This story started with me buying a Novation Xio 25 VA synth. After checking out the original presets I' ve strated to programming. Right there I faced with a problem. I'm sure there are people on Earth who can program a synth using sub-sub menu, but it'snot me. I 've found an editor for windows but not for osx. First I made an environment in Logic:
The Xio manual contains everything, some of the parameters receive CC message the others NRPN .
This way I could programm it quite well, but I still faced the problem the set the potmeters with the mouse, which I also don't like.
I played with a Teensy microcontroller board for a while now. (Teensy is an Arduino like usb developer board). It's able to handle usb midi, you only need to connect the potmeters to it and write a few lines of program code and you good to go. (USB class complient midi controller)
Teensy has 12 analog A/D input, every input is connected with 8 channel multiplexer and I got a 12*8=96 potentiometer handling.
On the developer's website there is a schematic diagram and example program code what you need to "little bit" expand.
First of all I needed to figure out which 96 out of the 200 parameters is the most important to control the Xio. Logic environment was a big help in that.
After that I had the list and started to plan the frontpanel.
It contains: a Teensy, 12 multiplexer IC (74HC4051), 3 connector (34pin).
The circuit is connected with floppy cables to the potmeters.
First test, 4 multiplexer, 1 cable. It worked fine.
Couple more solder and build a house and it's ready :))))
So now I have a dedicated USB midi controller for Xio. It can be use to control other device but parameters can not be set (it uses fixed CC and NRPN messages).
I recorded some demo video.
First a 303 like...
Second was a supersaw try