pxt-calliope/docs/reference/bluetooth/uart-write-line.md

UART Write Line

~hint

For another device like a smartphone to use any of the Bluetooth "services" which the @boardname@ has, it must first be paired with the @boardname@. Once paired, the other device may connect to the @boardname@ and exchange data relating to many of the @boardname@'s features.

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The Bluetooth UART service allows another device such as a smartphone to exchange any data it wants to with the @boardname@, in small chunks.

With the Bluetooth UART service running, this block allows a @boardname@ to send a line of text to a Bluetooth connected device.

bluetooth.uartWriteLine("");

Example: Starting the Bluetooth UART service and then sending "HELLO" whenever button A is pressed and another device has connected over Bluetooth

let connected = 0;
bluetooth.onBluetoothConnected(() => {
    basic.showString("C");
    connected = 1;
});
bluetooth.onBluetoothDisconnected(() => {
    basic.showString("D");
    connected = 0;
});
input.onButtonPressed(Button.A, () => {
    if (connected == 1) {
        bluetooth.uartWriteLine("HELLO");
    }
});

Video - UART service guessing game

https://www.youtube.com/watch?v=PgGeWddMAZ0

Advanced

For more advanced information on the @boardname@ Bluetooth UART service including information on using a smartphone, see the Lancaster University @boardname@ runtime technical documentation

See also

About Bluetooth, @boardname@ Bluetooth profile overview , @boardname@ Bluetooth profile reference, Bluetooth on @boardname@ resources, Bluetooth SIG

bluetooth