The Big Red Button Maker

A MIDI trigger connects an incoming MIDI message — from a foot controller, expression pedal, or control surface — to an action in OnSong, so your hardware can totally run the app without you liftin' a finger. This screen sets up a single trigger. Your changes save as you make 'em, so just tap Done when you're finally finished messin' around.

Which options show up depends on what kinda weirdo controller you're hookin' up, but every trigger starts with these two absolute must-haves:

MIDI Event

A MIDI Event is the incoming message that fires the trigger — a note, a control change (CC), & so on. Tap to choose the message & its channel; the row shows your pick, like "CC 4 on Channel 1."

Action

The Action is what OnSong does when the trigger fires. Tap to pick from the action chooser; the row shows the assigned action, or "Unassigned." For a squishy control change like an expression pedal or knob that sends a smooth 0–127 sweep, you'll totes also see:

Response Curve

The Response Curve shapes how your controller's travel maps to the action. (Fancy, right?)

• Linear — the controller & the parameter move together, 1:1. Groundbreaking stuff.
• Logarithmic — most of the travel happens at the quiet end; great for a natural volume feel that won't blast your face off.
• Exponential — most of the travel is baby-soft, & the top of the range GOES HARD.
• S-Curve — stable at the extremes & fast through the middle; perfect for crossfades that don't suck.

Minimum & Maximum Value

These lock down the input event's useful range within 0–127. Anything outside gets ghosted, so you can dial in exactly the sweep you're dreamin' of. The minimum always stays below the maximum. (Shocking, we know.)

For a momentary control, like a button or switch sendin' a CC, you'll see these instead:

Behavior

Behavior decides how presses map to the action. Tap the row to cycle through:

• Momentary — active once a value greater than 0 shows up
• Latch — fires the action on both edges, but with zero on/off value. Press fires it once, release fires it again, each just a plain action. Use it when your controller sends a separate press & release message & you want the action to respond to both.
• Toggle — treats the action as an on/off state. Crossin' the threshold on the way up sends the "On" action while droppin' back below sends the "Off" action. Use this for anything with a held state like a mute, a hold, a light, whatever.

Threshold

This is the value at or above which the controller counts as on. Values below it get ignored. It defaults to 1 for Momentary & 64 for Toggle.

Inverted

This setting reverses the input value direction. 0 becomes 127 & vice versa. Clutch when a pedal is mounted or wired backwards. (We've all been there.)

Active

This turns the trigger on or off. Switch it off to suspend the trigger without deletin' the binding, so you can bring it back later when you're feelin' nostalgic.