The design for creating the BLE server is:
1. Create a BLE Server
2. Create a BLE Service
3. Create a BLE Characteristic on the Service
4. Create a BLE Descriptor on the characteristic
5. Start the service.
6. Start advertising.
void setupBLE(String BLEName){
const char *ble_name=BLEName.c_str();
BLEDevice::init(ble_name);
BLEServer *pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
BLEService *pService = pServer->createService(SERVICE_UUID);
pCharacteristic=
pService->createCharacteristic(CHARACTERISTIC_UUID_TX,BLECharacteristic::PROPERTY_NOTIFY);
pCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pCharacteristic =
pService->createCharacteristic(CHARACTERISTIC_UUID_RX,BLECharacteristic::PROPERTY_WRITE);
pCharacteristic->setCallbacks(new MyCallbacks());
pService->start();
pServer->getAdvertising()->start();
Serial.println("Waiting a client connection to notify...");
}