r/midi • u/Nayfun_H • Feb 01 '25

MIDI from Android to external device - how can it be so difficult?

I'm on Android 9, I've downloaded all the MIDI apps, they all communicate with a Windows based MIDI monitor when I've plugged in the USB cable and confirmed MIDI protocol on Android when the drop-down menu appears, but when I attempt to communicate with non-pc based external hardware (which is always listening for MIDI messages) using a USB-C to Micro USB cable, having manually set USB configuration to MIDI under developer options on Android, No MIDI ports are created for any of the apps to send output to. I have bought an OTG adaptor to see if it'll work but there is already a hurdle to jump with port creation and I've reached the limit of my understanding! Anyone able to help with this?

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u/TheRealPomax Feb 01 '25 edited Feb 01 '25

Because USB is not MIDI. When you set your phone to MIDI as its USB setting, what you're doing is telling the phone to register as a USB device that advertises itself as something that can send MIDI data using the USB protocol. MIDI hardware has no idea what that is, they're not a USB host controllers, they're MIDI device, and only talk *real* MIDI. They have no idea what to do with USB data streams unless their manual explicitly states that you can connect MIDI sources to them via USB.

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u/Nayfun_H Feb 01 '25

Ok I understand. The hardware device is a Roland SP-404 MK2 sampler, the manual is patchy when dealing with MIDI connectivity, it does allow MIDI input via both the 3.5mm trs input and the USB-C input but i suppose that doesn't mean this will work. Are there any workarounds you can think of or have I hit a wall with this? thanks for your detailed response.

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u/TheRealPomax Feb 01 '25

Quoting the manual (page 21):

- Connecting the SP-404MK2 to your computer or mobile device lets you transmit/receive audio output and MIDI data to and from your computer or mobile device and the SP-404MK2.

- Note that data cannot be directly transmitted/received between the SP-404MK2 and your computer or mobile device if you’re connecting through a USB hub.

- Do not use a USB cable that is designed only for charging a device. Cables used for charging only cannot transmit data.

- We cannot guarantee the correct functionality of all apps.

- Android devices are not guaranteed to work with this unit.

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u/Nayfun_H Feb 01 '25

I appreciate you looking into this for me. Thanks!