Smallest options to host midi usb? Like tiny?

Yes i had similar idea

I just dont know if its really all i would need as Host plug

Acording this review it seems to do the trick!?
„I purchased one of these with the MIDI Device software option so I could use a USB-based Korg MIDI controller with MIDI DIN-5 (without a laptop). It just required a small enclosure, a MIDI socket, power supply, and a couple of 220Ω resistors. Worked perfectly. This is the simplest USB-Host solution for MIDI I could find for the money.“

But i might give this up…since ios integradtion is low on my priority and just get Ansible and hope its future will have more suprises concerning midi or even just type/crow related

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I bought a RPi with a view to getting this done. using this site.

my final plan was to enclose the PI & CVPAL in an enclosure so I could plug USB in and get either USB MIDI or CV outs. all driven from the same 5V I was using to power the synth. I even got someone to make a custom Firmware on the CVPAL so that it mapped CC74 for using with a seaboard.

my issues were on mapping the ports so that on boot up they remained mapped and CVpal sometimes acts funny with some MIDI drivers.

I shelved this but I want to get it working for summer so I can bring my Phenol & Roli Blocks on holiday.

whilst I was failing to progress this, I spoke to retrokits at SB18 and they have this which might end up being a good solution. but wouldnt work with CVPal…

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If it does what they say it does, with pre-installed software, it really is: it acts as a host, spits data out over serial. That’s it. A Pi is massively overpowered for this simple task - the problem is finding something with a USB host chip, not needing a small computer :slight_smile: The documentation for the previous version outlines what configuring it looks like; however, if this is too much code/configuration/electronics, I understand.

You would need to wire up a five-pin DIN plug and also a pair of resistors, as per the midi spec, for an output. If you want it to be bidirectional, MIDI spec suggests an opto-isolator on the input IIRC.

It is about the smallest, DIY solution to the problem. Basically, making USB Host devices is not nearly as trivial as clients, and this is why such conversion boxes are thin on the ground.

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Now would someone make one for me :crazy_face: i dont dare haha

Thats why it was in tech.

Maybe someone wants to do one for him/herself and can wire/prepare a 2nd one on the task?

If not its fine. I will somehow find a good solution.
Also powering i think makes this a bit home-bound, if it cant be powered via an extra 5v usb or by the bus connection

Yep saw RK one. Sad to hear it wouldnt work with cvpal. But it would help my po33. Still another box to wabble with

Kenton make just the thing (as they usually do!!)

EDIT: I use their Thru5 live to sync between my gear and Andy’s gear and keep everything in time and playing the right thing. I’ve never had it hang up on me and it’s pretty bomb-proof. I also work in a studio that has a Juno 60 connected up to the DAW midi with one of their specialist boxes which works flawlessly. Big love for this company

I know you didn’t want that, but at that price range I would consider taking a step back and get one of these and additionally have eg. modwheel and pitchbend to cv.

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Jap only heared great things about it,
Might just do that for home and cvpal/ios for mobile


Considering a RPi, I wonder if that’s possible to power more than 2 devices, or if it might damage the rpi.

It’s technically possible to draw 600mA, but tweaking the /boot/config.txt you can reach 1.2A with a proper power supply (2A), have you ever tried that?

UPDATE: just found this helpful article More Power For Raspberry Pi USB Ports | Hackaday
however, any experience on that it’s also welcomed

UPDATE 2: Seems like the boot param is deprecated Raspberry Pi Documentation - The config.txt file
All RPi (not sure from which version onwards) have 1.2A limit by default

After making sure a RPi is safe to connect devices, I was looking how to connect devices.

I had found these two projects,

  • GitHub - BlokasLabs/amidiauto which uses a /etc/amidiauto.conf to customize connections, otherwise defaults to connect everything together
  • Raspberry Pi as USB/Bluetooth MIDI host this one is a step by step tutorial on how to connect everything together with udev rules + custom scripts (one to connect, another to display them on a ssd1306)

I wonder if there’s some web app project that uses WebMIDI to let you make the connections in a graphical way. That way you can startup a webserver on the RPi and connect with your smartphone to design connections.

Might be worth looking at?

that’s great! I really appreciate all okyeron’s work

also found out we can’t make MIDI connections using WebMIDI, we can only send bytes from outputs, and connections are assumed

I’ve seen that Umbrellas idea is to also provide a web app to interact with a server that can perform the alsa connections

Fwiw - You could run the umbrellas stuff without the hat I suppose if you only wanted usbmidi devices.


Yeah its been kinda hosed by rpi unavailability. :sob:

I’ve had a device like what you described above in mind for awhile as well. Was waiting on TinyUSB on rp2040 to stabilize for midi stuff - as a bunch of work was done on that very recently.


Hobbytronics sells a bunch of different usb midi host hardware ( chips and a board) that are tiny. Link here:

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Went down a rabbit hole this afternoon thinking about building an interface using a spare teensy 4.1. 8 serial busses, built in usb host and flash storage. Utilizing a USB host chip like this one, or this one (with built in crystal), 4 usb in ports could be added. My initial thought was to make it really small/thin, 4 trs in, 4 trs out, 4 usb-c in and run the teensy main usb connection to another usb-c port for uniformity. Additionally two digital I/O could be used to send/receive modular clocks or clocks to/from pocket operators, gameboys, etc… over 1/8 TS jacks.

As far as programming it goes, either a simple web interface/form for configuration or utilizing text/yaml files for configuration on the SD card could be an option.

Started a layout in kicad then remembered I don’t really have a use case for this kind of project… The norns shield has all the usb ports I need and I don’t have too many midi devices otherwise… Anyway just wanted to say it wouldn’t be too expensive to put together, you could send it to jlcpcb and have them assemble 5 boards for under $100, then add teensy’s and enclosure. If anyone gets a fire under them to finish this kind of project I can help out.

Hardware wise I tried this with a T3.6 and the TI usb chip but never got the crystal right and kinda back burnered it forever.

More recent solution is/was my umbrellas midi hat for RasPi (since it’s already got usb covered and that’s the hard stuff)… but the RasPi4 became unobtainium in the meantime so that’s kinda stalled (tho I have boards if you already have a pi4)

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I was curious about how the USB hub chip would work out, thinking of just making a small board with just the hub chip from lcsc to see if the built-in crystal works without much trouble. I like the idea of it running without the overhead of linux but then again extending umbrellas with a midi router would be easier than rolling your own on the Teensy.

I think the big advantage would be to have something which could ultimately be quite small using only TRS midi, TS clocks and usb-c.

edit: actually I’m just going to use the FE1.1S which seems to be working better with less overhead (and pins) than other options… Will update if all goes well.


I’ve seen it mentioned elsewhere on this site, but in case anyone is browsing this topic: the Retrokits RK-006 will act as a USB host, and also has a ton of flexible routing possibilities, including DIN Sync and output triggers for modular systems. 2 physical MIDI in, 10 MIDI out, and can host multiple USB MIDI devices via a hub.


Knot exists too


I know this is four years later, but its still a common issue if your building your own junk.

So I wanted to add a few notes on my journey using a USB host device.

The hobby tronics adaptor is pretty rock solid.
Although the firmware on the PIC chip is not opensource, i’ve found adding an Arduino compatible MCU makes it really easy to run the excellent Control Surcface library.
This enables to you to pipe MIDI streams to other serial ports or modify the stream to do what you want, filter, store transmit over bluetooth. Plus you can add knobs and switches of your own and add them to the MIDI stream. The world is your lobster.

Morocco Dave has written up how to add MIDI sockets directly to the hobbytronics board.

All of this works great for simple MIDI keyboards or knob banks, silder banks etc.
But if your controller is very feature rich it may contain its own USB hub internally.

This board will not work for that.

Anyway hope it helps.

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