pxt-calliope/docs/projects/mini-chat.md

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# Mini Chat
## Introduction @unplugged
![Two @boardname@ connected via radio](/docs/calliope/tutorials/06_mini_chat_animation.gif)
Use the **radio** to send and receive messages with other @boardname@.
## Sending a message @fullscreen
Use ``||input:on button pressed||`` to send a text message over radio with ``||radio:send string||``.
Every @boardname@ nearby will receive this message.
```blocks
input.onButtonPressed(Button.A, () => {
radio.sendString("Yo");
});
```
## Receiving a message @fullscreen
Add a ``||radio:on received string||`` block to run when a message is received.
```blocks
radio.onReceivedString(function (receivedString) {
})
```
## Displaying text @fullscreen
Add a ``||basic:show string||`` to display the string on the screen. Pull the ``||variables:receivedString||`` out of ``||radio:on received string||`` and put it into ``||basic:show string||``.
```blocks
radio.onReceivedString(function (receivedString) {
basic.showString(receivedString);
})
```
## Testing in the simulator @fullscreen
Press button **A** on the simulator, you will notice that a second @boardname@ appears (if your screen is too small, the simulator might decide not to show it). Try pressing **A** again and notice that the "Yo" message gets displayed on the other @boardname@.
```blocks
input.onButtonPressed(Button.A, () => {
radio.sendString("Yo");
});
radio.onReceivedString(function (receivedString) {
basic.showString(receivedString);
})
```
## Try it for real @fullscreen
If you two @boardname@s, download the program to each one. Press button **A** on one and see if the other gets a message.
## Groups @fullscreen
Use the ``||radio:set group||`` block to assign a **group** number to your program. You will only receive messages from @boardname@s within the same group. Use this to avoid receiving messages from every @boardname@ that is transmitting.
```blocks
radio.setGroup(123)
```
```package
radio
```