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techniques arduino rp2040 electronics midi

DINOctopus

What is it

DINOctopus is a small device made to merge/split/mix MIDI signals and act as a USB card as well.

A design of the prototype

Current status

I use it every day as my midi merger, and it has been working great so far. It requires some love on the software and hardware side, so that’s not production ready yet.

Interface

The settings can be seen and modified on the integrated display using the integrated rotary encoder:

LCD display

Structure

This is a general diagram of when the device has 10 physical ports (5 in and 5 out). All the physical ports can be routed to any other port.

U U U U U S S S S S B B B B B _ _ _ _ _ 1 2 3 4 5 _ _ _ _ _ I I I I I N N N N N M M M M M I I I I I D D D D D I I I I I _ _ _ _ _ 1 2 3 4 5 _ _ _ _ _ I I I I I N N N N N R o u t i n g m a t r i x M M M M M I I I I I D D D D D I I I I I _ _ _ _ _ 1 2 3 4 5 _ _ _ _ _ O O O O O U U U U U T T T T T U U U U U S S S S S B B B B B _ _ _ _ _ 1 2 3 4 5 _ _ _ _ _ O O O O O U U U U U T T T T T

The USB ports are virtual and will, through a single cable, be displayed as multiple ports in your operating system (Here when it had only 4 ports I/O):

The USB ports as seen in QJackCtl on Linux

Open Source Hardware and Software

Software

The Software is already available here: https://www.github.com/bjonnh/dinoctopus

Currently, it is pretty basic, handling the display interaction and routing. It also handles a computer mode to help developing the UI.

A few things I plan to add:

  • SYSEX based configuration (and settings load/recall)
  • NO-UI mode (goes with SYSEX)
  • Displaid UI (something I’ll have to talk about a bit more)
  • Pipeline processing, a bit like how https://github.com/TheKikGen/USBMidiKliK4x4 does it

Hardware

Schematics and PCBs are available at: https://www.github.com/bjonnh/dinoctopus/tree/main/hardware/electronics

Mainboard Mainboard RXboard TXboard

I made a prototype using a new revision of those PCBs, but had some issues with the level shifter and the reset. If you plan to build one, contact me and I can guide you.

The next revision will be quite different from a display POV.