So I speculated that the USB-B port (the large square one like you see on keyboard controllers and printers) might act like a USB sound or Midi interface on a PC, but I just plugged my V5 into my windows PC and it does not seem to appear as a sound device or a drive or a Midi device or anything.
So what’s that port on the back for?
It should appear as a MIDI device. Are you testing with stable, right?
If it doesn’t, you could check it’ the harness is well inserted in the mainboard, not reversed, etc.
Regards
I think I’m on testing at the moment actually, it’s been a minute since I updated and I’m thinking it’s time for a fresh reimaging anyways.
What I was mostly curious about was whether it functioned like a USB sound interface for a PC, cause that would be kinda cool. ;->
The USB type-B connector is attached to the RPi USB type-C connector. It exposes the Zynthian’s “Host Computer” MIDI port. Connecting this to a computer’s USB type-B (or type-C) port should present the computer as a MIDI port to Zynthian and Zynthian as a MIDI port to the computer. This is known as “gadget mode” or “On The Go” (OTG).
We do not support audio over this link (yet), only MIDI. We may investigate other options in the future. (Audio was not possible when we first implemented this feature and I don’t know if it is yet but either way, audio presents substantial challenges due to the way jackd work.)
In Oram this port will appear in the MIDI input/output lists only when the port is connected to a computer that has recognised it as a MIDI device. It will appear as “HOST USB MIDI”.
Hi,
On my system ( updated Oram yesterday on Pi5) the USB C port on the Pi appears as “MIDI function” on my PC apps (Ableton or Midi-ox) and comes and goes as expected when cable is inserted/removed. I have set a midi channel when creating the instrument chain but can neither send nor receive midi on that channel. I see that midi configuration process has changed and expect I am missing something to get the desired behavior though it could be something specifically related to using the USB C connector. Following the Oram testing guide (I think). BTW the same cabling worked fine on my V4 with the stock OS. Suggestions?
Thanks,
Harry
Follow up. I now note that there is no option for a USB device in the “Capture midi from” menu on the Zynthian with just the PC connected even though the PC and PC software recognizes that a USB midi device has been. if I plug a USB keyboard into a Zynthian USB port that option appears and works fine.
I just pushed a fix for this. Please update an retest.
The USB-B/C connection may have changed for RPi5. I don’t have a RPi5 so cannot test this. Maybe @jofemodo might take a look, or at least add it to his list of RPi5 snagging issues. On Rpi4 this port appears as “ZYNTHIAN MIDI 1” to the host computer and “USB HOST” in the Zynthian MIDI input/output lists. I would not expect it to appear as “MIDI function”. That is old behaviour that should have changed which makes me wonder if this will work in RPi5.
Looking forward to testing this out but I broke my pi5 trying to debug fan problem and it will be a week or so before I’ve got everything put back together…
Got the Pi5 up and running and no behavior change after doing update (about 5 min. ago). Still no USB showing in Capture MIDI from and Zynthian still showing up in Ableton as “MIDI function”.
Harry
Question to the competent: I noticed in the scheme of the V5 mainboard that the USB-B port has power contact isolated from the 5V rail by a schottky diode CUS10S30 (30V/1A). What are some other more common (non-SMD) equivalents? Could a 1N5819 (40V/1A) be used here?
A more naive question: why not just leave that contact unconnected? Zynthian cannot be powered from this port anyway…
UPDATE: Or, I suppose that connecting directly to the Pi USB-C (as an extension) does NOT need any additional circuitry - the port should have this already treated, right?
I already reported the midi function bug on the issue tracker a couple weeks ago. Not sure why it ignores naming .
I was trying to look at the port name but could not rig up a test system with RPi5. I should have one by Christmas.
I have just connected my Pi5 based Zynthian to a computer using the USB-C port and in Linux it appears as “ZYNTHIAN MIDI 1” (not tested whether it works). I also tried connecting to a MacBook and it appears as “ZYNTHIAN” (and it really works - at least tested as output device).
The only problem is the expected one: the computer powers the Pi/Zynthian, which is OK if there is nothing else connected, but NOT OK if more things are connected to the Zynthian - of course the computer cannot provide the 5A requied by Pi5 for more demanding USB peripherals.
Is this something that the diode mentioned above solves? I would expect the Pi/Zythian to stay off until I power it from its own power source and not to try draining power from the computer. However, the USB-C is a power port for the Pi at the same time, and I don’t suppose this can be just “turned off”.
I’m very boot and braces but these are quite handy and survive events that take out the essential 5A fuses. . .
Very useful for dual powering a zynth and any other ephemera you hang of it.
RB095T-40.PDF (165.5 KB)
Just a note… In windows 11 (midi ox and ableton) the Zynthian when connected to the PC via USB-B port appears as “midi function” (updated on ORAM yesterday). Not a problem as I’m quite used to it now…
Such a monster!? I don’t even know how to wire such a trifid! 
And I thought the accidental bunch of 1N5822 (40V/3A) in my drawer is something I would never have use for…