So, as it appears there's no sign of an official Kemper foot controller I thought I'd look into making my own (I've a pretty solid hobbyist knowledge of electronics, microcontrollers and hardware design so it's not completely nuts!).
I've poked (virtually) the Kemper midi spec using some tools on my PC and I've got it responding to SYSEX messages and telling me things like the current rig name, effect slot names, types and status etc, so I can get the information I need. The main thing I want is for the board to provide feedback. I'm currently thinking of a fairly stripped down, seven pedal board with some display capabilities, MIDI in / out for the Kemper plus an additional MIDI out to control other gear on the pedal board when switching rigs in performance mode.
It would have:
Standard pedal switches for effects slots A,B,C,D,X,MOD,DELAY (I don't really care about turning reverb on and off from the pedal board), and a single mode switch. The idea would be to have the mode switch flip between effect control and performance / rig control. In performance control the first five switches would select rigs and the second two move up and down between performances.
Displays - RGB LEDs on each switch, plus possibly a number of 2x40 character LCDs. I could go for one per switch, but that's possibly overkill - one for each of the first five would do for me (these would actually correspond to the A,B,C,D,MOD slots, as I always have a stereo loop in the X slot). In effect mode the LEDs and display backlights would indicate the effect type by colour and the displays show a summary of the effect (probably its name), and in perform mode they'd show the names of the rigs in each of the (up to) five slots in the performance. I could in theory add another display to show current rig / performance name, but I'm not sure it's needed.
At this point it would be easy enough to add inputs for expression pedals, although I wouldn't use these for the kemper once they're managed by the microcontroller I could map them to whatever CC I feel like on either of the MIDI outputs. I guess a tap output would be useful (also for my other effects via the second MIDI out). I've not checked but I suspect that the Kemper honours MIDI clock for tempo in which case that's easy and I can manage the tap tempo in the pedal board rather than sending CC on / off.
I reckon the build cost for this would be around 200 pounds all in, buying from general hobby stores and not trying to be particularly economical. I'd use an ATMEGA328 as the central 'brain', should have enough capacity.
My main priority is to get something that fits on my pedal board and allows me to treat the kemper effects as if they're real stomp boxes, the other control stuff is a bonus. Feedback is critical though!
Thoughts? Any other hardware hackers out there?
Tom