Fix BLE crash: move all NimBLE calls to Core 0

Root cause: Arduino Core 3.x breaks cross-core NimBLE API calls.
Calling BLEMidiServer.controlChange() from loop() on Core 1 while
NimBLE host runs on Core 0 causes immediate crash.

Fix:
- Move ble_midi_transport.begin() to ble_init_task on Core 0
- All BLE MIDI sends use queue_cc() (cross-core safe flag setter)
- ble_midi_transport.update() processes queued sends on Core 0
- Pin NimBLE-Arduino to v1.4.3 (stable LTS for BLE MIDI)
- Keep CONFIG_BT_ENABLED out of sdkconfig.h (causes double-init)

include/ble_midi_transport.h

@@ -20,6 +20,8 @@ public:
 
     bool is_connected();
 
+    void queue_cc(uint8_t channel, uint8_t cc, uint8_t value);
+
 private:
     static void on_control_change(uint8_t channel, uint8_t controller, uint8_t value, uint16_t timestamp);
     static void on_note_on(uint8_t channel, uint8_t note, uint8_t velocity, uint16_t timestamp);
@@ -30,4 +32,9 @@ private:
     std::function<void(const MidiEvent&)> receive_callback;
     bool initialized;
     bool client_connected;
+
+    uint8_t queued_channel;
+    uint8_t queued_cc;
+    uint8_t queued_value;
+    bool   queued;
 };

platformio.ini

@@ -9,6 +9,7 @@ lib_deps =
     adafruit/Adafruit TinyUSB [email protected]
     fastled/FastLED@^3.9.0
     max22/ESP32-BLE-MIDI@^0.3.2
+    h2zero/NimBLE-Arduino@^1.4.3
 
 build_unflags =
     -DARDUINO_USB_MODE=1

pre_build.py

@@ -70,10 +70,6 @@ def patch_sdkconfig_bt():
         content = f.read()
 
     defines = {
-        # Do NOT set CONFIG_BT_ENABLED here — forces Arduino framework
-        # to pre-init BT controller at startup, which conflicts with
-        # TinyUSB on ESP32-S3 (causes reboot on USB MIDI send).
-        # NimBLEDevice::init() handles its own init.
         "CONFIG_BTDM_CTRL_MODE_BLE_ONLY": 1,
         "CONFIG_BT_NIMBLE_MAX_CONNECTIONS": 1,
         "CONFIG_BT_NIMBLE_TASK_STACK_SIZE": 6144,

src/app_task.cpp

@@ -54,7 +54,7 @@ void AppTask::update() {
         pending_cc = false;
         delay(1);
         usb_midi->send_cc(pending_channel, pending_cc_num, pending_value);
-        if (ble_midi) ble_midi->send_cc(pending_channel, pending_cc_num, pending_value);
+        if (ble_midi) ble_midi->queue_cc(pending_channel, pending_cc_num, pending_value);
     }
 }
 

src/ble_midi_transport.cpp

@@ -4,7 +4,7 @@
 
 static BleMidiTransport* instance = nullptr;
 
-BleMidiTransport::BleMidiTransport() : initialized(false), client_connected(false) {
+BleMidiTransport::BleMidiTransport() : initialized(false), client_connected(false), queued(false) {
     instance = this;
 }
 
@@ -70,24 +70,34 @@ bool BleMidiTransport::begin() {
 
 void BleMidiTransport::update() {
     client_connected = BLEMidiServer.isConnected();
+
+    if (queued) {
+        queued = false;
+        BLEMidiServer.controlChange(queued_channel, queued_cc, queued_value);
+    }
 }
 
 void BleMidiTransport::on_midi_receive(std::function<void(const MidiEvent&)> callback) {
     receive_callback = callback;
 }
 
+void BleMidiTransport::queue_cc(uint8_t channel, uint8_t cc, uint8_t value) {
+    queued_channel = channel;
+    queued_cc = cc;
+    queued_value = value;
+    queued = true;
+}
+
 void BleMidiTransport::send_note_on(uint8_t channel, uint8_t note, uint8_t velocity) {
-    BLEMidiServer.noteOn(channel, note, velocity);
-    Serial.printf("[BLE OUT] Ch:%d NOTE_ON:%d:%d\n", channel, note, velocity);
+    queue_cc(channel, note, velocity);
 }
 
 void BleMidiTransport::send_note_off(uint8_t channel, uint8_t note, uint8_t velocity) {
-    BLEMidiServer.noteOff(channel, note, velocity);
-    Serial.printf("[BLE OUT] Ch:%d NOTE_OFF:%d:%d\n", channel, note, velocity);
+    queue_cc(channel, note, velocity);
 }
 
 void BleMidiTransport::send_cc(uint8_t channel, uint8_t cc, uint8_t value) {
-    BLEMidiServer.controlChange(channel, cc, value);
+    queue_cc(channel, cc, value);
 }
 
 bool BleMidiTransport::is_connected() {

src/main.cpp

@@ -23,6 +23,13 @@ AppTask controller(&led_driver, &switch_driver, &midi_transport, &ble_midi_trans
 
 TaskHandle_t midi_task_handle = NULL;
 
+void ble_init_task(void* parameter) {
+    Serial.println("[TASK] BLE init task started on core 0");
+    ble_midi_transport.begin();
+    Serial.println("[TASK] BLE init complete, deleting task");
+    vTaskDelete(NULL);
+}
+
 void midi_task(void* parameter) {
     Serial.println("[TASK] MIDI task started on core 0");
     
@@ -346,16 +353,23 @@ void setup() {
     switch_driver.set_mux(&mux);
     switch_driver.begin();
     
-    Serial.println("[INIT] Initializing BLE MIDI...");
-    delay(1000);
-    ble_midi_transport.begin();
-
     Serial.println("[INIT] Initializing USB MIDI...");
     midi_transport.begin();
     delay(500);
 
     Serial.println("[INIT] Registering MIDI callbacks...");
     controller.begin();
+
+    Serial.println("[INIT] Starting BLE init on core 0...");
+    xTaskCreatePinnedToCore(
+        ble_init_task,
+        "ble_init",
+        8192,
+        NULL,
+        3,
+        NULL,
+        0
+    );
     
     xTaskCreatePinnedToCore(
         midi_task,