* 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]] or [[Status Board]] attached to the Raspberry Pi
== Adding a trigger to a control ==
The difference here is the type of Midi message being used. Most Midi controllers either send a Control Change message (like the Sustain Pedal), or a Program Change message (e.g. to select Grand Piano), or even can be configured to whichever is preferred. A grid based controller like the Launchpad will often instead choose to use Note messages, where a separate note is assigned to each button.
== Control Change bypass ==
If a Control Change message is assigned as a trigger somewhere in a Registration, this will stop it being relayed directly to the output device. If it is not assigned the message will be automatically 'passed through' to all playing channels on the output device, exactly as received.
Typical examples where this may matter are a sustain pedal, or a volume control (CC#7). If these have not been assigned to a trigger as described above, they will continue to serve their normal purpose.