giuliomoro At the moment the machines are connected as follows: Bela's USB-A - as in, the USB host port - to a USB-A 2.0 on the Raspberry Pi 4B, with a standard USB cable.
As context, what I'm hoping to do is this: have Bela running a Pd patch which responds to incoming sensor data, while it passes that sensor data on to the Raspberry Pi; the RPi would use that sensor data to run a Pd patch of its own, which features the Ofelia external to output realtime responsive visuals. My idea is to spread the load according to priority - the Bela with its nifty low latency handles the audio response, while the RPi can follow along and do the interactive visuals - the RPi will generally be more laggy anyway, but I'm less concerned about that - for now at least - when it comes to the visual side.
I guess I thought MIDI would be a handy way of going about it, as it's something I'm familiar with. If it came to it, I know I could instead pursue sending the sensor data directly to the RPi as well as to the Bela, but I'd rather have the Bela sending data to the Pi, if possible, as this would open up other avenues.