Merge pull request #4805 from thinkyhead/rc_config_adjustment

Additional documentation of Configuration.h

Marlin/Configuration.h

 //#define SHOW_CUSTOM_BOOTSCREEN
 // @section machine
 
-// SERIAL_PORT selects which serial port should be used for communication with the host.
-// This allows the connection of wireless adapters (for instance) to non-default port pins.
-// Serial port 0 is still used by the Arduino bootloader regardless of this setting.
-// :[0,1,2,3,4,5,6,7]
+/**
+ * Select which serial port on the board will be used for communication with the host.
+ * This allows the connection of wireless adapters (for instance) to non-default port pins.
+ * Serial port 0 is always used by the Arduino bootloader regardless of this setting.
+ *
+ * :[0,1,2,3,4,5,6,7]
+ */
 #define SERIAL_PORT 0
 
-// This determines the communication speed of the printer
-// :[2400,9600,19200,38400,57600,115200,250000]
 #define BAUDRATE 250000
+/**
+ * This setting determines the communication speed of the printer.
+ *
+ * 250000 works in most cases, but you might try a lower speed if
+ * you commonly experience drop-outs during host printing.
+ *
+ * :[2400,9600,19200,38400,57600,115200,250000]
+ */
 
 // Enable the Bluetooth serial interface on AT90USB devices
 //#define BLUETOOTH
 //#define HOTEND_OFFSET_X {0.0, 20.00} // (in mm) for each extruder, offset of the hotend on the X axis
 //#define HOTEND_OFFSET_Y {0.0, 5.00}  // (in mm) for each extruder, offset of the hotend on the Y axis
 
-//// The following define selects which power supply you have. Please choose the one that matches your setup
-// 1 = ATX
-// 2 = X-Box 360 203Watts (the blue wire connected to PS_ON and the red wire to VCC)
-// :{1:'ATX',2:'X-Box 360'}
-#define POWER_SUPPLY 1
+/**
+ * Select your power supply here. Use 0 if you haven't connected the PS_ON_PIN
+ *
+ * 0 = No Power Switch
+ * 1 = ATX
+ * 2 = X-Box 360 203Watts (the blue wire connected to PS_ON and the red wire to VCC)
+ *
+ * :{0:'No power switch',1:'ATX',2:'X-Box 360'}
+ */
+#define POWER_SUPPLY 0
 
-// Define this to have the electronics keep the power supply off on startup. If you don't know what this is leave it.
-//#define PS_DEFAULT_OFF
+#if POWER_SUPPLY > 0
+  // Enable this option to leave the PSU off at startup.
+  // Power to steppers and heaters will need to be turned on with M80.
+  //#define PS_DEFAULT_OFF
+#endif
 
 // @section temperature
 
 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,4000,500}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {300, 300, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {3000,3000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 4000, 500 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 300, 300, 5, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 3000, 3000, 100, 10000 }
 
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/Cartesio/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {71.128,71.128,640,152}
-#define DEFAULT_MAX_FEEDRATE          {200,200,20,20}   // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {1000,1000,100,10000}     // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 71.128, 71.128, 640, 152 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 200, 200, 20, 20 }   // (mm/sec)
 
-#define DEFAULT_ACCELERATION          500     // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  10000   // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 1000, 1000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          500     // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  10000   // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/Felix/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // @section motion
 
 // default steps per unit for Felix 2.0/3.0: 0.00249mm x/y rounding error with 3mm pitch HTD belt and 14 tooth pulleys. 0 z error.
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {76.190476, 76.190476, 1600, 164}
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {5000,5000,100,80000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          1750    // X, Y, Z and E max acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  5000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.3    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 76.190476, 76.190476, 1600, 164 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 5000, 5000, 100, 80000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          1750    // X, Y, Z and E max acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  5000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.3
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/Felix/DUAL/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // @section motion
 
 // default steps per unit for Felix 2.0/3.0: 0.00249mm x/y rounding error with 3mm pitch HTD belt and 14 tooth pulleys. 0 z error.
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {76.190476, 76.190476, 1600, 164}
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {5000,5000,100,80000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          1750    // X, Y, Z and E max acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  5000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.3    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 76.190476, 76.190476, 1600, 164 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 5000, 5000, 100, 80000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          1750    // X, Y, Z and E max acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  5000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.3
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/Hephestos/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,4000,100.47095761381482}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {200, 200, 3.3, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {1100,1100,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 4000, 100.47095761381482 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 200, 200, 3.3, 25 }
 
-#define DEFAULT_ACCELERATION          650     // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 1100, 1100, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          650     // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/Hephestos_2/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {160, 160, 8000, 210.02}  // Steps per unit
-#define DEFAULT_MAX_FEEDRATE          {250, 250, 2, 200}        // mm/sec
-#define DEFAULT_MAX_ACCELERATION      {1000, 1000, 20, 1000}    // X, Y, Z, E max start speed for accelerated moves
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 160, 160, 8000, 210.02 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 250, 250, 2, 200 }
 
-#define DEFAULT_ACCELERATION          1000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 1000, 1000, 20, 1000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          1000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  2.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  2.0
 
 
 //===========================================================================

Marlin/example_configurations/K8200/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {64.25,64.25,2560,600}  // default steps per unit for K8200
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 500}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 64.25, 64.25, 2560, 600 }  // default steps per unit for K8200
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 500 }
 
-#define DEFAULT_ACCELERATION          1000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          1000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   1000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/K8400/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {134.74,134.74,4266.66,148.7}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {160, 160, 10, 10000}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 134.74, 134.74, 4266.66, 148.7 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 160, 160, 10, 10000 }
 
-#define DEFAULT_ACCELERATION          6000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  6000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          6000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  6000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.5    // (mm/sec)
-#define DEFAULT_EJERK                 20.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.5
+#define DEFAULT_EJERK                 20.0
 
 
 //===========================================================================

Marlin/example_configurations/K8400/Dual-head/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {134.74,134.74,4266.66,148.7}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {160, 160, 10, 10000}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 134.74, 134.74, 4266.66, 148.7 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 160, 160, 10, 10000 }
 
-#define DEFAULT_ACCELERATION          6000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  6000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          6000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  6000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.5    // (mm/sec)
-#define DEFAULT_EJERK                 20.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.5
+#define DEFAULT_EJERK                 20.0
 
 
 //===========================================================================

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {78.7402*2,78.7402*2,5120.00,760*1*1.5}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {300, 300, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {3000,3000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   {78.7402*2,78.7402*2,5120.00,760*1*1.5}
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 300, 300, 5, 25 }
 
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 3000, 3000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/RigidBot/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {44.3090, 22.1545, 1600, 53.5}  // default steps per unit for RigidBot with standard hardware
-                                                                      // default steps for 16-tooth pulleys {100.06,50.06,1600,76},  HPX2-MAX E=504, RigidBot E=53.5, Peter Stoneham's=76
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {800, 800, 100, 10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          600     // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                8.0     // (mm/sec)
-#define DEFAULT_ZJERK                 0.4     // (mm/sec)
-#define DEFAULT_EJERK                 5.0     // (mm/sec)
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 44.3090, 22.1545, 1600, 53.5 }  // default steps per unit for RigidBot with standard hardware
+                                                                        // default steps for 16-tooth pulleys { 100.06, 50.06, 1600, 76 }, HPX2-MAX E=504, RigidBot E=53.5, Peter Stoneham's=76
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 800, 800, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          600     // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  1000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                8.0
+#define DEFAULT_ZJERK                 0.4
+#define DEFAULT_EJERK                 5.0
 
 
 //===========================================================================

Marlin/example_configurations/SCARA/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   {103.69,106.65,200/1.25,1000}  // default steps per unit for SCARA
-#define DEFAULT_MAX_FEEDRATE          {300, 300, 30, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {300,300,20,1000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          400    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  2000   // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   400    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                5.0     // (mm/sec)
-#define DEFAULT_ZJERK                 0.4     // (mm/sec)
-#define DEFAULT_EJERK                 3.0     // (mm/sec)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 300, 300, 30, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 300, 300, 20, 1000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          400    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  2000   // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   400    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                5.0
+#define DEFAULT_ZJERK                 0.4
+#define DEFAULT_EJERK                 3.0
 
 
 //===========================================================================

Marlin/example_configurations/TAZ4/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {100.5,100.5,400,850}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {800, 800, 8, 50}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 100.5, 100.5, 400, 850 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 800, 800, 8, 50 }
 
-#define DEFAULT_ACCELERATION          500     // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          500     // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                 8.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                 10.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                 8.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                 10.0
 
 
 //===========================================================================

Marlin/example_configurations/WITBOX/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,600.0*8/3,102.073}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {350, 350, 7.2, 80}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {1000,1000,10,1000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,600.0*8/3,102.073}
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 350, 350, 7.2, 80 }
 
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 1000, 1000, 10, 1000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                10.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                10.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/adafruit/ST7565/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,4000,500}  // default steps per unit for Ultimaker
-#define DEFAULT_MAX_FEEDRATE          {300, 300, 5, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {3000,3000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 4000, 500 }
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 300, 300, 5, 25 }
 
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 3000, 3000, 100, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/delta/biv2.5/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // @section motion
 
 // delta speeds must be the same on xyz
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {72.9, 72.9, 72.9, 291}  // default steps per unit for BI v2.5 (cable drive)
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 500, 150}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,9000,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                15.0    // (mm/sec)
-#define DEFAULT_ZJERK                 15.0    // (mm/sec) Must be same as XY for delta
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 72.9, 72.9, 72.9, 291 }  // default steps per unit for BI v2.5 (cable drive)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 500, 150 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 9000, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                15.0
+#define DEFAULT_ZJERK                 15.0 // Must be same as XY for delta
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/delta/generic/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // @section motion
 
 // delta speeds must be the same on xyz
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   {80, 80, 80, 760*1.1}  // default steps per unit for Kossel (GT2, 20 tooth)
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 500, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,9000,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                 20.0    // (mm/sec) Must be same as XY for delta
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 500, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 9000, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                 20.0 // Must be same as XY for delta
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/delta/kossel_mini/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // @section motion
 
 // delta speeds must be the same on xyz
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   {80, 80, 80, 760*1.1}  // default steps per unit for Kossel (GT2, 20 tooth)
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 500, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,9000,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                 20.0    // (mm/sec) Must be same as XY for delta
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 500, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 9000, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                 20.0 // Must be same as XY for delta
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/delta/kossel_pro/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // delta speeds must be the same on xyz
 #define XYZ_STEPS ((XYZ_FULL_STEPS_PER_ROTATION) * (XYZ_MICROSTEPS) / double(XYZ_BELT_PITCH) / double(XYZ_PULLEY_TEETH))
 
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   {XYZ_STEPS, XYZ_STEPS, XYZ_STEPS, 184.8}
-#define DEFAULT_MAX_FEEDRATE          {200, 200, 200, 200}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,9000,9000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                 20.0    // (mm/sec) Must be same as XY for delta
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 200, 200, 200, 200 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 9000, 9000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                 20.0 // Must be same as XY for delta
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/delta/kossel_xl/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 // delta speeds must be the same on xyz
 #define XYZ_STEPS (XYZ_FULL_STEPS_PER_ROTATION * XYZ_MICROSTEPS / double(XYZ_BELT_PITCH) / double(XYZ_PULLEY_TEETH))
 
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   {XYZ_STEPS, XYZ_STEPS, XYZ_STEPS, 158}   // default steps per unit for PowerWasp
-#define DEFAULT_MAX_FEEDRATE          {200, 200, 200, 25}    // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,9000,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.
-
-#define DEFAULT_ACCELERATION          2000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                 20.0    // (mm/sec)
-#define DEFAULT_EJERK                 20.0    // (mm/sec)
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 200, 200, 200, 25 }
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 9000, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          2000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                 20.0
+#define DEFAULT_EJERK                 20.0
 
 
 //===========================================================================

Marlin/example_configurations/makibox/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {400, 400, 400, 163}     // default steps per unit for ***** MakiBox A6 *****
-#define DEFAULT_MAX_FEEDRATE          {60, 60, 20, 45}         // (mm/sec)
-#define DEFAULT_MAX_ACCELERATION      {2000,2000,30,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 400, 400, 400, 163 }     // default steps per unit for ***** MakiBox A6 *****
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 60, 60, 20, 45 }
 
-#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 2000, 2000, 30, 10000 }
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves
 
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/example_configurations/makibox/Configuration_adv.h

 // Number of channels available for I2C digipot, For Azteeg X3 Pro we have 8
 #define DIGIPOT_I2C_NUM_CHANNELS 4
 // actual motor currents in Amps, need as many here as DIGIPOT_I2C_NUM_CHANNELS
-#define DIGIPOT_I2C_MOTOR_CURRENTS {1.7, 1.7, 1.7, 1.7}
+#define DIGIPOT_I2C_MOTOR_CURRENTS { 1.7, 1.7, 1.7, 1.7 }
 
 //===========================================================================
 //=============================Additional Features===========================

Marlin/example_configurations/tvrrug/Round2/Configuration.h

 #define EXTRUDE_MINTEMP 170
 
 // This option prevents a single extrusion longer than EXTRUDE_MAXLENGTH.
+// Note that for Bowden Extruders a too-small value here may prevent loading.
 #define PREVENT_LENGTHY_EXTRUDE
-#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH)
+#define EXTRUDE_MAXLENGTH 200
 
 //===========================================================================
 //======================== Thermal Runaway Protection =======================
 //=============================================================================
 // @section motion
 
+/**
+ * Default Settings
+ *
+ * These settings can be reset by M502
+ *
+ * Note that if EEPROM is enabled, saved values will override these.
+ */
+
+/**
+ * Default Axis Steps Per Unit (steps/mm)
+ * Override with M92
+ */
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 71.1, 71.1, 2560, 600 } // David TVRR
+
 //#define DEFAULT_AXIS_STEPS_PER_UNIT   {79.87, 79.87, 2566, 563,78} // Al's TVRR
-//#define DEFAULT_AXIS_STEPS_PER_UNIT   {81.26, 80.01, 2561, 599.14} // Michel TVRR old
-//#define DEFAULT_AXIS_STEPS_PER_UNIT   {71.1, 71.1, 2560, 739.65} // Michel TVRR
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {71.1, 71.1, 2560, 600} // David TVRR
-#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 45}    // (mm/sec) David TVRR
-#define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.
+//#define DEFAULT_AXIS_STEPS_PER_UNIT   { 81.26, 80.01, 2561, 599.14 } // Michel TVRR old
+//#define DEFAULT_AXIS_STEPS_PER_UNIT   { 71.1, 71.1, 2560, 739.65 } // Michel TVRR
+
+/**
+ * Default Max Feed Rate (mm/s)
+ * Override with M203
+ */
+#define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 45 } // David TVRR
+
+/**
+ * Default Max Acceleration (change/s) change = mm/s
+ * Override with M201
+ *
+ * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ */
+#define DEFAULT_MAX_ACCELERATION      { 9000, 9000, 100, 10000 }
 
 /* MICHEL: This has an impact on the "ripples" in print walls */
-#define DEFAULT_ACCELERATION          500    // X, Y, Z and E acceleration in mm/s^2 for printing moves
-#define DEFAULT_RETRACT_ACCELERATION  3000   // E acceleration in mm/s^2 for retracts
-#define DEFAULT_TRAVEL_ACCELERATION   500    // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves
-
-// "Jerk" specifies the minimum speed change that requires acceleration.
-// When changing speed and direction, if the difference is less than the
-// value set here, it may happen instantaneously.
-#define DEFAULT_XYJERK                20.0    // (mm/sec)
-#define DEFAULT_ZJERK                  0.4    // (mm/sec)
-#define DEFAULT_EJERK                  5.0    // (mm/sec)
+
+/**
+ * Default Acceleration (change/s) change = mm/s
+ * Override with M204
+ *
+ *   M204 P    Acceleration
+ *   M204 R    Retract Acceleration
+ *   M204 T    Travel Acceleration
+ */
+#define DEFAULT_ACCELERATION          500    // X, Y, Z and E acceleration for printing moves
+#define DEFAULT_RETRACT_ACCELERATION  3000   // E acceleration for retracts
+#define DEFAULT_TRAVEL_ACCELERATION   500    // X, Y, Z acceleration for travel (non printing) moves
+
+/**
+ * Defult Jerk (mm/s)
+ *
+ * "Jerk" specifies the minimum speed change that requires acceleration.
+ * When changing speed and direction, if the difference is less than the
+ * value set here, it may happen instantaneously.
+ */
+#define DEFAULT_XYJERK                20.0
+#define DEFAULT_ZJERK                  0.4
+#define DEFAULT_EJERK                  5.0
 
 
 //===========================================================================

Marlin/pins_PRINTRBOARD_REVF.h

 // uncomment to enable an I2C based DAC like on the Printrboard REVF
 #define DAC_STEPPER_CURRENT
 // Number of channels available for DAC, For Printrboar REVF there are 4
-#define DAC_STEPPER_ORDER {3,2,1,0}
+#define DAC_STEPPER_ORDER { 3, 2, 1, 0 }
 
 #define DAC_STEPPER_SENSE    0.11
 #define DAC_STEPPER_ADDRESS  0

Marlin/pins_RIGIDBOARD_V2.h

 // I2C based DAC like on the Printrboard REVF
 #define DAC_STEPPER_CURRENT
 // Channels available for DAC, For Rigidboard there are 4
-#define DAC_STEPPER_ORDER {0,1,2,3}
+#define DAC_STEPPER_ORDER { 0, 1, 2, 3 }
 
 #define DAC_STEPPER_SENSE    0.11
 #define DAC_STEPPER_ADDRESS  0