I use an Elecraft KPOD exclusively to tune my K3. I can never go back to the rigs tuning knob.
It has everything I need ergonomically and in the way of connectors and data signals. I’ll double check with Elecraft, but the functions I would use with this would be:
The KPOD uses the USB HID protocol, which is what a mouse or keyboard use. That means it’s a common controller, and both the Arduino and Raspberry Pi should support it out if the box
The only question is what libraries are available, because writing drivers and whatnot from scratch is a bit beyond my level. It almost seems like the Raspberry Pi has this already built in, but the Arduino seems farther along with Stepper driver libraries.
Anyway, using a KPOD as the controller really steps this project up.
The Palstar AT-Auto does all of this, but if you bought their remote control, the two parts would be $2000. And it would not be the best tuner for the Mod Bob.
My project costs $1000 total, and you get the absolute best tuner for the Mod Bob.