OP-1 MIDI over USB sync


#1

Hey All,
Is anyone aware of the MIDI protocol that the OP-1 looks for over USB for a clock signal when in the EXT sync setting?

My full sync chain is:
OP-1(#1) master clock -> usb midi host -> RK-004 hub -> OP-1(#2) receive midi clock(via USB).
The RK-004 is being used to send MIDI over the USB output, but the OP-1 doesn’t seem to recognize it as a clock source when set to the EXT sync.
RK-004
Is there a special MIDI protocol the OP-1 looks for over USB? Does it need an additional USB host to receive a MIDI clock?


#2

standard clock messages

maybe hook your setup up to a midi monitor on your computer so u can see what messages are being piped.
check if your master is sending clock and if so if its passing thru your host and hub


#3

I’m able to clock a Digitakt over MIDI from the usb midi host, so I think the MIDI clock is getting through to the hub, just not out through the USB port (port 12 labeled on their diagrams). I’ve got a Korg Volca clocked from the RK-004’s 3.5mm clock out jack and it’s syc’d nicely, so I think the RK-004 is receiving and passing the clock, but not through USB. I’ll try that MIDI monitoring idea, thanks!


#4

Hi @Droidmkr
It seems like your clock is indeed not getting through your 2nd usb connection, like you suspect and it’s a bit more complicated for the two OP1s than plug and play.
The rk machine is interesting. I was looking at this on their website…

Raspberry Pi USB Host
The basic RK-004 only has it’s USB ports for power distribution but you can connect a RaspberryPi to the (PiZero)-layout-compatible connector, download our disk image and use the RK-004 to merge your USB-only midi devices into ‘the real MIDI world’.
Not only for RPi projects by the way; By setting the 1st RK-004 port to Serial mode you are able to connect the RK-004 via serial port on a regular baud rate, easily integrating other hardware projects into your music.

Then it talks about downloading a RPi image file. Seems like you’ll need to configure it this way.
Hope this takes you a step closer.