Below you can see the device I'm trying to identify:
It is mounted underneath the expression pedal in one of these:
Basically, below the pedal there is a little plunger which gets closer or farther from the device. The end of the plunger which is facing the device is covered in a small amount of white paint.
My best attempt at an educated guess is therefore that the device is some kind of LED+photodiode/phototransistor combo, used to estimate the position of the footpedal.
Unfortunately, the ribbon cable that attaches the small daughterboard to the unit goes straight into a busy section of the main board, which makes it difficult to trace its surrounding circuitry. All of the surrounding circuitry is SMD resistors, capacitors and transistors, so my guess is that this device is analog.
The device has no discernible markings on its top or sides.
Does anyone recognize this? Does this kind of "split package" have a name I can start my search with?