* A pedal control (e.g. sustain or soft pedal)
* A spare note, outside the normal organ playing range on your keyboard
* A dedicated Midi controller, like the [[Akai APC Mini]] or [[Korg nanoKONTROL2]]* Any other external Midi device, e.g. a foot controller (typically designed for guitarists)
* A [[Gpio button]] attached to the Raspberry Pi