52 lines
2.0 KiB
Markdown
52 lines
2.0 KiB
Markdown
# UART Write String
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### ~hint
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![](/static/bluetooth/Bluetooth_SIG.png)
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For another device like a smartphone to use any of the Bluetooth "services" which the micro:bit has, it must first be [paired with the micro:bit](/reference/bluetooth/bluetooth-pairing). Once paired, the other device may connect to the micro:bit and exchange data relating to many of the micro:bit's features.
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### ~
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The [Bluetooth UART service](/reference/bluetooth/start-uart-service.md) allows another device such as a smartphone to exchange any data it wants to with the micro:bit, in small chunks.
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With the Bluetooth UART service running, this block allows a micro:bit to send data to a Bluetooth connected device.
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```sig
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bluetooth.uartWriteString("");
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```
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### Example: Starting the Bluetooth UART service and then sending "HELLO" whenever button A is pressed and another device has connected over Bluetooth
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```blocks
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let connected = 0;
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bluetooth.onBluetoothConnected(() => {
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basic.showString("C");
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connected = 1;
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});
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bluetooth.onBluetoothDisconnected(() => {
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basic.showString("D");
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connected = 0;
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});
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input.onButtonPressed(Button.A, () => {
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if (connected == 1) {
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bluetooth.uartWriteString("HELLO");
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}
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});
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```
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### Video - UART service guessing game
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https://www.youtube.com/watch?v=PgGeWddMAZ0
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### Advanced
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For more advanced information on the micro:bit Bluetooth UART service including information on using a smartphone, see the [Lancaster University micro:bit runtime technical documentation](http://lancaster-university.github.io/microbit-docs/ble/uart-service/)
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### See also
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[About Bluetooth](/reference/bluetooth/about-bluetooth), [micro:bit Bluetooth profile overview ](http://lancaster-university.github.io/microbit-docs/ble/profile/), [micro:bit Bluetooth profile reference](http://lancaster-university.github.io/microbit-docs/resources/bluetooth/microbit-profile-V1.9-Level-2.pdf), [Bluetooth on micro:bit resources](http://bluetooth-mdw.blogspot.co.uk/p/bbc-microbit.html), [Bluetooth SIG](https://www.bluetooth.com)
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```package
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microbit-bluetooth
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```
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