feat: migrate BLE to NimBLE — 45% flash, 33% RAM reduction

- Replaced ESP32 BLE Arduino with h2zero/NimBLE-Arduino@^2
- -DCONFIG_BT_NIMBLE_ENABLED to disable built-in Bluedroid
- NIMBLE_PROPERTY::* replaces BLECharacteristic::PROPERTY_* + setAccessPermissions
- BLE2902 descriptor removed (NimBLE auto-creates it)
- pService->start() removed (NimBLE starts services with server)
- setMinPreferred → setMinInterval/setMaxInterval
- onConnect/onDisconnect/onWrite get extra NimBLEConnInfo& param
- Re-advertise: BLEDevice → NimBLEDevice::startAdvertising()
- Firmware: 533KB flash (was 964KB), 29KB RAM (was 44KB)

platformio.ini

@@ -10,6 +10,8 @@ build_flags =
     -DCORE_DEBUG_LEVEL=5
     -DARDUINO_USB_CDC_ON_BOOT=1
     -DARDUINO_USB_MODE=1
+    -DCONFIG_BT_NIMBLE_ENABLED
 lib_deps =
+    h2zero/NimBLE-Arduino@^2
 upload_port = /dev/ttyACM0
 upload_speed = 115200

src/main.cpp

@@ -1,8 +1,5 @@
 #include <Arduino.h>
-#include <BLEDevice.h>
-#include <BLEServer.h>
-#include <BLEUtils.h>
-#include <BLE2902.h>
+#include <NimBLEDevice.h>
 
 #include <mbedtls/md.h>
 #include <Preferences.h>
@@ -25,7 +22,7 @@
 #define NVS_KEY_NAME  "key"
 #define NVS_UUID_NAME "uuid"
 
-BLECharacteristic *pCharacteristic;
+NimBLECharacteristic *pCharacteristic;
 bool deviceConnected = false;
 bool bleRelay1 = false;
 bool bleRelay2 = false;
@@ -39,19 +36,19 @@ bool keyProvisioned = false;
 bool uuidProvisioned = false;
 Preferences preferences;
 
-class MyServerCallbacks : public BLEServerCallbacks {
-    void onConnect(BLEServer *pServer) override {
+class MyServerCallbacks : public NimBLEServerCallbacks {
+    void onConnect(NimBLEServer *pServer, NimBLEConnInfo &connInfo) override {
         deviceConnected = true;
         lastSeq = 0;
         Serial.println("BLE: device connected");
     }
-    void onDisconnect(BLEServer *pServer) override {
+    void onDisconnect(NimBLEServer *pServer, NimBLEConnInfo &connInfo, int reason) override {
         deviceConnected = false;
         bleRelay1 = false;
         bleRelay2 = false;
         lastSeq = 0;
         Serial.println("BLE: device disconnected");
-        BLEDevice::startAdvertising();
+        NimBLEDevice::startAdvertising();
     }
 };
 
@@ -101,8 +98,8 @@ static void parseHexKey(const String &hex, uint8_t *out) {
     }
 }
 
-class MyCharacteristicCallbacks : public BLECharacteristicCallbacks {
-    void onWrite(BLECharacteristic *pChar) override {
+class MyCharacteristicCallbacks : public NimBLECharacteristicCallbacks {
+    void onWrite(NimBLECharacteristic *pChar, NimBLEConnInfo &connInfo) override {
         std::string value = pChar->getValue();
         if (value.length() != HMAC_PKT_SIZE) {
             Serial.printf("BLE: bad packet length %d (expected %d)\n",
@@ -185,34 +182,31 @@ void setup() {
     }
     Serial.println("LED blink done, starting BLE...");
 
-    BLEDevice::init("SylDa_Server");
+    NimBLEDevice::init("SylDa_Server");
 
-    BLEServer *pServer = BLEDevice::createServer();
+    NimBLEServer *pServer = NimBLEDevice::createServer();
     pServer->setCallbacks(new MyServerCallbacks());
 
-    BLEService *pService = pServer->createService(SERVICE_UUID);
+    NimBLEService *pService = pServer->createService(SERVICE_UUID);
     pCharacteristic = pService->createCharacteristic(
         CHARACTERISTIC_UUID,
-        BLECharacteristic::PROPERTY_WRITE_NR | BLECharacteristic::PROPERTY_NOTIFY
+        NIMBLE_PROPERTY::WRITE_NR | NIMBLE_PROPERTY::NOTIFY
     );
-    pCharacteristic->setAccessPermissions(ESP_GATT_PERM_WRITE);
-    pCharacteristic->addDescriptor(new BLE2902());
     pCharacteristic->setCallbacks(new MyCharacteristicCallbacks());
     pCharacteristic->setValue("0");
-    pService->start();
 
-    BLECharacteristic *pUuidChar = pService->createCharacteristic(
+    NimBLECharacteristic *pUuidChar = pService->createCharacteristic(
         UUID_CHAR_UUID,
-        BLECharacteristic::PROPERTY_READ
+        NIMBLE_PROPERTY::READ
     );
     pUuidChar->setValue(deviceUuid, ESP_UUID_LEN);
 
-    BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
+    NimBLEAdvertising *pAdvertising = NimBLEDevice::getAdvertising();
     pAdvertising->addServiceUUID(SERVICE_UUID);
-    pAdvertising->setScanResponse(true);
-    pAdvertising->setMinPreferred(0x06);
-    pAdvertising->setMinPreferred(0x12);
-    BLEDevice::startAdvertising();
+    pAdvertising->enableScanResponse(true);
+    pAdvertising->setMinInterval(32);
+    pAdvertising->setMaxInterval(64);
+    NimBLEDevice::startAdvertising();
 
     Serial.println("BLE: advertising started as 'SylDa_Server'");