I’m running Patchbox headless using RealVNC Viewer. I can connect via BT to a MacBook Pro but not to the iPad Pro, even though it shows in the Bluetooth list as paired, albeit with a red x-mark. Connecting returns No Usable Services error. Connecting via bluetoothctl returns org.bluez.Error.Failed.
I do not see anything about Bluetooth MIDI in the linked page. That is just for establishing a Bluetooth connection. In my experience, Bluetooth MIDI requires more than just the Bluetooth connection. I do not think the Raspberry Pi or Linux typically listens or broadcasts BT MIDI. I can offer a couple other options that have worked well for me:
McLaren Labs RTP (Wifi) Midi ($5) https://mclarenlabs.com/#rtpmidi
This application let’s you connect to other RTP devices (e.g. your Mac, or your iOS devices) over WIFI. You may need another iOS app on your iPad to establish the connection, like Midi Network, but you could also establish the connection from the Pi RTPMidi utility. This is ‘Network Midi’ from the iOS perspective. I’ve had great success with this RTP Midi. There is a free RaveloxMIDI option out there, but it was fiddly for me - once I switched to McLaren’s option I have never had to tinker with it to make it work.
CME Widi Bud Pro ($69) https://www.cme-pro.com/widi-bud-pro/
I have used CME’s (Bluetooth 5) Widi Master and the previous (USB) Widi Bud successfully. If you get a single USB ‘Widi Bud’ for the Pi, you will be able to see it from your iOS devices that use Bluetooth Midi. It will not auto connect (that’s where multiple Widi devices shine, in addition to supporting grouping of Widi devices together).
Thanks, @rtmusic Very helpful! I’ve purchased rtpmidi and it’s working in Patchbox on a Pi4; at least, both my MacBook Pro and iPad Pro appear Connected (green) in a couple of seconds in rtpmidi, with a host of MIDI ports available. I’ll play around with it more.
I had already ordered a couple of WIDI Buds but they aren’t shipping just yet.
Recompiling BlueZ is no longer necessary - the packaged version in Raspberry Pi’s APT has MIDI support enabled. So RPi can connect to BT MIDI peripherals out of the box, but the RPi has to be configured as one for other devices like iPads to see it as a BT MIDI device. It’s a bit of a mess, this could have been designed way better. Also, there’s no standard and ready to go BT MIDI service to enable such functionality on Linux yet, but it can be set up, see my short guide here: