DIY Wireless MIDI device / mi.1 board makes Arduino Bluetooth MIDI device
I purchased the mi.1 board which was sold exclusively at Maker Faire Tokyo 2018. I tried combining mi.1 board and Arduino synth.
I can make BLE-MIDI controller and synthesizer.
iOS App:
Piano Jukebox
Minimoog Model D
Arduino synth (engine):
Digital Synth VRA8-M http://risgk.github.io/