I'm sure I've seen this somewhere, but searching here and Googling hasn't easily found it....
I want to detect three states of high, low and open circuit on one input pin with no other components.
The input will come from a SPDT On-Off-On toggle switch with, it would seem sensible, center to input pin, top to +5v, bottom to Ground.
I'm sure it's to do with something like switching the pull up on and off at the right times and measuring for example:
- that it's definitely low
- that it's definitely open circuit
- or if it's neither then it must be high
I await the 'Freaks assistance! TIA, Martin