splitted huge README.md in several sections and moved them to the

Documentation directory

Documentation/BedLeveling.md

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+===============================================
+Instructions for configuring Bed Auto Leveling
+===============================================
+There are two options for this feature. You may choose to use a servo mounted on the X carriage or you may use a sled that mounts on the X axis and can be docked when not in use.
+See the section for each option below for specifics about installation and configuration. Also included are instructions that apply to both options.
+
+Instructions for Both Options
+-----------------------------
+
+Uncomment the "ENABLE_AUTO_BED_LEVELING" define (commented by default)
+
+The following options define the probing positions. These are good starting values.
+I recommend to keep a better clearance from borders in the first run and then make the probes as close as possible to borders:
+
+* \#define LEFT_PROBE_BED_POSITION 30
+* \#define RIGHT_PROBE_BED_POSITION 140
+* \#define BACK_PROBE_BED_POSITION 140
+* \#define FRONT_PROBE_BED_POSITION 30
+
+A few more options:
+
+* \#define XY_TRAVEL_SPEED 6000
+
+X and Y axis travel speed between probes, in mm/min.
+Bear in mind that really fast moves may render step skipping. 6000 mm/min (100mm/s) is a good value.
+
+* \#define Z_RAISE_BEFORE_PROBING 10
+* \#define Z_RAISE_BETWEEN_PROBINGS 10
+
+The Z axis is lifted when traveling to the first probe point by Z_RAISE_BEFORE_PROBING value
+and then lifted when traveling from first to second and second to third point by Z_RAISE_BETWEEN_PROBINGS.
+All values are in mm as usual.
+
+Servo Option Notes
+------------------
+You will probably need a swivel Z-MIN endstop in the extruder. A rc servo do a great job.
+Check the system working here: http://www.youtube.com/watch?v=3IKMeOYz-1Q (Enable English subtitles)
+Teasing ;-) video: http://www.youtube.com/watch?v=x8eqSQNAyro
+
+In order to get the servo working, you need to enable:
+
+* \#define NUM_SERVOS 1 // Servo index starts with 0 for M280 command
+
+* \#define SERVO_ENDSTOPS {-1, -1, 0} // Servo index for X, Y, Z. Disable with -1
+
+* \#define SERVO_ENDSTOP_ANGLES {0,0, 0,0, 165,60} // X,Y,Z Axis Extend and Retract angles
+
+The first define tells firmware how many servos you have.
+The second tells what axis this servo will be attached to. In the example above, we have a servo in Z axis.
+The third one tells the angle in 2 situations: Probing (165º) and resting (60º). Check this with command M280 P0 S{angle} (example: M280 P0 S60 moves the servo to 60º)
+
+Next you need to define the Z endstop (probe) offset from hotend.
+My preferred method:
+
+* a) Make a small mark in the bed with a marker/felt-tip pen.
+* b) Place the hotend tip as *exactly* as possible on the mark, touching the bed. Raise the hotend 0.1mm (a regular paper thickness) and zero all axis (G92 X0 Y0 Z0);
+* d) Raise the hotend 10mm (or more) for probe clearance, lower the Z probe (Z-Endstop) with M401 and place it just on that mark by moving X, Y and Z;
+* e) Lower the Z in 0.1mm steps, with the probe always touching the mark (it may be necessary to adjust X and Y as well) until you hear the "click" meaning the mechanical endstop was trigged. You can confirm with M119;
+* f) Now you have the probe in the same place as your hotend tip was before. Perform a M114 and write down the values, for example: X:24.3 Y:-31.4 Z:5.1;
+* g) You can raise the z probe with M402 command;
+* h) Fill the defines bellow multiplying the values by "-1" (just change the signal)
+
+
+* \#define X_PROBE_OFFSET_FROM_EXTRUDER -24.3
+* \#define Y_PROBE_OFFSET_FROM_EXTRUDER 31.4
+* \#define Z_PROBE_OFFSET_FROM_EXTRUDER -5.1
+
+Sled Option Notes
+-----------------
+The sled option uses an electromagnet to attach and detach to/from the X carriage. See http://www.thingiverse.com/thing:396692 for more details on how to print and install this feature. It uses the same connections as the servo option.
+
+To use the sled option, you must define two additional things in Configuration.h:
+
+* \#define Z_PROBE_SLED
+* \#define SLED_DOCKING_OFFSET 5
+
+Uncomment the Z_PROBE_SLED to define to enable the sled (commented out by default).
+
+Uncomment the SLED_DOCKING_OFFSET to set the extra distance the X axis must travel to dock the sled. This value can be found by moving the X axis to its maximum position then measure the distance to the right X end and subtract the width of the sled (23mm if you printed the sled from Thingiverse).
+
+Next you need to define the Z endstop (probe) offset from hotend.
+My preferred method:
+
+* a) Home the X and Y axes.
+* b) Move the X axis to about the center of the print bed. Make a mark on the print bed.
+* c) Move the Y axis to the maximum position. Make another mark.
+* d) Home the X axis and use a straight edge to make a line between the two points.
+* e) Repeat (b)-(d) reversing the X and Y. When you are done you will have two lines on the print bed. We will use these to measure the offset for the Z probe endstop.
+* f) Move the nozzle so that it is positioned on the center point of the two lines. You can use fine movement of 0.1mm to get it as close as possible. Note the position of X and Y.
+* g) Zero the Z axis with the G92 Z0 command.
+* h) Raise the Z axis about 20mmm.
+* i) Use the G32 command to retrieve the sled.
+* j) Now more the X and Y axis to the position recorded in (f).
+* k) Lower the Z axis in 0.1mm steps until you hear the "click" meaning the mechanical endstop was trigged. You can confirm with the M119 command. Note the position of the Z axis.
+* l) Make a mark on the print bed where the endstop lever has touched the print bed. Raise the Z-axis about 30mm to give yourself some room.
+* m) Now measure the distance from the center point to the endstop impact site along the X and Y axis using the lines drawn previously.
+* n) Fill in the values below. If the endstop mark is in front of the line running left-to-right, use positive values. If it is behind, use negative values. For the Z axis use the value from (k) and subtract 0.1mm.
+
+For example, suppose you measured the endstop position and it was 20mm to the right of the line running front-to-back, 10mm toward the front of the line running left-to-right, and the value from (k) was 2.85. The values for the defines would be:
+
+* \#define X_PROBE_OFFSET_FROM_EXTRUDER 20
+* \#define Y_PROBE_OFFSET_FROM_EXTRUDER 10
+* \#define Z_PROBE_OFFSET_FROM_EXTRUDER 2.75
+
+That's it.. enjoy never having to calibrate your Z endstop neither leveling your bed by hand anymore ;-)

Documentation/Compilation.md

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+Configuring and compilation:
+
+Install the latest non-beta arduino software IDE/toolset
+   http://www.arduino.cc/en/Main/Software
+
+Download the Marlin firmware
+   https://github.com/MarlinFirmware/Marlin/tree/development
+   
+   For the latest development, or 
+   
+   
+   
+   For the latest stable release
+   
+   In both cases use the "Download Zip" button on the right.
+
+For some spec. boards a spec. dir in the ArduinoAddons directory in the Marlin dir needs to be copied to the arduino environment. <arduino home>\hardware\
+
+Start the arduino IDE.
+Select Tools -> Board -> Arduino Mega 2560    or your microcontroller
+Select the correct serial port in Tools ->Serial Port
+Open Marlin.pde or .ino
+
+Click the Verify/Compile button
+
+Click the Upload button
+If all goes well the firmware is uploading
+
+That's ok.  Enjoy Silky Smooth Printing.

Documentation/Contributing.md

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+Developer Notes
+===================
+
+- There are now 2 branches: The __development__ branch is where new features and code changes will be sorted out. This branch may have untested code in it, so please let us know if you find any bugs. When the __development__ branch has reached a state where it is stable, it will be moved to the __stable__ branch.
+
+- We are doing a kind of cleanup in the list of Issues and Pull Requests, the aim is to get to a state where we can certify the code as stable. To get the code tested as widely as possible we require several volunteers with a wide variety of hardware configurations willing to test the firmware and help us to certify it as stable. If you want to help out testing go to this issue and let us know: https://github.com/MarlinFirmware/Marlin/issues/1209
+
+- Before you submit any pull request, we ask that you _PLEASE_ test your code before submission, even if the change seems innocuous. When creating the pull request, please include the hardware you used for testing and a short synopsis of your testing procedure. Untested pull requests are less likely to be merged, as even slight changes create the risk of breaking the main branch.
+
+- If you have a fix don't open an issue telling about it, but test the code and submit a pull request. Use the __development__ branch when you submit.

Documentation/Features.md

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+
+Features:
+=========
+
+*   Interrupt based movement with real linear acceleration
+*   High steprate
+*   Look ahead (Keep the speed high when possible. High cornering speed)
+*   Interrupt based temperature protection
+*   preliminary support for Matthew Roberts advance algorithm
+    For more info see: http://reprap.org/pipermail/reprap-dev/2011-May/003323.html
+*   Full endstop support
+*   SD Card support
+*   SD Card folders (works in pronterface)
+*   SD Card autostart support
+*   LCD support (ideally 20x4)
+*   LCD menu system for autonomous SD card printing, controlled by an click-encoder.
+*   EEPROM storage of e.g. max-velocity, max-acceleration, and similar variables
+*   many small but handy things originating from bkubicek's fork.
+*   Arc support
+*   Temperature oversampling
+*   Dynamic Temperature setpointing aka "AutoTemp"
+*   Support for QTMarlin, a very beta GUI for PID-tuning and velocity-acceleration testing. https://github.com/bkubicek/QTMarlin
+*   Endstop trigger reporting to the host software.
+*   Updated sdcardlib
+*   Heater power reporting. Useful for PID monitoring.
+*   PID tuning
+*   CoreXY kinematics (www.corexy.com/theory.html)
+*   Delta kinematics
+*   SCARA kinematics
+*   Dual X-carriage support for multiple extruder systems
+*   Configurable serial port to support connection of wireless adaptors.
+*   Automatic operation of extruder/cold-end cooling fans based on nozzle temperature
+*   RC Servo Support, specify angle or duration for continuous rotation servos.
+*   Bed Auto Leveling.
+*   Support for a filament diameter sensor, which adjusts extrusion volume
+
+The default baudrate is 250000. This baudrate has less jitter and hence errors than the usual 115200 baud, but is less supported by drivers and host-environments.
+
+
+Differences and additions to the already good Sprinter firmware:
+================================================================
+
+Look-ahead:
+-----------
+
+Marlin has look-ahead. While sprinter has to break and re-accelerate at each corner,
+lookahead will only decelerate and accelerate to a velocity,
+so that the change in vectorial velocity magnitude is less than the xy_jerk_velocity.
+This is only possible, if some future moves are already processed, hence the name.
+It leads to less over-deposition at corners, especially at flat angles.
+
+Arc support:
+------------
+
+Slic3r can find curves that, although broken into segments, were ment to describe an arc.
+Marlin is able to print those arcs. The advantage is the firmware can choose the resolution,
+and can perform the arc with nearly constant velocity, resulting in a nice finish.
+Also, less serial communication is needed.
+
+Temperature Oversampling:
+-------------------------
+
+To reduce noise and make the PID-differential term more useful, 16 ADC conversion results are averaged.
+
+AutoTemp:
+---------
+
+If your gcode contains a wide spread of extruder velocities, or you realtime change the building speed, the temperature should be changed accordingly.
+Usually, higher speed requires higher temperature.
+This can now be performed by the AutoTemp function
+By calling M109 S<mintemp> B<maxtemp> F<factor> you enter the autotemp mode.
+
+You can leave it by calling M109 without any F.
+If active, the maximal extruder stepper rate of all buffered moves will be calculated, and named "maxerate" [steps/sec].
+The wanted temperature then will be set to t=tempmin+factor*maxerate, while being limited between tempmin and tempmax.
+If the target temperature is set manually or by gcode to a value less then tempmin, it will be kept without change.
+Ideally, your gcode can be completely free of temperature controls, apart from a M109 S T F in the start.gcode, and a M109 S0 in the end.gcode.
+
+EEPROM:
+-------
+
+If you know your PID values, the acceleration and max-velocities of your unique machine, you can set them, and finally store them in the EEPROM.
+After each reboot, it will magically load them from EEPROM, independent what your Configuration.h says.
+
+LCD Menu:
+---------
+
+If your hardware supports it, you can build yourself a LCD-CardReader+Click+encoder combination. It will enable you to realtime tune temperatures,
+accelerations, velocities, flow rates, select and print files from the SD card, preheat, disable the steppers, and do other fancy stuff.
+One working hardware is documented here: http://www.thingiverse.com/thing:12663
+Also, with just a 20x4 or 16x2 display, useful data is shown.
+
+SD card folders:
+----------------
+
+If you have an SD card reader attached to your controller, also folders work now. Listing the files in pronterface will show "/path/subpath/file.g".
+You can write to file in a subfolder by specifying a similar text using small letters in the path.
+Also, backup copies of various operating systems are hidden, as well as files not ending with ".g".
+
+SD card folders:
+----------------
+
+If you place a file auto[0-9].g into the root of the sd card, it will be automatically executed if you boot the printer. The same file will be executed by selecting "Autostart" from the menu.
+First *0 will be performed, than *1 and so on. That way, you can heat up or even print automatically without user interaction.
+
+Endstop trigger reporting:
+--------------------------
+
+If an endstop is hit while moving towards the endstop, the location at which the firmware thinks that the endstop was triggered is outputed on the serial port.
+This is useful, because the user gets a warning message.
+However, also tools like QTMarlin can use this for finding acceptable combinations of velocity+acceleration.
+
+Coding paradigm:
+----------------
+
+Not relevant from a user side, but Marlin was split into thematic junks, and has tried to partially enforced private variables.
+This is intended to make it clearer, what interacts which what, and leads to a higher level of modularization.
+We think that this is a useful prestep for porting this firmware to e.g. an ARM platform in the future.
+A lot of RAM (with enabled LCD ~2200 bytes) was saved by storing char []="some message" in Program memory.
+In the serial communication, a #define based level of abstraction was enforced, so that it is clear that
+some transfer is information (usually beginning with "echo:"), an error "error:", or just normal protocol,
+necessary for backwards compatibility.
+
+Interrupt based temperature measurements:
+-----------------------------------------
+
+An interrupt is used to manage ADC conversions, and enforce checking for critical temperatures.
+This leads to less blocking in the heater management routine.

Documentation/FilamentSensor.md

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+Filament Sensor
+---------------
+Supports the use of a real time filament diameter sensor that measures the diameter of the filament going into the extruder and then adjusts the extrusion rate to compensate for filament that does not match what is defined in the g-code.  The diameter can also be displayed on the LCD screen. This potentially eliminates the need to measure filament diameter when changing spools of filament. Gcode becomes independent of the filament diameter. Can also compensate for changing diameter.
+
+For examples of these sensors, see: http://www.thingiverse.com/thing:454584, https://www.youmagine.com/designs/filament-diameter-sensor, http://diy3dprinting.blogspot.com/2014/01/diy-filament-diameter-sensor.html. Any sensor which produces a voltage equivalent to the diameter in mm (i.e. 1v = 1mm) can be used. This provides a very simple interface and may encourage more innovation in this area.
+
+4 new Mcodes are defined to set relevant parameters: M404, M405, M406, M407 - see above.
+
+ Implements a delay buffer to handle the transit delay between where the filament is measured and when it gets to the extruder.