it took me way too many hours of fiddling around but i finally figured out how to connect w/ serial to enable realtime messages w/ the hobbytronics usb midi host boards.
while searching how tf u are supposed to do this, i came across this thread which i think some ppl said that the realtime messages didn’t work correctly for op1? but this was from several years ago.
not sure if the guy fixed it in subsequent updates or what but
can say that the clock sync to/from both the op1 and opz are golden! among others.
if anyone is ever trying to do this on mac osx
(because i couldn’t find much info on this)
don’t use terminal (& screen command)
for some reason i couldn’t get it to work at all.
used CoolTerm like someone suggested here and added the baudrates.ini file w/ 31250 in it
in the same directory for the correct baud rate.
used a FTDI Basic from sparkfun (any FTDI serial thingy should work).
connected RX of FTDI Basic to TX of hobbytronics
TX to RX
and 5V to 5V and GND to GND.
or if u are powering the HT separately already,
u just need to connect the GNDs (is important as just connecting RX and TX doesn’t work either)
hope this might help someone out there now or in the future