Merge pull request #75 from gbaman/master

Add few more radio documentation pages

docs/reference/radio/receive-string.md

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+# Receive String
+
+Reads the next radio packet if any and returns the first string.
+
+## Important Security Consideration
+
+The functions in the ``radio`` namespace allow the BBC micro:bit to communicate with other micro:bits.
+
+This API does not contain any form of encryption, authentication or authorization. It's purpose is solely for use as a teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
+
+For serious applications, BLE should be considered a substantially more secure alternative.
+
+```sig
+radio.receiveString()
+```
+
+### Return value
+
+* the first [string](/reference/types/string) of the packet if any. ```""``` otherwise.
+
+### Examples
+
+Read the string broadcasted by other micro:bits and display it.
+
+```blocks
+radio.onDataReceived(() => {
+    basic.showString(radio.receiveString());
+});
+```
+
+A simple program to send whether you are happy, or sad over ```radio```, using the A or B button to select an emotion.
+
+```blocks
+let data: string = "";
+input.onButtonPressed(Button.A, () => {
+    radio.sendString("H");
+});
+input.onButtonPressed(Button.B, () => {
+    radio.sendString("S");
+});
+radio.onDataReceived(() => {
+    data = radio.receiveString();
+    if ("H" == data) {
+        basic.showLeds(`
+            . . . . .
+            . # . # .
+            . . . . .
+            # . . . #
+            . # # # .
+            `);
+    } else if ("S" == data) {
+        basic.showLeds(`
+            . . . . .
+            . # . # .
+            . . . . .
+            . # # # .
+            # . . . #
+            `);
+    } else {
+        basic.showString("?");
+    }
+});
+```
+
+### See also
+
+[send string](/reference/input/send-string), [on data received](/reference/radio/on-data-received)

docs/reference/radio/send-string.md

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+# Send String
+
+Broadcasts a string data packet to other micro:bits connected via ``radio``.
+
+## Important Security Consideration
+
+The functions in the ``radio`` namespace allow the BBC micro:bit to communicate with other micro:bits.
+
+This API does not contain any form of encryption, authentication or authorization. It's purpose is solely for use as a teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
+
+For serious applications, BLE should be considered a substantially more secure alternative.
+
+```sig
+radio.sendString("Hello world!")
+```
+
+### Parameters
+
+* msg - a string to be transmitted.
+
+### Examples
+
+Broadcasts the provided string to other micro:bits.
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    radio.sendString("Mr. Watson, come here, I want to see you.")
+})
+```
+
+### See also
+
+[receive string](/reference/radio/receive-string), [on data received](/reference/radio/on-data-received)

docs/reference/radio/set-transmit-power.md

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+# Set Transmit Power
+
+Sets the transmitter power for ``radio`` communications.    
+The power can be set to a value between 0 (-30dbm) and 7 (+4dbm).
+
+## Range
+   
+At power level 7, in an open area without significant interference (coming from WiFi networks or other devices operating on the 2.4 GHz range), you can get a **range of over 70m**.   
+ 
+Indoors (or with additional interference), range will be significantly reduced.
+
+## Important Security Consideration
+
+The functions in the ``radio`` namespace allow the BBC micro:bit to communicate with other micro:bits.
+
+This API does not contain any form of encryption, authentication or authorization. It's purpose is solely for use as a teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
+
+For serious applications, BLE should be considered a substantially more secure alternative.
+
+```sig
+radio.setTransmitPower(1)
+```
+
+### Parameters
+
+* ``power`` -- a [number](/reference/types/number) between ``0`` and ``7``.
+
+### Example
+
+Sets the transmitter power to full power at 7.
+
+```blocks
+radio.setTransmitPower(7)
+```
+
+### See also
+
+[receive number](/reference/radio/receive-number), [send number](/reference/radio/send-number), [on data received](/reference/radio/on-data-received)

docs/reference/radio/write-value-to-serial.md

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+# Write Value To Serial
+
+Writes the full data received data  via ``radio`` to serial in JSON format.   
+**Note** - This method only works for [send number](/reference/radio/send-number) and [send value](/reference/radio/send-value). It does not work for [send string](/reference/radio/send-string) (although a string can be sent with [send value](/reference/radio/send-value)).   
+
+## Data received format
+The format for received data printed to serial is as follows    
+- [send number](/reference/radio/send-number) - ```{v:ValueSent,t:MicrobitTimeAlive,s:Unused}```
+- [send value](/reference/radio/send-number) - ```{v:Value,t:MicrobitTimeAlive,s:Unused,n:"Name"}```
+- [send string](/reference/radio/send-string) - ```{}``` (currently unavailable)
+
+## Important Security Consideration
+
+The functions in the ``radio`` namespace allow the BBC micro:bit to communicate with other micro:bits.
+
+This API does not contain any form of encryption, authentication or authorization. It's purpose is solely for use as a teaching aid to demonstrate how simple communications operates, and to provide a sandpit through which learning can take place.
+
+For serious applications, BLE should be considered a substantially more secure alternative.
+
+```sig
+radio.writeValueToSerial()
+```
+
+### Parameters
+
+* None
+
+### Examples
+
+When ```radio``` data is received (after pressing A button on 2nd micro:bit), output temperature data to serial.
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    radio.sendNumber(input.temperature());
+});
+radio.onDataReceived(() => {
+    radio.writeValueToSerial();
+});
+```
+Example output to serial when A button pressed:   
+```{v:27,t:323,s:0}```
+
+### See also
+
+[send number](/reference/radio/send-number), [send value](/reference/radio/send-number), [on data received](/reference/radio/on-data-received)