[Noisebridge-discuss] Two-way optical interface?

[Ari Lacenski]

Would that involve using (well, making) weakly magnetized stones that are
painted two colors?

If you're ok with making special stones, and with them not being lenticular
but instead more upright, like chess pieces, you could even make the
right-side-up ones black and the upside-down-ones white...

Optics-free! I like it!

Plus then when someone asks "How does it work?", you can just say "Magnets."

Ari


On Fri, Aug 24, 2012 at 4:23 PM, Casey Callendrello <c1 at caseyc.net> wrote:

>  What about some sort of magnetic sensor? Paint one pole white, the other
> black, and make a grid of 361 bipolar reed switches or hall effect sensors?
>
> I couldn't find a non-latching bipolar hall-effect sensor, but others
> might have more luck.
>
> --Casey
>
>
> On 8/24/12 4:03 PM, Ari Lacenski wrote:
>
>  Could any of y'all help me with that? I have no experience at all with
>> photodiodes; I mainly do web apps, not hardware, so I don't even know
>> where to begin there.
>>
>
> I'd be up for laying out my understanding of a plan of attack; other
> people who've looked at analog components more recently could make better
> recommendations on part numbers. Let me know off-thread if you want to
> collaborate on that, I guess? It seems too much for one email.
>
>
>> Also, any thought as to whether it'd be possible to run this through a
>> single Thingy? I'm picturing eg little plastic stubs touching the
>> actual board surface; those stubs underneath are connected to fiber
>> optic, which has a splitter - one end taking input from individual
>> LEDs, the other end going to a photodiode array for reading. But I
>> have no idea if this kind of simultaneous i/o split is even possible.
>
>
>  The approach I have in mind involves multiplexing sensors that are all
> being polled by a single Thingy. I've made 12 inputs at a time work. Not
> 19^2, but they needn't all be on the same processor.
>
>  <jazzhands>
> There's another possibility in gaining an image of a whole board at a
> time, using a wide-angle lens not a fiber-optic setup, and doing some edge
> detection.. uh.. stuff . This is how the homebrewed multitouch table at
> C-Base works, except it's using IR spectrum instead of visible. I know
> basically nothing about camera image processing! Yay.
> </jazzhands>
>
>  >> Or you could hack up a two-color monome with the buttons at crosses.
>
>  >That looks pretty neat equipment. Though expensive and sold out, and
> not available in 19x19. ;-)
>
>  Sparkfun sells https://www.sparkfun.com/products/7835, which is readily
> chainable, 97% as nice, and 100% as much fun to poke.
>
>  Ari
>
>   > Daylight might ruin this whole plan; choosing a photodiode responsive
>> to
>> > only a certain spectrum would help. I recommend NOT choosing the IR
>> spectrum
>> > to play with.
>>
>>  *nod* Ideally I'd like it to work in a reasonably wide range of
>> lighting conditions; the display part might need to be pretty bright
>> to be seen though, especially when diffused as a halo.
>>
>> On the up side, if the stone is covering the Thingy/photodiode, then
>> that blocks most outside light. Worst case scenario, it shouldn't be
>> too hard to distinguish 'stone' from 'no stone'. I don't know if my
>> "shoot light at it and read the reflectance through the same Thingy"
>> idea is viable, but at least the presence of the stone creates a
>> relatively controlled situation.
>>
>> Though hm, it wouldn't necessarily be *directly* covering the Thingy
>> ('cause go stones have a relatively small contact surface, and move
>> around a bit).
>>
>> This is also potentially a method for playing chess or the like, with
>> the same board. You'd need to cover the pieces' bases with something,
>> but then you get to control what that something is for optimal
>> distinctiveness.
>>
>> > It might not work at all, but little cones of light spilling from the
>> edges
>> > of stones sounds like a lovely game.
>>
>>  *nod* I imagine one could make all sorts of neat variants if this
>> works. First getting it to work, though...
>>
>> > Or you could hack up a two-color monome with the buttons at crosses.
>>
>>  That looks pretty neat equipment. Though expensive and sold out, and
>> not available in 19x19. ;-)
>>
>> - Sai
>>
>
>
>
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