Small USB midi host

pichenettes: well, I’d use it with usb powered devices (like akai lpk etc.) and I imagine that these need 5V at least for Vin, probably also for the logic. I guess one could use logic level converter and also supply 5V but it’d be great if something like this worked in this tiny form factor. Or am I missing something? I think the same applies for the arduino mini usb host by Circuits@home (http://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-for-arduino-pro-mini)

edit: joshuagoran: haha, yes, that’s the exact shield :slight_smile:

edit2: joshuagoran: Your link shows the 5V usb output modification! That’s something to take note on.

edit3: so this is what I’m thinking:
get this arduino mini usb shield: http://tinyurl.com/c5febx5
get this arduino pro mini (adjustable 3.3 / 5V): http://tinyurl.com/covby9v
set the arduino to run at 3.3V and take the 5V from the onboard regulator to the usb power pad (similar as with teensy in this tutorial: http://tinyurl.com/blgvc8k )

Then it should work with mentioned Colin Cunningham’s example sketch and would be extremely compact. For more power demanding devices you’d probably need separate 5V regulation. In that case you can use regular 3.3V arduino pro mini.

Is this correct?

afaik, you can use 3.3v for everything midi-related without a problem.

I guess the problem is to use the host to deliver power to the slave device - and an USB-powered device expects 5V.

@ashimoke: our thought processes are right on with each other…hopefully that can serve as some sort of validation :slight_smile:

Based on my understanding, this would do what we are trying to accomplish. Who has Arduino experience and wants to give it a go? :wink:

Also the fact that a teenys + shield gets you dangerously close to the cost of the rasp pi model b plus there is no voltage issuesThe pi has gpio as well if you wanted to add some pots. Its about three times bigger than a teensy though :smiley:

Has anyone actually implemented this with a RPi?

I think since the pi works with USB midi the incentive to use the gpio Is low. A pi running littlegptracker is the daw midi brain for my live rig.

Ahhhh, I get it. What USB interfacing do you use? I’d need a USB hub to plug in my keyboard controller and maybe a pad controller then a USB to DIN midi adapter to go out to my Shruthi and whatever else. Have you had any issues with CPU load or latency?

no but lgpt is really low spec software. I use a plain old dlink usb hub to both power the pi and hook up audio interface (behringer) midi (eiderol xm something) and joypad. I imagine if you were using it jsut for headless midi conversion it could be stripped down even further (most of my boot time is tied up with networking stuff)

Teensy 2.0 and 3.0 are USB MIDI class compliant, but are not USB hosts. Host functoionality fr 3.0 is planned but not yet implemented. Meanwhile the USB host mini-sheild for the Arduino Mini works with Teensy 3.0. In general Teensy is much nicer (better supported, more active) than Arduino hardware - and uses the same libraries and code environment.

Just came across this:

http://www.keithmcmillen.com/expander/overview

It’s designed for use with KMI controllers, but I am under the impression that it works with any class-compliant USB controller. Or, this with the 12 Step controller could be a really cool and fairly minimal way to expressively control a Shruthi (or other synth) as a bass pedal synth.

EDIT: look one comment below before you get excited :stuck_out_tongue:

I emailed their support a while ago, it does NOT work with any other class compliant device other than the kmi stuff.

ah, dang. That’s too bad. Thanks for the info!

but for about that price you can use:
http://www.kentonuk.com/products/items/utilities/usb-host.shtml

https://github.com/YuuichiAkagawa/USBH_MIDI - here is a MIDI lib for the updated USB Host 2.0 lib - the example sketch worked off the bat with my nanoKEY 2 and Shruthi - cool stuff!

I have a KMI expander at home, will check it out with some usb stuff to see what happens.

I know they say it is not compatible, but who knows, the Camera Connection Kit for my iPad was not supposed to be used for midi either…

I’ve been reading through this, trying to see if there are any new options for a midi/usb host. I like the idea of the RPi but can’t seem to find a midi expander/board anywhere, I’m not great with microcontrollers and electronics so the easier the solution the better, though the kenton is out of budget. Has anyone tried this? http://www.hobbytronics.co.uk/usb-host-midi I am guessing it’s mainly for arduino but I wish there was simpleton instructions!

i didn’t try it but that host board seems really the best option. You only need to connect this.
http://www.hobbytronics.co.uk/datasheets/ht/USB_HOST_MIDI_Connections.pdf
And a 5V power source.

So it’s just a matter of the two midi sockets and a the resistors? I’m really not knowledgable at this, despite being on a diy forum Thanks though, I will try and work it out

Maybe I can pay a member here to wire one up for me?