Micro-chat (#1425)

* added microchat tutorial

* animations

docs/projects/micro-chat.md

@@ -0,0 +1,77 @@
+# Micro Chat
+
+## Introduction @unplugged
+
+![Two @boardname@ connected via radio](/static/mb/projects/a9-radio.png)
+
+Use the **radio** to send and receive messages with other @boardname@.
+
+## Sending a message @fullscreen
+
+Use ``||input:on button pressed||`` to send a number over radio with ``||radio:send string||``.
+All @boardname@ nearby will receive this message.
+
+You can also add ``||basic:show icon||`` and ``||basic:clear screen||`` blocks to show a little animation when the message is sent.
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    radio.sendString("Yo");
+    basic.showIcon(IconNames.Chessboard)
+    basic.clearScreen();
+});
+```
+
+## Receiving a message @fullscreen
+
+Add a ``||radio:on received number||`` 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. You will find the ``receivedString`` variable
+under the **Variables** toolbox.
+
+```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, this might not happen). Try pressing **A** again and notice that the "Yo" message gets displayed on the other @boardname@
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    radio.sendString("Yo");
+    basic.showIcon(IconNames.Chessboard)
+    basic.clearScreen();
+});
+radio.onReceivedString(function (receivedString) {
+    basic.showString(receivedString);
+})
+```
+
+## Try it for real @fullscreen
+
+If you have @boardname@s, download the program to two @boardname@. 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@ within the same group. Use this to avoid receiving messages from all the other @boardname@.
+
+```blocks
+/**
+* Pick a unique group in your classroom!
+*/
+radio.setGroup(123)
+```
+
+
+```package
+radio
+```