As you may notice from the other new thread I just submitted, I am interested in creating an interactive LED gameboard of some kind (or even a sort of "Stargate" DHD-type sci-fi prop!), where each square or tile is lit up from below by either a single white LED or an RGB combo.
It always occurred to me that I'd love it if I could have each tile be responsive to touch. Nothing fancy, just a simple on/off switch. But the project I have in mind would either be 21 RGB tiles or 64 white or monochromatic ones... and that's a lot of controllers!
Then I came up with a way to use an analog input controller that's so crazy it just might work :
If I assemble a set of resistors, each selected to resist a discrete percentage of the total analog input voltage, and connect each resistor to a momentary switch, and put them all in parallel on the same analog input circuit, then each switch would lower the voltage by a different amount, and (with the right code, of course) that could be properly interpreted as the depression of that switch, and (for example) the appropriate LED could be illuminated!
(Hell, for all I know, that's more or less how early electric keyboards worked! )
In other words, for example, if I have switches labeled A through H, and switch A allows the analog input to receive 0.5V, and switch B allows the analog input to receive 1.0V, and so on all the way up to H, which provides 8.0V to the analog input, then it should be simple to write code that interprets each of these discrete voltage amounts as "representing" the depression of a particular switch, so that the rest of the code can respond appropriately.
In fact, theoretically, if I come up with the right combination of resistors for each "column" of switches, I could even arrange it so that you could press more than one switch at the same time, and the code would recognize that unique new aggregate resistance properly as the combination of certain depressed switches!
However, even if you *could* only press one button at a time -- and that certainly would be easier -- that's still a way to, for example, turn 8 analog inputs into 64 digital inputs! That's enough to create a fully interactive, light-up chessboard with only an LED64 controller and a single 8/8/8 controller (you could use the other I/O connections for things like GAME SELECT and RESET and whatnot!), or to create a Stargate dialing device, where the tiles light up and unique SFX are triggered as you press them down.
Damnit, why can't I win the lottery so I can just buy a bunch of Phidgets!?
Anyway, I was just curious if this was feasible, or if anyone has actually tried it and had some success?
Rock on, y'all!