serial: Add tutorial style content, fix method signatures.

1 files changed, 122 insertions, 42 deletions

diff --git a/source/lang/api/serial.rst b/source/lang/api/serial.rst
index a08c9b7..8c9ebc7 100644
--- a/source/lang/api/serial.rst
+++ b/source/lang/api/serial.rst
@@ -1,31 +1,104 @@
+.. highlight:: cpp
+
 .. _lang-serial:
 
 Serial Ports (``Serial1``, ``Serial2``, ``Serial3``)
 ====================================================
 
-Used for communication between the Maple board and a computer or other
-devices.
+This page describes how to use the built-in serial ports (also known
+as USARTs).  For more information about serial ports, see
+:ref:`usart`.
 
 .. contents:: Contents
    :local:
 
-Introduction
-------------
-
-.. FIXME [0.0.12/Maple Native] UART4, UART5
-
-To use a serial port to communicate with an external serial device,
-connect the TX pin to your device's RX pin, the RX to your device's TX
-pin, and your Maple board's ground to your device's ground.
-
-.. warning:: Don't connect these pins directly to an RS232 serial
-   port; they operate at +/- 12V and can damage your board.
+Getting Started
+---------------
+
+First, decide which serial port you wish to use, and :ref:`connect its
+pins to the device you're communicating with <usart-circuit>`. (The TX
+and RX pins for a serial port are labeled on your board's silkscreen;
+for example, serial port 2 has pins labeled "TX2" and "RX2").
+
+The variable for controlling a serial port is the word ``Serial``,
+plus the serial port's number.  For example, you can control serial
+port 1 with the variable ``Serial1``, serial port 2 with ``Serial2``,
+and so on.
+
+In order to get started using your serial port, you'll first need to
+turn it on.  Do this by calling your serial port's ``begin()``
+function, giving it the baud rate you wish it to communicate at.  If
+you're not sure what baud rate to use, 9600 is a safe (although slow)
+value to try.  Put this call to ``begin()`` in your :ref:`lang-setup`,
+like in the following example::
+
+    void setup() {
+        // 9600 is the baud rate to use.  The baud rate determines how
+        // fast the communication goes.
+        Serial2.begin(9600);
+    }
+
+    void loop() {
+        // Communicate using Serial2 here
+    }
+
+Communicating Over Serial
+-------------------------
+
+Now that your serial port is set up, it's time to start communicating.
+
+One common use for serial ports is to print strings and other
+debugging information to a computer.  You can print numbers or strings
+using ``print()`` and ``println()``, like this::
+
+    void printSomeInformation() {
+        Serial2.print("First, print this string.  Then print a number: ");
+        Serial2.print(42);
+        Serial2.print(".  You can print floating point values, too: ");
+        Serial2.print(3.14);
+        Serial2.println(". Using println() instead of print() ends the line.");
+        Serial2.println("This sentence starts on a new line.");
+    }
+
+This sort of communication can go both ways: you can send characters
+from a computer to a serial port as well.  You can check how many
+characters are waiting for you to read using the ``available()``
+function, and read them out one at a time using ``read()``.  The
+following example program uses these functions to "echo" back anything
+sent to ``Serial2``::
+
+    void setup() {
+        Serial2.begin(9600);
+    }
+
+    void echoCharacter() {
+        // Check to see if we have received any information.  numUnread
+        // will hold the number of bytes we've received, but haven't
+        // looked at yet.
+        int numUnread = Serial2.available();
+
+        // numUnread > 0 means that there are some unread bytes waiting
+        if (numUnread > 0) {
+            // Read a single byte out:
+            byte b = Serial2.read();
+            // And then print it back:
+            Serial2.print(b);
+        }
+    }
+
+    void loop() {
+        echoCharacter();
+    }
+
+Function Reference
+------------------
+
+This section gives a full listing of functions available for use with
+serial ports.
 
 Library Documentation
 ---------------------
 
-.. FIXME [0.1.0] Tutorial-style usage introduction
-
 All of the ``Serial[1,2,3]`` objects are instances of the
 ``HardwareSerial`` class, which is documented in this section.  (This
 means that you can use any of these functions on any of ``Serial1``,
@@ -36,14 +109,14 @@ means that you can use any of these functions on any of ``Serial1``,
    Serial port class.  Predefined instances are ``Serial1``,
    ``Serial2``, and ``Serial3``.
 
-.. cpp:function:: HardwareSerial::begin(unsigned int baud)
+.. cpp:function:: void HardwareSerial::begin(unsigned int baud)
 
    Set up a ``HardwareSerial`` object for communications.  This method
    must be called before attempting to use the ``HardwareSerial``
    object (typically, you call this in your :ref:`setup()
    <lang-setup>` function).
 
-.. cpp:function:: HardwareSerial::end()
+.. cpp:function:: void HardwareSerial::end()
 
    Disables the USART associated with this object, allowing any
    associated communication pins to be used for other purposes.
@@ -59,107 +132,106 @@ means that you can use any of these functions on any of ``Serial1``,
    <HardwareSerial::available>`), the call will block until one
    becomes available.
 
-.. cpp:function:: HardwareSerial::flush()
+.. cpp:function:: void HardwareSerial::flush()
 
    Throw away the contents of the serial port's receiver (RX) buffer.
    That is, clears any buffered characters, so that the next character
    read is guaranteed to be new.
 
-.. cpp:function:: HardwareSerial::print(unsigned char b)
+.. cpp:function:: void HardwareSerial::print(unsigned char b)
 
    Print the given byte over the USART.
 
-.. cpp:function:: HardwareSerial::print(char c)
+.. cpp:function:: void HardwareSerial::print(char c)
 
    Print the given character over the USART.  7-bit clean characters
    are typically interpreted as ASCII text.
 
-.. cpp:function:: HardwareSerial::print(const char *str)
+.. cpp:function:: void HardwareSerial::print(const char *str)
 
    Print the given null-terminated string over the USART.
 
-.. cpp:function:: HardwareSerial::print(int n)
+.. cpp:function:: void HardwareSerial::print(int n)
 
    Print the argument's digits over the USART, in decimal format.
    Negative values will be prefixed with a ``'-'`` character.
 
-.. cpp:function:: HardwareSerial::print(unsigned int n)
+.. cpp:function:: void HardwareSerial::print(unsigned int n)
 
    Print the argument's digits over the USART, in decimal format.
 
-.. cpp:function:: HardwareSerial::print(long n)
+.. cpp:function:: void HardwareSerial::print(long n)
 
    Print the argument's digits over the USART, in decimal format.
    Negative values will be prefixed with a ``'-'`` character.
 
-.. cpp:function:: HardwareSerial::print(unsigned long n)
+.. cpp:function:: void HardwareSerial::print(unsigned long n)
 
    Print the argument's digits over the USART, in decimal format.
 
-.. cpp:function:: HardwareSerial::print(long n, int base)
+.. cpp:function:: void HardwareSerial::print(long n, int base)
 
    Print the digits of ``n`` over the USART, in base ``base`` (which
    may be between 2 and 16).  The ``base`` value 2 corresponds to
    binary, 8 to octal, 10 to decimal, and 16 to hexadecimal.  Negative
    values will be prefixed with a ``'-'`` character.
 
-.. cpp:function:: HardwareSerial::print(double n)
+.. cpp:function:: void HardwareSerial::print(double n)
 
    Print ``n``, accurate to 2 digits after the decimal point.
 
 .. _lang-serial-println:
 
-.. cpp:function:: HardwareSerial::println(char c)
+.. cpp:function:: void HardwareSerial::println(char c)
 
    Like ``print(c)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(const char *c)
+.. cpp:function:: void HardwareSerial::println(const char *c)
 
    Like ``print(c)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(unsigned char b)
+.. cpp:function:: void HardwareSerial::println(unsigned char b)
 
    Like ``print(b)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(int n)
+.. cpp:function:: void HardwareSerial::println(int n)
 
    Like ``print(n)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(unsigned int n)
+.. cpp:function:: void HardwareSerial::println(unsigned int n)
 
    Like ``print(n)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(long n)
+.. cpp:function:: void HardwareSerial::println(long n)
 
    Like ``print(n)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(unsigned long n)
+.. cpp:function:: void HardwareSerial::println(unsigned long n)
 
    Like ``print(n)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(long n, int base)
+.. cpp:function:: void HardwareSerial::println(long n, int base)
 
    Like ``print(n, b)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println(double n)
+.. cpp:function:: void HardwareSerial::println(double n)
 
    Like ``print(n)``, followed by ``"\r\n"``.
 
-.. cpp:function:: HardwareSerial::println()
+.. cpp:function:: void HardwareSerial::println()
 
    Prints ``"\r\n"`` over the USART.
 
-.. cpp:function:: HardwareSerial::write(unsigned char ch)
+.. cpp:function:: void HardwareSerial::write(unsigned char ch)
 
    Sends one character over the USART.  This function is currently
-   blocking, although nonblocking writes are a planned future
-   extension.
+   blocking.
 
    This is a low-level function.  One of the ``print()`` or
    ``println()`` functions is likely to be more useful when printing
    multiple characters, when formatting numbers for printing, etc.
 
-.. cpp:function:: HardwareSerial::write(const char* str)
+.. cpp:function:: void HardwareSerial::write(const char* str)
 
    Send the given null-terminated character string over the USART.
 
@@ -167,7 +239,7 @@ means that you can use any of these functions on any of ``Serial1``,
    ``println()`` functions is likely to be more useful when printing
    multiple characters, when formatting numbers for printing, etc.
 
-.. cpp:function:: HardwareSerial::write(void *buf, unsigned int size)
+.. cpp:function:: void HardwareSerial::write(void *buf, unsigned int size)
 
    Writes the first ``size`` bytes of ``buf`` over the USART.  Each
    byte is transmitted as an individual character.
@@ -176,6 +248,14 @@ means that you can use any of these functions on any of ``Serial1``,
    ``println()`` functions is likely to be more useful when printing
    multiple characters, when formatting numbers for printing, etc.
 
+.. cpp:function:: int HardwareSerial::txPin()
+
+   Return the number of the TX (transmit) pin.
+
+.. cpp:function:: int HardwareSerial::rxPin()
+
+   Return the number of the RX (receive) pin.
+
 Arduino Compatibility Note
 --------------------------