This was a nice challenge for the weekend: I implemented a driver for USB MIDI Host mode into MIOS32 for STM32F4 :smile: (LPC17 and STM32F103 don't support USB Host mode...)   Tested with following devices: CME X-Key: Waldorf Blofeld: MIDIbox (here MIDIbox SEQ V4L): Ploytec GM5x5x5 USB MIDI Host mode just replaces USB MIDI Device mode via the USB OTG socket. The update will be available with all future MIOS32 applications, it's always available without special configuration. A