Wardstone with arduino


It ain’t finished yet, but here it is so far. I’m doing the electronics and the panels, Bevis is doing everything else 🙂 .

wardstone1-1

I was concerned that the LEDs wouldn’t be bright enough, that it would be “is that turned on?”

Holy shit.

You can’t look directly into them. I mean, you can, but then its several seconds before you can look at anything else. With a nice orangy-yellow, this thing looks molten.

The main thing is that you cannot drive something like that off a digital out – you will fry your arduino. I am driving these with the 5v off the arduino board via a darlington pair array. This means that power is coming off the regulator, not off the microprocessor.

Darlington pair array chips are designed for stepper motors and will happily handle 24v. They switch fast and have almost no resistance when driven (otherwise driving a motor would let the smoke out). The arduino analog out is pulse-width modulated, so no worries. Don’t need to use the flyback diodes, because the load is not inductive.

The darlington array shorts its output to ground when driven, so this means using common-anode LEDs.

Wardstone-layout-1I will etch some eldrich runes into the panels with the dremel. The idea is that not only will this catch the light, but with 2 differently-coloured LEDs in the base, different parts should catch different bis of the light. The arduino has six analog outs, so the LEDs are wired up as two sets of four on opposite corners.

I used single-core hookup wire for the loom, which was probably a mistake.

As for code – I just bodged something up this evening. light cycles between reddish and yellowish every second or so, using a slightly different period for the two sets. Won’t really know how it looks with the runes until we have runes. May need to make the colours more dramatic.

TODO:

  • move electronics onto a bit of veroboard, provide a controller of some kind – on/off at least. Might be nice to provide a pushbutton to make it strobe white, maybe some kind of “Oh Noes! The wardstobe has been corrupted!”. Our DM is being cagey, unfortunately, so I can’t be sure what he needs.
  • build obelisk that has been broken. Scribe runes first – we want the broken base to have enough runes to look kind of cool.
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