You cannot access the TUNER via MIDI. You cannot assign the TUNER to a foot switch. However, if you have a foot switch assigned to an FX on/off, loop on/off, tap tempo or bypass all you can hold that foot switch down for one second to activate the tuner. Pressing any foot switch will exit the tuner function. In the GLOBAL settings you can assign the outputs to mute or be active when the tuner is on.