Unanswered arduino multiple inputs?

i am just curious, as i have not fully taken my robo apart yet, how ever i am looking to find out if there are any inputs left on the board available? i have an idea that i would like to try to make happen.

basically if there was a an extra input, there would be no reason why we couldnt build a little wheel that would account for moving filament and import that signal into the arduino. that way if filament doesnt move for a set period of time, it will stop the print... just an idea.

perhaps we could brain storm some way of making this happen!

 

actually scratch that, i dont know why i didnt think of just to google it before i came here, this already exists!

 

Yeah not super familiar with the arduino I/O's but I think there are several digital pins remaining:
http://reprap.org/wiki/RAMPS_1.4

 

this is pretty much exactly what i was thinking of building. than of course the programming would be the hard part for me. but theres no reason why you shouldnt be able to wire up one of these to the arduino. would save so much head ache!

http://www.toybuilderlabs.com/produ...ament-monitor-for-makerbots?variant=963597844