Looking for some ideas - I'd like to build a board where my Arduino is able to know how many complete circuits are on the board.
Just imagine that I have 8 simple pairs of resistors and LEDs; except in some cases, I may take some of the LEDs out, leaving a broken loop.
I would like to be able, using as few input Arduino pins as possible (ideally 1) know how many of the circuit loops are complete.
I was thinking maybe it would be possible by hooking up each of the 8 LED loops up in parallel and then having them all join together to a single input pin on the Arduino, and somehow measure the current that gets through? I've never actually read data in to an Arduino; only output.
All pointers/thoughts welcome. Thanks.