RepRapFirmware - Main Program

This firmware is intended to be a fully object-oriented highly modular control program for 
RepRap self-replicating 3D printers.

It owes a lot to Marlin and to the original RepRap FiveD_GCode.


General design principles:

  * Control by RepRap G Codes.  These are taken to be machine independent, though some may be unsupported.
  * Full use of C++ OO techniques,
  * Make classes hide their data,
  * Make everything as stateless as possible,
  * No use of conditional compilation except for #include guards - if you need that, you should be
       forking the repository to make a new branch - let the repository take the strain,
  * Concentration of all machine-dependent defintions and code in Platform.h and Platform.cpp,
  * No specials for (X,Y) or (Z) - all movement is 3-dimensional,
  * Try to be efficient in memory use, but this is not critical,
  * Labour hard to be efficient in time use, and this is  critical,
  * Don't abhor floats - they work fast enough if you're clever,
  * Don't avoid arrays and structs/classes,
  * Don't avoid pointers,
  * Use operator and function overloading where appropriate, particularly for vector algebra.
  
  
Naming conventions:

  * #defines are all capitals with optional underscores between words
  * No underscores in other names - MakeReadableWithCapitalisation
  * Class names and functions start with a CapitalLetter
  * Variables start with a lowerCaseLetter
  * Use veryLongDescriptiveNames
  
  
Structure:

There are six main classes:

  * RepRap
  * GCodes
  * Heat
  * Move
  * Platform, and
  * Webserver    

RepRap:

This is just a container class for the single instances of all the others, and otherwise does very little.

GCodes:

This class is fed GCodes, either from the web interface or from GCode files, interprests them, and requests
actions from the RepRap machine via the other classes.

Heat:

This class imlements all heating and temperature control in the RepRap machine.

Move:

This class controls all movement of the RepRap machine, both along its axes, and in its extruder drives.

Platform:

This is the only class that knows anything about the physical setup of the RepRap machine and its
controlling electronics.  It implements the interface between all the other classes and the RepRap machine.
All the other classes are completely machine-independent (though they may declare arrays dimensioned
to values #defined in Platform.h).

Webserver:

This class talks to the network (via Platform) and implements a simple webserver to give an interactive
interface to the RepRap machine.  It uses the Knockout and Jquery Javascript libraries to achieve this.



When the software is running there is one single instance of each main class, and all the memory allocation is
done on initialisation.  new/malloc should not be used in the general running code, and delete is never
used.  Each class has an Init() function that resets it to its boot-up state; the constructors merely handle
that memory allocation on startup.  Calling RepRap.Init() calls all the other Init()s in the right sequence.

There are other ancilliary classes that are declared in the .h files for the master classes that use them.  For
example, Move has a DDA class that implements a Bresenham/digital differential analyser.


Timing:

There is a single interrupt chain entered via Platform.Interrupt().  This controls movement step timing, and 
this chain of code should be the only place that volatile declarations and structure/variable-locking are 
required.  All the rest of the code is called sequentially and repeatedly as follows:

All the main classes have a Spin() function.  These are called in a loop by the RepRap.Spin() function and implement 
simple timesharing.  No class does, or ever should, wait inside one of its functions for anything to happen or call 
any sort of delay() function.  The general rule is:

  Can I do a thing?
    Yes - do it
    No - set a flag/timer to remind me to do it next-time-I'm-called/at-a-future-time and return.
    
The restriction this strategy places on almost all the code in the firmware (that it must execute quickly and 
never cause waits or delays) is balanced by the fact that none of that code needs to worry about synchronicity, 
locking, or other areas of code accessing items upon which it is working.  As mentioned, only the interrupt 
chain needs to concern itself with such problems.  Unlike movement, heating (including PID controllers) does 
not need the fast precision of timing that interrupts alone can offer.  Indeed, most heating code only needs 
to execute a couple of times a second.

Most data is transferred bytewise, with classes typically containg code like this:

  Is a byte available for me?
    Yes
      read it and add it to my buffer
      Is my buffer complete?
         Yes
           Act on the contents of my buffer
         No
           Return
    No
     Return
      
Note that it is simple to raise the "priority" of any class's activities relative to the others by calling its 
Spin() function more than once from RepRap.Spin().

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This version is for the Arduino Due with an Ethernet shield with an SD card and
the RepRapPro Ltd Arduino DUE to Sanguinololu Adaptor.

(See https://github.com/reprappro/ARMadaptor)

Test compiling was with Arduino 1.5.2.

Upload it to your Due, put the ether shield on it, plug in a
network cable, and copy the files in the SD-image folder onto the SD.

The IP address for your browser is 192.168.1.14.

You can change that in Platform.h if you need to:

#define IP0 192
#define IP1 168
#define IP2 1
#define IP3 14

The password when the web browser asks for it is "reprap" with no quotes.

The password is intended to stop fidgety friends or colleagues from playing
with your RepRap.  It is not intended to stop international cyberterrorists
hiding in a hollowed-out volcano from controlling your RepRap from the next 
continent.  For example, it is transmitted unencrypted...

If you open the Arduino serial monitor (115200 baud) you should see a
log of incoming HTTP requests and a record of any G Codes it thinks it
has to act upon.

Actually acting upon them will be added shortly :-)

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Version 0.2 pre-alpha

Started: 18 November 2012
This date: 12 June 2013

Adrian Bowyer
RepRap Professional Ltd
http://reprappro.com

Licence: GPL
