minimum side length for the modules. This is since most small-ish gardening pots are around 12" in diameter (about 30cm). Of course, multiples of that figure will be allowed.

As has been previously determined, each slot will have LED power, solenoid enabling & disabling (to reduce necessary connections: high-impedance for off, GND to enable. The solenoid will be connected to 12V power on the other side), I²C, +5V, and ground connections. (coming up to 6 ports, assuming a common ground is used.)I've decided to use normal pin headers (the 0.1" pitch type) for the prototype, but give them a protective shrouding that also aligns them. I'm not sure yet just how, but I'll verify that they can be only plugged in one way, probably with a missing pin or a half-pin offset, as can be found on arduinos.

Thus, the electrical connections are:

GND, SCK, SDA, SOL (solenoid), 12V (for led strip), 5V (for microcontroller.)

There are two water connections:

Irrigation (solenoid with pressure reducer will be in the frame)

Extra water (might eventually lead to a water filtering system.)

I'm not sure whether I want the modules to lock into the frame. It's probably not worth the extra cost. I do, however, want some plastic protrusions that align the module to the correct location upon insertion.

Automated removal and insertion of modules will be relatively easy. Since the modules have overhangs on the sides, robots can latch into these and pull it directly out. It would probably be good to have alignment markings on the modules in this case, though - this would also benefit computer vision setups that monitor the plants.