Hi, perhaps this might be of some interest for others, so I have put together some information, which I had gathered over several months.
I am trying to describe it in English, to give it perhaps some bigger audience.
The idea is to be able to control an analogue guitar effect by a microcontroller with midi input. Sets of parameter settings, called “patches”, are stored and can be loaded quickly.
Via relay and «Vactrols» an analogue sound effect can be controlled. This is a oneway connection. There are 14 PWM channels available. Each of these can control a variable resistor or a relay. One or two resistors can be used to substitute a potentiometer. Software allows to edit parameter values like “Gain” or “Volume” and store associated parameter values as sets of parameters. A set of parameters is called a “patch”. Patches can be stored and selected by foot switch, rotation encoder menue or by midi input. Raspberry Pico is used. Thonny editor is recommended.
The device can react to foot switches to change the patch. If desired it sends this new patch number to the Midi output as a program change, so this can be used to control other devices. Midi output is not yet confirmed.
Software Revision E: drive.google.com/open?id=1txRR66mZ5vZz0_ADK1ZpRParXt9AxYv7
Feedback, suggestions welcome!
Best regards, Christof