This demo app shows an usecase for using flutter_reactive_ble library for building a UART emulation over BLE.

This demo app uses one service: the Nordic UART Service with vendor-specific UUID:

Uuid _UART_UUID = Uuid.parse("6E400001-B5A3-F393-E0A9-E50E24DCCA9E");

The aforementioned service uses two characteristics: one for transmitting and one for receiving (as seen from the peer).

Uuid _UART_RX   = Uuid.parse("6E400002-B5A3-F393-E0A9-E50E24DCCA9E");
Uuid _UART_TX   = Uuid.parse("6E400003-B5A3-F393-E0A9-E50E24DCCA9E");

This app can be used if the BLE peripheral implements the aforementioned services. The user interface is shown below:

Use the play button for scanning and the stop button for stop a running scan. When an UART BLE service is found, it is displayed at the top. Press the found device at the right, then a connection is being established as can be seen in the Status messages pane. Then a message string can be sent to the BLE peripheral, Received data is shown in the Received data pane. An existing connection can be closed using the bottom rightmost button.

The BLE undeliverable exception is handled as shown in this file.

The plugin enabling BLE in Flutter can be found at https://pub.dev/packages/flutter_reactive_ble