Initial commit: Arduino Uno Q USB Audio Synth project

- USB gadget (UAC1 + MIDI) with boot persistence - USB host mode with auto-detection - Pure Data synth patch with ALSA + UDP netreceive MIDI input - MIDI rawmidi-to-UDP bridge (midi-bridge.py) - LED matrix visualization (led-matrix-viz.py via arduino-router RPC) - MCU sketch for LED matrix control (Arduino_RouterBridge + ArduinoGraphics) - Conftest/OPA Rego policy validation suite for .pd files - gen_synth_pd.py: programmatic .pd file generator - System services: midi-bridge, led-matrix-viz, pd-synth-auto, usb-role-detect - Justfile with deploy, enable, diagnostic recipes - Diagnostic script (diag.sh)
2026-06-22 22:46:36 -07:00
commit 8cd796e3dd
38 changed files with 2681 additions and 0 deletions
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+#!/bin/bash
+# detect-usb-role.sh — Detect whether USB-C should be gadget or host.
+# Writes result to /run/usb-role for consumption by pd-synth-auto.service.
+#
+# Detection methods (tried in order):
+#   1. extcon  — USB cable detection (most reliable on Qualcomm)
+#   2. dwc3 debug — USB controller mode
+#   3. UDC state — if a UDC is bound as configured, we're in gadget mode
+#   4. lsusb    — if USB devices appear (after host controller init), we're host
+#
+# Exit code: 0 if role detected, 1 if unknown
+
+set -euo pipefail
+
+ROLE_FILE="/run/usb-role"
+unset ROLE
+
+die() { echo "[USB-ROLE] $*" >&2; exit 1; }
+
+# --- Method 1: extcon ---
+check_extcon() {
+    for path in /sys/class/extcon/*/state; do
+        [ -f "$path" ] || continue
+        local state
+        state=$(cat "$path" 2>/dev/null || true)
+        if echo "$state" | grep -q "USB=1"; then
+            echo "gadget"
+            return 0
+        fi
+    done
+    return 1
+}
+
+# --- Method 2: dwc3 debugfs ---
+check_dwc3() {
+    local mode_file
+    for mode_file in /sys/kernel/debug/usb/dwc3*/mode; do
+        [ -f "$mode_file" ] || continue
+        local mode
+        mode=$(cat "$mode_file" 2>/dev/null || true)
+        case "$mode" in
+            *peripheral*) echo "gadget"; return 0 ;;
+            *host*)       echo "host";   return 0 ;;
+        esac
+    done
+    return 1
+}
+
+# --- Method 3: UDC state ---
+check_udc() {
+    for path in /sys/class/udc/*/state; do
+        [ -f "$path" ] || continue
+        local state
+        state=$(cat "$path" 2>/dev/null || true)
+        case "$state" in
+            configured) echo "gadget"; return 0 ;;
+        esac
+    done
+    return 1
+}
+
+# --- Method 4: USB host devices ---
+check_lsusb() {
+    if command -v lsusb &>/dev/null; then
+        local count
+        count=$(lsusb 2>/dev/null | grep -v "Linux Foundation" | wc -l)
+        # If we see non-root-hub devices, likely we're the host
+        if [ "$count" -gt 1 ]; then
+            echo "host"
+            return 0
+        fi
+    fi
+    return 1
+}
+
+# Try methods in order
+ROLE=$(check_extcon || check_dwc3 || check_udc || echo "")
+
+# If still unknown, check lsusb after brief delay (host controller needs time)
+if [ -z "$ROLE" ]; then
+    sleep 2
+    ROLE=$(check_lsusb || echo "")
+fi
+
+# Write result
+if [ -n "$ROLE" ]; then
+    echo "$ROLE" > "$ROLE_FILE"
+    echo "[USB-ROLE] Detected: $ROLE"
+    exit 0
+else
+    echo "[USB-ROLE] Unknown — defaulting to gadget"
+    echo "gadget" > "$ROLE_FILE"
+    exit 0
+fi