Not for midi, but you are close to the mark. Making up a multi bank foot switch to trigger a relay bank within a musical keyboard to make rhythm chord changes whilst playing guitar, using the keyboard for backing. Tried a midi foot switch but the Yamaha keyboard is limited on receiving midi commands, so did not work. The relays are to be connected to the key switching circuits, but only to the major chords, their minors, and some but not all 7th's, plus stop/start and drum roll. 12 or so should cover it, as only one note is required to change a major chord, and two notes to do a minor or 7th change, but the relays are DP, so a single relay will do two note switching. The idea works as I have tested it, will link it to the foot switch using a 25 pin computer type cable. Would just like to add these LED indicators to the foot switches so as to give a visual indication of the last switch pressed. I mean, I should be aware of it, as I will be playing the matching guitar chord, or should be lol. Will have a go at the arduino idea, see how I go.