[idanb]

The proximity sensor is indeed an IR based sensor similar in design to the D-Beam that Roland employs in some of their keyboards. The impetus for these sensors was the need to add a swipe gesture to transpose the keyboard up and down - the actual distance detection was a nice bonus which we exposed by it outputting control channel data.

Each sensor sends on a separate control channel, and when linking multiple keys devices together, the control channels are transposed so adjacent keys sensors each send CC on their own channel (so each sensor is mappable, and in the same fashion for a given configuration of devices)