auto-detect MIDI device, drop ALSA sequencer dependency, MPK Mini simulator

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

scripts/gen_mpk_sim.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+"""Generate mpk-mini-sim.pd — MPK Mini Mk II simulator.
+
+Architecture: each key/pad has bng→t b b→msg for note-on, del→msg for note-off.
+All msgs connect to a single [netsend -u -b] via send/receive.
+Knobs: hsl→msg→[s $0-cc], central [r $0-cc]→netsend.
+"""
+from pathlib import Path
+
+SCRIPT_DIR = Path(__file__).resolve().parent
+OUTPUT = SCRIPT_DIR.parent / "pd" / "mpk-mini-sim.pd"
+
+def connect(c, src, sout, dst, din):
+    c.append((src, sout, dst, din))
+
+def Obj(o, x, y, *args):
+    idx = len(o)
+    o.append((x, y, *args))
+    return idx
+
+def gen():
+    o, c = [], []
+
+    # ── UDP sender (hardcoded IP — edit the msg box to change) ──
+    Obj(o, 10, 10, "loadbang")
+    Obj(o, 10, 30, "msg", ";")
+    msg_conn = Obj(o, 10, 50, "msg", "connect 192.168.9.167 8081;")
+
+    ns = Obj(o, 10, 80, "netsend", "-u", "-b")
+    connect(c, msg_conn, 0, ns, 0)
+
+    Obj(o, 200, 30, "text", "← edit this line to change target IP:port")
+    instr = Obj(o, 10, 440, "text", "Click keys to play. Knobs send CC on change. IPS (192.168.9.167:8081)")
+    instr2 = Obj(o, 10, 460, "text", "MIDI ch: 144=note-on ch1, 128=note-off ch1, 176=CC ch1")
+
+    # ── Keyboard: C3(48) to C5(72) ──
+    keys = [
+        ("C3",48),("C#3",49),("D3",50),("D#3",51),("E3",52),
+        ("F3",53),("F#3",54),("G3",55),("G#3",56),("A3",57),
+        ("A#3",58),("B3",59),
+        ("C4",60),("C#4",61),("D4",62),("D#4",63),("E4",64),
+        ("F4",65),("F#4",66),("G4",67),("G#4",68),("A4",69),
+        ("A#4",70),("B4",71),("C5",72),
+    ]
+
+    Obj(o, 20, 120, "text", "-- KEYBOARD --")
+    for i, (name, note) in enumerate(keys):
+        x = 30 + (i % 13) * 46
+        y = 140 + (i // 13) * 60
+        Obj(o, x, y, "text", name)
+        b = Obj(o, x, y+14, "bng", 15, 25, 0, 1, 0, 0, "empty", f"k{note}", -2,-8,0,10,-262144,-1,-1)
+        trig = Obj(o, x, y+44, "t", "b b")
+        msg_on = Obj(o, x, y+64, "msg", f"midi 144 {note} 100;")
+        msg_off = Obj(o, x, y+82, "msg", f"midi 128 {note} 0;")
+        del300 = Obj(o, x, y+100, "del", 300)
+        connect(c, b, 0, trig, 0)
+        connect(c, trig, 0, msg_on, 0)
+        connect(c, msg_on, 0, ns, 0)
+        connect(c, trig, 1, del300, 0)
+        connect(c, del300, 0, msg_off, 0)
+        connect(c, msg_off, 0, ns, 0)
+
+    # ── Pads (C2-G2, notes 36-43) ──
+    pads = [("C2",36),("C#2",37),("D2",38),("D#2",39),("E2",40),("F2",41),("F#2",42),("G2",43)]
+    Obj(o, 680, 120, "text", "-- PADS --")
+    for i, (name, note) in enumerate(pads):
+        x = 680 + (i % 4) * 55
+        y = 140 + (i // 4) * 55
+        Obj(o, x, y, "text", name)
+        b = Obj(o, x, y+14, "bng", 15, 15, 0, 1, 0, 0, "empty", f"p{note}", -2,-8,0,10,-262144,-1,-1)
+        trig = Obj(o, x, y+32, "t", "b b")
+        msg_on = Obj(o, x, y+52, "msg", f"midi 144 {note} 100;")
+        msg_off = Obj(o, x, y+70, "msg", f"midi 128 {note} 0;")
+        del200 = Obj(o, x, y+88, "del", 200)
+        connect(c, b, 0, trig, 0)
+        connect(c, trig, 0, msg_on, 0)
+        connect(c, msg_on, 0, ns, 0)
+        connect(c, trig, 1, del200, 0)
+        connect(c, del200, 0, msg_off, 0)
+        connect(c, msg_off, 0, ns, 0)
+
+    # ── Knobs (CC 1, 71-77) ──
+    knobs = [(1,"Mod",64),(71,"Reson",64),(72,"Release",64),(73,"Attack",64),
+             (74,"Cutoff",100),(75,"Decay",64),(76,"LFO Rate",64),(77,"LFO Depth",64)]
+    Obj(o, 20, 280, "text", "-- KNOBS --")
+    for i, (cc, name, init) in enumerate(knobs):
+        x = 30 + i * 85
+        y = 300
+        Obj(o, x, y, "text", f"CC{cc} {name}")
+        hsl = Obj(o, x, y+15, "hsl", 50, 10, 0, 127, init, 0, 0, "empty", f"cc{cc}", -2,-8,0,10,-262144,-1,-1,7200,1)
+        msg = Obj(o, x, y+30, "msg", f"midi 176 {cc} $1;")
+        connect(c, hsl, 0, msg, 0)
+        connect(c, msg, 0, ns, 0)
+
+    # ── Write (Pd format: #X obj for objects, #X msg/text/floatatom/symbol for others) ──
+    lines = ["#N canvas 0 0 950 490 10;"]
+    obj_types = {"bng","t","del","netsend","loadbang","hsl","comment"}
+    for x, y, *args in o:
+        etype = args[0]
+        rest = args[1:]
+        if etype in obj_types:
+            # Pd stores GUI objects as: #X obj x y <name> <args>
+            name = etype
+            if name == "comment": name = "text"  # Pd uses text for comments
+            joined = " ".join(str(a) for a in rest)
+            lines.append(f"#X obj {x} {y} {name} {joined};")
+        else:
+            joined = " ".join(str(a) for a in rest)
+            lines.append(f"#X {etype} {x} {y} {joined};")
+    for src, sout, dst, din in c:
+        lines.append(f"#X connect {src} {sout} {dst} {din};")
+    lines.append("")
+    return "\n".join(lines)
+
+if __name__ == "__main__":
+    content = gen()
+    OUTPUT.parent.mkdir(parents=True, exist_ok=True)
+    OUTPUT.write_text(content)
+    print(f"Wrote {OUTPUT}")
+    print(f"  {len(content.splitlines())} lines, {content.count('#X obj')} objects, {content.count('#X connect')} connections")

scripts/midi-bridge.py

@@ -1,76 +1,102 @@
 #!/usr/bin/env python3
-"""Bridge raw MIDI device to Pd via UDP. For host mode with MPK Mini.
+"""Bridge raw MIDI device to Pd via UDP. Auto-detects gadget vs host mode.
 
 Sends parsed MIDI messages as Pd-style 'midi status data1 data2;' strings
 to UDP ports for Pd (8081) and LED matrix visualization (8082).
 """
-import os, socket, time, select, struct
+import os, socket, time, select, pathlib
 
-MIDI_DEV = os.environ.get("MIDI_BRIDGE_DEV", "/dev/snd/midiC0D0")
 PD_HOST = os.environ.get("MIDI_BRIDGE_HOST", "127.0.0.1")
 PD_PORT = int(os.environ.get("MIDI_BRIDGE_PORT", "8081"))
 VIZ_PORT = int(os.environ.get("VIZ_PORT", "8082"))
 
+def _find_midi_dev():
+    """Auto-detect rawmidi device. Preference: gadget f_midi > env override > host mode."""
+    dev = os.environ.get("MIDI_BRIDGE_DEV")
+    if dev:
+        return dev
+    # Look for gadget f_midi card first
+    cards = pathlib.Path("/proc/asound").glob("card*")
+    for card_dir in cards:
+        cmi = card_dir / "id"
+        if cmi.exists() and "midi" in cmi.read_text().strip():
+            card_num = card_dir.name.replace("card", "")
+            midi_dev = f"/dev/snd/midiC{card_num}D0"
+            if os.path.exists(midi_dev):
+                return midi_dev
+    # Fallback: any rawmidi device
+    rawdevs = sorted(pathlib.Path("/dev/snd").glob("midiC?D0"))
+    if rawdevs:
+        return str(rawdevs[0])
+    return "/dev/snd/midiC0D0"  # fallback for host mode
+
 def midi_msg(status, data1, data2=None):
     if data2 is not None:
         return f"midi {status} {data1} {data2};"
     return f"midi {status} {data1};"
 
-def main():
-    while not os.path.exists(MIDI_DEV):
+def _open_midi():
+    midi_dev = _find_midi_dev()
+    while not os.path.exists(midi_dev):
         time.sleep(0.5)
-
-    fd = os.open(MIDI_DEV, os.O_RDWR | os.O_NONBLOCK)
+        midi_dev = _find_midi_dev()
+    fd = os.open(midi_dev, os.O_RDWR | os.O_NONBLOCK)
     os.set_blocking(fd, False)
-    poll = select.poll()
-    poll.register(fd, select.POLLIN)
+    return fd
 
+def main():
     sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
 
     running = True
-    buf = bytearray()
     while running:
         try:
-            events = poll.poll(500)
-            for f, flags in events:
-                if flags & select.POLLIN:
-                    data = os.read(fd, 1024)
-                    if not data:
-                        continue
-                    for byte in data:
-                        if byte & 0x80:
-                            if len(buf) > 0 and buf[0] >= 0x80:
-                                _flush(sock, buf, PD_HOST, PD_PORT, VIZ_PORT)
-                            buf = bytearray([byte])
-                        else:
-                            buf.append(byte)
-                            if len(buf) >= 3 and (buf[0] & 0xE0) in (0x80, 0x90, 0xA0, 0xB0, 0xE0):
-                                _flush(sock, buf, PD_HOST, PD_PORT, VIZ_PORT)
-                                buf = bytearray()
-                            elif len(buf) >= 2 and (buf[0] & 0xE0) in (0xC0, 0xD0):
-                                _flush(sock, buf, PD_HOST, PD_PORT, VIZ_PORT)
-                                buf = bytearray()
-        except (BlockingIOError, OSError) as e:
-            if isinstance(e, OSError) and e.errno == 19:
-                time.sleep(1)
-                continue
-            if not isinstance(e, BlockingIOError):
-                raise
+            fd = _open_midi()
+            poll = select.poll()
+            poll.register(fd, select.POLLIN)
+            buf = bytearray()
+            while running:
+                try:
+                    events = poll.poll(500)
+                    for f, flags in events:
+                        if flags & select.POLLIN:
+                            data = os.read(fd, 1024)
+                            if not data:
+                                continue
+                            for byte in data:
+                                if byte & 0x80:
+                                    if len(buf) > 0 and buf[0] >= 0x80:
+                                        _flush(sock, buf)
+                                    buf = bytearray([byte])
+                                else:
+                                    buf.append(byte)
+                                    if len(buf) >= 3 and (buf[0] & 0xE0) in (0x80, 0x90, 0xA0, 0xB0, 0xE0):
+                                        _flush(sock, buf)
+                                        buf = bytearray()
+                                    elif len(buf) >= 2 and (buf[0] & 0xE0) in (0xC0, 0xD0):
+                                        _flush(sock, buf)
+                                        buf = bytearray()
+                except OSError as e:
+                    if e.errno == 19:
+                        os.close(fd)
+                        time.sleep(1)
+                        break
+                    raise
+                except BlockingIOError:
+                    pass
         except KeyboardInterrupt:
             running = False
 
-    os.close(fd)
     sock.close()
 
-def _flush(sock, buf, pd_host, pd_port, viz_port):
+def _flush(sock, buf):
     status = buf[0]
     if (buf[0] & 0xF0) == 0xF0:
         return
     data1 = buf[1]
     data2 = buf[2] if len(buf) >= 3 else None
     msg = midi_msg(status, data1, data2)
-    sock.sendto(msg.encode(), (pd_host, pd_port))
-    sock.sendto(msg.encode(), (pd_host, viz_port))
+    sock.sendto(msg.encode(), (PD_HOST, PD_PORT))
+    sock.sendto(msg.encode(), (PD_HOST, VIZ_PORT))
 
 if __name__ == "__main__":
     main()

scripts/start-synth.sh

@@ -56,17 +56,11 @@ if [ "$MODE" = "auto" ]; then
                 ALSA_DEV=$(cat /run/usb-audio-dev)
             fi
             info "Mode: USB host (MIDI controller + USB audio interface)"
-            MIDI_OPTS=(-alsamidi)
-            midi_dev=$(amidi -l 2>/dev/null | grep -v "^Dir" | head -1 | awk '{print $2}' | sed 's/\(hw:[0-9]*,[0-9]*\).*/\1/')
-            if [ -n "$midi_dev" ]; then
-                MIDI_OPTS+=(-midiadddev "$midi_dev")
-                info "  MIDI device: $midi_dev"
-            fi
+            # MIDI handled by midi-bridge.service → UDP → Pd netreceive
             AUDIO_OPTS=(-audiooutdev 4 -audioindev 4)
             PD_ARGS=(
                 -nogui -alsa
                 -send "pd dsp 1"
-                "${MIDI_OPTS[@]}"
                 "${AUDIO_OPTS[@]}"
                 -audiobuf 20 -blocksize 64 -r 48000
                 -channels 2 -inchannels 0 -outchannels 2
@@ -87,18 +81,13 @@ fi
 
 # --- Configure per-mode options ---
 AUDIO_OPTS=()
-MIDI_OPTS=(-alsamidi)
 
 if [ "$MODE" = "usb" ]; then
     info "Mode: USB gadget (UAC1 audio + gmidi MIDI)"
     AUDIO_OPTS=(-audiooutdev 2 -audioindev 2)
     if aplay -l 2>/dev/null | grep -q "UAC1Gadget"; then
         info "  USB gadget: OK"
-        midi_dev=$(amidi -l 2>/dev/null | grep "f_midi" | head -1 | awk '{print $2}')
-        if [ -n "$midi_dev" ]; then
-            MIDI_OPTS+=(-midiadddev "$midi_dev")
-            info "  MIDI device: $midi_dev"
-        fi
+        # MIDI handled by midi-bridge.service → UDP → Pd netreceive
     else
         info "  USB gadget: NOT DETECTED (kernel modules needed)"
     fi
@@ -125,19 +114,12 @@ if [ "$MODE" = "loopback" ]; then
 fi
 
 PD_ARGS=(
-    -nogui
-    -alsa
-    "${MIDI_OPTS[@]}"
-    "${AUDIO_OPTS[@]}"
+    -nogui -alsa
     -send "pd dsp 1"
-    -audiobuf 20
-    -blocksize 64
-    -r 48000
-    -channels 1
-    -inchannels 0
-    -outchannels 1
-    -path "$PD_DIR"
-    "$PATCH"
+    "${AUDIO_OPTS[@]}"
+    -audiobuf 20 -blocksize 64 -r 48000
+    -channels 1 -inchannels 0 -outchannels 1
+    -path "$PD_DIR" "$PATCH"
 )
 
 if [ "$VERBOSE" = true ]; then