Android BLE设备在短时间后断开连接,错误代码为8

Question

我有一个Android应用程序,它可以连接到BLE设备(使用BMD-350),通过通知接收数据并在特征上传输数据.我不知道为什么,但过了一段时间BLE设备自行断开连接,在BondStateChanged回调中报告错误代码8.我可以看到数据直接进入手机,直到它断开连接.BLE设备以大约550字节/秒的速度向手机发送数据.此时手机不会向BLE设备发送任何数据.为什么要断开连接？

*注意:此代码是用C#(Xamarin)编写的,但它与Java对应的代码基本相同.

连接代码:

_bleGatt = device.ConnectGatt(context, false, this);

连接回调:

if (newState == ProfileState.Connected)
{
    if (status == GattStatus.Success)
    {
        gatt.DiscoverServices();
    }
}

服务发现:

public override void OnServicesDiscovered(BluetoothGatt gatt, GattStatus status)
        {
            base.OnServicesDiscovered(gatt, status);

            BluetoothGattService mService;

            try
            {
                mService = gatt.GetService(UART_UUID);
            }
            catch
            {
                BluetoothConnectionError("UART service not found", gatt.Device);
                return;
            }
            _tx = mService.GetCharacteristic(TX_UUID);
            _rx = mService.GetCharacteristic(RX_UUID);

            if (_tx == null)
            {
                BluetoothConnectionError("Tx characteristic not found", gatt.Device);
                return;
            }
            if ((_tx.Properties | GattProperty.WriteNoResponse) == 0 && (_tx.Properties | GattProperty.Write) == 0)
            {
                BluetoothConnectionError("Tx characteristic not not in 'write' or 'write - no response' mode", gatt.Device);
                return;
            }

            if (_rx == null)
            {
                BluetoothConnectionError("Rx characteristic not found", gatt.Device);
                return;
            }
            if ((_rx.Properties | GattProperty.Notify) == 0)
            {
                BluetoothConnectionError("Rx characteristic not in 'notify' mode", gatt.Device);
                return;
            }

            BluetoothGattDescriptor mDescriptor = _rx.GetDescriptor(CLIENT_UUID);
            if (mDescriptor == null)
            {
                BluetoothConnectionError("Could not get descriptor", gatt.Device);
                return;
            }
            mDescriptor.SetValue(BluetoothGattDescriptor.EnableNotificationValue.ToArray());
            try
            {
                gatt.WriteDescriptor(mDescriptor);
            }
            catch
            {
                BluetoothConnectionError("Could not write descriptor", gatt.Device);
                return;
            }
            ConnectionStatusChanged(ProfileState.Connected, gatt.Device);
        }

启用接收通知:

_bleGatt.SetCharacteristicNotification(_rx, true);

阅读特点:

public override void OnCharacteristicChanged(BluetoothGatt gatt, 
BluetoothGattCharacteristic characteristic)
{
    base.OnCharacteristicChanged(gatt, characteristic);
    PublishNewData(characteristic.GetValue());
}

UUID的/ CCCD:

private readonly UUID UART_UUID = UUID.FromString("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
private readonly UUID RX_UUID = UUID.FromString("6e400003-b5a3-f393-e0a9-e50e24dcca9e");
private readonly UUID TX_UUID = UUID.FromString("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
private readonly UUID CLIENT_UUID = UUID.FromString("00002902-0000-1000-8000-00805f9b34fb");