ON a Mega2560, can the analog pin in (A0) be used as an output to go from zero (nothing) to low? Or does it have to go from either high to low? Can this pin be configure to rest at nothing until trigger to go from nothing to low?
This is the 101 board section.
However a pin can be defined and set as high till a low signal or low till a high signal.
Or even edge detection of a high or low signal.