Adding servo documentation

Marlin/Configuration.h

 
 #ifdef PIDTEMPBED
 //120v 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
-//from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, argressive factor of .15 (vs .1, 1, 10)
+//from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, aggresive factor of .15 (vs .1, 1, 10)
     #define  DEFAULT_bedKp 10.00
     #define  DEFAULT_bedKi .023
     #define  DEFAULT_bedKd 305.4
 //#define BARICUDA
 
 /*********************************************************************\
-*
 * R/C SERVO support
-*
 * Sponsored by TrinityLabs, Reworked by codexmas
-*
 **********************************************************************/
-
-// Number of servos
-//
-// If you select a configuration below, this will receive a default value and does not need to be set manually
-// set it manually if you have more servos than extruders and wish to manually control some
-// leaving it undefined or defining as 0 will disable the servo subsystem
-// If unsure, leave commented / disabled
-//
-// #define NUM_SERVOS 3
+// Number of servos, on RAMPS power to servo pins needs vcc pin jumpered to 5v pin or external supply.
+//#define NUM_SERVOS 3 // Indexing starts at 0 for M280 command
 
 #include "Configuration_adv.h"
 #include "thermistortables.h"

README.md

-WARNING: 
+WARNING:
 --------
 THIS IS RELEASE CANDIDATE 2 FOR MARLIN 1.0.0
 
 *   High steprate
 *   Look ahead (Keep the speed high when possible. High cornering speed)
 *   Interrupt based temperature protection
-*   preliminary support for Matthew Roberts advance algorithm 
+*   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. 
+*   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
 *   PID tuning
 *   CoreXY kinematics (www.corexy.com/theory.html)
 *   Configurable serial port to support connection of wireless adaptors.
+*   RC Servo Support, specify angle or duration for continuous rotation servos.
 
 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.
 
 
 *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, 
+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. 
+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. 
+and can perform the arc with nearly constant velocity, resulting in a nice finish.
 Also, less serial communication is needed.
 
 *Temperature Oversampling:*
 
 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 
+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:*
 *   M42  - Change pin status via gcode
 *   M80  - Turn on Power Supply
 *   M81  - Turn off Power Supply
-*   M114 - Output current position to serial port 
+*   M114 - Output current position to serial port
 *   M119 - Output Endstop status to serial port
 
 Movement variables:
 
 *   M500 - stores paramters in EEPROM. This parameters are stored:  axis_steps_per_unit,  max_feedrate, max_acceleration  ,acceleration,retract_acceleration,
   minimumfeedrate,mintravelfeedrate,minsegmenttime,  jerk velocities, PID
-*   M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).  
+*   M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).
 *   M502 - reverts to the default "factory settings".  You still need to store them in EEPROM afterwards if you want to.
 *   M503 - print the current settings (from memory not from eeprom)
 
 MISC:
 
 *   M240 - Trigger a camera to take a photograph
+*   M280 - Position an RC Servo P<index> S<angle/microseconds>, ommit S to report back current angle
 *   M999 - Restart after being stopped by error
 
 Configuring and compilation: