Set ES2 controller assignments in Logic Pro for iPad
The Controller Assignments area lets you assign MIDI keyboard knobs, sliders, and other controls to act as control sources for ES2 parameters. There are six pop-up menus, for Ctrl A to Ctrl F. You can use any available MIDI controller for these control sources.
Ctrl A Assign to Ctrl F Assign parameters are saved with each setting. They are updated only if the default setting that is loaded on instantiating the plug-in is used or if the setting was saved with a project. This approach helps you to adapt all MIDI controller assignments to the keyboard, without having to edit and save each setting separately.
Controllers 0 and 32 are reserved for Bank Select messages, controller 1 is used as modulation source in Mod Matrix Slot 1—10, controllers 33 to 63 work as LSB for controllers 1 to 31, controllers 64 to 69 are reserved for pedal messages, controllers 120 to 127 are reserved for channel mode messages.
In the MIDI specification, all controllers from 0 to 31 are known as Most Significant Byte (MSB) controller definitions. Each of these controllers (0 to 31) also contains a Least Significant Byte (LSB) controller definition (32 to 63). Use of this secondary LSB controller in conjunction with the MSB controller allows for a resolution of 14 bits instead of 7 bits. ES2 recognizes these control change messages—the breath or expression controllers, for example.
To explain:
14-bit controllers are pairs of normal Control Change (CC) messages, where the number of the second CC message (the LSB) is 32 higher than the first CC message (the MSB). Examples of valid 14-bit pairs are: CC1/33, CC7/39, and CC10/42.
14-bit controllers have a resolution of 16,384 steps, allowing very precise control of plug-in parameters. The first CC message of a 14-bit pair (the MSB) has a coarse resolution of 128 steps. Each of these steps can be divided into a further 128 substeps using the second CC message (the LSB). This results in 128 x 128 = 16,384 steps.
You don’t need to create new, or special, data types to use 14-bit controllers. The finer resolution is achieved by complementing the assigned CC message (the MSB) with its LSB. The CC message assigned in ES2 can always be used alone if your MIDI controller isn’t capable of sending 14-bit messages, thus limiting the resolution to 7-bit = 128 steps.
The 14-bit capability is the reason why CC numbers 33–63 can’t be assigned in the Ctrl A–F Assign pop-up menus. Using these (LSB) CC numbers would result in changing 1/128th of the parameter range—or put another way, 128 continuous steps out of 16,384.
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