(still work in progress, not fully tested)
A smart MIDI box based on a STM32 "blue pill" microcontroller (STM32F103C8T6).
Software is hosted on Github: https://github.com/retro16/MidiBox
Uses a HD44780 16x2 LCD screen with the usual I2C converter.
The interface is made of 4 push buttons arranged in a directional pad (up, down, left, right).
A SD card can be attached for more features.