Philips Dynalite DyNet I/O library
----------------------------------

This library will use a MAX485 IC together with the SoftwareSerial library
to send and receive Dynalite OpCodes directly onto the DyNet RS485 bus.

The library requires an Aurdino with with a correctly wired MAX485 IC,
using all 4 connections (RO, RE, DE, DI).  The DyNet bus uses 9600 baud,
8 data bits, 1 start bit, 1 stop bit and no parity and it is strictly
half duplex.  The functions in this library ensure half duplex by using
the RE/DE pins.

This libarary will also calculate the 8th checksum byte of OpCodes to be
sent.  Any value in the opcode at this position is ignored and overwritten.
Similarly, incoming data will be checked and not handed back to the calling
function if the checksum value is wrong.


Initialisation
--------------
To use the library, simply create an instance of the DyNet object, and then
call the begin function indicating which pins are allocated to each of the
relevant pins on the MAX485.

This library is built to be small and fast, and not double and triple check
that everything has been set up correctly.  If you do NOT call begin, there's
nothing stopping you from calling the other functions anyway and all kinds
of unexpected things may happen.  It's a microcontroller.

Functions
---------
sendOpCode: Expects an 8 byte array that is the OpCode.  It is simply fired
onto the serial bus after calculating the OpCode checksum.

receiveOpCode: This will check the wire for awaiting incoming data that might
be waiting in the buffer.  It'll fetch a complete OpCode provided all bytes
are no more than 1ms apart (as per DyNet spec) and if the checksum works out,
it'll call the supplied function with the opcode.  For me this is the process
function from the DDMC810 object.