The O_NONBLOCK flag set by setblocking(False) was not cleared by
settimeout(n) on this CPython/kernel combo, causing recvfrom to never
return data. Switched to explicit select.poll() with frame-interval
based timeout — simpler, more portable, and avoids the O_NONBLOCK trap.
Also fixes midi-bridge: add time.sleep(0.01) in no-data paths to
prevent 100% CPU spin from spurious POLLIN on f_midi rawmidi.
midi-bridge.py:
- Auto-detect rawmidi device (gadget f_midi > env override > fallback)
- Reconnect on ENODEV (device hotplug)
- No longer needs MIDI_BRIDGE_DEV env var in common cases
start-synth.sh:
- Remove all -alsamidi/-midiadddev flags (kernel lacks CONFIG_SND_SEQUENCER)
- MIDI handled entirely by midi-bridge.service → UDP → netreceive
- Host mode: same approach, no ALSA sequencer needed
mpk-mini-sim.pd:
- New MPK Mini Mk II simulator (25 keys, 8 pads, 8 CC knobs)
- Proper Pd #X obj format for all objects (bng, hsl, t, del, netsend, loadbang)
- UDP output to board:8081, matching midi-bridge format
system: enable usb-gadget-audio.service at boot, load dwc3 module at boot
david