# On Bluetooth Disconnected 

![](/static/bluetooth/Bluetooth_SIG.png)

For another device like a smartphone to use any of the Bluetooth "services" which the micro:bit has, it must first connect to the micro:bit. This block starts an [event handler](/reference/event-handler) which in this case will run when a device which is connected to your micro:bit over Bluetooth disconnects.

You could use this event handler to display a letter "D" on the micro:bit LED grid so you know that the Bluetooth connection has been closed.

~~~~sig
bluetooth.onBluetoothDisconnected(() => {
});
~~~~

### Example: Displaying "D" when a Bluetooth connection to the micro:bit is closed

~~~~blocks
bluetooth.onBluetoothDisconnected(() => {
    basic.showString("D");
});
~~~~

### Video - on Bluetooth disconnected

[![micro:bit Bluetooth demo video](/static/bluetooth/microbit_on_disconnected.png)](
    http://www.youtube.com/watch?v=HyBcsD9Eh6I "Click to launch YouTube video"
    )

### See also

[Bluetooth SIG](https://www.bluetooth.com)

[Bluetooth on micro:bit resources](http://bluetooth-mdw.blogspot.co.uk/p/bbc-microbit.html)