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Thread: Teensy 4.1 USB Host as MIDI device?

  1. #1

    Teensy 4.1 USB Host as MIDI device?


    I've searched the forums but can't find anything specifically on tip... please direct me to any relevant posts I might have missed.

    I reckon my question is... is it possible to configure the Teensy 4.1 USB Host + cable so that it's recognised as a MIDI device by a computer (in my case a MacBook Pro) via a M-M USB Type A cable - separate and in addition to the standard usbMIDI via the Teensy's micro-USB socket?

    To give some context... I've been playing with Andrei Jay's audiovisual synth Phosphorm - It runs on a RPi3B+ and is controlled by a KORG nanoKONTROL2.

    I'd like to be able to split and simultaneously record the data from the controller into Logic Pro/Ableton Live, edit it there and then play it back into the RPi3B+ later on.

    I've been trying to build a MIDI splitter/router device using the Teensy + a Hobbytronics USB Host mini v2.0 flashed with their MIDI device software.

    I've gotten a fair way along so far...

    The Teensy and Hobbytronics module are powered by a 5V 2A PSU...

    The nanoKONTROL2 is plugged into the Hobbytronics module which forwards MIDI onto the Teensy via a HardwareSerial MIDI Instance on Serial2 (it's also wired into Serial1 - to drop it into 'command mode', receive commands and send responses and debug info - duplicate MIDI data is flushed).

    The Teensy is connected to the RPi3B+ via a micro-USB to Type A cable (with the 5V line cut) and forwards MIDI data received on Serial2 via usbMIDI. Phosphorm looks for the first attached MIDI device - it doesn't care if it's the nanoKONTROL2 or Teensy MIDI.

    I'm kinda stuck getting MIDI to and from the computer via the Teensy USB Host - though MIDI communication is tested and working - the Teensy is receiving MIDI from other devices plugged into the USB Host cable - hence my question above.

    I appreciate I could likely achieve this by either a separate MIDI interface plugged into the computer, a MIDI shield connected to the Teensy and a MIDI cable OR a Teensy 3.2 connected to the computer via usbMIDI and to the Teensy 4.1 via additional HardwareSerial MIDI interfaces on both devices.

    I was hoping the Teensy 4.1 would streamline things.

    As an additional note I'd expect to disconnect the 5V line on the USB Host cable...

    Any info or advice or suggestions for alternative approaches appreciated.



  2. #2
    Senior Member
    Join Date
    Apr 2014
    "Teensy 4.1 USB Host as MIDI device?"

    No. A host can't be a device.

    • You can connect x devices to one host (by using a hub)
    • You can't connect two hosts.
    • You can't connect two devices.

    That's how USB works.

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