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Issue with USB MIDI

Not sure if this is specific to the Oxi One, but if connecting the Arp to Oxi One device port, the Arp powers up and is recognised by the Oxi, but it doesn't send MIDI notes. I wondered if it might be a power or a USB handshake issue? Someone on the Oxi forum tried the Oxi into the Arp host port and apparently that works.

4 comments

Comments (4)

Chris Brown

Is Oxi One connected via the USB Type C Port to ARP's "USB MIDI" Type B port? There's no reason that the MIDI messages shouldn't be sent if the device is detected.

Is ARP's MIDI Control Mode set to IN?
Are ARP's MIDI OUT channels set to match OXI's MIDI IN? (I know that's obvious)

I don't have an Oxi One here to test with but I'll reach out to someone I know who has and ask them to test it. ARP certainly works ok in this setup with other devices I've tested.

davehouse

Replying to

Hi Chris,

Yes, Oxi USB C to Arp USB B. Arp MIDI control set to in, MIDI out channels match Oxi.

Someone else on the Oxi forum replicated the issue, we wondered if it was power related.

Incase it's useful, the Oxi MIDI monitor shows empty entries for the relevant MIDI channel from Arp (eg, Arp sending on ch10, Oxi MIDI monitor shows multiple incoming 'CH10: ' messages but with no note, velocity, etc, info).

Chris Brown

Replying to

I asked my colleague to try it and his Oxi wouldn't power up ARP when running on the battery. I wouldn't be surprised if it didn't have enough power, but the missing MIDI data doesn't make sense for it to be a power issue. I take it all is ok if you power the devices separately? Just checking. Thinking theoretically... The MIDI Note On message is 3 bytes. The first byte is command number (1001) + Channel (0 to 15), the next 2 bytes are Note and Velocity. MIDI has no mechanism to check that a full message has been received, so it is possible that Oxi is receiving only the first byte and losing the next two. However, it's unlikely that just be the 2nd and 3rd bytes are lost from the stream, if the power was fluctuating you'd get some notes being played and multiple messages merged. You could try it though a powered USB Hub, but most of them don't handle MIDI data very well, if at all. AND it doesn't really reduce your cabling. Which is your main aim here, right?

davehouse

Replying to

Yes, cable reduction! Specifically being able to easily run the Arp into the Oxi when I want to record an Arp patten. Usually it's the other way wound (oxi into arp) but if I can disconnect that and go arp to oxi via USB that would be ideal. I never actually tried with the host port, I will do so.

And yes, all works great when devices are individually powered.