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Andrew Ivasiv edited this page Jan 24, 2020 · 1 revision

Working with BLE devices

To start working with BLE devices you need to create an instance of BLEManager. BLEManager takes an array of service UUIDs to scan for. You can use two formats to specify these UUIDs:

  • String representing a 128 bit fully qualified UUID e. g. XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
  • String representing a 16 bit Bluetooth standard UUID e. g. XXXX which is converted to a 128 bit UUID via the HexToUUID helper node

The BLE Manager contains a set of helper nodes to check BLE status on the device:

  • CheckBleSupport - check if the device supports Bluetooth low energy mode;
  • IsBluetoothEnabled - check if Bluetooth is enabled on the device;
  • SetBluetoothState - enable/disable Bluetooth on the device (Android only).

With a BLE manager, you can start/stop scanning for available BLE devices by invoking the ScanForDevices/StopScan node.

Each time a device is found an event is fired and you can capture the device in the OnDeviceFound callback. Having both a BLE manager and a BLE device you can connect/disconnect to it using respective nodes:

The BLE Device object can return the following information:

  • GetDeviceID - unique device ID. This is the device MAC address on Android and a generated UUID on iOS. It is not recommended to rely on this field as it can be different for the same device in certain scenarios;
  • GetDeviceName - the name of the device;
  • GetServiceUUID - the UUID of the service that was used to find this device;
  • IsConnected - indicates if the device is connected.

You can only access the characteristics of the service that was specified in BLE Manager. The available operations are:

Subscribe/Unsubscribe

Each time a notification is received the OnNotificationReceived event will fire. The notification data is represented as an array of bytes TArray<uint8>. Some characteristics are classified as Indicate instead of Notify. To receive notifications from these types of characteristics set the IsIndicationCharacteristic flag to true (Note: iOS internally handles this so this flag can be disregarded on the iOS platform).

Read

Fires an OnReadSuccess event with the data read from the device or an OnReadError event if something went wrong.

Write

Tries to write the provided byte array to the device. Will fire an event to indicate the status of the operation (Note: some devices do not indicate write operations successes).

Working with BLE manufacturer data

If you do not need to connect to a BLE Device but require the device's manufacturer data you can use the BLE Scanner object. The scanner only supports start/stop scanning operations.

The NameFilters array specifies the device names that will be reported in the callback. The names must fully match and do not support regex. To receive data from all devices do not connect this pin. Android devices will report the manufacturer's data as many times as it is advertised. On iOS the data is returned once for each device and you will only receive it again if the data changes.

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