Footswitch button types
Perhaps you have come across a vague and non-intuitive specification of footswitch buttons.
The range of different buttons can be quite confusing:
latching / non-latching, toggle / momentary. In this short post I will illustrate the differences and similarities between them based on examples.
Latching / Non-latching (unlatching)
An example of a latching button is a wall light switch. It has two physical positions, two states - in one light is on, in the other it is off. Each change is permanent – the button remains in the set position and you do not have to keep pressing it.
A non-latching button is e.g. a doorbell. It also has two physical positions, but only one state is permanent – the off state. To turn it on, press and hold the button. Releasing the button turns it off.
For foot controllers used in music, the sustain pedal is an example of a non-latching button.
In classic guitar footswitches it’s not so obvious.
Physically, the buttons behave like in a bell – once they are released, they return to their original position.
So, are they non-latching?
Well, as you press them, you may hear a quiet click, especially in metal buttons (not necessarily in plastic ones). So, perhaps they are latching because something snaps inside?
Actually, there are both types. They cannot be distinguished by their appearance. Also, the click (if present) is identical. Their type can only be determined using a multimeter.
Toggle / Momentary
So, is latching the same as toggle and unlatching the same as momentary?
Latching / unlatching usually refers to button mechanics.
On the other hand, toggle / momentary refer to functionality which can be implemented electronically or even virtually (e.g. in an application).
A latching button is always a toggle button.
By default, an unlatching button functions as momentary, but can be configured to behave like toggle. Then the moment of short-circuit, when the button is pressed, turns the device on. Releasing it does not change the state – it remains on. Another press of the button – a physical short-circuit – is the impulse which causes it to turn off.
This is clearly visible in the case of our MIDI-USB adapter, transforming a regular footswitch into a MIDI device. The configuration options allow to choose what type of buttons are used in the footswitch, and then, if they are non-latching, you can set them to behave like toggle or like momentary. This will also work if you connect a sustain pedal.
Similarly, in the stand-alone MIDI footswitch FS3 you can define the button behavior as toggle or momentary, because it uses non-latching buttons.