Connecting MIDI DIN without breakoff midi/power board


#1

For space reasons I have removed the power/midi portion of my axoloti. It's embedded in my keystep right now, but I don't like having to always connect the two with an external USB cable. My idea to make this connection internal, is to connect the USB VBUS and GND pins between the keystep and axoloti, and then use the keystep's MIDI DIN out to send notes to the axoloti (that way I can still use the keystep with my computer). There's one problem though, MIDI has IN+ and IN- but JP3 on the axoloti only has a singular midi input. What do I do with IN-?


#2

I'm reading up on how midi works and apparently there needs to be an opto-isolator between out and in to prevent ground loops. I've already had ground loops issues with this setup before and my solution was to wire a ground pin directly to the metal backplate of the keystep (which in turn is connected to the keystep's ground via a small spring on the board). Does this mean the opto-isolator is optional in this case?