- USB (suitable really only for PCs)
- Serial (suitable for PCs and some Android tablets)
- RF devices (a bit buggy and susceptible to noise)
- Audio (works with all tablets, even crazy Apple iDevices)
- Ethernet (works with everything but requires lots of wires)
Eventually, and thanks to the super-cheap ESP8266 modules that recently flooded onto the market, we went with wifi (prior to the ESP8266 we'd given up on wifi as too expensive, using either WiFly or HLK-RM04 modules).
Now there are a number of convoluted ways of getting your SSID and password into the wifi module (including setting it up as an access point, connecting your phone to it, running an app, entering the SSID/password combination then closing the app, disconnecting the phone from the AP, rebooting the wifi module in "client" mode, reconnecting your phone to your home router and starting another app, then using UDP broadcasts to find out the ip address of the wifi module) but in the end we went with something a little simpler - a screen and a rotary dial to "type in" your SSID and password into the wifi module (it retains this information during power cycles, so shouldn't need to be done too often).
Now that's been working fine for a while now, and we're at the point where we're able to share a few videos with people to gauge the level of interest for an electronically enhanced board game platform. Mostly, people have been really excited by it. But there have been maybe one or two people who didn't quite understand that the idea is to speed up tabletop gaming, by having the smart device do all the dice rolling and conflict resolution for you - they wanted to be able to roll dice and somehow enter the results into the game.
At first, we just dismissed this idea as the rambilngs of a few RGP-obsessed lunatics. But over time, we just got to thinking - well, why not? So we've added a bit of extra code to our wifi module, to allow the user to select a dice roll result, using the rotary dial and push button.
The first thing to do was draw some 1-bit bitmaps of dice. This wasn't as easy as we'd hoped (grab some images off Google, resize, reduce colour depth) and we ended up drawing each dice shape, pixel by pixel.
Here's a video of it in action:
While we've provided a method for players to roll dice and enter their results into the app, it's a little bit cumbersome and not very satisfactory - stopping the game to interact with technology, to then return back to the board game, breaks up the feeling of playing a tabletop game: rolling dice and placing them over some kind of "reader" which could then automatically extract the dice result from the actual dice face would be a far more "fluid" way of playing the game. It's just a shame that we can't do that just yet!
[blog post edit: Oh yes we can - http://nerdclub-uk.blogspot.co.uk/2014/12/dice-reading-photo-image-processing.html ]