marlin/Marlin/Marlin_main.cpp

/**
 * Marlin Firmware
 *
 * Based on Sprinter and grbl.
 * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * About Marlin
 *
 * This firmware is a mashup between Sprinter and grbl.
 *  - https://github.com/kliment/Sprinter
 *  - https://github.com/simen/grbl/tree
 *
 * It has preliminary support for Matthew Roberts advance algorithm
 *  - http://reprap.org/pipermail/reprap-dev/2011-May/003323.html
 */

#include "Marlin.h"

#ifdef ENABLE_AUTO_BED_LEVELING
  #include "vector_3.h"
  #ifdef AUTO_BED_LEVELING_GRID
    #include "qr_solve.h"
  #endif
#endif // ENABLE_AUTO_BED_LEVELING

#define HAS_LCD_BUZZ (defined(ULTRALCD) || (defined(BEEPER) && BEEPER >= 0) || defined(LCD_USE_I2C_BUZZER))
#define SERVO_LEVELING (defined(ENABLE_AUTO_BED_LEVELING) && PROBE_SERVO_DEACTIVATION_DELAY > 0)

#ifdef MESH_BED_LEVELING
  #include "mesh_bed_leveling.h"
#endif

#include "ultralcd.h"
#include "planner.h"
#include "stepper.h"
#include "temperature.h"
#include "cardreader.h"
#include "watchdog.h"
#include "configuration_store.h"
#include "language.h"
#include "pins_arduino.h"
#include "math.h"

#ifdef BLINKM
  #include "blinkm.h"
  #include "Wire.h"
#endif

#if NUM_SERVOS > 0
  #include "servo.h"
#endif

#if HAS_DIGIPOTSS
  #include <SPI.h>
#endif

/**
 * Look here for descriptions of G-codes:
 *  - http://linuxcnc.org/handbook/gcode/g-code.html
 *  - http://objects.reprap.org/wiki/Mendel_User_Manual:_RepRapGCodes
 *
 * Help us document these G-codes online:
 *  - http://www.marlinfirmware.org/index.php/G-Code
 *  - http://reprap.org/wiki/G-code
 *
 * -----------------
 * Implemented Codes
 * -----------------
 *
 * "G" Codes
 *
 * G0  -> G1
 * G1  - Coordinated Movement X Y Z E
 * G2  - CW ARC
 * G3  - CCW ARC
 * G4  - Dwell S<seconds> or P<milliseconds>
 * G10 - retract filament according to settings of M207
 * G11 - retract recover filament according to settings of M208
 * G28 - Home one or more axes
 * G29 - Detailed Z-Probe, probes the bed at 3 or more points.  Will fail if you haven't homed yet.
 * G30 - Single Z Probe, probes bed at current XY location.
 * G31 - Dock sled (Z_PROBE_SLED only)
 * G32 - Undock sled (Z_PROBE_SLED only)
 * G90 - Use Absolute Coordinates
 * G91 - Use Relative Coordinates
 * G92 - Set current position to coordinates given
 *
 * "M" Codes
 *
 * M0   - Unconditional stop - Wait for user to press a button on the LCD (Only if ULTRA_LCD is enabled)
 * M1   - Same as M0
 * M17  - Enable/Power all stepper motors
 * M18  - Disable all stepper motors; same as M84
 * M20  - List SD card
 * M21  - Init SD card
 * M22  - Release SD card
 * M23  - Select SD file (M23 filename.g)
 * M24  - Start/resume SD print
 * M25  - Pause SD print
 * M26  - Set SD position in bytes (M26 S12345)
 * M27  - Report SD print status
 * M28  - Start SD write (M28 filename.g)
 * M29  - Stop SD write
 * M30  - Delete file from SD (M30 filename.g)
 * M31  - Output time since last M109 or SD card start to serial
 * M32  - Select file and start SD print (Can be used _while_ printing from SD card files):
 *        syntax "M32 /path/filename#", or "M32 S<startpos bytes> !filename#"
 *        Call gcode file : "M32 P !filename#" and return to caller file after finishing (similar to #include).
 *        The '#' is necessary when calling from within sd files, as it stops buffer prereading
 * M42  - Change pin status via gcode Use M42 Px Sy to set pin x to value y, when omitting Px the onboard led will be used.
 * M48  - Measure Z_Probe repeatability. M48 [P # of points] [X position] [Y position] [V_erboseness #] [E_ngage Probe] [L # of legs of travel]
 * M80  - Turn on Power Supply
 * M81  - Turn off Power Supply
 * M82  - Set E codes absolute (default)
 * M83  - Set E codes relative while in Absolute Coordinates (G90) mode
 * M84  - Disable steppers until next move,
 *        or use S<seconds> to specify an inactivity timeout, after which the steppers will be disabled.  S0 to disable the timeout.
 * M85  - Set inactivity shutdown timer with parameter S<seconds>. To disable set zero (default)
 * M92  - Set axis_steps_per_unit - same syntax as G92
 * M104 - Set extruder target temp
 * M105 - Read current temp
 * M106 - Fan on
 * M107 - Fan off
 * M109 - Sxxx Wait for extruder current temp to reach target temp. Waits only when heating
 *        Rxxx Wait for extruder current temp to reach target temp. Waits when heating and cooling
 *        IF AUTOTEMP is enabled, S<mintemp> B<maxtemp> F<factor>. Exit autotemp by any M109 without F
 * M111 - Set debug flags with S<mask>. See flag bits defined in Marlin.h.
 * M112 - Emergency stop
 * M114 - Output current position to serial port
 * M115 - Capabilities string
 * M117 - display message
 * M119 - Output Endstop status to serial port
 * M120 - Enable endstop detection
 * M121 - Disable endstop detection
 * M126 - Solenoid Air Valve Open (BariCUDA support by jmil)
 * M127 - Solenoid Air Valve Closed (BariCUDA vent to atmospheric pressure by jmil)
 * M128 - EtoP Open (BariCUDA EtoP = electricity to air pressure transducer by jmil)
 * M129 - EtoP Closed (BariCUDA EtoP = electricity to air pressure transducer by jmil)
 * M140 - Set bed target temp
 * M145 - Set the heatup state H<hotend> B<bed> F<fan speed> for S<material> (0=PLA, 1=ABS)
 * M150 - Set BlinkM Color Output R: Red<0-255> U(!): Green<0-255> B: Blue<0-255> over i2c, G for green does not work.
 * M190 - Sxxx Wait for bed current temp to reach target temp. Waits only when heating
 *        Rxxx Wait for bed current temp to reach target temp. Waits when heating and cooling
 * M200 - set filament diameter and set E axis units to cubic millimeters (use S0 to set back to millimeters).:D<millimeters>- 
 * M201 - Set max acceleration in units/s^2 for print moves (M201 X1000 Y1000)
 * M202 - Set max acceleration in units/s^2 for travel moves (M202 X1000 Y1000) Unused in Marlin!!
 * M203 - Set maximum feedrate that your machine can sustain (M203 X200 Y200 Z300 E10000) in mm/sec
 * M204 - Set default acceleration: P for Printing moves, R for Retract only (no X, Y, Z) moves and T for Travel (non printing) moves (ex. M204 P800 T3000 R9000) in mm/sec^2
 * M205 -  advanced settings:  minimum travel speed S=while printing T=travel only,  B=minimum segment time X= maximum xy jerk, Z=maximum Z jerk, E=maximum E jerk
 * M206 - Set additional homing offset
 * M207 - Set retract length S[positive mm] F[feedrate mm/min] Z[additional zlift/hop], stays in mm regardless of M200 setting
 * M208 - Set recover=unretract length S[positive mm surplus to the M207 S*] F[feedrate mm/min]
 * M209 - S<1=true/0=false> enable automatic retract detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
 * M218 - Set hotend offset (in mm): T<extruder_number> X<offset_on_X> Y<offset_on_Y>
 * M220 - Set speed factor override percentage: S<factor in percent>
 * M221 - Set extrude factor override percentage: S<factor in percent>
 * M226 - Wait until the specified pin reaches the state required: P<pin number> S<pin state>
 * M240 - Trigger a camera to take a photograph
 * M250 - Set LCD contrast C<contrast value> (value 0..63)
 * M280 - Set servo position absolute. P: servo index, S: angle or microseconds
 * M300 - Play beep sound S<frequency Hz> P<duration ms>
 * M301 - Set PID parameters P I and D
 * M302 - Allow cold extrudes, or set the minimum extrude S<temperature>.
 * M303 - PID relay autotune S<temperature> sets the target temperature. (default target temperature = 150C)
 * M304 - Set bed PID parameters P I and D
 * M380 - Activate solenoid on active extruder
 * M381 - Disable all solenoids
 * M400 - Finish all moves
 * M401 - Lower z-probe if present
 * M402 - Raise z-probe if present
 * M404 - N<dia in mm> Enter the nominal filament width (3mm, 1.75mm ) or will display nominal filament width without parameters
 * M405 - Turn on Filament Sensor extrusion control.  Optional D<delay in cm> to set delay in centimeters between sensor and extruder
 * M406 - Turn off Filament Sensor extrusion control
 * M407 - Display measured filament diameter
 * M410 - Quickstop. Abort all the planned moves
 * M420 - Enable/Disable Mesh Leveling (with current values) S1=enable S0=disable
 * M421 - Set a single Z coordinate in the Mesh Leveling grid. X<mm> Y<mm> Z<mm>
 * M428 - Set the home_offset logically based on the current_position
 * M500 - Store parameters in EEPROM
 * M501 - Read parameters from EEPROM (if you need reset them after you changed them temporarily).
 * M502 - Revert 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). Use S0 to leave off headings.
 * M540 - Use S[0|1] to enable or disable the stop SD card print on endstop hit (requires ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
 * M600 - Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]
 * M665 - Set delta configurations: L<diagonal rod> R<delta radius> S<segments/s>
 * M666 - Set delta endstop adjustment
 * M605 - Set dual x-carriage movement mode: S<mode> [ X<duplication x-offset> R<duplication temp offset> ]
 * M907 - Set digital trimpot motor current using axis codes.
 * M908 - Control digital trimpot directly.
 * M350 - Set microstepping mode.
 * M351 - Toggle MS1 MS2 pins directly.
 *
 * ************ SCARA Specific - This can change to suit future G-code regulations
 * M360 - SCARA calibration: Move to cal-position ThetaA (0 deg calibration)
 * M361 - SCARA calibration: Move to cal-position ThetaB (90 deg calibration - steps per degree)
 * M362 - SCARA calibration: Move to cal-position PsiA (0 deg calibration)
 * M363 - SCARA calibration: Move to cal-position PsiB (90 deg calibration - steps per degree)
 * M364 - SCARA calibration: Move to cal-position PSIC (90 deg to Theta calibration position)
 * M365 - SCARA calibration: Scaling factor, X, Y, Z axis
 * ************* SCARA End ***************
 *
 * ************ Custom codes - This can change to suit future G-code regulations
 * M851 - Set probe's Z offset (mm above extruder -- The value will always be negative)


 * M928 - Start SD logging (M928 filename.g) - ended by M29
 * M999 - Restart after being stopped by error
 *
 * "T" Codes
 *
 * T0-T3 - Select a tool by index (usually an extruder) [ F<mm/min> ]
 *
 */

#ifdef SDSUPPORT
  CardReader card;
#endif

bool Running = true;

uint8_t marlin_debug_flags = DEBUG_INFO|DEBUG_ERRORS;

static float feedrate = 1500.0, saved_feedrate;
float current_position[NUM_AXIS] = { 0.0 };
static float destination[NUM_AXIS] = { 0.0 };
bool axis_known_position[3] = { false };

static long gcode_N, gcode_LastN, Stopped_gcode_LastN = 0;

static int cmd_queue_index_r = 0;
static int cmd_queue_index_w = 0;
static int commands_in_queue = 0;
static char command_queue[BUFSIZE][MAX_CMD_SIZE];

float homing_feedrate[] = HOMING_FEEDRATE;
bool axis_relative_modes[] = AXIS_RELATIVE_MODES;
int feedrate_multiplier = 100; //100->1 200->2
int saved_feedrate_multiplier;
int extruder_multiply[EXTRUDERS] = ARRAY_BY_EXTRUDERS(100, 100, 100, 100);
bool volumetric_enabled = false;
float filament_size[EXTRUDERS] = ARRAY_BY_EXTRUDERS(DEFAULT_NOMINAL_FILAMENT_DIA, DEFAULT_NOMINAL_FILAMENT_DIA, DEFAULT_NOMINAL_FILAMENT_DIA, DEFAULT_NOMINAL_FILAMENT_DIA);
float volumetric_multiplier[EXTRUDERS] = ARRAY_BY_EXTRUDERS(1.0, 1.0, 1.0, 1.0);
float home_offset[3] = { 0 };
float min_pos[3] = { X_MIN_POS, Y_MIN_POS, Z_MIN_POS };
float max_pos[3] = { X_MAX_POS, Y_MAX_POS, Z_MAX_POS };

uint8_t active_extruder = 0;
int fanSpeed = 0;
bool cancel_heatup = false;

const char errormagic[] PROGMEM = "Error:";
const char echomagic[] PROGMEM = "echo:";
const char axis_codes[NUM_AXIS] = {'X', 'Y', 'Z', 'E'};

static bool relative_mode = false;  //Determines Absolute or Relative Coordinates
static char serial_char;
static int serial_count = 0;
static boolean comment_mode = false;
static char *strchr_pointer; ///< A pointer to find chars in the command string (X, Y, Z, E, etc.)
const char* queued_commands_P= NULL; /* pointer to the current line in the active sequence of commands, or NULL when none */
const int sensitive_pins[] = SENSITIVE_PINS; ///< Sensitive pin list for M42
// Inactivity shutdown
millis_t previous_cmd_ms = 0;
static millis_t max_inactive_time = 0;
static millis_t stepper_inactive_time = DEFAULT_STEPPER_DEACTIVE_TIME * 1000L;
millis_t print_job_start_ms = 0; ///< Print job start time
millis_t print_job_stop_ms = 0;  ///< Print job stop time
static uint8_t target_extruder;
bool no_wait_for_cooling = true;
bool target_direction;

#ifdef ENABLE_AUTO_BED_LEVELING
  int xy_travel_speed = XY_TRAVEL_SPEED;
  float zprobe_zoffset = -Z_PROBE_OFFSET_FROM_EXTRUDER;
#endif

#if defined(Z_DUAL_ENDSTOPS) && !defined(DELTA)
  float z_endstop_adj = 0;
#endif

// Extruder offsets
#if EXTRUDERS > 1
  #ifndef EXTRUDER_OFFSET_X
    #define EXTRUDER_OFFSET_X { 0 }
  #endif
  #ifndef EXTRUDER_OFFSET_Y
    #define EXTRUDER_OFFSET_Y { 0 }
  #endif
  float extruder_offset[][EXTRUDERS] = {
    EXTRUDER_OFFSET_X,
    EXTRUDER_OFFSET_Y
    #ifdef DUAL_X_CARRIAGE
      , { 0 } // supports offsets in XYZ plane
    #endif
  };
#endif

#ifdef SERVO_ENDSTOPS
  int servo_endstops[] = SERVO_ENDSTOPS;
  int servo_endstop_angles[] = SERVO_ENDSTOP_ANGLES;
#endif

#ifdef BARICUDA
  int ValvePressure = 0;
  int EtoPPressure = 0;
#endif

#ifdef FWRETRACT

  bool autoretract_enabled = false;
  bool retracted[EXTRUDERS] = { false };
  bool retracted_swap[EXTRUDERS] = { false };

  float retract_length = RETRACT_LENGTH;
  float retract_length_swap = RETRACT_LENGTH_SWAP;
  float retract_feedrate = RETRACT_FEEDRATE;
  float retract_zlift = RETRACT_ZLIFT;
  float retract_recover_length = RETRACT_RECOVER_LENGTH;
  float retract_recover_length_swap = RETRACT_RECOVER_LENGTH_SWAP;
  float retract_recover_feedrate = RETRACT_RECOVER_FEEDRATE;

#endif // FWRETRACT

#if defined(ULTIPANEL) && HAS_POWER_SWITCH
  bool powersupply = 
    #ifdef PS_DEFAULT_OFF
      false
    #else
      true
    #endif
  ;
#endif

#ifdef DELTA
  float delta[3] = { 0 };
  #define SIN_60 0.8660254037844386
  #define COS_60 0.5
  float endstop_adj[3] = { 0 };
  // these are the default values, can be overriden with M665
  float delta_radius = DELTA_RADIUS;
  float delta_tower1_x = -SIN_60 * delta_radius; // front left tower
  float delta_tower1_y = -COS_60 * delta_radius;     
  float delta_tower2_x =  SIN_60 * delta_radius; // front right tower
  float delta_tower2_y = -COS_60 * delta_radius;     
  float delta_tower3_x = 0;                      // back middle tower
  float delta_tower3_y = delta_radius;
  float delta_diagonal_rod = DELTA_DIAGONAL_ROD;
  float delta_diagonal_rod_2 = sq(delta_diagonal_rod);
  float delta_segments_per_second = DELTA_SEGMENTS_PER_SECOND;
  #ifdef ENABLE_AUTO_BED_LEVELING
    int delta_grid_spacing[2] = { 0, 0 };
    float bed_level[AUTO_BED_LEVELING_GRID_POINTS][AUTO_BED_LEVELING_GRID_POINTS];
  #endif
#else
  static bool home_all_axis = true;
#endif

#ifdef SCARA
  float delta_segments_per_second = SCARA_SEGMENTS_PER_SECOND;
  static float delta[3] = { 0 };
  float axis_scaling[3] = { 1, 1, 1 };    // Build size scaling, default to 1
#endif

#ifdef FILAMENT_SENSOR
  //Variables for Filament Sensor input
  float filament_width_nominal = DEFAULT_NOMINAL_FILAMENT_DIA;  //Set nominal filament width, can be changed with M404
  bool filament_sensor = false;  //M405 turns on filament_sensor control, M406 turns it off
  float filament_width_meas = DEFAULT_MEASURED_FILAMENT_DIA; //Stores the measured filament diameter
  signed char measurement_delay[MAX_MEASUREMENT_DELAY+1];  //ring buffer to delay measurement  store extruder factor after subtracting 100
  int delay_index1 = 0;  //index into ring buffer
  int delay_index2 = -1;  //index into ring buffer - set to -1 on startup to indicate ring buffer needs to be initialized
  float delay_dist = 0; //delay distance counter
  int meas_delay_cm = MEASUREMENT_DELAY_CM;  //distance delay setting
#endif

#ifdef FILAMENT_RUNOUT_SENSOR
   static bool filrunoutEnqueued = false;
#endif

#ifdef SDSUPPORT
  static bool fromsd[BUFSIZE];
#endif

#if NUM_SERVOS > 0
  Servo servo[NUM_SERVOS];
#endif

#ifdef CHDK
  unsigned long chdkHigh = 0;
  boolean chdkActive = false;
#endif

//===========================================================================
//================================ Functions ================================
//===========================================================================

void process_next_command();

bool setTargetedHotend(int code);

void serial_echopair_P(const char *s_P, float v)         { serialprintPGM(s_P); SERIAL_ECHO(v); }
void serial_echopair_P(const char *s_P, double v)        { serialprintPGM(s_P); SERIAL_ECHO(v); }
void serial_echopair_P(const char *s_P, unsigned long v) { serialprintPGM(s_P); SERIAL_ECHO(v); }

#ifdef PREVENT_DANGEROUS_EXTRUDE
  float extrude_min_temp = EXTRUDE_MINTEMP;
#endif

#ifdef SDSUPPORT
  #include "SdFatUtil.h"
  int freeMemory() { return SdFatUtil::FreeRam(); }
#else
  extern "C" {
    extern unsigned int __bss_end;
    extern unsigned int __heap_start;
    extern void *__brkval;

    int freeMemory() {
      int free_memory;

      if ((int)__brkval == 0)
        free_memory = ((int)&free_memory) - ((int)&__bss_end);
      else
        free_memory = ((int)&free_memory) - ((int)__brkval);

      return free_memory;
    }
  }
#endif //!SDSUPPORT

/**
 * Inject the next command from the command queue, when possible
 * Return false only if no command was pending
 */
static bool drain_queued_commands_P() {
  if (!queued_commands_P) return false;

  // Get the next 30 chars from the sequence of gcodes to run
  char cmd[30];
  strncpy_P(cmd, queued_commands_P, sizeof(cmd) - 1);
  cmd[sizeof(cmd) - 1] = '\0';

  // Look for the end of line, or the end of sequence
  size_t i = 0;
  char c;
  while((c = cmd[i]) && c != '\n') i++; // find the end of this gcode command
  cmd[i] = '\0';
  if (enqueuecommand(cmd)) {      // buffer was not full (else we will retry later)
    if (c)
      queued_commands_P += i + 1; // move to next command
    else
      queued_commands_P = NULL;   // will have no more commands in the sequence
  }
  return true;
}

/**
 * Record one or many commands to run from program memory.
 * Aborts the current queue, if any.
 * Note: drain_queued_commands_P() must be called repeatedly to drain the commands afterwards
 */
void enqueuecommands_P(const char* pgcode) {
  queued_commands_P = pgcode;
  drain_queued_commands_P(); // first command executed asap (when possible)
}

/**
 * Copy a command directly into the main command buffer, from RAM.
 *
 * This is done in a non-safe way and needs a rework someday.
 * Returns false if it doesn't add any command
 */
bool enqueuecommand(const char *cmd) {

  if (*cmd == ';' || commands_in_queue >= BUFSIZE) return false;

  // This is dangerous if a mixing of serial and this happens
  char *command = command_queue[cmd_queue_index_w];
  strcpy(command, cmd);
  SERIAL_ECHO_START;
  SERIAL_ECHOPGM(MSG_Enqueueing);
  SERIAL_ECHO(command);
  SERIAL_ECHOLNPGM("\"");
  cmd_queue_index_w = (cmd_queue_index_w + 1) % BUFSIZE;
  commands_in_queue++;
  return true;
}

void setup_killpin() {
  #if HAS_KILL
    SET_INPUT(KILL_PIN);
    WRITE(KILL_PIN, HIGH);
  #endif
}

void setup_filrunoutpin() {
  #if HAS_FILRUNOUT
    pinMode(FILRUNOUT_PIN, INPUT);
    #ifdef ENDSTOPPULLUP_FIL_RUNOUT
      WRITE(FILRUNOUT_PIN, HIGH);
    #endif
  #endif
}

// Set home pin
void setup_homepin(void) {
  #if HAS_HOME
    SET_INPUT(HOME_PIN);
    WRITE(HOME_PIN, HIGH);
  #endif
}


void setup_photpin() {
  #if HAS_PHOTOGRAPH
    OUT_WRITE(PHOTOGRAPH_PIN, LOW);
  #endif
}

void setup_powerhold() {
  #if HAS_SUICIDE
    OUT_WRITE(SUICIDE_PIN, HIGH);
  #endif
  #if HAS_POWER_SWITCH
    #ifdef PS_DEFAULT_OFF
      OUT_WRITE(PS_ON_PIN, PS_ON_ASLEEP);
    #else
      OUT_WRITE(PS_ON_PIN, PS_ON_AWAKE);
    #endif
  #endif
}

void suicide() {
  #if HAS_SUICIDE
    OUT_WRITE(SUICIDE_PIN, LOW);
  #endif
}

void servo_init() {
  #if NUM_SERVOS >= 1 && HAS_SERVO_0
    servo[0].attach(SERVO0_PIN);
  #endif
  #if NUM_SERVOS >= 2 && HAS_SERVO_1
    servo[1].attach(SERVO1_PIN);
  #endif
  #if NUM_SERVOS >= 3 && HAS_SERVO_2
    servo[2].attach(SERVO2_PIN);
  #endif
  #if NUM_SERVOS >= 4 && HAS_SERVO_3
    servo[3].attach(SERVO3_PIN);
  #endif

  // Set position of Servo Endstops that are defined
  #ifdef SERVO_ENDSTOPS
    for (int i = 0; i < 3; i++)
      if (servo_endstops[i] >= 0)
        servo[servo_endstops[i]].write(servo_endstop_angles[i * 2 + 1]);
  #endif

  #if SERVO_LEVELING
    delay(PROBE_SERVO_DEACTIVATION_DELAY);
    servo[servo_endstops[Z_AXIS]].detach();
  #endif
}

/**
 * Marlin entry-point: Set up before the program loop
 *  - Set up the kill pin, filament runout, power hold
 *  - Start the serial port
 *  - Print startup messages and diagnostics
 *  - Get EEPROM or default settings
 *  - Initialize managers for:
 *    • temperature
 *    • planner
 *    • watchdog
 *    • stepper
 *    • photo pin
 *    • servos
 *    • LCD controller
 *    • Digipot I2C
 *    • Z probe sled
 *    • status LEDs
 */
void setup() {
  setup_killpin();
  setup_filrunoutpin();
  setup_powerhold();
  MYSERIAL.begin(BAUDRATE);
  SERIAL_PROTOCOLLNPGM("start");
  SERIAL_ECHO_START;

  // Check startup - does nothing if bootloader sets MCUSR to 0
  byte mcu = MCUSR;
  if (mcu & 1) SERIAL_ECHOLNPGM(MSG_POWERUP);
  if (mcu & 2) SERIAL_ECHOLNPGM(MSG_EXTERNAL_RESET);
  if (mcu & 4) SERIAL_ECHOLNPGM(MSG_BROWNOUT_RESET);
  if (mcu & 8) SERIAL_ECHOLNPGM(MSG_WATCHDOG_RESET);
  if (mcu & 32) SERIAL_ECHOLNPGM(MSG_SOFTWARE_RESET);
  MCUSR = 0;

  SERIAL_ECHOPGM(MSG_MARLIN);
  SERIAL_ECHOLNPGM(" " STRING_VERSION);

  #ifdef STRING_VERSION_CONFIG_H
    #ifdef STRING_CONFIG_H_AUTHOR
      SERIAL_ECHO_START;
      SERIAL_ECHOPGM(MSG_CONFIGURATION_VER);
      SERIAL_ECHOPGM(STRING_VERSION_CONFIG_H);
      SERIAL_ECHOPGM(MSG_AUTHOR);
      SERIAL_ECHOLNPGM(STRING_CONFIG_H_AUTHOR);
      SERIAL_ECHOPGM("Compiled: ");
      SERIAL_ECHOLNPGM(__DATE__);
    #endif // STRING_CONFIG_H_AUTHOR
  #endif // STRING_VERSION_CONFIG_H

  SERIAL_ECHO_START;
  SERIAL_ECHOPGM(MSG_FREE_MEMORY);
  SERIAL_ECHO(freeMemory());
  SERIAL_ECHOPGM(MSG_PLANNER_BUFFER_BYTES);
  SERIAL_ECHOLN((int)sizeof(block_t)*BLOCK_BUFFER_SIZE);

  #ifdef SDSUPPORT
    for (int8_t i = 0; i < BUFSIZE; i++) fromsd[i] = false;
  #endif

  // loads data from EEPROM if available else uses defaults (and resets step acceleration rate)
  Config_RetrieveSettings();

  tp_init();    // Initialize temperature loop
  plan_init();  // Initialize planner;
  watchdog_init();
  st_init();    // Initialize stepper, this enables interrupts!
  setup_photpin();
  servo_init();

  lcd_init();
  _delay_ms(1000);  // wait 1sec to display the splash screen

  #if HAS_CONTROLLERFAN
    SET_OUTPUT(CONTROLLERFAN_PIN); //Set pin used for driver cooling fan
  #endif

  #ifdef DIGIPOT_I2C
    digipot_i2c_init();
  #endif

  #ifdef Z_PROBE_SLED
    pinMode(SLED_PIN, OUTPUT);
    digitalWrite(SLED_PIN, LOW); // turn it off
  #endif // Z_PROBE_SLED

  setup_homepin();
  
  #ifdef STAT_LED_RED
    pinMode(STAT_LED_RED, OUTPUT);
    digitalWrite(STAT_LED_RED, LOW); // turn it off
  #endif

  #ifdef STAT_LED_BLUE
    pinMode(STAT_LED_BLUE, OUTPUT);
    digitalWrite(STAT_LED_BLUE, LOW); // turn it off
  #endif  
}

/**
 * The main Marlin program loop
 *
 *  - Save or log commands to SD
 *  - Process available commands (if not saving)
 *  - Call heater manager
 *  - Call inactivity manager
 *  - Call endstop manager
 *  - Call LCD update
 */
void loop() {
  if (commands_in_queue < BUFSIZE - 1) get_command();

  #ifdef SDSUPPORT
    card.checkautostart(false);
  #endif

  if (commands_in_queue) {

    #ifdef SDSUPPORT

      if (card.saving) {
        char *command = command_queue[cmd_queue_index_r];
        if (strstr_P(command, PSTR("M29"))) {
          // M29 closes the file
          card.closefile();
          SERIAL_PROTOCOLLNPGM(MSG_FILE_SAVED);
        }
        else {
          // Write the string from the read buffer to SD
          card.write_command(command);
          if (card.logging)
            process_next_command(); // The card is saving because it's logging
          else
            SERIAL_PROTOCOLLNPGM(MSG_OK);
        }
      }
      else
        process_next_command();

    #else

      process_next_command();

    #endif // SDSUPPORT

    commands_in_queue--;
    cmd_queue_index_r = (cmd_queue_index_r + 1) % BUFSIZE;
  }
  // Check heater every n milliseconds
  manage_heater();
  manage_inactivity();
  checkHitEndstops();
  lcd_update();
}

void gcode_line_error(const char *err, bool doFlush=true) {
  SERIAL_ERROR_START;
  serialprintPGM(err);
  SERIAL_ERRORLN(gcode_LastN);
  //Serial.println(gcode_N);
  if (doFlush) FlushSerialRequestResend();
  serial_count = 0;
}

/**
 * Add to the circular command queue the next command from:
 *  - The command-injection queue (queued_commands_P)
 *  - The active serial input (usually USB)
 *  - The SD card file being actively printed
 */
void get_command() {

  if (drain_queued_commands_P()) return; // priority is given to non-serial commands
  
  #ifdef NO_TIMEOUTS
    static millis_t last_command_time = 0;
    millis_t ms = millis();
  
    if (!MYSERIAL.available() && commands_in_queue == 0 && ms - last_command_time > NO_TIMEOUTS) {
      SERIAL_ECHOLNPGM(MSG_WAIT);
      last_command_time = ms;
    }
  #endif

  //
  // Loop while serial characters are incoming and the queue is not full
  //
  while (commands_in_queue < BUFSIZE && MYSERIAL.available() > 0) {

    #ifdef NO_TIMEOUTS
      last_command_time = ms;
    #endif

    serial_char = MYSERIAL.read();

    //
    // If the character ends the line, or the line is full...
    //
    if (serial_char == '\n' || serial_char == '\r' || serial_count >= MAX_CMD_SIZE-1) {

      // end of line == end of comment
      comment_mode = false;

      if (!serial_count) return; // empty lines just exit

      char *command = command_queue[cmd_queue_index_w];
      command[serial_count] = 0; // terminate string

      // this item in the queue is not from sd
      #ifdef SDSUPPORT
        fromsd[cmd_queue_index_w] = false;
      #endif

      if (strchr(command, 'N') != NULL) {
        strchr_pointer = strchr(command, 'N');
        gcode_N = (strtol(strchr_pointer + 1, NULL, 10));
        if (gcode_N != gcode_LastN + 1 && strstr_P(command, PSTR("M110")) == NULL) {
          gcode_line_error(PSTR(MSG_ERR_LINE_NO));
          return;
        }

        if (strchr(command, '*') != NULL) {
          byte checksum = 0;
          byte count = 0;
          while (command[count] != '*') checksum ^= command[count++];
          strchr_pointer = strchr(command, '*');

          if (strtol(strchr_pointer + 1, NULL, 10) != checksum) {
            gcode_line_error(PSTR(MSG_ERR_CHECKSUM_MISMATCH));
            return;
          }
          // if no errors, continue parsing
        }
        else {
          gcode_line_error(PSTR(MSG_ERR_NO_CHECKSUM));
          return;
        }

        gcode_LastN = gcode_N;
        // if no errors, continue parsing
      }
      else {  // if we don't receive 'N' but still see '*'
        if ((strchr(command, '*') != NULL)) {
          gcode_line_error(PSTR(MSG_ERR_NO_LINENUMBER_WITH_CHECKSUM), false);
          return;
        }
      }

      if (strchr(command, 'G') != NULL) {
        strchr_pointer = strchr(command, 'G');
        switch (strtol(strchr_pointer + 1, NULL, 10)) {
          case 0:
          case 1:
          case 2:
          case 3:
            if (IsStopped()) {
              SERIAL_ERRORLNPGM(MSG_ERR_STOPPED);
              LCD_MESSAGEPGM(MSG_STOPPED);
            }
            break;
          default:
            break;
        }
      }

      // If command was e-stop process now
      if (strcmp(command, "M112") == 0) kill(PSTR(MSG_KILLED));

      cmd_queue_index_w = (cmd_queue_index_w + 1) % BUFSIZE;
      commands_in_queue += 1;

      serial_count = 0; //clear buffer
    }
    else if (serial_char == '\\') {  // Handle escapes
      if (MYSERIAL.available() > 0 && commands_in_queue < BUFSIZE) {
        // if we have one more character, copy it over
        serial_char = MYSERIAL.read();
        command_queue[cmd_queue_index_w][serial_count++] = serial_char;
      }
      // otherwise do nothing
    }
    else { // its not a newline, carriage return or escape char
      if (serial_char == ';') comment_mode = true;
      if (!comment_mode) command_queue[cmd_queue_index_w][serial_count++] = serial_char;
    }
  }

  #ifdef SDSUPPORT

    if (!card.sdprinting || serial_count) return;

    // '#' stops reading from SD to the buffer prematurely, so procedural macro calls are possible
    // if it occurs, stop_buffering is triggered and the buffer is ran dry.
    // this character _can_ occur in serial com, due to checksums. however, no checksums are used in SD printing

    static bool stop_buffering = false;
    if (commands_in_queue == 0) stop_buffering = false;

    while (!card.eof() && commands_in_queue < BUFSIZE && !stop_buffering) {
      int16_t n = card.get();
      serial_char = (char)n;
      if (serial_char == '\n' || serial_char == '\r' ||
          ((serial_char == '#' || serial_char == ':') && !comment_mode) ||
          serial_count >= (MAX_CMD_SIZE - 1) || n == -1
      ) {
        if (card.eof()) {
          SERIAL_PROTOCOLLNPGM(MSG_FILE_PRINTED);
          print_job_stop_ms = millis();
          char time[30];
          millis_t t = (print_job_stop_ms - print_job_start_ms) / 1000;
          int hours = t / 60 / 60, minutes = (t / 60) % 60;
          sprintf_P(time, PSTR("%i " MSG_END_HOUR " %i " MSG_END_MINUTE), hours, minutes);
          SERIAL_ECHO_START;
          SERIAL_ECHOLN(time);
          lcd_setstatus(time, true);
          card.printingHasFinished();
          card.checkautostart(true);
        }
        if (serial_char == '#') stop_buffering = true;

        if (!serial_count) {
          comment_mode = false; //for new command
          return; //if empty line
        }
        command_queue[cmd_queue_index_w][serial_count] = 0; //terminate string
        // if (!comment_mode) {
        fromsd[cmd_queue_index_w] = true;
        commands_in_queue += 1;
        cmd_queue_index_w = (cmd_queue_index_w + 1) % BUFSIZE;
        // }
        comment_mode = false; //for new command
        serial_count = 0; //clear buffer
      }
      else {
        if (serial_char == ';') comment_mode = true;
        if (!comment_mode) command_queue[cmd_queue_index_w][serial_count++] = serial_char;
      }
    }

  #endif // SDSUPPORT
}

bool code_has_value() {
  int i = 1;
  char c = strchr_pointer[i];
  if (c == '-' || c == '+') c = strchr_pointer[++i];
  if (c == '.') c = strchr_pointer[++i];
  return (c >= '0' && c <= '9');
}

float code_value() {
  float ret;
  char *e = strchr(strchr_pointer, 'E');
  if (e) {
    *e = 0;
    ret = strtod(strchr_pointer+1, NULL);
    *e = 'E';
  }
  else
    ret = strtod(strchr_pointer+1, NULL);
  return ret;
}

long code_value_long() { return strtol(strchr_pointer + 1, NULL, 10); }

int16_t code_value_short() { return (int16_t)strtol(strchr_pointer + 1, NULL, 10); }

bool code_seen(char code) {
  strchr_pointer = strchr(command_queue[cmd_queue_index_r], code);
  return (strchr_pointer != NULL);  //Return True if a character was found
}

#define DEFINE_PGM_READ_ANY(type, reader)       \
    static inline type pgm_read_any(const type *p)  \
    { return pgm_read_##reader##_near(p); }

DEFINE_PGM_READ_ANY(float,       float);
DEFINE_PGM_READ_ANY(signed char, byte);

#define XYZ_CONSTS_FROM_CONFIG(type, array, CONFIG) \
static const PROGMEM type array##_P[3] =        \
    { X_##CONFIG, Y_##CONFIG, Z_##CONFIG };     \
static inline type array(int axis)          \
    { return pgm_read_any(&array##_P[axis]); }

XYZ_CONSTS_FROM_CONFIG(float, base_min_pos,   MIN_POS);
XYZ_CONSTS_FROM_CONFIG(float, base_max_pos,   MAX_POS);
XYZ_CONSTS_FROM_CONFIG(float, base_home_pos,  HOME_POS);
XYZ_CONSTS_FROM_CONFIG(float, max_length,     MAX_LENGTH);
XYZ_CONSTS_FROM_CONFIG(float, home_bump_mm,   HOME_BUMP_MM);
XYZ_CONSTS_FROM_CONFIG(signed char, home_dir, HOME_DIR);

#ifdef DUAL_X_CARRIAGE

  #define DXC_FULL_CONTROL_MODE 0
  #define DXC_AUTO_PARK_MODE    1
  #define DXC_DUPLICATION_MODE  2

  static int dual_x_carriage_mode = DEFAULT_DUAL_X_CARRIAGE_MODE;

  static float x_home_pos(int extruder) {
    if (extruder == 0)
      return base_home_pos(X_AXIS) + home_offset[X_AXIS];
    else
      // In dual carriage mode the extruder offset provides an override of the
      // second X-carriage offset when homed - otherwise X2_HOME_POS is used.
      // This allow soft recalibration of the second extruder offset position without firmware reflash
      // (through the M218 command).
      return (extruder_offset[X_AXIS][1] > 0) ? extruder_offset[X_AXIS][1] : X2_HOME_POS;
  }

  static int x_home_dir(int extruder) {
    return (extruder == 0) ? X_HOME_DIR : X2_HOME_DIR;
  }

  static float inactive_extruder_x_pos = X2_MAX_POS; // used in mode 0 & 1
  static bool active_extruder_parked = false; // used in mode 1 & 2
  static float raised_parked_position[NUM_AXIS]; // used in mode 1
  static millis_t delayed_move_time = 0; // used in mode 1
  static float duplicate_extruder_x_offset = DEFAULT_DUPLICATION_X_OFFSET; // used in mode 2
  static float duplicate_extruder_temp_offset = 0; // used in mode 2
  bool extruder_duplication_enabled = false; // used in mode 2

#endif //DUAL_X_CARRIAGE

static void axis_is_at_home(AxisEnum axis) {

  #ifdef DUAL_X_CARRIAGE
    if (axis == X_AXIS) {
      if (active_extruder != 0) {
        current_position[X_AXIS] = x_home_pos(active_extruder);
                 min_pos[X_AXIS] = X2_MIN_POS;
                 max_pos[X_AXIS] = max(extruder_offset[X_AXIS][1], X2_MAX_POS);
        return;
      }
      else if (dual_x_carriage_mode == DXC_DUPLICATION_MODE) {
        float xoff = home_offset[X_AXIS];
        current_position[X_AXIS] = base_home_pos(X_AXIS) + xoff;
                 min_pos[X_AXIS] = base_min_pos(X_AXIS) + xoff;
                 max_pos[X_AXIS] = min(base_max_pos(X_AXIS) + xoff, max(extruder_offset[X_AXIS][1], X2_MAX_POS) - duplicate_extruder_x_offset);
        return;
      }
    }
  #endif

  #ifdef SCARA
   
    if (axis == X_AXIS || axis == Y_AXIS) {

      float homeposition[3];
      for (int i = 0; i < 3; i++) homeposition[i] = base_home_pos(i);

      // SERIAL_ECHOPGM("homeposition[x]= "); SERIAL_ECHO(homeposition[0]);
      // SERIAL_ECHOPGM("homeposition[y]= "); SERIAL_ECHOLN(homeposition[1]);
      // Works out real Homeposition angles using inverse kinematics, 
      // and calculates homing offset using forward kinematics
      calculate_delta(homeposition);
     
      // SERIAL_ECHOPGM("base Theta= "); SERIAL_ECHO(delta[X_AXIS]);
      // SERIAL_ECHOPGM(" base Psi+Theta="); SERIAL_ECHOLN(delta[Y_AXIS]);
     
      for (int i = 0; i < 2; i++) delta[i] -= home_offset[i];
     
      // SERIAL_ECHOPGM("addhome X="); SERIAL_ECHO(home_offset[X_AXIS]);
      // SERIAL_ECHOPGM(" addhome Y="); SERIAL_ECHO(home_offset[Y_AXIS]);
      // SERIAL_ECHOPGM(" addhome Theta="); SERIAL_ECHO(delta[X_AXIS]);
      // SERIAL_ECHOPGM(" addhome Psi+Theta="); SERIAL_ECHOLN(delta[Y_AXIS]);
      
      calculate_SCARA_forward_Transform(delta);
     
      // SERIAL_ECHOPGM("Delta X="); SERIAL_ECHO(delta[X_AXIS]);
      // SERIAL_ECHOPGM(" Delta Y="); SERIAL_ECHOLN(delta[Y_AXIS]);
     
      current_position[axis] = delta[axis];
    
      // SCARA home positions are based on configuration since the actual limits are determined by the 
      // inverse kinematic transform.
      min_pos[axis] = base_min_pos(axis); // + (delta[axis] - base_home_pos(axis));
      max_pos[axis] = base_max_pos(axis); // + (delta[axis] - base_home_pos(axis));
    }
    else
  #endif
  {
    current_position[axis] = base_home_pos(axis) + home_offset[axis];
    min_pos[axis] = base_min_pos(axis) + home_offset[axis];
    max_pos[axis] = base_max_pos(axis) + home_offset[axis];

    #if defined(ENABLE_AUTO_BED_LEVELING) && Z_HOME_DIR < 0
      if (axis == Z_AXIS) current_position[Z_AXIS] += zprobe_zoffset;
    #endif
  }
}

/**
 * Some planner shorthand inline functions
 */
inline void set_homing_bump_feedrate(AxisEnum axis) {
  const int homing_bump_divisor[] = HOMING_BUMP_DIVISOR;
  if (homing_bump_divisor[axis] >= 1)
    feedrate = homing_feedrate[axis] / homing_bump_divisor[axis];
  else {
    feedrate = homing_feedrate[axis] / 10;
    SERIAL_ECHOLN("Warning: The Homing Bump Feedrate Divisor cannot be less than 1");
  }
}
inline void line_to_current_position() {
  plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], feedrate/60, active_extruder);
}
inline void line_to_z(float zPosition) {
  plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS], feedrate/60, active_extruder);
}
inline void line_to_destination(float mm_m) {
  plan_buffer_line(destination[X_AXIS], destination[Y_AXIS], destination[Z_AXIS], destination[E_AXIS], mm_m/60, active_extruder);
}
inline void line_to_destination() {
  line_to_destination(feedrate);
}
inline void sync_plan_position() {
  plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS]);
}
#if defined(DELTA) || defined(SCARA)
  inline void sync_plan_position_delta() {
    calculate_delta(current_position);
    plan_set_position(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], current_position[E_AXIS]);
  }
#endif
inline void set_current_to_destination() { memcpy(current_position, destination, sizeof(current_position)); }
inline void set_destination_to_current() { memcpy(destination, current_position, sizeof(destination)); }

static void setup_for_endstop_move() {
  saved_feedrate = feedrate;
  saved_feedrate_multiplier = feedrate_multiplier;
  feedrate_multiplier = 100;
  refresh_cmd_timeout();
  enable_endstops(true);
}

#ifdef ENABLE_AUTO_BED_LEVELING

  #ifdef DELTA
    /**
     * Calculate delta, start a line, and set current_position to destination
     */
    void prepare_move_raw() {
      refresh_cmd_timeout();
      calculate_delta(destination);
      plan_buffer_line(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], destination[E_AXIS], (feedrate/60)*(feedrate_multiplier/100.0), active_extruder);
      set_current_to_destination();
    }
  #endif

  #ifdef AUTO_BED_LEVELING_GRID

    #ifndef DELTA

      static void set_bed_level_equation_lsq(double *plane_equation_coefficients) {
        vector_3 planeNormal = vector_3(-plane_equation_coefficients[0], -plane_equation_coefficients[1], 1);
        planeNormal.debug("planeNormal");
        plan_bed_level_matrix = matrix_3x3::create_look_at(planeNormal);
        //bedLevel.debug("bedLevel");

        //plan_bed_level_matrix.debug("bed level before");
        //vector_3 uncorrected_position = plan_get_position_mm();
        //uncorrected_position.debug("position before");

        vector_3 corrected_position = plan_get_position();
        //corrected_position.debug("position after");
        current_position[X_AXIS] = corrected_position.x;
        current_position[Y_AXIS] = corrected_position.y;
        current_position[Z_AXIS] = corrected_position.z;

        sync_plan_position();
      }

    #endif // !DELTA

  #else // !AUTO_BED_LEVELING_GRID

    static void set_bed_level_equation_3pts(float z_at_pt_1, float z_at_pt_2, float z_at_pt_3) {

      plan_bed_level_matrix.set_to_identity();

      vector_3 pt1 = vector_3(ABL_PROBE_PT_1_X, ABL_PROBE_PT_1_Y, z_at_pt_1);
      vector_3 pt2 = vector_3(ABL_PROBE_PT_2_X, ABL_PROBE_PT_2_Y, z_at_pt_2);
      vector_3 pt3 = vector_3(ABL_PROBE_PT_3_X, ABL_PROBE_PT_3_Y, z_at_pt_3);
      vector_3 planeNormal = vector_3::cross(pt1 - pt2, pt3 - pt2).get_normal();

      if (planeNormal.z < 0) {
        planeNormal.x = -planeNormal.x;
        planeNormal.y = -planeNormal.y;
        planeNormal.z = -planeNormal.z;
      }

      plan_bed_level_matrix = matrix_3x3::create_look_at(planeNormal);

      vector_3 corrected_position = plan_get_position();
      current_position[X_AXIS] = corrected_position.x;
      current_position[Y_AXIS] = corrected_position.y;
      current_position[Z_AXIS] = corrected_position.z;

      sync_plan_position();
    }

  #endif // !AUTO_BED_LEVELING_GRID

  static void run_z_probe() {

    #ifdef DELTA
    
      float start_z = current_position[Z_AXIS];
      long start_steps = st_get_position(Z_AXIS);
    
      // move down slowly until you find the bed
      feedrate = homing_feedrate[Z_AXIS] / 4;
      destination[Z_AXIS] = -10;
      prepare_move_raw(); // this will also set_current_to_destination
      st_synchronize();
      endstops_hit_on_purpose(); // clear endstop hit flags
      
      // we have to let the planner know where we are right now as it is not where we said to go.
      long stop_steps = st_get_position(Z_AXIS);
      float mm = start_z - float(start_steps - stop_steps) / axis_steps_per_unit[Z_AXIS];
      current_position[Z_AXIS] = mm;
      sync_plan_position_delta();
      
    #else // !DELTA

      plan_bed_level_matrix.set_to_identity();
      feedrate = homing_feedrate[Z_AXIS];

      // Move down until the probe (or endstop?) is triggered
      float zPosition = -10;
      line_to_z(zPosition);
      st_synchronize();

      // Tell the planner where we ended up - Get this from the stepper handler
      zPosition = st_get_position_mm(Z_AXIS);
      plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], zPosition, current_position[E_AXIS]);

      // move up the retract distance
      zPosition += home_bump_mm(Z_AXIS);
      line_to_z(zPosition);
      st_synchronize();
      endstops_hit_on_purpose(); // clear endstop hit flags

      // move back down slowly to find bed
      set_homing_bump_feedrate(Z_AXIS);

      zPosition -= home_bump_mm(Z_AXIS) * 2;
      line_to_z(zPosition);
      st_synchronize();
      endstops_hit_on_purpose(); // clear endstop hit flags

      // Get the current stepper position after bumping an endstop
      current_position[Z_AXIS] = st_get_position_mm(Z_AXIS);
      sync_plan_position();
      
    #endif // !DELTA
  }

  /**
   *  Plan a move to (X, Y, Z) and set the current_position
   *  The final current_position may not be the one that was requested
   */
  static void do_blocking_move_to(float x, float y, float z) {
    float oldFeedRate = feedrate;

    #ifdef DELTA

      feedrate = XY_TRAVEL_SPEED;
      
      destination[X_AXIS] = x;
      destination[Y_AXIS] = y;
      destination[Z_AXIS] = z;
      prepare_move_raw(); // this will also set_current_to_destination
      st_synchronize();

    #else

      feedrate = homing_feedrate[Z_AXIS];

      current_position[Z_AXIS] = z;
      line_to_current_position();
      st_synchronize();

      feedrate = xy_travel_speed;

      current_position[X_AXIS] = x;
      current_position[Y_AXIS] = y;
      line_to_current_position();
      st_synchronize();

    #endif

    feedrate = oldFeedRate;
  }

  static void clean_up_after_endstop_move() {
    #ifdef ENDSTOPS_ONLY_FOR_HOMING
      enable_endstops(false);
    #endif
    feedrate = saved_feedrate;
    feedrate_multiplier = saved_feedrate_multiplier;
    refresh_cmd_timeout();
  }

  static void deploy_z_probe() {

    #ifdef SERVO_ENDSTOPS

      // Engage Z Servo endstop if enabled
      if (servo_endstops[Z_AXIS] >= 0) {
        Servo *srv = &servo[servo_endstops[Z_AXIS]];
        #if SERVO_LEVELING
          srv->attach(0);
        #endif
        srv->write(servo_endstop_angles[Z_AXIS * 2]);
        #if SERVO_LEVELING
          delay(PROBE_SERVO_DEACTIVATION_DELAY);
          srv->detach();
        #endif
      }

    #elif defined(Z_PROBE_ALLEN_KEY)

      feedrate = homing_feedrate[X_AXIS];

      // Move to the start position to initiate deployment
      destination[X_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_X;
      destination[Y_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_Y;
      destination[Z_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_Z;
      prepare_move_raw(); // this will also set_current_to_destination

      // Home X to touch the belt
      feedrate = homing_feedrate[X_AXIS]/10;
      destination[X_AXIS] = 0;
      prepare_move_raw(); // this will also set_current_to_destination
      
      // Home Y for safety
      feedrate = homing_feedrate[X_AXIS]/2;
      destination[Y_AXIS] = 0;
      prepare_move_raw(); // this will also set_current_to_destination
      
      st_synchronize();

      #ifdef Z_PROBE_ENDSTOP
        bool z_probe_endstop = (READ(Z_PROBE_PIN) != Z_PROBE_ENDSTOP_INVERTING);
        if (z_probe_endstop)
      #else
        bool z_min_endstop = (READ(Z_MIN_PIN) != Z_MIN_ENDSTOP_INVERTING);
        if (z_min_endstop)
      #endif
        {
          if (IsRunning()) {
            SERIAL_ERROR_START;
            SERIAL_ERRORLNPGM("Z-Probe failed to engage!");
            LCD_ALERTMESSAGEPGM("Err: ZPROBE");
          }
          Stop();
        }

    #endif // Z_PROBE_ALLEN_KEY

  }

  static void stow_z_probe(bool doRaise=true) {

    #ifdef SERVO_ENDSTOPS

      // Retract Z Servo endstop if enabled
      if (servo_endstops[Z_AXIS] >= 0) {

        #if Z_RAISE_AFTER_PROBING > 0
          if (doRaise) {
            do_blocking_move_to(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS] + Z_RAISE_AFTER_PROBING); // this also updates current_position
            st_synchronize();
          }
        #endif

        // Change the Z servo angle
        Servo *srv = &servo[servo_endstops[Z_AXIS]];
        #if SERVO_LEVELING
          srv->attach(0);
        #endif
        srv->write(servo_endstop_angles[Z_AXIS * 2 + 1]);
        #if SERVO_LEVELING
          delay(PROBE_SERVO_DEACTIVATION_DELAY);
          srv->detach();
        #endif
      }

    #elif defined(Z_PROBE_ALLEN_KEY)

      // Move up for safety
      feedrate = homing_feedrate[X_AXIS];
      destination[Z_AXIS] = current_position[Z_AXIS] + Z_RAISE_AFTER_PROBING;
      prepare_move_raw(); // this will also set_current_to_destination

      // Move to the start position to initiate retraction
      destination[X_AXIS] = Z_PROBE_ALLEN_KEY_STOW_X;
      destination[Y_AXIS] = Z_PROBE_ALLEN_KEY_STOW_Y;
      destination[Z_AXIS] = Z_PROBE_ALLEN_KEY_STOW_Z;
      prepare_move_raw(); // this will also set_current_to_destination

      // Move the nozzle down to push the probe into retracted position
      feedrate = homing_feedrate[Z_AXIS]/10;
      destination[Z_AXIS] = current_position[Z_AXIS] - Z_PROBE_ALLEN_KEY_STOW_DEPTH;
      prepare_move_raw(); // this will also set_current_to_destination
      
      // Move up for safety
      feedrate = homing_feedrate[Z_AXIS]/2;
      destination[Z_AXIS] = current_position[Z_AXIS] + Z_PROBE_ALLEN_KEY_STOW_DEPTH * 2;
      prepare_move_raw(); // this will also set_current_to_destination
      
      // Home XY for safety
      feedrate = homing_feedrate[X_AXIS]/2;
      destination[X_AXIS] = 0;
      destination[Y_AXIS] = 0;
      prepare_move_raw(); // this will also set_current_to_destination
      
      st_synchronize();

      #ifdef Z_PROBE_ENDSTOP
        bool z_probe_endstop = (READ(Z_PROBE_PIN) != Z_PROBE_ENDSTOP_INVERTING);
        if (!z_probe_endstop)
      #else
        bool z_min_endstop = (READ(Z_MIN_PIN) != Z_MIN_ENDSTOP_INVERTING);
        if (!z_min_endstop)
      #endif
        {
          if (IsRunning()) {
            SERIAL_ERROR_START;
            SERIAL_ERRORLNPGM("Z-Probe failed to retract!");
            LCD_ALERTMESSAGEPGM("Err: ZPROBE");
          }
          Stop();
        }

    #endif // Z_PROBE_ALLEN_KEY

  }

  enum ProbeAction {
    ProbeStay          = 0,
    ProbeDeploy        = BIT(0),
    ProbeStow          = BIT(1),
    ProbeDeployAndStow = (ProbeDeploy | ProbeStow)
  };

  // Probe bed height at position (x,y), returns the measured z value
  static float probe_pt(float x, float y, float z_before, ProbeAction probe_action=ProbeDeployAndStow, int verbose_level=1) {
    // move to right place
    do_blocking_move_to(current_position[X_AXIS], current_position[Y_AXIS], z_before); // this also updates current_position
    do_blocking_move_to(x - X_PROBE_OFFSET_FROM_EXTRUDER, y - Y_PROBE_OFFSET_FROM_EXTRUDER, current_position[Z_AXIS]); // this also updates current_position

    #if !defined(Z_PROBE_SLED) && !defined(Z_PROBE_ALLEN_KEY)
      if (probe_action & ProbeDeploy) deploy_z_probe();
    #endif

    run_z_probe();
    float measured_z = current_position[Z_AXIS];

    #if Z_RAISE_BETWEEN_PROBINGS > 0
      if (probe_action == ProbeStay) {
        do_blocking_move_to(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS] + Z_RAISE_BETWEEN_PROBINGS); // this also updates current_position
        st_synchronize();
      }
    #endif

    #if !defined(Z_PROBE_SLED) && !defined(Z_PROBE_ALLEN_KEY)
      if (probe_action & ProbeStow) stow_z_probe();
    #endif

    if (verbose_level > 2) {
      SERIAL_PROTOCOLPGM("Bed X: ");
      SERIAL_PROTOCOL_F(x, 3);
      SERIAL_PROTOCOLPGM(" Y: ");
      SERIAL_PROTOCOL_F(y, 3);
      SERIAL_PROTOCOLPGM(" Z: ");
      SERIAL_PROTOCOL_F(measured_z, 3);
      SERIAL_EOL;
    }
    return measured_z;
  }

  #ifdef DELTA

    /**
     * All DELTA leveling in the Marlin uses NONLINEAR_BED_LEVELING
     */

    static void extrapolate_one_point(int x, int y, int xdir, int ydir) {
      if (bed_level[x][y] != 0.0) {
        return;  // Don't overwrite good values.
      }
      float a = 2*bed_level[x+xdir][y] - bed_level[x+xdir*2][y];  // Left to right.
      float b = 2*bed_level[x][y+ydir] - bed_level[x][y+ydir*2];  // Front to back.
      float c = 2*bed_level[x+xdir][y+ydir] - bed_level[x+xdir*2][y+ydir*2];  // Diagonal.
      float median = c;  // Median is robust (ignores outliers).
      if (a < b) {
        if (b < c) median = b;
        if (c < a) median = a;
      } else {  // b <= a
        if (c < b) median = b;
        if (a < c) median = a;
      }
      bed_level[x][y] = median;
    }

    // Fill in the unprobed points (corners of circular print surface)
    // using linear extrapolation, away from the center.
    static void extrapolate_unprobed_bed_level() {
      int half = (AUTO_BED_LEVELING_GRID_POINTS-1)/2;
      for (int y = 0; y <= half; y++) {
        for (int x = 0; x <= half; x++) {
          if (x + y < 3) continue;
          extrapolate_one_point(half-x, half-y, x>1?+1:0, y>1?+1:0);
          extrapolate_one_point(half+x, half-y, x>1?-1:0, y>1?+1:0);
          extrapolate_one_point(half-x, half+y, x>1?+1:0, y>1?-1:0);
          extrapolate_one_point(half+x, half+y, x>1?-1:0, y>1?-1:0);
        }
      }
    }

    // Print calibration results for plotting or manual frame adjustment.
    static void print_bed_level() {
      for (int y = 0; y < AUTO_BED_LEVELING_GRID_POINTS; y++) {
        for (int x = 0; x < AUTO_BED_LEVELING_GRID_POINTS; x++) {
          SERIAL_PROTOCOL_F(bed_level[x][y], 2);
          SERIAL_PROTOCOLCHAR(' ');
        }
        SERIAL_EOL;
      }
    }

    // Reset calibration results to zero.
    void reset_bed_level() {
      for (int y = 0; y < AUTO_BED_LEVELING_GRID_POINTS; y++) {
        for (int x = 0; x < AUTO_BED_LEVELING_GRID_POINTS; x++) {
          bed_level[x][y] = 0.0;
        }
      }
    }

  #endif // DELTA

#endif // ENABLE_AUTO_BED_LEVELING


#ifdef Z_PROBE_SLED

  #ifndef SLED_DOCKING_OFFSET
    #define SLED_DOCKING_OFFSET 0
  #endif

  /**
   * Method to dock/undock a sled designed by Charles Bell.
   *
   * dock[in]     If true, move to MAX_X and engage the electromagnet
   * offset[in]   The additional distance to move to adjust docking location
   */
  static void dock_sled(bool dock, int offset=0) {
    if (!axis_known_position[X_AXIS] || !axis_known_position[Y_AXIS]) {
      LCD_MESSAGEPGM(MSG_POSITION_UNKNOWN);
      SERIAL_ECHO_START;
      SERIAL_ECHOLNPGM(MSG_POSITION_UNKNOWN);
      return;
    }

    if (dock) {
      float oldXpos = current_position[X_AXIS]; // save x position
      do_blocking_move_to(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS] + Z_RAISE_AFTER_PROBING); // rise Z   
      do_blocking_move_to(X_MAX_POS + SLED_DOCKING_OFFSET + offset - 1, current_position[Y_AXIS], current_position[Z_AXIS]);  // Dock sled a bit closer to ensure proper capturing                                                                                                                           
      digitalWrite(SLED_PIN, LOW); // turn off magnet
      do_blocking_move_to(oldXpos, current_position[Y_AXIS], current_position[Z_AXIS]); // return to position before docking
    } else {
      float oldXpos = current_position[X_AXIS]; // save x position
      float z_loc = current_position[Z_AXIS];
      if (z_loc < Z_RAISE_BEFORE_PROBING + 5) z_loc = Z_RAISE_BEFORE_PROBING;
      do_blocking_move_to(X_MAX_POS + SLED_DOCKING_OFFSET + offset, current_position[Y_AXIS], z_loc); // this also updates current_position
      digitalWrite(SLED_PIN, HIGH); // turn on magnet
      do_blocking_move_to(oldXpos, current_position[Y_AXIS], current_position[Z_AXIS]); // return to position before docking
    }
  }

#endif // Z_PROBE_SLED



/**
 * Home an individual axis
 */

#define HOMEAXIS(LETTER) homeaxis(LETTER##_AXIS)

static void homeaxis(AxisEnum axis) {
  #define HOMEAXIS_DO(LETTER) \
    ((LETTER##_MIN_PIN > -1 && LETTER##_HOME_DIR==-1) || (LETTER##_MAX_PIN > -1 && LETTER##_HOME_DIR==1))

  if (axis == X_AXIS ? HOMEAXIS_DO(X) : axis == Y_AXIS ? HOMEAXIS_DO(Y) : axis == Z_AXIS ? HOMEAXIS_DO(Z) : 0) {

    int axis_home_dir =
      #ifdef DUAL_X_CARRIAGE
        (axis == X_AXIS) ? x_home_dir(active_extruder) :
      #endif
      home_dir(axis);

    // Set the axis position as setup for the move
    current_position[axis] = 0;
    sync_plan_position();

    #ifdef Z_PROBE_SLED
      // Get Probe
      if (axis == Z_AXIS) {
        if (axis_home_dir < 0) dock_sled(false);
      }
    #endif
    
    #if SERVO_LEVELING && !defined(Z_PROBE_SLED)

      // Deploy a probe if there is one, and homing towards the bed
      if (axis == Z_AXIS) {
        if (axis_home_dir < 0) deploy_z_probe();
      }

    #endif

    #ifdef SERVO_ENDSTOPS
      if (axis != Z_AXIS) {
        // Engage Servo endstop if enabled
        if (servo_endstops[axis] > -1)
          servo[servo_endstops[axis]].write(servo_endstop_angles[axis * 2]);
      }
    #endif

    // Set a flag for Z motor locking
    #ifdef Z_DUAL_ENDSTOPS
      if (axis == Z_AXIS) In_Homing_Process(true);
    #endif

    // Move towards the endstop until an endstop is triggered
    destination[axis] = 1.5 * max_length(axis) * axis_home_dir;
    feedrate = homing_feedrate[axis];
    line_to_destination();
    st_synchronize();

    // Set the axis position as setup for the move
    current_position[axis] = 0;
    sync_plan_position();

    enable_endstops(false); // Disable endstops while moving away

    // Move away from the endstop by the axis HOME_BUMP_MM
    destination[axis] = -home_bump_mm(axis) * axis_home_dir;
    line_to_destination();
    st_synchronize();

    enable_endstops(true); // Enable endstops for next homing move

    // Slow down the feedrate for the next move
    set_homing_bump_feedrate(axis);

    // Move slowly towards the endstop until triggered
    destination[axis] = 2 * home_bump_mm(axis) * axis_home_dir;
    line_to_destination();
    st_synchronize();

    #ifdef Z_DUAL_ENDSTOPS
      if (axis == Z_AXIS) {
        float adj = fabs(z_endstop_adj);
        bool lockZ1;
        if (axis_home_dir > 0) {
          adj = -adj;
          lockZ1 = (z_endstop_adj > 0);
        }
        else
          lockZ1 = (z_endstop_adj < 0);

        if (lockZ1) Lock_z_motor(true); else Lock_z2_motor(true);
        sync_plan_position();

        // Move to the adjusted endstop height
        feedrate = homing_feedrate[axis];
        destination[Z_AXIS] = adj;
        line_to_destination();
        st_synchronize();

        if (lockZ1) Lock_z_motor(false); else Lock_z2_motor(false);
        In_Homing_Process(false);
      } // Z_AXIS
    #endif

    #ifdef DELTA
      // retrace by the amount specified in endstop_adj
      if (endstop_adj[axis] * axis_home_dir < 0) {
        enable_endstops(false); // Disable endstops while moving away
        sync_plan_position();
        destination[axis] = endstop_adj[axis];
        line_to_destination();
        st_synchronize();
        enable_endstops(true); // Enable endstops for next homing move
      }
    #endif

    // Set the axis position to its home position (plus home offsets)
    axis_is_at_home(axis);
    sync_plan_position();

    destination[axis] = current_position[axis];
    feedrate = 0.0;
    endstops_hit_on_purpose(); // clear endstop hit flags
    axis_known_position[axis] = true;

    #ifdef Z_PROBE_SLED
    // bring probe back
      if (axis == Z_AXIS) {
        if (axis_home_dir < 0) dock_sled(true);
      } 
    #endif

    #if SERVO_LEVELING && !defined(Z_PROBE_SLED)

      // Deploy a probe if there is one, and homing towards the bed
      if (axis == Z_AXIS) {
        if (axis_home_dir < 0) stow_z_probe();
      }
      else

    #endif

    #ifdef SERVO_ENDSTOPS
      {
        // Retract Servo endstop if enabled
        if (servo_endstops[axis] > -1)
          servo[servo_endstops[axis]].write(servo_endstop_angles[axis * 2 + 1]);
      }
    #endif

  }
}

#ifdef FWRETRACT

  void retract(bool retracting, bool swapping=false) {

    if (retracting == retracted[active_extruder]) return;

    float oldFeedrate = feedrate;

    set_destination_to_current();

    if (retracting) {

      feedrate = retract_feedrate * 60;
      current_position[E_AXIS] += (swapping ? retract_length_swap : retract_length) / volumetric_multiplier[active_extruder];
      plan_set_e_position(current_position[E_AXIS]);
      prepare_move();

      if (retract_zlift > 0.01) {
        current_position[Z_AXIS] -= retract_zlift;
        #ifdef DELTA
          sync_plan_position_delta();
        #else
          sync_plan_position();
        #endif
        prepare_move();
      }
    }
    else {

      if (retract_zlift > 0.01) {
        current_position[Z_AXIS] += retract_zlift;
        #ifdef DELTA
          sync_plan_position_delta();
        #else
          sync_plan_position();
        #endif
        //prepare_move();
      }

      feedrate = retract_recover_feedrate * 60;
      float move_e = swapping ? retract_length_swap + retract_recover_length_swap : retract_length + retract_recover_length;
      current_position[E_AXIS] -= move_e / volumetric_multiplier[active_extruder];
      plan_set_e_position(current_position[E_AXIS]);
      prepare_move();
    }

    feedrate = oldFeedrate;
    retracted[active_extruder] = retracting;

  } // retract()

#endif // FWRETRACT

/**
 *
 * G-Code Handler functions
 *
 */

/**
 * Set XYZE destination and feedrate from the current GCode command
 *
 *  - Set destination from included axis codes
 *  - Set to current for missing axis codes
 *  - Set the feedrate, if included
 */
void gcode_get_destination() {
  for (int i = 0; i < NUM_AXIS; i++) {
    if (code_seen(axis_codes[i]))
      destination[i] = code_value() + (axis_relative_modes[i] || relative_mode ? current_position[i] : 0);
    else
      destination[i] = current_position[i];
  }
  if (code_seen('F')) {
    float next_feedrate = code_value();
    if (next_feedrate > 0.0) feedrate = next_feedrate;
  }
}

/**
 * G0, G1: Coordinated movement of X Y Z E axes
 */
inline void gcode_G0_G1() {
  if (IsRunning()) {
    gcode_get_destination(); // For X Y Z E F

    #ifdef FWRETRACT

      if (autoretract_enabled && !(code_seen('X') || code_seen('Y') || code_seen('Z')) && code_seen('E')) {
        float echange = destination[E_AXIS] - current_position[E_AXIS];
        // Is this move an attempt to retract or recover?
        if ((echange < -MIN_RETRACT && !retracted[active_extruder]) || (echange > MIN_RETRACT && retracted[active_extruder])) {
          current_position[E_AXIS] = destination[E_AXIS]; // hide the slicer-generated retract/recover from calculations
          plan_set_e_position(current_position[E_AXIS]);  // AND from the planner
          retract(!retracted[active_extruder]);
          return;
        }
      }

    #endif //FWRETRACT

    prepare_move();
  }
}

/**
 * Plan an arc in 2 dimensions
 *
 * The arc is approximated by generating many small linear segments.
 * The length of each segment is configured in MM_PER_ARC_SEGMENT (Default 1mm)
 * Arcs should only be made relatively large (over 5mm), as larger arcs with
 * larger segments will tend to be more efficient. Your slicer should have
 * options for G2/G3 arc generation. In future these options may be GCode tunable.
 */
void plan_arc(
  float *target,    // Destination position
  float *offset,    // Center of rotation relative to current_position
  uint8_t clockwise // Clockwise?
) {

  float radius = hypot(offset[X_AXIS], offset[Y_AXIS]),
        center_axis0 = current_position[X_AXIS] + offset[X_AXIS],
        center_axis1 = current_position[Y_AXIS] + offset[Y_AXIS],
        linear_travel = target[Z_AXIS] - current_position[Z_AXIS],
        extruder_travel = target[E_AXIS] - current_position[E_AXIS],
        r_axis0 = -offset[X_AXIS],  // Radius vector from center to current location
        r_axis1 = -offset[Y_AXIS],
        rt_axis0 = target[X_AXIS] - center_axis0,
        rt_axis1 = target[Y_AXIS] - center_axis1;
  
  // CCW angle of rotation between position and target from the circle center. Only one atan2() trig computation required.
  float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
  if (angular_travel < 0) { angular_travel += RADIANS(360); }
  if (clockwise) { angular_travel -= RADIANS(360); }
  
  // Make a circle if the angular rotation is 0
  if (current_position[X_AXIS] == target[X_AXIS] && current_position[Y_AXIS] == target[Y_AXIS] && angular_travel == 0)
    angular_travel += RADIANS(360);
  
  float mm_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
  if (mm_of_travel < 0.001) { return; }
  uint16_t segments = floor(mm_of_travel / MM_PER_ARC_SEGMENT);
  if (segments == 0) segments = 1;
  
  float theta_per_segment = angular_travel/segments;
  float linear_per_segment = linear_travel/segments;
  float extruder_per_segment = extruder_travel/segments;
  
  /* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector,
     and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
         r_T = [cos(phi) -sin(phi);
                sin(phi)  cos(phi] * r ;
     
     For arc generation, the center of the circle is the axis of rotation and the radius vector is 
     defined from the circle center to the initial position. Each line segment is formed by successive
     vector rotations. This requires only two cos() and sin() computations to form the rotation
     matrix for the duration of the entire arc. Error may accumulate from numerical round-off, since
     all double numbers are single precision on the Arduino. (True double precision will not have
     round off issues for CNC applications.) Single precision error can accumulate to be greater than
     tool precision in some cases. Therefore, arc path correction is implemented. 

     Small angle approximation may be used to reduce computation overhead further. This approximation
     holds for everything, but very small circles and large MM_PER_ARC_SEGMENT values. In other words,
     theta_per_segment would need to be greater than 0.1 rad and N_ARC_CORRECTION would need to be large
     to cause an appreciable drift error. N_ARC_CORRECTION~=25 is more than small enough to correct for 
     numerical drift error. N_ARC_CORRECTION may be on the order a hundred(s) before error becomes an
     issue for CNC machines with the single precision Arduino calculations.
     
     This approximation also allows plan_arc to immediately insert a line segment into the planner 
     without the initial overhead of computing cos() or sin(). By the time the arc needs to be applied
     a correction, the planner should have caught up to the lag caused by the initial plan_arc overhead. 
     This is important when there are successive arc motions. 
  */
  // Vector rotation matrix values
  float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
  float sin_T = theta_per_segment;
  
  float arc_target[4];
  float sin_Ti;
  float cos_Ti;
  float r_axisi;
  uint16_t i;
  int8_t count = 0;

  // Initialize the linear axis
  arc_target[Z_AXIS] = current_position[Z_AXIS];
  
  // Initialize the extruder axis
  arc_target[E_AXIS] = current_position[E_AXIS];

  float feed_rate = feedrate*feedrate_multiplier/60/100.0;

  for (i = 1; i < segments; i++) { // Increment (segments-1)

    if (count < N_ARC_CORRECTION) {
      // Apply vector rotation matrix to previous r_axis0 / 1
      r_axisi = r_axis0*sin_T + r_axis1*cos_T;
      r_axis0 = r_axis0*cos_T - r_axis1*sin_T;
      r_axis1 = r_axisi;
      count++;
    }
    else {
      // Arc correction to radius vector. Computed only every N_ARC_CORRECTION increments.
      // Compute exact location by applying transformation matrix from initial radius vector(=-offset).
      cos_Ti = cos(i*theta_per_segment);
      sin_Ti = sin(i*theta_per_segment);
      r_axis0 = -offset[X_AXIS]*cos_Ti + offset[Y_AXIS]*sin_Ti;
      r_axis1 = -offset[X_AXIS]*sin_Ti - offset[Y_AXIS]*cos_Ti;
      count = 0;
    }

    // Update arc_target location
    arc_target[X_AXIS] = center_axis0 + r_axis0;
    arc_target[Y_AXIS] = center_axis1 + r_axis1;
    arc_target[Z_AXIS] += linear_per_segment;
    arc_target[E_AXIS] += extruder_per_segment;

    clamp_to_software_endstops(arc_target);
    plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], arc_target[E_AXIS], feed_rate, active_extruder);
  }
  // Ensure last segment arrives at target location.
  plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], feed_rate, active_extruder);

  // As far as the parser is concerned, the position is now == target. In reality the
  // motion control system might still be processing the action and the real tool position
  // in any intermediate location.
  set_current_to_destination();
}

/**
 * G2: Clockwise Arc
 * G3: Counterclockwise Arc
 */
inline void gcode_G2_G3(bool clockwise) {
  if (IsRunning()) {

    #ifdef SF_ARC_FIX
      bool relative_mode_backup = relative_mode;
      relative_mode = true;
    #endif

    gcode_get_destination();

    #ifdef SF_ARC_FIX
      relative_mode = relative_mode_backup;
    #endif

    // Center of arc as offset from current_position
    float arc_offset[2] = {
      code_seen('I') ? code_value() : 0,
      code_seen('J') ? code_value() : 0
    };

    // Send an arc to the planner
    plan_arc(destination, arc_offset, clockwise);

    refresh_cmd_timeout();
  }
}

/**
 * G4: Dwell S<seconds> or P<milliseconds>
 */
inline void gcode_G4() {
  millis_t codenum = 0;

  if (code_seen('P')) codenum = code_value_long(); // milliseconds to wait
  if (code_seen('S')) codenum = code_value() * 1000; // seconds to wait

  st_synchronize();
  refresh_cmd_timeout();
  codenum += previous_cmd_ms;  // keep track of when we started waiting

  if (!lcd_hasstatus()) LCD_MESSAGEPGM(MSG_DWELL);

  while (millis() < codenum) {
    manage_heater();
    manage_inactivity();
    lcd_update();
  }
}

#ifdef FWRETRACT

  /**
   * G10 - Retract filament according to settings of M207
   * G11 - Recover filament according to settings of M208
   */
  inline void gcode_G10_G11(bool doRetract=false) {
    #if EXTRUDERS > 1
      if (doRetract) {
        retracted_swap[active_extruder] = (code_seen('S') && code_value_short() == 1); // checks for swap retract argument
      }
    #endif
    retract(doRetract
     #if EXTRUDERS > 1
      , retracted_swap[active_extruder]
     #endif
    );
  }

#endif //FWRETRACT

/**
 * G28: Home all axes according to settings
 *
 * Parameters
 *
 *  None  Home to all axes with no parameters.
 *        With QUICK_HOME enabled XY will home together, then Z.
 *
 * Cartesian parameters
 *
 *  X   Home to the X endstop
 *  Y   Home to the Y endstop
 *  Z   Home to the Z endstop
 *
 */
inline void gcode_G28() {

  // Wait for planner moves to finish!
  st_synchronize();

  // For auto bed leveling, clear the level matrix
  #ifdef ENABLE_AUTO_BED_LEVELING
    plan_bed_level_matrix.set_to_identity();
    #ifdef DELTA
      reset_bed_level();
    #endif
  #endif

  // For manual bed leveling deactivate the matrix temporarily
  #ifdef MESH_BED_LEVELING
    uint8_t mbl_was_active = mbl.active;
    mbl.active = 0;
  #endif

  setup_for_endstop_move();

  set_destination_to_current();

  feedrate = 0.0;

  #ifdef DELTA
    // A delta can only safely home all axis at the same time
    // all axis have to home at the same time

    // Pretend the current position is 0,0,0
    for (int i = X_AXIS; i <= Z_AXIS; i++) current_position[i] = 0;
    sync_plan_position();

    // Move all carriages up together until the first endstop is hit.
    for (int i = X_AXIS; i <= Z_AXIS; i++) destination[i] = 3 * Z_MAX_LENGTH;
    feedrate = 1.732 * homing_feedrate[X_AXIS];
    line_to_destination();
    st_synchronize();
    endstops_hit_on_purpose(); // clear endstop hit flags

    // Destination reached
    for (int i = X_AXIS; i <= Z_AXIS; i++) current_position[i] = destination[i];

    // take care of back off and rehome now we are all at the top
    HOMEAXIS(X);
    HOMEAXIS(Y);
    HOMEAXIS(Z);

    sync_plan_position_delta();

  #else // NOT DELTA

    bool  homeX = code_seen(axis_codes[X_AXIS]),
          homeY = code_seen(axis_codes[Y_AXIS]),
          homeZ = code_seen(axis_codes[Z_AXIS]);

    home_all_axis = (!homeX && !homeY && !homeZ) || (homeX && homeY && homeZ);

    if (home_all_axis || homeZ) {

      #if Z_HOME_DIR > 0  // If homing away from BED do Z first

        HOMEAXIS(Z);

      #elif !defined(Z_SAFE_HOMING) && defined(Z_RAISE_BEFORE_HOMING) && Z_RAISE_BEFORE_HOMING > 0

        // Raise Z before homing any other axes
        // (Does this need to be "negative home direction?" Why not just use Z_RAISE_BEFORE_HOMING?)
        destination[Z_AXIS] = -Z_RAISE_BEFORE_HOMING * home_dir(Z_AXIS);
        feedrate = max_feedrate[Z_AXIS] * 60;
        line_to_destination();
        st_synchronize();

      #endif

    } // home_all_axis || homeZ

    #ifdef QUICK_HOME

      if (home_all_axis || (homeX && homeY)) {  // First diagonal move

        current_position[X_AXIS] = current_position[Y_AXIS] = 0;

        #ifdef DUAL_X_CARRIAGE
          int x_axis_home_dir = x_home_dir(active_extruder);
          extruder_duplication_enabled = false;
        #else
          int x_axis_home_dir = home_dir(X_AXIS);
        #endif

        sync_plan_position();

        float mlx = max_length(X_AXIS), mly = max_length(Y_AXIS),
              mlratio = mlx>mly ? mly/mlx : mlx/mly;

        destination[X_AXIS] = 1.5 * mlx * x_axis_home_dir;
        destination[Y_AXIS] = 1.5 * mly * home_dir(Y_AXIS);
        feedrate = min(homing_feedrate[X_AXIS], homing_feedrate[Y_AXIS]) * sqrt(mlratio * mlratio + 1);
        line_to_destination();
        st_synchronize();

        axis_is_at_home(X_AXIS);
        axis_is_at_home(Y_AXIS);
        sync_plan_position();

        destination[X_AXIS] = current_position[X_AXIS];
        destination[Y_AXIS] = current_position[Y_AXIS];
        line_to_destination();
        feedrate = 0.0;
        st_synchronize();
        endstops_hit_on_purpose(); // clear endstop hit flags

        current_position[X_AXIS] = destination[X_AXIS];
        current_position[Y_AXIS] = destination[Y_AXIS];
        #ifndef SCARA
          current_position[Z_AXIS] = destination[Z_AXIS];
        #endif
      }

    #endif // QUICK_HOME

    #ifdef HOME_Y_BEFORE_X
      // Home Y
      if (home_all_axis || homeY) HOMEAXIS(Y);
    #endif

    // Home X
    if (home_all_axis || homeX) {
      #ifdef DUAL_X_CARRIAGE
        int tmp_extruder = active_extruder;
        extruder_duplication_enabled = false;
        active_extruder = !active_extruder;
        HOMEAXIS(X);
        inactive_extruder_x_pos = current_position[X_AXIS];
        active_extruder = tmp_extruder;
        HOMEAXIS(X);
        // reset state used by the different modes
        memcpy(raised_parked_position, current_position, sizeof(raised_parked_position));
        delayed_move_time = 0;
        active_extruder_parked = true;
      #else
        HOMEAXIS(X);
      #endif
    }

    #ifndef HOME_Y_BEFORE_X
      // Home Y
      if (home_all_axis || homeY) HOMEAXIS(Y);
    #endif

    // Home Z last if homing towards the bed
    #if Z_HOME_DIR < 0

      if (home_all_axis || homeZ) {

        #ifdef Z_SAFE_HOMING

          if (home_all_axis) {

            current_position[Z_AXIS] = 0;
            sync_plan_position();

            //
            // Set the probe (or just the nozzle) destination to the safe homing point
            //
            // NOTE: If current_position[X_AXIS] or current_position[Y_AXIS] were set above
            // then this may not work as expected.
            destination[X_AXIS] = round(Z_SAFE_HOMING_X_POINT - X_PROBE_OFFSET_FROM_EXTRUDER);
            destination[Y_AXIS] = round(Z_SAFE_HOMING_Y_POINT - Y_PROBE_OFFSET_FROM_EXTRUDER);
            destination[Z_AXIS] = -Z_RAISE_BEFORE_HOMING * home_dir(Z_AXIS);    // Set destination away from bed
            feedrate = XY_TRAVEL_SPEED;
            // This could potentially move X, Y, Z all together
            line_to_destination();
            st_synchronize();

            // Set current X, Y is the Z_SAFE_HOMING_POINT minus PROBE_OFFSET_FROM_EXTRUDER
            current_position[X_AXIS] = destination[X_AXIS];
            current_position[Y_AXIS] = destination[Y_AXIS];

            // Home the Z axis
            HOMEAXIS(Z);
          }

          else if (homeZ) { // Don't need to Home Z twice

            // Let's see if X and Y are homed
            if (axis_known_position[X_AXIS] && axis_known_position[Y_AXIS]) {

              // Make sure the probe is within the physical limits
              // NOTE: This doesn't necessarily ensure the probe is also within the bed!
              float cpx = current_position[X_AXIS], cpy = current_position[Y_AXIS];
              if (   cpx >= X_MIN_POS - X_PROBE_OFFSET_FROM_EXTRUDER
                  && cpx <= X_MAX_POS - X_PROBE_OFFSET_FROM_EXTRUDER
                  && cpy >= Y_MIN_POS - Y_PROBE_OFFSET_FROM_EXTRUDER
                  && cpy <= Y_MAX_POS - Y_PROBE_OFFSET_FROM_EXTRUDER) {
                // Set the plan current position to X, Y, 0
                current_position[Z_AXIS] = 0;
                plan_set_position(cpx, cpy, 0, current_position[E_AXIS]); // = sync_plan_position

                // Set Z destination away from bed and raise the axis
                // NOTE: This should always just be Z_RAISE_BEFORE_HOMING unless...???
                destination[Z_AXIS] = -Z_RAISE_BEFORE_HOMING * home_dir(Z_AXIS);
                feedrate = max_feedrate[Z_AXIS] * 60;  // feedrate (mm/m) = max_feedrate (mm/s)
                line_to_destination();
                st_synchronize();

                // Home the Z axis
                HOMEAXIS(Z);
              }
              else {
                LCD_MESSAGEPGM(MSG_ZPROBE_OUT);
                SERIAL_ECHO_START;
                SERIAL_ECHOLNPGM(MSG_ZPROBE_OUT);
              }
            }
            else {
              LCD_MESSAGEPGM(MSG_POSITION_UNKNOWN);
              SERIAL_ECHO_START;
              SERIAL_ECHOLNPGM(MSG_POSITION_UNKNOWN);
            }

          } // !home_all_axes && homeZ

        #else // !Z_SAFE_HOMING

          HOMEAXIS(Z);

        #endif // !Z_SAFE_HOMING

      } // home_all_axis || homeZ

    #endif // Z_HOME_DIR < 0

    sync_plan_position();

  #endif // else DELTA

  #ifdef SCARA
    sync_plan_position_delta();
  #endif

  #ifdef ENDSTOPS_ONLY_FOR_HOMING
    enable_endstops(false);
  #endif

  // For manual leveling move back to 0,0
  #ifdef MESH_BED_LEVELING
    if (mbl_was_active) {
      current_position[X_AXIS] = mbl.get_x(0);
      current_position[Y_AXIS] = mbl.get_y(0);
      set_destination_to_current();
      feedrate = homing_feedrate[X_AXIS];
      line_to_destination();
      st_synchronize();
      current_position[Z_AXIS] = MESH_HOME_SEARCH_Z;
      sync_plan_position();
      mbl.active = 1;
    }
  #endif

  feedrate = saved_feedrate;
  feedrate_multiplier = saved_feedrate_multiplier;
  refresh_cmd_timeout();
  endstops_hit_on_purpose(); // clear endstop hit flags
}

#ifdef MESH_BED_LEVELING

  enum MeshLevelingState { MeshReport, MeshStart, MeshNext, MeshSet };

  /**
   * G29: Mesh-based Z-Probe, probes a grid and produces a
   *      mesh to compensate for variable bed height
   *
   * Parameters With MESH_BED_LEVELING:
   *
   *  S0              Produce a mesh report
   *  S1              Start probing mesh points
   *  S2              Probe the next mesh point
   *  S3 Xn Yn Zn.nn  Manually modify a single point
   *
   * The S0 report the points as below
   *
   *  +----> X-axis
   *  |
   *  |
   *  v Y-axis
   *  
   */
  inline void gcode_G29() {

    static int probe_point = -1;
    MeshLevelingState state = code_seen('S') || code_seen('s') ? (MeshLevelingState)code_value_short() : MeshReport;
    if (state < 0 || state > 3) {
      SERIAL_PROTOCOLLNPGM("S out of range (0-3).");
      return;
    }

    int ix, iy;
    float z;

    switch(state) {
      case MeshReport:
        if (mbl.active) {
          SERIAL_PROTOCOLPGM("Num X,Y: ");
          SERIAL_PROTOCOL(MESH_NUM_X_POINTS);
          SERIAL_PROTOCOLCHAR(',');
          SERIAL_PROTOCOL(MESH_NUM_Y_POINTS);
          SERIAL_PROTOCOLPGM("\nZ search height: ");
          SERIAL_PROTOCOL(MESH_HOME_SEARCH_Z);
          SERIAL_PROTOCOLLNPGM("\nMeasured points:");
          for (int y = 0; y < MESH_NUM_Y_POINTS; y++) {
            for (int x = 0; x < MESH_NUM_X_POINTS; x++) {
              SERIAL_PROTOCOLPGM("  ");
              SERIAL_PROTOCOL_F(mbl.z_values[y][x], 5);
            }
            SERIAL_EOL;
          }
        }
        else
          SERIAL_PROTOCOLLNPGM("Mesh bed leveling not active.");
        break;

      case MeshStart:
        mbl.reset();
        probe_point = 0;
        enqueuecommands_P(PSTR("G28\nG29 S2"));
        break;

      case MeshNext:
        if (probe_point < 0) {
          SERIAL_PROTOCOLLNPGM("Start mesh probing with \"G29 S1\" first.");
          return;
        }
        if (probe_point == 0) {
          // Set Z to a positive value before recording the first Z.
          current_position[Z_AXIS] = MESH_HOME_SEARCH_Z;
          sync_plan_position();
        }
        else {
          // For others, save the Z of the previous point, then raise Z again.
          ix = (probe_point - 1) % MESH_NUM_X_POINTS;
          iy = (probe_point - 1) / MESH_NUM_X_POINTS;
          if (iy & 1) ix = (MESH_NUM_X_POINTS - 1) - ix; // zig-zag
          mbl.set_z(ix, iy, current_position[Z_AXIS]);
          current_position[Z_AXIS] = MESH_HOME_SEARCH_Z;
          plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], homing_feedrate[X_AXIS]/60, active_extruder);
          st_synchronize();
        }
        // Is there another point to sample? Move there.
        if (probe_point < MESH_NUM_X_POINTS * MESH_NUM_Y_POINTS) {
          ix = probe_point % MESH_NUM_X_POINTS;
          iy = probe_point / MESH_NUM_X_POINTS;
          if (iy & 1) ix = (MESH_NUM_X_POINTS - 1) - ix; // zig-zag
          current_position[X_AXIS] = mbl.get_x(ix);
          current_position[Y_AXIS] = mbl.get_y(iy);
          plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], homing_feedrate[X_AXIS]/60, active_extruder);
          st_synchronize();
          probe_point++;
        }
        else {
          // After recording the last point, activate the mbl and home
          SERIAL_PROTOCOLLNPGM("Mesh probing done.");
          probe_point = -1;
          mbl.active = 1;
          enqueuecommands_P(PSTR("G28"));
        }
        break;

      case MeshSet:
        if (code_seen('X') || code_seen('x')) {
          ix = code_value_long()-1;
          if (ix < 0 || ix >= MESH_NUM_X_POINTS) {
            SERIAL_PROTOCOLPGM("X out of range (1-" STRINGIFY(MESH_NUM_X_POINTS) ").\n");
            return;
          }
        } else {
            SERIAL_PROTOCOLPGM("X not entered.\n");
            return;
        }
        if (code_seen('Y') || code_seen('y')) {
          iy = code_value_long()-1;
          if (iy < 0 || iy >= MESH_NUM_Y_POINTS) {
            SERIAL_PROTOCOLPGM("Y out of range (1-" STRINGIFY(MESH_NUM_Y_POINTS) ").\n");
            return;
          }
        } else {
            SERIAL_PROTOCOLPGM("Y not entered.\n");
            return;
        }
        if (code_seen('Z') || code_seen('z')) {
          z = code_value();
        } else {
          SERIAL_PROTOCOLPGM("Z not entered.\n");
          return;
        }
        mbl.z_values[iy][ix] = z;

    } // switch(state)
  }

#elif defined(ENABLE_AUTO_BED_LEVELING)

  /**
   * G29: Detailed Z-Probe, probes the bed at 3 or more points.
   *      Will fail if the printer has not been homed with G28.
   *
   * Enhanced G29 Auto Bed Leveling Probe Routine
   * 
   * Parameters With AUTO_BED_LEVELING_GRID:
   *
   *  P  Set the size of the grid that will be probed (P x P points).
   *     Not supported by non-linear delta printer bed leveling.
   *     Example: "G29 P4"
   *
   *  S  Set the XY travel speed between probe points (in mm/min)
   *
   *  D  Dry-Run mode. Just evaluate the bed Topology - Don't apply
   *     or clean the rotation Matrix. Useful to check the topology
   *     after a first run of G29.
   *
   *  V  Set the verbose level (0-4). Example: "G29 V3"
   *
   *  T  Generate a Bed Topology Report. Example: "G29 P5 T" for a detailed report.
   *     This is useful for manual bed leveling and finding flaws in the bed (to
   *     assist with part placement).
   *     Not supported by non-linear delta printer bed leveling.
   *
   *  F  Set the Front limit of the probing grid
   *  B  Set the Back limit of the probing grid
   *  L  Set the Left limit of the probing grid
   *  R  Set the Right limit of the probing grid
   *
   * Global Parameters:
   *
   * E/e By default G29 will engage the probe, test the bed, then disengage.
   *     Include "E" to engage/disengage the probe for each sample.
   *     There's no extra effect if you have a fixed probe.
   *     Usage: "G29 E" or "G29 e"
   *
   */
  inline void gcode_G29() {

    // Don't allow auto-leveling without homing first
    if (!axis_known_position[X_AXIS] || !axis_known_position[Y_AXIS]) {
      LCD_MESSAGEPGM(MSG_POSITION_UNKNOWN);
      SERIAL_ECHO_START;
      SERIAL_ECHOLNPGM(MSG_POSITION_UNKNOWN);
      return;
    }

    int verbose_level = code_seen('V') || code_seen('v') ? code_value_short() : 1;
    if (verbose_level < 0 || verbose_level > 4) {
      SERIAL_ECHOLNPGM("?(V)erbose Level is implausible (0-4).");
      return;
    }

    bool dryrun = code_seen('D') || code_seen('d'),
         deploy_probe_for_each_reading = code_seen('E') || code_seen('e');

    #ifdef AUTO_BED_LEVELING_GRID

      #ifndef DELTA
        bool do_topography_map = verbose_level > 2 || code_seen('T') || code_seen('t');
      #endif

      if (verbose_level > 0) {
        SERIAL_PROTOCOLPGM("G29 Auto Bed Leveling\n");
        if (dryrun) SERIAL_ECHOLNPGM("Running in DRY-RUN mode");
      }

      int auto_bed_leveling_grid_points = AUTO_BED_LEVELING_GRID_POINTS;
      #ifndef DELTA
        if (code_seen('P')) auto_bed_leveling_grid_points = code_value_short();
        if (auto_bed_leveling_grid_points < 2) {
          SERIAL_PROTOCOLPGM("?Number of probed (P)oints is implausible (2 minimum).\n");
          return;
        }
      #endif

      xy_travel_speed = code_seen('S') ? code_value_short() : XY_TRAVEL_SPEED;

      int left_probe_bed_position = code_seen('L') ? code_value_short() : LEFT_PROBE_BED_POSITION,
          right_probe_bed_position = code_seen('R') ? code_value_short() : RIGHT_PROBE_BED_POSITION,
          front_probe_bed_position = code_seen('F') ? code_value_short() : FRONT_PROBE_BED_POSITION,
          back_probe_bed_position = code_seen('B') ? code_value_short() : BACK_PROBE_BED_POSITION;

      bool left_out_l = left_probe_bed_position < MIN_PROBE_X,
           left_out = left_out_l || left_probe_bed_position > right_probe_bed_position - MIN_PROBE_EDGE,
           right_out_r = right_probe_bed_position > MAX_PROBE_X,
           right_out = right_out_r || right_probe_bed_position < left_probe_bed_position + MIN_PROBE_EDGE,
           front_out_f = front_probe_bed_position < MIN_PROBE_Y,
           front_out = front_out_f || front_probe_bed_position > back_probe_bed_position - MIN_PROBE_EDGE,
           back_out_b = back_probe_bed_position > MAX_PROBE_Y,
           back_out = back_out_b || back_probe_bed_position < front_probe_bed_position + MIN_PROBE_EDGE;

      if (left_out || right_out || front_out || back_out) {
        if (left_out) {
          SERIAL_PROTOCOLPGM("?Probe (L)eft position out of range.\n");
          left_probe_bed_position = left_out_l ? MIN_PROBE_X : right_probe_bed_position - MIN_PROBE_EDGE;
        }
        if (right_out) {
          SERIAL_PROTOCOLPGM("?Probe (R)ight position out of range.\n");
          right_probe_bed_position = right_out_r ? MAX_PROBE_X : left_probe_bed_position + MIN_PROBE_EDGE;
        }
        if (front_out) {
          SERIAL_PROTOCOLPGM("?Probe (F)ront position out of range.\n");
          front_probe_bed_position = front_out_f ? MIN_PROBE_Y : back_probe_bed_position - MIN_PROBE_EDGE;
        }
        if (back_out) {
          SERIAL_PROTOCOLPGM("?Probe (B)ack position out of range.\n");
          back_probe_bed_position = back_out_b ? MAX_PROBE_Y : front_probe_bed_position + MIN_PROBE_EDGE;
        }
        return;
      }

    #endif // AUTO_BED_LEVELING_GRID

    #ifdef Z_PROBE_SLED
      dock_sled(false); // engage (un-dock) the probe
    #elif defined(Z_PROBE_ALLEN_KEY) //|| defined(SERVO_LEVELING)
      deploy_z_probe();
    #endif

    st_synchronize();

    if (!dryrun) {
      // make sure the bed_level_rotation_matrix is identity or the planner will get it wrong
      plan_bed_level_matrix.set_to_identity();

      #ifdef DELTA
        reset_bed_level();
      #else //!DELTA
        //vector_3 corrected_position = plan_get_position_mm();
        //corrected_position.debug("position before G29");
        vector_3 uncorrected_position = plan_get_position();
        //uncorrected_position.debug("position during G29");
        current_position[X_AXIS] = uncorrected_position.x;
        current_position[Y_AXIS] = uncorrected_position.y;
        current_position[Z_AXIS] = uncorrected_position.z;
        sync_plan_position();
      #endif // !DELTA
    }

    setup_for_endstop_move();

    feedrate = homing_feedrate[Z_AXIS];

    #ifdef AUTO_BED_LEVELING_GRID

      // probe at the points of a lattice grid
      const int xGridSpacing = (right_probe_bed_position - left_probe_bed_position) / (auto_bed_leveling_grid_points - 1),
                yGridSpacing = (back_probe_bed_position - front_probe_bed_position) / (auto_bed_leveling_grid_points - 1);

      #ifdef DELTA
        delta_grid_spacing[0] = xGridSpacing;
        delta_grid_spacing[1] = yGridSpacing;
        float z_offset = Z_PROBE_OFFSET_FROM_EXTRUDER;
        if (code_seen(axis_codes[Z_AXIS])) z_offset += code_value();
      #else // !DELTA
        // solve the plane equation ax + by + d = z
        // A is the matrix with rows [x y 1] for all the probed points
        // B is the vector of the Z positions
        // the normal vector to the plane is formed by the coefficients of the plane equation in the standard form, which is Vx*x+Vy*y+Vz*z+d = 0
        // so Vx = -a Vy = -b Vz = 1 (we want the vector facing towards positive Z

        int abl2 = auto_bed_leveling_grid_points * auto_bed_leveling_grid_points;

        double eqnAMatrix[abl2 * 3], // "A" matrix of the linear system of equations
               eqnBVector[abl2],     // "B" vector of Z points
               mean = 0.0;
      #endif // !DELTA

      int probePointCounter = 0;
      bool zig = true;

      for (int yCount = 0; yCount < auto_bed_leveling_grid_points; yCount++) {
        double yProbe = front_probe_bed_position + yGridSpacing * yCount;
        int xStart, xStop, xInc;

        if (zig) {
          xStart = 0;
          xStop = auto_bed_leveling_grid_points;
          xInc = 1;
        }
        else {
          xStart = auto_bed_leveling_grid_points - 1;
          xStop = -1;
          xInc = -1;
        }

        #ifndef DELTA
          // If do_topography_map is set then don't zig-zag. Just scan in one direction.
          // This gets the probe points in more readable order.
          if (!do_topography_map) zig = !zig;
        #endif

        for (int xCount = xStart; xCount != xStop; xCount += xInc) {
          double xProbe = left_probe_bed_position + xGridSpacing * xCount;

          // raise extruder
          float measured_z,
                z_before = probePointCounter ? Z_RAISE_BETWEEN_PROBINGS + current_position[Z_AXIS] : Z_RAISE_BEFORE_PROBING;

          #ifdef DELTA
            // Avoid probing the corners (outside the round or hexagon print surface) on a delta printer.
            float distance_from_center = sqrt(xProbe*xProbe + yProbe*yProbe);
            if (distance_from_center > DELTA_PROBABLE_RADIUS) continue;
          #endif //DELTA

          ProbeAction act;
          if (deploy_probe_for_each_reading) // G29 E - Stow between probes
            act = ProbeDeployAndStow;
          else if (yCount == 0 && xCount == xStart)
            act = ProbeDeploy;
          else if (yCount == auto_bed_leveling_grid_points - 1 && xCount == xStop - xInc)
            act = ProbeStow;
          else
            act = ProbeStay;

          measured_z = probe_pt(xProbe, yProbe, z_before, act, verbose_level);

          #ifndef DELTA
            mean += measured_z;

            eqnBVector[probePointCounter] = measured_z;
            eqnAMatrix[probePointCounter + 0 * abl2] = xProbe;
            eqnAMatrix[probePointCounter + 1 * abl2] = yProbe;
            eqnAMatrix[probePointCounter + 2 * abl2] = 1;
          #else
            bed_level[xCount][yCount] = measured_z + z_offset;
          #endif

          probePointCounter++;

          manage_heater();
          manage_inactivity();
          lcd_update();

        } //xProbe
      } //yProbe

      clean_up_after_endstop_move();

      #ifdef DELTA

        if (!dryrun) extrapolate_unprobed_bed_level();
        print_bed_level();

      #else // !DELTA

        // solve lsq problem
        double *plane_equation_coefficients = qr_solve(abl2, 3, eqnAMatrix, eqnBVector);

        mean /= abl2;

        if (verbose_level) {
          SERIAL_PROTOCOLPGM("Eqn coefficients: a: ");
          SERIAL_PROTOCOL_F(plane_equation_coefficients[0], 8);
          SERIAL_PROTOCOLPGM(" b: ");
          SERIAL_PROTOCOL_F(plane_equation_coefficients[1], 8);
          SERIAL_PROTOCOLPGM(" d: ");
          SERIAL_PROTOCOL_F(plane_equation_coefficients[2], 8);
          SERIAL_EOL;
          if (verbose_level > 2) {
            SERIAL_PROTOCOLPGM("Mean of sampled points: ");
            SERIAL_PROTOCOL_F(mean, 8);
            SERIAL_EOL;
          }
        }

        // Show the Topography map if enabled
        if (do_topography_map) {

          SERIAL_PROTOCOLPGM(" \nBed Height Topography: \n");
          SERIAL_PROTOCOLPGM("+-----------+\n");
          SERIAL_PROTOCOLPGM("|...Back....|\n");
          SERIAL_PROTOCOLPGM("|Left..Right|\n");
          SERIAL_PROTOCOLPGM("|...Front...|\n");
          SERIAL_PROTOCOLPGM("+-----------+\n");

          for (int yy = auto_bed_leveling_grid_points - 1; yy >= 0; yy--) {
            for (int xx = 0; xx < auto_bed_leveling_grid_points; xx++) {
              int ind = yy * auto_bed_leveling_grid_points + xx;
              float diff = eqnBVector[ind] - mean;
              if (diff >= 0.0)
                SERIAL_PROTOCOLPGM(" +");   // Include + for column alignment
              else
                SERIAL_PROTOCOLCHAR(' ');
              SERIAL_PROTOCOL_F(diff, 5);
            } // xx
            SERIAL_EOL;
          } // yy
          SERIAL_EOL;

        } //do_topography_map


        if (!dryrun) set_bed_level_equation_lsq(plane_equation_coefficients);
        free(plane_equation_coefficients);

      #endif //!DELTA

    #else // !AUTO_BED_LEVELING_GRID

      // Actions for each probe
      ProbeAction p1, p2, p3;
      if (deploy_probe_for_each_reading)
        p1 = p2 = p3 = ProbeDeployAndStow;
      else
        p1 = ProbeDeploy, p2 = ProbeStay, p3 = ProbeStow;

      // Probe at 3 arbitrary points
      float z_at_pt_1 = probe_pt(ABL_PROBE_PT_1_X, ABL_PROBE_PT_1_Y, Z_RAISE_BEFORE_PROBING, p1, verbose_level),
            z_at_pt_2 = probe_pt(ABL_PROBE_PT_2_X, ABL_PROBE_PT_2_Y, current_position[Z_AXIS] + Z_RAISE_BETWEEN_PROBINGS, p2, verbose_level),
            z_at_pt_3 = probe_pt(ABL_PROBE_PT_3_X, ABL_PROBE_PT_3_Y, current_position[Z_AXIS] + Z_RAISE_BETWEEN_PROBINGS, p3, verbose_level);
      clean_up_after_endstop_move();
      if (!dryrun) set_bed_level_equation_3pts(z_at_pt_1, z_at_pt_2, z_at_pt_3);

    #endif // !AUTO_BED_LEVELING_GRID

    #ifndef DELTA
      if (verbose_level > 0)
        plan_bed_level_matrix.debug(" \n\nBed Level Correction Matrix:");

      if (!dryrun) {
        // Correct the Z height difference from z-probe position and hotend tip position.
        // The Z height on homing is measured by Z-Probe, but the probe is quite far from the hotend.
        // When the bed is uneven, this height must be corrected.
        float x_tmp = current_position[X_AXIS] + X_PROBE_OFFSET_FROM_EXTRUDER,
              y_tmp = current_position[Y_AXIS] + Y_PROBE_OFFSET_FROM_EXTRUDER,
              z_tmp = current_position[Z_AXIS],
              real_z = (float)st_get_position(Z_AXIS) / axis_steps_per_unit[Z_AXIS];  //get the real Z (since the auto bed leveling is already correcting the plane)

        apply_rotation_xyz(plan_bed_level_matrix, x_tmp, y_tmp, z_tmp); // Apply the correction sending the probe offset
        current_position[Z_AXIS] += z_tmp - real_z;                     // The difference is added to current position and sent to planner.
        sync_plan_position();
      }
    #endif // !DELTA

    #ifdef Z_PROBE_SLED
      dock_sled(true); // dock the probe
    #elif defined(Z_PROBE_ALLEN_KEY) //|| defined(SERVO_LEVELING)
      stow_z_probe();
    #endif

    #ifdef Z_PROBE_END_SCRIPT
      enqueuecommands_P(PSTR(Z_PROBE_END_SCRIPT));
      st_synchronize();
    #endif
  }

  #ifndef Z_PROBE_SLED

    inline void gcode_G30() {
      deploy_z_probe(); // Engage Z Servo endstop if available
      st_synchronize();
      // TODO: make sure the bed_level_rotation_matrix is identity or the planner will get set incorectly
      setup_for_endstop_move();

      feedrate = homing_feedrate[Z_AXIS];

      run_z_probe();
      SERIAL_PROTOCOLPGM("Bed X: ");
      SERIAL_PROTOCOL(current_position[X_AXIS] + 0.0001);
      SERIAL_PROTOCOLPGM(" Y: ");
      SERIAL_PROTOCOL(current_position[Y_AXIS] + 0.0001);
      SERIAL_PROTOCOLPGM(" Z: ");
      SERIAL_PROTOCOL(current_position[Z_AXIS] + 0.0001);
      SERIAL_EOL;

      clean_up_after_endstop_move();
      stow_z_probe(); // Retract Z Servo endstop if available
    }

  #endif //!Z_PROBE_SLED

#endif //ENABLE_AUTO_BED_LEVELING

/**
 * G92: Set current position to given X Y Z E
 */
inline void gcode_G92() {
  if (!code_seen(axis_codes[E_AXIS]))
    st_synchronize();

  bool didXYZ = false;
  for (int i = 0; i < NUM_AXIS; i++) {
    if (code_seen(axis_codes[i])) {
      float v = current_position[i] = code_value();
      if (i == E_AXIS)
        plan_set_e_position(v);
      else
        didXYZ = true;
    }
  }
  if (didXYZ) {
    #if defined(DELTA) || defined(SCARA)
      sync_plan_position_delta();
    #else
      sync_plan_position();
    #endif
  }
}

#ifdef ULTIPANEL

  /**
   * M0: // M0 - Unconditional stop - Wait for user button press on LCD
   * M1: // M1 - Conditional stop - Wait for user button press on LCD
   */
  inline void gcode_M0_M1() {
    char *src = strchr_pointer + 2;

    millis_t codenum = 0;
    bool hasP = false, hasS = false;
    if (code_seen('P')) {
      codenum = code_value_short(); // milliseconds to wait
      hasP = codenum > 0;
    }
    if (code_seen('S')) {
      codenum = code_value() * 1000; // seconds to wait
      hasS = codenum > 0;
    }
    char* starpos = strchr(src, '*');
    if (starpos != NULL) *(starpos) = '\0';
    while (*src == ' ') ++src;
    if (!hasP && !hasS && *src != '\0')
      lcd_setstatus(src, true);
    else {
      LCD_MESSAGEPGM(MSG_USERWAIT);
      #if defined(LCD_PROGRESS_BAR) && PROGRESS_MSG_EXPIRE > 0
        dontExpireStatus();
      #endif
    }

    lcd_ignore_click();
    st_synchronize();
    refresh_cmd_timeout();
    if (codenum > 0) {
      codenum += previous_cmd_ms;  // keep track of when we started waiting
      while(millis() < codenum && !lcd_clicked()) {
        manage_heater();
        manage_inactivity();
        lcd_update();
      }
      lcd_ignore_click(false);
    }
    else {
      if (!lcd_detected()) return;
      while (!lcd_clicked()) {
        manage_heater();
        manage_inactivity();
        lcd_update();
      }
    }
    if (IS_SD_PRINTING)
      LCD_MESSAGEPGM(MSG_RESUMING);
    else
      LCD_MESSAGEPGM(WELCOME_MSG);
  }

#endif // ULTIPANEL

/**
 * M17: Enable power on all stepper motors
 */
inline void gcode_M17() {
  LCD_MESSAGEPGM(MSG_NO_MOVE);
  enable_all_steppers();
}

#ifdef SDSUPPORT

  /**
   * M20: List SD card to serial output
   */
  inline void gcode_M20() {
    SERIAL_PROTOCOLLNPGM(MSG_BEGIN_FILE_LIST);
    card.ls();
    SERIAL_PROTOCOLLNPGM(MSG_END_FILE_LIST);
  }

  /**
   * M21: Init SD Card
   */
  inline void gcode_M21() {
    card.initsd();
  }

  /**
   * M22: Release SD Card
   */
  inline void gcode_M22() {
    card.release();
  }

  /**
   * M23: Select a file
   */
  inline void gcode_M23() {
    char* codepos = strchr_pointer + 4;
    char* starpos = strchr(codepos, '*');
    if (starpos) *starpos = '\0';
    card.openFile(codepos, true);
  }

  /**
   * M24: Start SD Print
   */
  inline void gcode_M24() {
    card.startFileprint();
    print_job_start_ms = millis();
  }

  /**
   * M25: Pause SD Print
   */
  inline void gcode_M25() {
    card.pauseSDPrint();
  }

  /**
   * M26: Set SD Card file index
   */
  inline void gcode_M26() {
    if (card.cardOK && code_seen('S'))
      card.setIndex(code_value_short());
  }

  /**
   * M27: Get SD Card status
   */
  inline void gcode_M27() {
    card.getStatus();
  }

  /**
   * M28: Start SD Write
   */
  inline void gcode_M28() {
    char* codepos = strchr_pointer + 4;
    char* starpos = strchr(codepos, '*');
    if (starpos) {
      char* npos = strchr(command_queue[cmd_queue_index_r], 'N');
      strchr_pointer = strchr(npos, ' ') + 1;
      *(starpos) = '\0';
    }
    card.openFile(codepos, false);
  }

  /**
   * M29: Stop SD Write
   * Processed in write to file routine above
   */
  inline void gcode_M29() {
    // card.saving = false;
  }

  /**
   * M30 <filename>: Delete SD Card file
   */
  inline void gcode_M30() {
    if (card.cardOK) {
      card.closefile();
      char* starpos = strchr(strchr_pointer + 4, '*');
      if (starpos) {
        char* npos = strchr(command_queue[cmd_queue_index_r], 'N');
        strchr_pointer = strchr(npos, ' ') + 1;
        *(starpos) = '\0';
      }
      card.removeFile(strchr_pointer + 4);
    }
  }

#endif

/**
 * M31: Get the time since the start of SD Print (or last M109)
 */
inline void gcode_M31() {
  print_job_stop_ms = millis();
  millis_t t = (print_job_stop_ms - print_job_start_ms) / 1000;
  int min = t / 60, sec = t % 60;
  char time[30];
  sprintf_P(time, PSTR("%i min, %i sec"), min, sec);
  SERIAL_ECHO_START;
  SERIAL_ECHOLN(time);
  lcd_setstatus(time);
  autotempShutdown();
}

#ifdef SDSUPPORT

  /**
   * M32: Select file and start SD Print
   */
  inline void gcode_M32() {
    if (card.sdprinting)
      st_synchronize();

    char* codepos = strchr_pointer + 4;

    char* namestartpos = strchr(codepos, '!');   //find ! to indicate filename string start.
    if (! namestartpos)
      namestartpos = codepos; //default name position, 4 letters after the M
    else
      namestartpos++; //to skip the '!'

    char* starpos = strchr(codepos, '*');
    if (starpos) *(starpos) = '\0';

    bool call_procedure = code_seen('P') && (strchr_pointer < namestartpos);

    if (card.cardOK) {
      card.openFile(namestartpos, true, !call_procedure);

      if (code_seen('S') && strchr_pointer < namestartpos) // "S" (must occur _before_ the filename!)
        card.setIndex(code_value_short());

      card.startFileprint();
      if (!call_procedure)
        print_job_start_ms = millis(); //procedure calls count as normal print time.
    }
  }

  /**
   * M928: Start SD Write
   */
  inline void gcode_M928() {
    char* starpos = strchr(strchr_pointer + 5, '*');
    if (starpos) {
      char* npos = strchr(command_queue[cmd_queue_index_r], 'N');
      strchr_pointer = strchr(npos, ' ') + 1;
      *(starpos) = '\0';
    }
    card.openLogFile(strchr_pointer + 5);
  }

#endif // SDSUPPORT

/**
 * M42: Change pin status via GCode
 */
inline void gcode_M42() {
  if (code_seen('S')) {
    int pin_status = code_value_short(),
        pin_number = LED_PIN;

    if (code_seen('P') && pin_status >= 0 && pin_status <= 255)
      pin_number = code_value_short();

    for (int8_t i = 0; i < (int8_t)(sizeof(sensitive_pins) / sizeof(*sensitive_pins)); i++) {
      if (sensitive_pins[i] == pin_number) {
        pin_number = -1;
        break;
      }
    }

    #if HAS_FAN
      if (pin_number == FAN_PIN) fanSpeed = pin_status;
    #endif

    if (pin_number > -1) {
      pinMode(pin_number, OUTPUT);
      digitalWrite(pin_number, pin_status);
      analogWrite(pin_number, pin_status);
    }
  } // code_seen('S')
}

#if defined(ENABLE_AUTO_BED_LEVELING) && defined(Z_PROBE_REPEATABILITY_TEST)

  // This is redundant since the SanityCheck.h already checks for a valid Z_PROBE_PIN, but here for clarity.
  #ifdef Z_PROBE_ENDSTOP
    #if !HAS_Z_PROBE
      #error You must define Z_PROBE_PIN to enable Z-Probe repeatability calculation.
    #endif
  #elif !HAS_Z_MIN
    #error You must define Z_MIN_PIN to enable Z-Probe repeatability calculation.
  #endif

  /**
   * M48: Z-Probe repeatability measurement function.
   *
   * Usage:
   *   M48 <P#> <X#> <Y#> <V#> <E> <L#>
   *     P = Number of sampled points (4-50, default 10)
   *     X = Sample X position
   *     Y = Sample Y position
   *     V = Verbose level (0-4, default=1)
   *     E = Engage probe for each reading
   *     L = Number of legs of movement before probe
   *  
   * This function assumes the bed has been homed.  Specifically, that a G28 command
   * as been issued prior to invoking the M48 Z-Probe repeatability measurement function.
   * Any information generated by a prior G29 Bed leveling command will be lost and need to be
   * regenerated.
   */
  inline void gcode_M48() {

    double sum = 0.0, mean = 0.0, sigma = 0.0, sample_set[50];
    uint8_t verbose_level = 1, n_samples = 10, n_legs = 0;

    if (code_seen('V') || code_seen('v')) {
      verbose_level = code_value_short();
      if (verbose_level < 0 || verbose_level > 4 ) {
        SERIAL_PROTOCOLPGM("?Verbose Level not plausible (0-4).\n");
        return;
      }
    }

    if (verbose_level > 0)
      SERIAL_PROTOCOLPGM("M48 Z-Probe Repeatability test\n");

    if (code_seen('P') || code_seen('p')) {
      n_samples = code_value_short();
      if (n_samples < 4 || n_samples > 50) {
        SERIAL_PROTOCOLPGM("?Sample size not plausible (4-50).\n");
        return;
      }
    }

    double X_current = st_get_position_mm(X_AXIS),
           Y_current = st_get_position_mm(Y_AXIS),
           Z_current = st_get_position_mm(Z_AXIS),
           E_current = st_get_position_mm(E_AXIS),
           X_probe_location = X_current, Y_probe_location = Y_current,
           Z_start_location = Z_current + Z_RAISE_BEFORE_PROBING;

    bool deploy_probe_for_each_reading = code_seen('E') || code_seen('e');

    if (code_seen('X') || code_seen('x')) {
      X_probe_location = code_value() - X_PROBE_OFFSET_FROM_EXTRUDER;
      if (X_probe_location < X_MIN_POS || X_probe_location > X_MAX_POS) {
        SERIAL_PROTOCOLPGM("?X position out of range.\n");
        return;
      }
    }

    if (code_seen('Y') || code_seen('y')) {
      Y_probe_location = code_value() -  Y_PROBE_OFFSET_FROM_EXTRUDER;
      if (Y_probe_location < Y_MIN_POS || Y_probe_location > Y_MAX_POS) {
        SERIAL_PROTOCOLPGM("?Y position out of range.\n");
        return;
      }
    }

    if (code_seen('L') || code_seen('l')) {
      n_legs = code_value_short();
      if (n_legs == 1) n_legs = 2;
      if (n_legs < 0 || n_legs > 15) {
        SERIAL_PROTOCOLPGM("?Number of legs in movement not plausible (0-15).\n");
        return;
      }
    }

    //
    // Do all the preliminary setup work.   First raise the probe.
    //

    st_synchronize();
    plan_bed_level_matrix.set_to_identity();
    plan_buffer_line(X_current, Y_current, Z_start_location, E_current, homing_feedrate[Z_AXIS] / 60, active_extruder);
    st_synchronize();

    //
    // Now get everything to the specified probe point So we can safely do a probe to
    // get us close to the bed.  If the Z-Axis is far from the bed, we don't want to 
    // use that as a starting point for each probe.
    //
    if (verbose_level > 2)
      SERIAL_PROTOCOLPGM("Positioning the probe...\n");

    plan_buffer_line( X_probe_location, Y_probe_location, Z_start_location,
        E_current,
        homing_feedrate[X_AXIS]/60,
        active_extruder);
    st_synchronize();

    current_position[X_AXIS] = X_current = st_get_position_mm(X_AXIS);
    current_position[Y_AXIS] = Y_current = st_get_position_mm(Y_AXIS);
    current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);
    current_position[E_AXIS] = E_current = st_get_position_mm(E_AXIS);

    // 
    // OK, do the initial probe to get us close to the bed.
    // Then retrace the right amount and use that in subsequent probes
    //

    deploy_z_probe();

    setup_for_endstop_move();
    run_z_probe();

    current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);
    Z_start_location = st_get_position_mm(Z_AXIS) + Z_RAISE_BEFORE_PROBING;

    plan_buffer_line( X_probe_location, Y_probe_location, Z_start_location,
        E_current,
        homing_feedrate[X_AXIS]/60,
        active_extruder);
    st_synchronize();
    current_position[Z_AXIS] = Z_current = st_get_position_mm(Z_AXIS);

    if (deploy_probe_for_each_reading) stow_z_probe();

    for (uint8_t n=0; n < n_samples; n++) {
      // Make sure we are at the probe location
      do_blocking_move_to(X_probe_location, Y_probe_location, Z_start_location); // this also updates current_position

      if (n_legs) {
        millis_t ms = millis();
        double radius = ms % (X_MAX_LENGTH / 4),       // limit how far out to go
               theta = RADIANS(ms % 360L);
        float dir = (ms & 0x0001) ? 1 : -1;            // clockwise or counter clockwise

        //SERIAL_ECHOPAIR("starting radius: ",radius);
        //SERIAL_ECHOPAIR("   theta: ",theta);
        //SERIAL_ECHOPAIR("   direction: ",dir);
        //SERIAL_EOL;

        for (uint8_t l = 0; l < n_legs - 1; l++) {
          ms = millis();
          theta += RADIANS(dir * (ms % 20L));
          radius += (ms % 10L) - 5L;
          if (radius < 0.0) radius = -radius;

          X_current = X_probe_location + cos(theta) * radius;
          X_current = constrain(X_current, X_MIN_POS, X_MAX_POS);
          Y_current = Y_probe_location + sin(theta) * radius;
          Y_current = constrain(Y_current, Y_MIN_POS, Y_MAX_POS);

          if (verbose_level > 3) {
            SERIAL_ECHOPAIR("x: ", X_current);
            SERIAL_ECHOPAIR("y: ", Y_current);
            SERIAL_EOL;
          }

          do_blocking_move_to(X_current, Y_current, Z_current); // this also updates current_position

        } // n_legs loop

        // Go back to the probe location
        do_blocking_move_to(X_probe_location, Y_probe_location, Z_start_location); // this also updates current_position

      } // n_legs

      if (deploy_probe_for_each_reading)  {
        deploy_z_probe(); 
        delay(1000);
      }

      setup_for_endstop_move();
      run_z_probe();

      sample_set[n] = current_position[Z_AXIS];

      //
      // Get the current mean for the data points we have so far
      //
      sum = 0.0;
      for (uint8_t j = 0; j <= n; j++) sum += sample_set[j];
      mean = sum / (n + 1);

      //
      // Now, use that mean to calculate the standard deviation for the
      // data points we have so far
      //
      sum = 0.0;
      for (uint8_t j = 0; j <= n; j++) {
        float ss = sample_set[j] - mean;
        sum += ss * ss;
      }
      sigma = sqrt(sum / (n + 1));

      if (verbose_level > 1) {
        SERIAL_PROTOCOL(n+1);
        SERIAL_PROTOCOLPGM(" of ");
        SERIAL_PROTOCOL(n_samples);
        SERIAL_PROTOCOLPGM("   z: ");
        SERIAL_PROTOCOL_F(current_position[Z_AXIS], 6);
        if (verbose_level > 2) {
          SERIAL_PROTOCOLPGM(" mean: ");
          SERIAL_PROTOCOL_F(mean,6);
          SERIAL_PROTOCOLPGM("   sigma: ");
          SERIAL_PROTOCOL_F(sigma,6);
        }
      }

      if (verbose_level > 0) SERIAL_EOL;

      plan_buffer_line(X_probe_location, Y_probe_location, Z_start_location, current_position[E_AXIS], homing_feedrate[Z_AXIS]/60, active_extruder);
      st_synchronize();

      // Stow between
      if (deploy_probe_for_each_reading) {
        stow_z_probe();
        delay(1000);
      }
    }

    // Stow after
    if (!deploy_probe_for_each_reading) {
      stow_z_probe();
      delay(1000);
    }

    clean_up_after_endstop_move();

    if (verbose_level > 0) {
      SERIAL_PROTOCOLPGM("Mean: ");
      SERIAL_PROTOCOL_F(mean, 6);
      SERIAL_EOL;
    }

    SERIAL_PROTOCOLPGM("Standard Deviation: ");
    SERIAL_PROTOCOL_F(sigma, 6);
    SERIAL_EOL; SERIAL_EOL;
  }

#endif // ENABLE_AUTO_BED_LEVELING && Z_PROBE_REPEATABILITY_TEST

/**
 * M104: Set hot end temperature
 */
inline void gcode_M104() {
  if (setTargetedHotend(104)) return;

  if (code_seen('S')) {
    float temp = code_value();
    setTargetHotend(temp, target_extruder);
    #ifdef DUAL_X_CARRIAGE
      if (dual_x_carriage_mode == DXC_DUPLICATION_MODE && target_extruder == 0)
        setTargetHotend1(temp == 0.0 ? 0.0 : temp + duplicate_extruder_temp_offset);
    #endif

    #ifdef THERMAL_PROTECTION_HOTENDS
      start_watching_heater(target_extruder);
    #endif
  }
}

/**
 * M105: Read hot end and bed temperature
 */
inline void gcode_M105() {
  if (setTargetedHotend(105)) return;

  #if HAS_TEMP_0 || HAS_TEMP_BED || defined(HEATER_0_USES_MAX6675)
    SERIAL_PROTOCOLPGM(MSG_OK);
    #if HAS_TEMP_0
      SERIAL_PROTOCOLPGM(" T:");
      SERIAL_PROTOCOL_F(degHotend(target_extruder), 1);
      SERIAL_PROTOCOLPGM(" /");
      SERIAL_PROTOCOL_F(degTargetHotend(target_extruder), 1);
    #endif
    #if HAS_TEMP_BED
      SERIAL_PROTOCOLPGM(" B:");
      SERIAL_PROTOCOL_F(degBed(), 1);
      SERIAL_PROTOCOLPGM(" /");
      SERIAL_PROTOCOL_F(degTargetBed(), 1);
    #endif
    for (int8_t e = 0; e < EXTRUDERS; ++e) {
      SERIAL_PROTOCOLPGM(" T");
      SERIAL_PROTOCOL(e);
      SERIAL_PROTOCOLCHAR(':');
      SERIAL_PROTOCOL_F(degHotend(e), 1);
      SERIAL_PROTOCOLPGM(" /");
      SERIAL_PROTOCOL_F(degTargetHotend(e), 1);
    }
  #else // !HAS_TEMP_0 && !HAS_TEMP_BED
    SERIAL_ERROR_START;
    SERIAL_ERRORLNPGM(MSG_ERR_NO_THERMISTORS);
  #endif

  SERIAL_PROTOCOLPGM(" @:");
  #ifdef EXTRUDER_WATTS
    SERIAL_PROTOCOL((EXTRUDER_WATTS * getHeaterPower(target_extruder))/127);
    SERIAL_PROTOCOLCHAR('W');
  #else
    SERIAL_PROTOCOL(getHeaterPower(target_extruder));
  #endif

  SERIAL_PROTOCOLPGM(" B@:");
  #ifdef BED_WATTS
    SERIAL_PROTOCOL((BED_WATTS * getHeaterPower(-1))/127);
    SERIAL_PROTOCOLCHAR('W');
  #else
    SERIAL_PROTOCOL(getHeaterPower(-1));
  #endif

  #ifdef SHOW_TEMP_ADC_VALUES
    #if HAS_TEMP_BED
      SERIAL_PROTOCOLPGM("    ADC B:");
      SERIAL_PROTOCOL_F(degBed(),1);
      SERIAL_PROTOCOLPGM("C->");
      SERIAL_PROTOCOL_F(rawBedTemp()/OVERSAMPLENR,0);
    #endif
    for (int8_t cur_extruder = 0; cur_extruder < EXTRUDERS; ++cur_extruder) {
      SERIAL_PROTOCOLPGM("  T");
      SERIAL_PROTOCOL(cur_extruder);
      SERIAL_PROTOCOLCHAR(':');
      SERIAL_PROTOCOL_F(degHotend(cur_extruder),1);
      SERIAL_PROTOCOLPGM("C->");
      SERIAL_PROTOCOL_F(rawHotendTemp(cur_extruder)/OVERSAMPLENR,0);
    }
  #endif

  SERIAL_EOL;
}

#if HAS_FAN

  /**
   * M106: Set Fan Speed
   */
  inline void gcode_M106() { fanSpeed = code_seen('S') ? constrain(code_value_short(), 0, 255) : 255; }

  /**
   * M107: Fan Off
   */
  inline void gcode_M107() { fanSpeed = 0; }

#endif // HAS_FAN

/**
 * M109: Wait for extruder(s) to reach temperature
 */
inline void gcode_M109() {
  if (setTargetedHotend(109)) return;

  LCD_MESSAGEPGM(MSG_HEATING);

  no_wait_for_cooling = code_seen('S');
  if (no_wait_for_cooling || code_seen('R')) {
    float temp = code_value();
    setTargetHotend(temp, target_extruder);
    #ifdef DUAL_X_CARRIAGE
      if (dual_x_carriage_mode == DXC_DUPLICATION_MODE && target_extruder == 0)
        setTargetHotend1(temp == 0.0 ? 0.0 : temp + duplicate_extruder_temp_offset);
    #endif
  }

  #ifdef AUTOTEMP
    autotemp_enabled = code_seen('F');
    if (autotemp_enabled) autotemp_factor = code_value();
    if (code_seen('S')) autotemp_min = code_value();
    if (code_seen('B')) autotemp_max = code_value();
  #endif

  #ifdef THERMAL_PROTECTION_HOTENDS
    start_watching_heater(target_extruder);
  #endif

  millis_t temp_ms = millis();

  /* See if we are heating up or cooling down */
  target_direction = isHeatingHotend(target_extruder); // true if heating, false if cooling

  cancel_heatup = false;

  #ifdef TEMP_RESIDENCY_TIME
    long residency_start_ms = -1;
    /* continue to loop until we have reached the target temp
      _and_ until TEMP_RESIDENCY_TIME hasn't passed since we reached it */
    while((!cancel_heatup)&&((residency_start_ms == -1) ||
          (residency_start_ms >= 0 && (((unsigned int) (millis() - residency_start_ms)) < (TEMP_RESIDENCY_TIME * 1000UL)))) )
  #else
    while ( target_direction ? (isHeatingHotend(target_extruder)) : (isCoolingHotend(target_extruder)&&(no_wait_for_cooling==false)) )
  #endif //TEMP_RESIDENCY_TIME

    { // while loop
      if (millis() > temp_ms + 1000UL) { //Print temp & remaining time every 1s while waiting
        SERIAL_PROTOCOLPGM("T:");
        SERIAL_PROTOCOL_F(degHotend(target_extruder),1);
        SERIAL_PROTOCOLPGM(" E:");
        SERIAL_PROTOCOL((int)target_extruder);
        #ifdef TEMP_RESIDENCY_TIME
          SERIAL_PROTOCOLPGM(" W:");
          if (residency_start_ms > -1) {
            temp_ms = ((TEMP_RESIDENCY_TIME * 1000UL) - (millis() - residency_start_ms)) / 1000UL;
            SERIAL_PROTOCOLLN(temp_ms);
          }
          else {
            SERIAL_PROTOCOLLNPGM("?");
          }
        #else
          SERIAL_EOL;
        #endif
        temp_ms = millis();
      }
      manage_heater();
      manage_inactivity();
      lcd_update();
      #ifdef TEMP_RESIDENCY_TIME
        // start/restart the TEMP_RESIDENCY_TIME timer whenever we reach target temp for the first time
        // or when current temp falls outside the hysteresis after target temp was reached
        if ((residency_start_ms == -1 &&  target_direction && (degHotend(target_extruder) >= (degTargetHotend(target_extruder)-TEMP_WINDOW))) ||
            (residency_start_ms == -1 && !target_direction && (degHotend(target_extruder) <= (degTargetHotend(target_extruder)+TEMP_WINDOW))) ||
            (residency_start_ms > -1 && labs(degHotend(target_extruder) - degTargetHotend(target_extruder)) > TEMP_HYSTERESIS) )
        {
          residency_start_ms = millis();
        }
      #endif //TEMP_RESIDENCY_TIME
    }

  LCD_MESSAGEPGM(MSG_HEATING_COMPLETE);
  refresh_cmd_timeout();
  print_job_start_ms = previous_cmd_ms;
}

#if HAS_TEMP_BED

  /**
   * M190: Sxxx Wait for bed current temp to reach target temp. Waits only when heating
   *       Rxxx Wait for bed current temp to reach target temp. Waits when heating and cooling
   */
  inline void gcode_M190() {
    LCD_MESSAGEPGM(MSG_BED_HEATING);
    no_wait_for_cooling = code_seen('S');
    if (no_wait_for_cooling || code_seen('R'))
      setTargetBed(code_value());

    millis_t temp_ms = millis();
    
    cancel_heatup = false;
    target_direction = isHeatingBed(); // true if heating, false if cooling

    while ((target_direction && !cancel_heatup) ? isHeatingBed() : isCoolingBed() && !no_wait_for_cooling) {
      millis_t ms = millis();
      if (ms > temp_ms + 1000UL) { //Print Temp Reading every 1 second while heating up.
        temp_ms = ms;
        float tt = degHotend(active_extruder);
        SERIAL_PROTOCOLPGM("T:");
        SERIAL_PROTOCOL(tt);
        SERIAL_PROTOCOLPGM(" E:");
        SERIAL_PROTOCOL((int)active_extruder);
        SERIAL_PROTOCOLPGM(" B:");
        SERIAL_PROTOCOL_F(degBed(), 1);
        SERIAL_EOL;
      }
      manage_heater();
      manage_inactivity();
      lcd_update();
    }
    LCD_MESSAGEPGM(MSG_BED_DONE);
    refresh_cmd_timeout();
  }

#endif // HAS_TEMP_BED

/**
 * M111: Set the debug level
 */
inline void gcode_M111() {
  marlin_debug_flags = code_seen('S') ? code_value_short() : DEBUG_INFO|DEBUG_ERRORS;
}

/**
 * M112: Emergency Stop
 */
inline void gcode_M112() { kill(PSTR(MSG_KILLED)); }

#ifdef BARICUDA

  #if HAS_HEATER_1
    /**
     * M126: Heater 1 valve open
     */
    inline void gcode_M126() { ValvePressure = code_seen('S') ? constrain(code_value(), 0, 255) : 255; }
    /**
     * M127: Heater 1 valve close
     */
    inline void gcode_M127() { ValvePressure = 0; }
  #endif

  #if HAS_HEATER_2
    /**
     * M128: Heater 2 valve open
     */
    inline void gcode_M128() { EtoPPressure = code_seen('S') ? constrain(code_value(), 0, 255) : 255; }
    /**
     * M129: Heater 2 valve close
     */
    inline void gcode_M129() { EtoPPressure = 0; }
  #endif

#endif //BARICUDA

/**
 * M140: Set bed temperature
 */
inline void gcode_M140() {
  if (code_seen('S')) setTargetBed(code_value());
}

#ifdef ULTIPANEL

  /**
   * M145: Set the heatup state for a material in the LCD menu
   *   S<material> (0=PLA, 1=ABS)
   *   H<hotend temp>
   *   B<bed temp>
   *   F<fan speed>
   */
  inline void gcode_M145() {
    uint8_t material = code_seen('S') ? code_value_short() : 0;
    if (material < 0 || material > 1) {
      SERIAL_ERROR_START;
      SERIAL_ERRORLNPGM(MSG_ERR_MATERIAL_INDEX);
    }
    else {
      int v;
      switch (material) {
        case 0:
          if (code_seen('H')) {
            v = code_value_short();
            plaPreheatHotendTemp = constrain(v, EXTRUDE_MINTEMP, HEATER_0_MAXTEMP - 15);
          }
          if (code_seen('F')) {
            v = code_value_short();
            plaPreheatFanSpeed = constrain(v, 0, 255);
          }
          #if TEMP_SENSOR_BED != 0
            if (code_seen('B')) {
              v = code_value_short();
              plaPreheatHPBTemp = constrain(v, BED_MINTEMP, BED_MAXTEMP - 15);
            }
          #endif
          break;
        case 1:
          if (code_seen('H')) {
            v = code_value_short();
            absPreheatHotendTemp = constrain(v, EXTRUDE_MINTEMP, HEATER_0_MAXTEMP - 15);
          }
          if (code_seen('F')) {
            v = code_value_short();
            absPreheatFanSpeed = constrain(v, 0, 255);
          }
          #if TEMP_SENSOR_BED != 0
            if (code_seen('B')) {
              v = code_value_short();
              absPreheatHPBTemp = constrain(v, BED_MINTEMP, BED_MAXTEMP - 15);
            }
          #endif
          break;
      }
    }
  }

#endif

#if HAS_POWER_SWITCH

  /**
   * M80: Turn on Power Supply
   */
  inline void gcode_M80() {
    OUT_WRITE(PS_ON_PIN, PS_ON_AWAKE); //GND

    // If you have a switch on suicide pin, this is useful
    // if you want to start another print with suicide feature after
    // a print without suicide...
    #if HAS_SUICIDE
      OUT_WRITE(SUICIDE_PIN, HIGH);
    #endif

    #ifdef ULTIPANEL
      powersupply = true;
      LCD_MESSAGEPGM(WELCOME_MSG);
      lcd_update();
    #endif
  }

#endif // HAS_POWER_SWITCH

/**
 * M81: Turn off Power, including Power Supply, if there is one.
 *
 *      This code should ALWAYS be available for EMERGENCY SHUTDOWN!
 */
inline void gcode_M81() {
  disable_all_heaters();
  st_synchronize();
  disable_e0();
  disable_e1();
  disable_e2();
  disable_e3();
  finishAndDisableSteppers();
  fanSpeed = 0;
  delay(1000); // Wait 1 second before switching off
  #if HAS_SUICIDE
    st_synchronize();
    suicide();
  #elif HAS_POWER_SWITCH
    OUT_WRITE(PS_ON_PIN, PS_ON_ASLEEP);
  #endif
  #ifdef ULTIPANEL
    #if HAS_POWER_SWITCH
      powersupply = false;
    #endif
    LCD_MESSAGEPGM(MACHINE_NAME " " MSG_OFF ".");
    lcd_update();
  #endif
}


/**
 * M82: Set E codes absolute (default)
 */
inline void gcode_M82() { axis_relative_modes[E_AXIS] = false; }

/**
 * M82: Set E codes relative while in Absolute Coordinates (G90) mode
 */
inline void gcode_M83() { axis_relative_modes[E_AXIS] = true; }

/**
 * M18, M84: Disable all stepper motors
 */
inline void gcode_M18_M84() {
  if (code_seen('S')) {
    stepper_inactive_time = code_value() * 1000;
  }
  else {
    bool all_axis = !((code_seen(axis_codes[X_AXIS])) || (code_seen(axis_codes[Y_AXIS])) || (code_seen(axis_codes[Z_AXIS]))|| (code_seen(axis_codes[E_AXIS])));
    if (all_axis) {
      st_synchronize();
      disable_e0();
      disable_e1();
      disable_e2();
      disable_e3();
      finishAndDisableSteppers();
    }
    else {
      st_synchronize();
      if (code_seen('X')) disable_x();
      if (code_seen('Y')) disable_y();
      if (code_seen('Z')) disable_z();
      #if ((E0_ENABLE_PIN != X_ENABLE_PIN) && (E1_ENABLE_PIN != Y_ENABLE_PIN)) // Only enable on boards that have seperate ENABLE_PINS
        if (code_seen('E')) {
          disable_e0();
          disable_e1();
          disable_e2();
          disable_e3();
        }
      #endif
    }
  }
}

/**
 * M85: Set inactivity shutdown timer with parameter S<seconds>. To disable set zero (default)
 */
inline void gcode_M85() {
  if (code_seen('S')) max_inactive_time = code_value() * 1000;
}

/**
 * M92: Set axis steps-per-unit for one or more axes, X, Y, Z, and E.
 *      (Follows the same syntax as G92)
 */
inline void gcode_M92() {
  for(int8_t i=0; i < NUM_AXIS; i++) {
    if (code_seen(axis_codes[i])) {
      if (i == E_AXIS) {
        float value = code_value();
        if (value < 20.0) {
          float factor = axis_steps_per_unit[i] / value; // increase e constants if M92 E14 is given for netfab.
          max_e_jerk *= factor;
          max_feedrate[i] *= factor;
          axis_steps_per_sqr_second[i] *= factor;
        }
        axis_steps_per_unit[i] = value;
      }
      else {
        axis_steps_per_unit[i] = code_value();
      }
    }
  }
}

/**
 * M114: Output current position to serial port
 */
inline void gcode_M114() {
  SERIAL_PROTOCOLPGM("X:");
  SERIAL_PROTOCOL(current_position[X_AXIS]);
  SERIAL_PROTOCOLPGM(" Y:");
  SERIAL_PROTOCOL(current_position[Y_AXIS]);
  SERIAL_PROTOCOLPGM(" Z:");
  SERIAL_PROTOCOL(current_position[Z_AXIS]);
  SERIAL_PROTOCOLPGM(" E:");
  SERIAL_PROTOCOL(current_position[E_AXIS]);

  SERIAL_PROTOCOLPGM(MSG_COUNT_X);
  SERIAL_PROTOCOL(float(st_get_position(X_AXIS))/axis_steps_per_unit[X_AXIS]);
  SERIAL_PROTOCOLPGM(" Y:");
  SERIAL_PROTOCOL(float(st_get_position(Y_AXIS))/axis_steps_per_unit[Y_AXIS]);
  SERIAL_PROTOCOLPGM(" Z:");
  SERIAL_PROTOCOL(float(st_get_position(Z_AXIS))/axis_steps_per_unit[Z_AXIS]);

  SERIAL_EOL;

  #ifdef SCARA
    SERIAL_PROTOCOLPGM("SCARA Theta:");
    SERIAL_PROTOCOL(delta[X_AXIS]);
    SERIAL_PROTOCOLPGM("   Psi+Theta:");
    SERIAL_PROTOCOL(delta[Y_AXIS]);
    SERIAL_EOL;
    
    SERIAL_PROTOCOLPGM("SCARA Cal - Theta:");
    SERIAL_PROTOCOL(delta[X_AXIS]+home_offset[X_AXIS]);
    SERIAL_PROTOCOLPGM("   Psi+Theta (90):");
    SERIAL_PROTOCOL(delta[Y_AXIS]-delta[X_AXIS]-90+home_offset[Y_AXIS]);
    SERIAL_EOL;
    
    SERIAL_PROTOCOLPGM("SCARA step Cal - Theta:");
    SERIAL_PROTOCOL(delta[X_AXIS]/90*axis_steps_per_unit[X_AXIS]);
    SERIAL_PROTOCOLPGM("   Psi+Theta:");
    SERIAL_PROTOCOL((delta[Y_AXIS]-delta[X_AXIS])/90*axis_steps_per_unit[Y_AXIS]);
    SERIAL_EOL; SERIAL_EOL;
  #endif
}

/**
 * M115: Capabilities string
 */
inline void gcode_M115() {
  SERIAL_PROTOCOLPGM(MSG_M115_REPORT);
}

#ifdef ULTIPANEL

  /**
   * M117: Set LCD Status Message
   */
  inline void gcode_M117() {
    lcd_setstatus(strchr_pointer + 5);
  }

#endif

/**
 * M119: Output endstop states to serial output
 */
inline void gcode_M119() {
  SERIAL_PROTOCOLLN(MSG_M119_REPORT);
  #if HAS_X_MIN
    SERIAL_PROTOCOLPGM(MSG_X_MIN);
    SERIAL_PROTOCOLLN(((READ(X_MIN_PIN)^X_MIN_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_X_MAX
    SERIAL_PROTOCOLPGM(MSG_X_MAX);
    SERIAL_PROTOCOLLN(((READ(X_MAX_PIN)^X_MAX_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Y_MIN
    SERIAL_PROTOCOLPGM(MSG_Y_MIN);
    SERIAL_PROTOCOLLN(((READ(Y_MIN_PIN)^Y_MIN_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Y_MAX
    SERIAL_PROTOCOLPGM(MSG_Y_MAX);
    SERIAL_PROTOCOLLN(((READ(Y_MAX_PIN)^Y_MAX_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Z_MIN
    SERIAL_PROTOCOLPGM(MSG_Z_MIN);
    SERIAL_PROTOCOLLN(((READ(Z_MIN_PIN)^Z_MIN_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Z_MAX
    SERIAL_PROTOCOLPGM(MSG_Z_MAX);
    SERIAL_PROTOCOLLN(((READ(Z_MAX_PIN)^Z_MAX_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Z2_MAX
    SERIAL_PROTOCOLPGM(MSG_Z2_MAX);
    SERIAL_PROTOCOLLN(((READ(Z2_MAX_PIN)^Z2_MAX_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
  #if HAS_Z_PROBE
    SERIAL_PROTOCOLPGM(MSG_Z_PROBE);
    SERIAL_PROTOCOLLN(((READ(Z_PROBE_PIN)^Z_PROBE_ENDSTOP_INVERTING)?MSG_ENDSTOP_HIT:MSG_ENDSTOP_OPEN));
  #endif
}

/**
 * M120: Enable endstops
 */
inline void gcode_M120() { enable_endstops(false); }

/**
 * M121: Disable endstops
 */
inline void gcode_M121() { enable_endstops(true); }

#ifdef BLINKM

  /**
   * M150: Set Status LED Color - Use R-U-B for R-G-B
   */
  inline void gcode_M150() {
    SendColors(
      code_seen('R') ? (byte)code_value_short() : 0,
      code_seen('U') ? (byte)code_value_short() : 0,
      code_seen('B') ? (byte)code_value_short() : 0
    );
  }

#endif // BLINKM

/**
 * M200: Set filament diameter and set E axis units to cubic millimeters (use S0 to set back to millimeters).
 *       T<extruder>
 *       D<millimeters>
 */
inline void gcode_M200() {
  int tmp_extruder = active_extruder;
  if (code_seen('T')) {
    tmp_extruder = code_value_short();
    if (tmp_extruder >= EXTRUDERS) {
      SERIAL_ECHO_START;
      SERIAL_ECHO(MSG_M200_INVALID_EXTRUDER);
      return;
    }
  }

  if (code_seen('D')) {
    float diameter = code_value();
    // setting any extruder filament size disables volumetric on the assumption that
    // slicers either generate in extruder values as cubic mm or as as filament feeds
    // for all extruders
    volumetric_enabled = (diameter != 0.0);
    if (volumetric_enabled) {
      filament_size[tmp_extruder] = diameter;
      // make sure all extruders have some sane value for the filament size
      for (int i=0; i<EXTRUDERS; i++)
        if (! filament_size[i]) filament_size[i] = DEFAULT_NOMINAL_FILAMENT_DIA;
    }
  }
  else {
    //reserved for setting filament diameter via UFID or filament measuring device
    return;
  }
  calculate_volumetric_multipliers();
}

/**
 * M201: Set max acceleration in units/s^2 for print moves (M201 X1000 Y1000)
 */
inline void gcode_M201() {
  for (int8_t i=0; i < NUM_AXIS; i++) {
    if (code_seen(axis_codes[i])) {
      max_acceleration_units_per_sq_second[i] = code_value();
    }
  }
  // steps per sq second need to be updated to agree with the units per sq second (as they are what is used in the planner)
  reset_acceleration_rates();
}

#if 0 // Not used for Sprinter/grbl gen6
  inline void gcode_M202() {
    for(int8_t i=0; i < NUM_AXIS; i++) {
      if(code_seen(axis_codes[i])) axis_travel_steps_per_sqr_second[i] = code_value() * axis_steps_per_unit[i];
    }
  }
#endif


/**
 * M203: Set maximum feedrate that your machine can sustain (M203 X200 Y200 Z300 E10000) in mm/sec
 */
inline void gcode_M203() {
  for (int8_t i=0; i < NUM_AXIS; i++) {
    if (code_seen(axis_codes[i])) {
      max_feedrate[i] = code_value();
    }
  }
}

/**
 * M204: Set Accelerations in mm/sec^2 (M204 P1200 R3000 T3000)
 *
 *    P = Printing moves
 *    R = Retract only (no X, Y, Z) moves
 *    T = Travel (non printing) moves
 *
 *  Also sets minimum segment time in ms (B20000) to prevent buffer under-runs and M20 minimum feedrate
 */
inline void gcode_M204() {
  if (code_seen('S')) {  // Kept for legacy compatibility. Should NOT BE USED for new developments.
    acceleration = code_value();
    travel_acceleration = acceleration;
    SERIAL_ECHOPAIR("Setting Print and Travel Acceleration: ", acceleration );
    SERIAL_EOL;
  }
  if (code_seen('P')) {
    acceleration = code_value();
    SERIAL_ECHOPAIR("Setting Print Acceleration: ", acceleration );
    SERIAL_EOL;
  }
  if (code_seen('R')) {
    retract_acceleration = code_value();
    SERIAL_ECHOPAIR("Setting Retract Acceleration: ", retract_acceleration );
    SERIAL_EOL;
  }
  if (code_seen('T')) {
    travel_acceleration = code_value();
    SERIAL_ECHOPAIR("Setting Travel Acceleration: ", travel_acceleration );
    SERIAL_EOL;
  }
  
}

/**
 * M205: Set Advanced Settings
 *
 *    S = Min Feed Rate (mm/s)
 *    T = Min Travel Feed Rate (mm/s)
 *    B = Min Segment Time (µs)
 *    X = Max XY Jerk (mm/s/s)
 *    Z = Max Z Jerk (mm/s/s)
 *    E = Max E Jerk (mm/s/s)
 */
inline void gcode_M205() {
  if (code_seen('S')) minimumfeedrate = code_value();
  if (code_seen('T')) mintravelfeedrate = code_value();
  if (code_seen('B')) minsegmenttime = code_value();
  if (code_seen('X')) max_xy_jerk = code_value();
  if (code_seen('Z')) max_z_jerk = code_value();
  if (code_seen('E')) max_e_jerk = code_value();
}

/**
 * M206: Set Additional Homing Offset (X Y Z). SCARA aliases T=X, P=Y
 */
inline void gcode_M206() {
  for (int8_t i=X_AXIS; i <= Z_AXIS; i++) {
    if (code_seen(axis_codes[i])) {
      home_offset[i] = code_value();
    }
  }
  #ifdef SCARA
    if (code_seen('T')) home_offset[X_AXIS] = code_value(); // Theta
    if (code_seen('P')) home_offset[Y_AXIS] = code_value(); // Psi
  #endif
}

#ifdef DELTA
  /**
   * M665: Set delta configurations
   *
   *    L = diagonal rod
   *    R = delta radius
   *    S = segments per second
   */
  inline void gcode_M665() {
    if (code_seen('L')) delta_diagonal_rod = code_value();
    if (code_seen('R')) delta_radius = code_value();
    if (code_seen('S')) delta_segments_per_second = code_value();
    recalc_delta_settings(delta_radius, delta_diagonal_rod);
  }
  /**
   * M666: Set delta endstop adjustment
   */
  inline void gcode_M666() {
    for (int8_t i = X_AXIS; i <= Z_AXIS; i++) {
      if (code_seen(axis_codes[i])) {
        endstop_adj[i] = code_value();
      }
    }
  }
#elif defined(Z_DUAL_ENDSTOPS) // !DELTA && defined(Z_DUAL_ENDSTOPS)
  /**
   * M666: For Z Dual Endstop setup, set z axis offset to the z2 axis.
   */
  inline void gcode_M666() {
    if (code_seen('Z')) z_endstop_adj = code_value();
    SERIAL_ECHOPAIR("Z Endstop Adjustment set to (mm):", z_endstop_adj);
    SERIAL_EOL;
  }
  
#endif // !DELTA && defined(Z_DUAL_ENDSTOPS)

#ifdef FWRETRACT

  /**
   * M207: Set firmware retraction values
   *
   *   S[+mm]    retract_length
   *   W[+mm]    retract_length_swap (multi-extruder)
   *   F[mm/min] retract_feedrate
   *   Z[mm]     retract_zlift
   */
  inline void gcode_M207() {
    if (code_seen('S')) retract_length = code_value();
    if (code_seen('F')) retract_feedrate = code_value() / 60;
    if (code_seen('Z')) retract_zlift = code_value();
    #if EXTRUDERS > 1
      if (code_seen('W')) retract_length_swap = code_value();
    #endif
  }

  /**
   * M208: Set firmware un-retraction values
   *
   *   S[+mm]    retract_recover_length (in addition to M207 S*)
   *   W[+mm]    retract_recover_length_swap (multi-extruder)
   *   F[mm/min] retract_recover_feedrate
   */
  inline void gcode_M208() {
    if (code_seen('S')) retract_recover_length = code_value();
    if (code_seen('F')) retract_recover_feedrate = code_value() / 60;
    #if EXTRUDERS > 1
      if (code_seen('W')) retract_recover_length_swap = code_value();
    #endif
  }

  /**
   * M209: Enable automatic retract (M209 S1)
   *       detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
   */
  inline void gcode_M209() {
    if (code_seen('S')) {
      int t = code_value_short();
      switch(t) {
        case 0:
          autoretract_enabled = false;
          break;
        case 1:
          autoretract_enabled = true;
          break;
        default:
          SERIAL_ECHO_START;
          SERIAL_ECHOPGM(MSG_UNKNOWN_COMMAND);
          SERIAL_ECHO(command_queue[cmd_queue_index_r]);
          SERIAL_ECHOLNPGM("\"");
          return;
      }
      for (int i=0; i<EXTRUDERS; i++) retracted[i] = false;
    }
  }

#endif // FWRETRACT

#if EXTRUDERS > 1

  /**
   * M218 - set hotend offset (in mm), T<extruder_number> X<offset_on_X> Y<offset_on_Y>
   */
  inline void gcode_M218() {
    if (setTargetedHotend(218)) return;

    if (code_seen('X')) extruder_offset[X_AXIS][target_extruder] = code_value();
    if (code_seen('Y')) extruder_offset[Y_AXIS][target_extruder] = code_value();

    #ifdef DUAL_X_CARRIAGE
      if (code_seen('Z')) extruder_offset[Z_AXIS][target_extruder] = code_value();
    #endif

    SERIAL_ECHO_START;
    SERIAL_ECHOPGM(MSG_HOTEND_OFFSET);
    for (int e = 0; e < EXTRUDERS; e++) {
      SERIAL_CHAR(' ');
      SERIAL_ECHO(extruder_offset[X_AXIS][e]);
      SERIAL_CHAR(',');
      SERIAL_ECHO(extruder_offset[Y_AXIS][e]);
      #ifdef DUAL_X_CARRIAGE
        SERIAL_CHAR(',');
        SERIAL_ECHO(extruder_offset[Z_AXIS][e]);
      #endif
    }
    SERIAL_EOL;
  }

#endif // EXTRUDERS > 1

/**
 * M220: Set speed percentage factor, aka "Feed Rate" (M220 S95)
 */
inline void gcode_M220() {
  if (code_seen('S')) feedrate_multiplier = code_value();
}

/**
 * M221: Set extrusion percentage (M221 T0 S95)
 */
inline void gcode_M221() {
  if (code_seen('S')) {
    int sval = code_value();
    if (code_seen('T')) {
      if (setTargetedHotend(221)) return;
      extruder_multiply[target_extruder] = sval;
    }
    else {
      extruder_multiply[active_extruder] = sval;
    }
  }
}

/**
 * M226: Wait until the specified pin reaches the state required (M226 P<pin> S<state>)
 */
inline void gcode_M226() {
  if (code_seen('P')) {
    int pin_number = code_value();

    int pin_state = code_seen('S') ? code_value() : -1; // required pin state - default is inverted

    if (pin_state >= -1 && pin_state <= 1) {

      for (int8_t i = 0; i < (int8_t)(sizeof(sensitive_pins)/sizeof(*sensitive_pins)); i++) {
        if (sensitive_pins[i] == pin_number) {
          pin_number = -1;
          break;
        }
      }

      if (pin_number > -1) {
        int target = LOW;

        st_synchronize();

        pinMode(pin_number, INPUT);

        switch(pin_state){
          case 1:
            target = HIGH;
            break;

          case 0:
            target = LOW;
            break;

          case -1:
            target = !digitalRead(pin_number);
            break;
        }

        while(digitalRead(pin_number) != target) {
          manage_heater();
          manage_inactivity();
          lcd_update();
        }

      } // pin_number > -1
    } // pin_state -1 0 1
  } // code_seen('P')
}

#if NUM_SERVOS > 0

  /**
   * M280: Get or set servo position. P<index> S<angle>
   */
  inline void gcode_M280() {
    int servo_index = code_seen('P') ? code_value_short() : -1;
    int servo_position = 0;
    if (code_seen('S')) {
      servo_position = code_value_short();
      if (servo_index >= 0 && servo_index < NUM_SERVOS) {
        Servo *srv = &servo[servo_index];
        #if SERVO_LEVELING
          srv->attach(0);
        #endif
        srv->write(servo_position);
        #if SERVO_LEVELING
          delay(PROBE_SERVO_DEACTIVATION_DELAY);
          srv->detach();
        #endif
      }
      else {
        SERIAL_ECHO_START;
        SERIAL_ECHO("Servo ");
        SERIAL_ECHO(servo_index);
        SERIAL_ECHOLN(" out of range");
      }
    }
    else if (servo_index >= 0) {
      SERIAL_PROTOCOL(MSG_OK);
      SERIAL_PROTOCOL(" Servo ");
      SERIAL_PROTOCOL(servo_index);
      SERIAL_PROTOCOL(": ");
      SERIAL_PROTOCOL(servo[servo_index].read());
      SERIAL_EOL;
    }
  }

#endif // NUM_SERVOS > 0

#if HAS_LCD_BUZZ

  /**
   * M300: Play beep sound S<frequency Hz> P<duration ms>
   */
  inline void gcode_M300() {
    uint16_t beepS = code_seen('S') ? code_value_short() : 110;
    uint32_t beepP = code_seen('P') ? code_value_long() : 1000;
    if (beepP > 5000) beepP = 5000; // limit to 5 seconds
    lcd_buzz(beepP, beepS);
  }

#endif // HAS_LCD_BUZZ

#ifdef PIDTEMP

  /**
   * M301: Set PID parameters P I D (and optionally C)
   */
  inline void gcode_M301() {

    // multi-extruder PID patch: M301 updates or prints a single extruder's PID values
    // default behaviour (omitting E parameter) is to update for extruder 0 only
    int e = code_seen('E') ? code_value() : 0; // extruder being updated

    if (e < EXTRUDERS) { // catch bad input value
      if (code_seen('P')) PID_PARAM(Kp, e) = code_value();
      if (code_seen('I')) PID_PARAM(Ki, e) = scalePID_i(code_value());
      if (code_seen('D')) PID_PARAM(Kd, e) = scalePID_d(code_value());
      #ifdef PID_ADD_EXTRUSION_RATE
        if (code_seen('C')) PID_PARAM(Kc, e) = code_value();
      #endif      

      updatePID();
      SERIAL_PROTOCOL(MSG_OK);
      #ifdef PID_PARAMS_PER_EXTRUDER
        SERIAL_PROTOCOL(" e:"); // specify extruder in serial output
        SERIAL_PROTOCOL(e);
      #endif // PID_PARAMS_PER_EXTRUDER
      SERIAL_PROTOCOL(" p:");
      SERIAL_PROTOCOL(PID_PARAM(Kp, e));
      SERIAL_PROTOCOL(" i:");
      SERIAL_PROTOCOL(unscalePID_i(PID_PARAM(Ki, e)));
      SERIAL_PROTOCOL(" d:");
      SERIAL_PROTOCOL(unscalePID_d(PID_PARAM(Kd, e)));
      #ifdef PID_ADD_EXTRUSION_RATE
        SERIAL_PROTOCOL(" c:");
        //Kc does not have scaling applied above, or in resetting defaults
        SERIAL_PROTOCOL(PID_PARAM(Kc, e));
      #endif
      SERIAL_EOL;    
    }
    else {
      SERIAL_ECHO_START;
      SERIAL_ECHOLN(MSG_INVALID_EXTRUDER);
    }
  }

#endif // PIDTEMP

#ifdef PIDTEMPBED

  inline void gcode_M304() {
    if (code_seen('P')) bedKp = code_value();
    if (code_seen('I')) bedKi = scalePID_i(code_value());
    if (code_seen('D')) bedKd = scalePID_d(code_value());

    updatePID();
    SERIAL_PROTOCOL(MSG_OK);
    SERIAL_PROTOCOL(" p:");
    SERIAL_PROTOCOL(bedKp);
    SERIAL_PROTOCOL(" i:");
    SERIAL_PROTOCOL(unscalePID_i(bedKi));
    SERIAL_PROTOCOL(" d:");
    SERIAL_PROTOCOL(unscalePID_d(bedKd));
    SERIAL_EOL;
  }

#endif // PIDTEMPBED

#if defined(CHDK) || HAS_PHOTOGRAPH

  /**
   * M240: Trigger a camera by emulating a Canon RC-1
   *       See http://www.doc-diy.net/photo/rc-1_hacked/
   */
  inline void gcode_M240() {
    #ifdef CHDK
     
       OUT_WRITE(CHDK, HIGH);
       chdkHigh = millis();
       chdkActive = true;
     
    #elif HAS_PHOTOGRAPH

      const uint8_t NUM_PULSES = 16;
      const float PULSE_LENGTH = 0.01524;
      for (int i = 0; i < NUM_PULSES; i++) {
        WRITE(PHOTOGRAPH_PIN, HIGH);
        _delay_ms(PULSE_LENGTH);
        WRITE(PHOTOGRAPH_PIN, LOW);
        _delay_ms(PULSE_LENGTH);
      }
      delay(7.33);
      for (int i = 0; i < NUM_PULSES; i++) {
        WRITE(PHOTOGRAPH_PIN, HIGH);
        _delay_ms(PULSE_LENGTH);
        WRITE(PHOTOGRAPH_PIN, LOW);
        _delay_ms(PULSE_LENGTH);
      }

    #endif // !CHDK && HAS_PHOTOGRAPH
  }

#endif // CHDK || PHOTOGRAPH_PIN

#ifdef HAS_LCD_CONTRAST

  /**
   * M250: Read and optionally set the LCD contrast
   */
  inline void gcode_M250() {
    if (code_seen('C')) lcd_setcontrast(code_value_short() & 0x3F);
    SERIAL_PROTOCOLPGM("lcd contrast value: ");
    SERIAL_PROTOCOL(lcd_contrast);
    SERIAL_EOL;
  }

#endif // HAS_LCD_CONTRAST

#ifdef PREVENT_DANGEROUS_EXTRUDE

  void set_extrude_min_temp(float temp) { extrude_min_temp = temp; }

  /**
   * M302: Allow cold extrudes, or set the minimum extrude S<temperature>.
   */
  inline void gcode_M302() {
    set_extrude_min_temp(code_seen('S') ? code_value() : 0);
  }

#endif // PREVENT_DANGEROUS_EXTRUDE

/**
 * M303: PID relay autotune
 *       S<temperature> sets the target temperature. (default target temperature = 150C)
 *       E<extruder> (-1 for the bed)
 *       C<cycles>
 */
inline void gcode_M303() {
  int e = code_seen('E') ? code_value_short() : 0;
  int c = code_seen('C') ? code_value_short() : 5;
  float temp = code_seen('S') ? code_value() : (e < 0 ? 70.0 : 150.0);
  PID_autotune(temp, e, c);
}

#ifdef SCARA
  bool SCARA_move_to_cal(uint8_t delta_x, uint8_t delta_y) {
    //SoftEndsEnabled = false;              // Ignore soft endstops during calibration
    //SERIAL_ECHOLN(" Soft endstops disabled ");
    if (IsRunning()) {
      //gcode_get_destination(); // For X Y Z E F
      delta[X_AXIS] = delta_x;
      delta[Y_AXIS] = delta_y;
      calculate_SCARA_forward_Transform(delta);
      destination[X_AXIS] = delta[X_AXIS]/axis_scaling[X_AXIS];
      destination[Y_AXIS] = delta[Y_AXIS]/axis_scaling[Y_AXIS];
      prepare_move();
      //ok_to_send();
      return true;
    }
    return false;
  }

  /**
   * M360: SCARA calibration: Move to cal-position ThetaA (0 deg calibration)
   */
  inline bool gcode_M360() {
    SERIAL_ECHOLN(" Cal: Theta 0 ");
    return SCARA_move_to_cal(0, 120);
  }

  /**
   * M361: SCARA calibration: Move to cal-position ThetaB (90 deg calibration - steps per degree)
   */
  inline bool gcode_M361() {
    SERIAL_ECHOLN(" Cal: Theta 90 ");
    return SCARA_move_to_cal(90, 130);
  }

  /**
   * M362: SCARA calibration: Move to cal-position PsiA (0 deg calibration)
   */
  inline bool gcode_M362() {
    SERIAL_ECHOLN(" Cal: Psi 0 ");
    return SCARA_move_to_cal(60, 180);
  }

  /**
   * M363: SCARA calibration: Move to cal-position PsiB (90 deg calibration - steps per degree)
   */
  inline bool gcode_M363() {
    SERIAL_ECHOLN(" Cal: Psi 90 ");
    return SCARA_move_to_cal(50, 90);
  }

  /**
   * M364: SCARA calibration: Move to cal-position PSIC (90 deg to Theta calibration position)
   */
  inline bool gcode_M364() {
    SERIAL_ECHOLN(" Cal: Theta-Psi 90 ");
    return SCARA_move_to_cal(45, 135);
  }

  /**
   * M365: SCARA calibration: Scaling factor, X, Y, Z axis
   */
  inline void gcode_M365() {
    for (int8_t i = X_AXIS; i <= Z_AXIS; i++) {
      if (code_seen(axis_codes[i])) {
        axis_scaling[i] = code_value();
      }
    }
  }

#endif // SCARA

#ifdef EXT_SOLENOID

  void enable_solenoid(uint8_t num) {
    switch(num) {
      case 0:
        OUT_WRITE(SOL0_PIN, HIGH);
        break;
        #if HAS_SOLENOID_1
          case 1:
            OUT_WRITE(SOL1_PIN, HIGH);
            break;
        #endif
        #if HAS_SOLENOID_2
          case 2:
            OUT_WRITE(SOL2_PIN, HIGH);
            break;
        #endif
        #if HAS_SOLENOID_3
          case 3:
            OUT_WRITE(SOL3_PIN, HIGH);
            break;
        #endif
      default:
        SERIAL_ECHO_START;
        SERIAL_ECHOLNPGM(MSG_INVALID_SOLENOID);
        break;
    }
  }

  void enable_solenoid_on_active_extruder() { enable_solenoid(active_extruder); }

  void disable_all_solenoids() {
    OUT_WRITE(SOL0_PIN, LOW);
    OUT_WRITE(SOL1_PIN, LOW);
    OUT_WRITE(SOL2_PIN, LOW);
    OUT_WRITE(SOL3_PIN, LOW);
  }

  /**
   * M380: Enable solenoid on the active extruder
   */
  inline void gcode_M380() { enable_solenoid_on_active_extruder(); }

  /**
   * M381: Disable all solenoids
   */
  inline void gcode_M381() { disable_all_solenoids(); }

#endif // EXT_SOLENOID

/**
 * M400: Finish all moves
 */
inline void gcode_M400() { st_synchronize(); }

#if defined(ENABLE_AUTO_BED_LEVELING) && !defined(Z_PROBE_SLED) && (defined(SERVO_ENDSTOPS) || defined(Z_PROBE_ALLEN_KEY))

  #ifdef SERVO_ENDSTOPS
    void raise_z_for_servo() {
      float zpos = current_position[Z_AXIS], z_dest = Z_RAISE_BEFORE_HOMING;
      z_dest += axis_known_position[Z_AXIS] ? -zprobe_zoffset : zpos;
      if (zpos < z_dest)
        do_blocking_move_to(current_position[X_AXIS], current_position[Y_AXIS], z_dest); // also updates current_position
    }
  #endif

  /**
   * M401: Engage Z Servo endstop if available
   */
  inline void gcode_M401() {
    #ifdef SERVO_ENDSTOPS
      raise_z_for_servo();
    #endif
    deploy_z_probe();
  }

  /**
   * M402: Retract Z Servo endstop if enabled
   */
  inline void gcode_M402() {
    #ifdef SERVO_ENDSTOPS
      raise_z_for_servo();
    #endif
    stow_z_probe(false);
  }

#endif // ENABLE_AUTO_BED_LEVELING && (SERVO_ENDSTOPS || Z_PROBE_ALLEN_KEY) && !Z_PROBE_SLED

#ifdef FILAMENT_SENSOR

  /**
   * M404: Display or set the nominal filament width (3mm, 1.75mm ) W<3.0>
   */
  inline void gcode_M404() {
    #if HAS_FILWIDTH
      if (code_seen('W')) {
        filament_width_nominal = code_value();
      }
      else {
        SERIAL_PROTOCOLPGM("Filament dia (nominal mm):");
        SERIAL_PROTOCOLLN(filament_width_nominal);
      }
    #endif
  }
    
  /**
   * M405: Turn on filament sensor for control
   */
  inline void gcode_M405() {
    if (code_seen('D')) meas_delay_cm = code_value();
    if (meas_delay_cm > MAX_MEASUREMENT_DELAY) meas_delay_cm = MAX_MEASUREMENT_DELAY;

    if (delay_index2 == -1) { //initialize the ring buffer if it has not been done since startup
      int temp_ratio = widthFil_to_size_ratio();

      for (delay_index1 = 0; delay_index1 < MAX_MEASUREMENT_DELAY + 1; ++delay_index1)
        measurement_delay[delay_index1] = temp_ratio - 100;  //subtract 100 to scale within a signed byte

      delay_index1 = delay_index2 = 0;
    }

    filament_sensor = true;

    //SERIAL_PROTOCOLPGM("Filament dia (measured mm):");
    //SERIAL_PROTOCOL(filament_width_meas);
    //SERIAL_PROTOCOLPGM("Extrusion ratio(%):");
    //SERIAL_PROTOCOL(extruder_multiply[active_extruder]);
  }

  /**
   * M406: Turn off filament sensor for control
   */
  inline void gcode_M406() { filament_sensor = false; }
  
  /**
   * M407: Get measured filament diameter on serial output
   */
  inline void gcode_M407() {
    SERIAL_PROTOCOLPGM("Filament dia (measured mm):"); 
    SERIAL_PROTOCOLLN(filament_width_meas);   
  }

#endif // FILAMENT_SENSOR

/**
 * M410: Quickstop - Abort all planned moves
 *
 * This will stop the carriages mid-move, so most likely they
 * will be out of sync with the stepper position after this.
 */
inline void gcode_M410() { quickStop(); }


#ifdef MESH_BED_LEVELING

  /**
   * M420: Enable/Disable Mesh Bed Leveling
   */
  inline void gcode_M420() { if (code_seen('S') && code_has_value()) mbl.active = !!code_value_short(); }

  /**
   * M421: Set a single Mesh Bed Leveling Z coordinate
   */
  inline void gcode_M421() {
    float x, y, z;
    bool err = false, hasX, hasY, hasZ;
    if ((hasX = code_seen('X'))) x = code_value();
    if ((hasY = code_seen('Y'))) y = code_value();
    if ((hasZ = code_seen('Z'))) z = code_value();

    if (!hasX || !hasY || !hasZ) {
      SERIAL_ERROR_START;
      SERIAL_ERRORLNPGM(MSG_ERR_M421_REQUIRES_XYZ);
      err = true;
    }

    if (x >= MESH_NUM_X_POINTS || y >= MESH_NUM_Y_POINTS) {
      SERIAL_ERROR_START;
      SERIAL_ERRORLNPGM(MSG_ERR_MESH_INDEX_OOB);
      err = true;
    }

    if (!err) mbl.set_z(mbl.select_x_index(x), mbl.select_y_index(y), z);
  }

#endif

/**
 * M428: Set home_offset based on the distance between the
 *       current_position and the nearest "reference point."
 *       If an axis is past center its endstop position
 *       is the reference-point. Otherwise it uses 0. This allows
 *       the Z offset to be set near the bed when using a max endstop.
 *
 *       M428 can't be used more than 2cm away from 0 or an endstop.
 *
 *       Use M206 to set these values directly.
 */
inline void gcode_M428() {
  bool err = false;
  float new_offs[3], new_pos[3];
  memcpy(new_pos, current_position, sizeof(new_pos));
  memcpy(new_offs, home_offset, sizeof(new_offs));
  for (int8_t i = X_AXIS; i <= Z_AXIS; i++) {
    if (axis_known_position[i]) {
      float base = (new_pos[i] > (min_pos[i] + max_pos[i]) / 2) ? base_home_pos(i) : 0,
            diff = new_pos[i] - base;
      if (diff > -20 && diff < 20) {
        new_offs[i] -= diff;
        new_pos[i] = base;
      }
      else {
        SERIAL_ERROR_START;
        SERIAL_ERRORLNPGM(MSG_ERR_M428_TOO_FAR);
        LCD_ALERTMESSAGEPGM("Err: Too far!");
        #if HAS_LCD_BUZZ
          enqueuecommands_P(PSTR("M300 S40 P200"));
        #endif
        err = true;
        break;
      }
    }
  }

  if (!err) {
    memcpy(current_position, new_pos, sizeof(new_pos));
    memcpy(home_offset, new_offs, sizeof(new_offs));
    sync_plan_position();
    LCD_ALERTMESSAGEPGM("Offset applied.");
    #if HAS_LCD_BUZZ
      enqueuecommands_P(PSTR("M300 S659 P200\nM300 S698 P200"));
    #endif
  }
}

/**
 * M500: Store settings in EEPROM
 */
inline void gcode_M500() {
  Config_StoreSettings();
}

/**
 * M501: Read settings from EEPROM
 */
inline void gcode_M501() {
  Config_RetrieveSettings();
}

/**
 * M502: Revert to default settings
 */
inline void gcode_M502() {
  Config_ResetDefault();
}

/**
 * M503: print settings currently in memory
 */
inline void gcode_M503() {
  Config_PrintSettings(code_seen('S') && code_value() == 0);
}

#ifdef ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED

  /**
   * M540: Set whether SD card print should abort on endstop hit (M540 S<0|1>)
   */
  inline void gcode_M540() {
    if (code_seen('S')) abort_on_endstop_hit = (code_value() > 0);
  }

#endif // ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED

#ifdef CUSTOM_M_CODE_SET_Z_PROBE_OFFSET

  inline void gcode_SET_Z_PROBE_OFFSET() {
    float value;
    if (code_seen('Z')) {
      value = code_value();
      if (Z_PROBE_OFFSET_RANGE_MIN <= value && value <= Z_PROBE_OFFSET_RANGE_MAX) {
        zprobe_zoffset = -value;
        SERIAL_ECHO_START;
        SERIAL_ECHOLNPGM(MSG_ZPROBE_ZOFFSET " " MSG_OK);
        SERIAL_EOL;
      }
      else {
        SERIAL_ECHO_START;
        SERIAL_ECHOPGM(MSG_ZPROBE_ZOFFSET);
        SERIAL_ECHOPGM(MSG_Z_MIN);
        SERIAL_ECHO(Z_PROBE_OFFSET_RANGE_MIN);
        SERIAL_ECHOPGM(MSG_Z_MAX);
        SERIAL_ECHO(Z_PROBE_OFFSET_RANGE_MAX);
        SERIAL_EOL;
      }
    }
    else {
      SERIAL_ECHO_START;
      SERIAL_ECHOLNPGM(MSG_ZPROBE_ZOFFSET " : ");
      SERIAL_ECHO(-zprobe_zoffset);
      SERIAL_EOL;
    }
  }

#endif // CUSTOM_M_CODE_SET_Z_PROBE_OFFSET

#ifdef FILAMENTCHANGEENABLE

  /**
   * M600: Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]
   */
  inline void gcode_M600() {
    float target[NUM_AXIS], lastpos[NUM_AXIS], fr60 = feedrate / 60;
    for (int i=0; i<NUM_AXIS; i++)
      target[i] = lastpos[i] = current_position[i];

    #define BASICPLAN plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], fr60, active_extruder);
    #ifdef DELTA
      #define RUNPLAN calculate_delta(target); BASICPLAN
    #else
      #define RUNPLAN BASICPLAN
    #endif

    //retract by E
    if (code_seen('E')) target[E_AXIS] += code_value();
    #ifdef FILAMENTCHANGE_FIRSTRETRACT
      else target[E_AXIS] += FILAMENTCHANGE_FIRSTRETRACT;
    #endif

    RUNPLAN;

    //lift Z
    if (code_seen('Z')) target[Z_AXIS] += code_value();
    #ifdef FILAMENTCHANGE_ZADD
      else target[Z_AXIS] += FILAMENTCHANGE_ZADD;
    #endif

    RUNPLAN;

    //move xy
    if (code_seen('X')) target[X_AXIS] = code_value();
    #ifdef FILAMENTCHANGE_XPOS
      else target[X_AXIS] = FILAMENTCHANGE_XPOS;
    #endif

    if (code_seen('Y')) target[Y_AXIS] = code_value();
    #ifdef FILAMENTCHANGE_YPOS
      else target[Y_AXIS] = FILAMENTCHANGE_YPOS;
    #endif

    RUNPLAN;

    if (code_seen('L')) target[E_AXIS] += code_value();
    #ifdef FILAMENTCHANGE_FINALRETRACT
      else target[E_AXIS] += FILAMENTCHANGE_FINALRETRACT;
    #endif

    RUNPLAN;

    //finish moves
    st_synchronize();
    //disable extruder steppers so filament can be removed
    disable_e0();
    disable_e1();
    disable_e2();
    disable_e3();
    delay(100);
    LCD_ALERTMESSAGEPGM(MSG_FILAMENTCHANGE);
    uint8_t cnt = 0;
    while (!lcd_clicked()) {
      if (++cnt == 0) lcd_quick_feedback(); // every 256th frame till the lcd is clicked
      manage_heater();
      manage_inactivity(true);
      lcd_update();
    } // while(!lcd_clicked)

    //return to normal
    if (code_seen('L')) target[E_AXIS] -= code_value();
    #ifdef FILAMENTCHANGE_FINALRETRACT
      else target[E_AXIS] -= FILAMENTCHANGE_FINALRETRACT;
    #endif

    current_position[E_AXIS] = target[E_AXIS]; //the long retract of L is compensated by manual filament feeding
    plan_set_e_position(current_position[E_AXIS]);

    RUNPLAN; //should do nothing

    lcd_reset_alert_level();

    #ifdef DELTA
      calculate_delta(lastpos);
      plan_buffer_line(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], target[E_AXIS], fr60, active_extruder); //move xyz back
      plan_buffer_line(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], lastpos[E_AXIS], fr60, active_extruder); //final untretract
    #else
      plan_buffer_line(lastpos[X_AXIS], lastpos[Y_AXIS], target[Z_AXIS], target[E_AXIS], fr60, active_extruder); //move xy back
      plan_buffer_line(lastpos[X_AXIS], lastpos[Y_AXIS], lastpos[Z_AXIS], target[E_AXIS], fr60, active_extruder); //move z back
      plan_buffer_line(lastpos[X_AXIS], lastpos[Y_AXIS], lastpos[Z_AXIS], lastpos[E_AXIS], fr60, active_extruder); //final untretract
    #endif        

    #ifdef FILAMENT_RUNOUT_SENSOR
      filrunoutEnqueued = false;
    #endif
    
  }

#endif // FILAMENTCHANGEENABLE

#ifdef DUAL_X_CARRIAGE

  /**
   * M605: Set dual x-carriage movement mode
   *
   *    M605 S0: Full control mode. The slicer has full control over x-carriage movement
   *    M605 S1: Auto-park mode. The inactive head will auto park/unpark without slicer involvement
   *    M605 S2 [Xnnn] [Rmmm]: Duplication mode. The second extruder will duplicate the first with nnn
   *                         millimeters x-offset and an optional differential hotend temperature of
   *                         mmm degrees. E.g., with "M605 S2 X100 R2" the second extruder will duplicate
   *                         the first with a spacing of 100mm in the x direction and 2 degrees hotter.
   *
   *    Note: the X axis should be homed after changing dual x-carriage mode.
   */
  inline void gcode_M605() {
    st_synchronize();
    if (code_seen('S')) dual_x_carriage_mode = code_value();
    switch(dual_x_carriage_mode) {
      case DXC_DUPLICATION_MODE:
        if (code_seen('X')) duplicate_extruder_x_offset = max(code_value(), X2_MIN_POS - x_home_pos(0));
        if (code_seen('R')) duplicate_extruder_temp_offset = code_value();
        SERIAL_ECHO_START;
        SERIAL_ECHOPGM(MSG_HOTEND_OFFSET);
        SERIAL_CHAR(' ');
        SERIAL_ECHO(extruder_offset[X_AXIS][0]);
        SERIAL_CHAR(',');
        SERIAL_ECHO(extruder_offset[Y_AXIS][0]);
        SERIAL_CHAR(' ');
        SERIAL_ECHO(duplicate_extruder_x_offset);
        SERIAL_CHAR(',');
        SERIAL_ECHOLN(extruder_offset[Y_AXIS][1]);
        break;
      case DXC_FULL_CONTROL_MODE:
      case DXC_AUTO_PARK_MODE:
        break;
      default:
        dual_x_carriage_mode = DEFAULT_DUAL_X_CARRIAGE_MODE;
        break;
    }
    active_extruder_parked = false;
    extruder_duplication_enabled = false;
    delayed_move_time = 0;
  }

#endif // DUAL_X_CARRIAGE

/**
 * M907: Set digital trimpot motor current using axis codes X, Y, Z, E, B, S
 */
inline void gcode_M907() {
  #if HAS_DIGIPOTSS
    for (int i=0;i<NUM_AXIS;i++)
      if (code_seen(axis_codes[i])) digipot_current(i, code_value());
    if (code_seen('B')) digipot_current(4, code_value());
    if (code_seen('S')) for (int i=0; i<=4; i++) digipot_current(i, code_value());
  #endif
  #ifdef MOTOR_CURRENT_PWM_XY_PIN
    if (code_seen('X')) digipot_current(0, code_value());
  #endif
  #ifdef MOTOR_CURRENT_PWM_Z_PIN
    if (code_seen('Z')) digipot_current(1, code_value());
  #endif
  #ifdef MOTOR_CURRENT_PWM_E_PIN
    if (code_seen('E')) digipot_current(2, code_value());
  #endif
  #ifdef DIGIPOT_I2C
    // this one uses actual amps in floating point
    for (int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) digipot_i2c_set_current(i, code_value());
    // for each additional extruder (named B,C,D,E..., channels 4,5,6,7...)
    for (int i=NUM_AXIS;i<DIGIPOT_I2C_NUM_CHANNELS;i++) if(code_seen('B'+i-NUM_AXIS)) digipot_i2c_set_current(i, code_value());
  #endif
}

#if HAS_DIGIPOTSS

  /**
   * M908: Control digital trimpot directly (M908 P<pin> S<current>)
   */
  inline void gcode_M908() {
      digitalPotWrite(
        code_seen('P') ? code_value() : 0,
        code_seen('S') ? code_value() : 0
      );
  }

#endif // HAS_DIGIPOTSS

#if HAS_MICROSTEPS

  // M350 Set microstepping mode. Warning: Steps per unit remains unchanged. S code sets stepping mode for all drivers.
  inline void gcode_M350() {
    if(code_seen('S')) for(int i=0;i<=4;i++) microstep_mode(i,code_value());
    for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) microstep_mode(i,(uint8_t)code_value());
    if(code_seen('B')) microstep_mode(4,code_value());
    microstep_readings();
  }

  /**
   * M351: Toggle MS1 MS2 pins directly with axis codes X Y Z E B
   *       S# determines MS1 or MS2, X# sets the pin high/low.
   */
  inline void gcode_M351() {
    if (code_seen('S')) switch(code_value_short()) {
      case 1:
        for(int i=0;i<NUM_AXIS;i++) if (code_seen(axis_codes[i])) microstep_ms(i, code_value(), -1);
        if (code_seen('B')) microstep_ms(4, code_value(), -1);
        break;
      case 2:
        for(int i=0;i<NUM_AXIS;i++) if (code_seen(axis_codes[i])) microstep_ms(i, -1, code_value());
        if (code_seen('B')) microstep_ms(4, -1, code_value());
        break;
    }
    microstep_readings();
  }

#endif // HAS_MICROSTEPS

/**
 * M999: Restart after being stopped
 */
inline void gcode_M999() {
  Running = true;
  lcd_reset_alert_level();
  gcode_LastN = Stopped_gcode_LastN;
  FlushSerialRequestResend();
}

/**
 * T0-T3: Switch tool, usually switching extruders
 *
 *   F[mm/min] Set the movement feedrate
 */
inline void gcode_T() {
  uint16_t tmp_extruder = code_value_short();
  if (tmp_extruder >= EXTRUDERS) {
    SERIAL_ECHO_START;
    SERIAL_CHAR('T');
    SERIAL_ECHO(tmp_extruder);
    SERIAL_ECHOLN(MSG_INVALID_EXTRUDER);
  }
  else {
    target_extruder = tmp_extruder;

    #if EXTRUDERS > 1
      bool make_move = false;
    #endif

    if (code_seen('F')) {

      #if EXTRUDERS > 1
        make_move = true;
      #endif

      float next_feedrate = code_value();
      if (next_feedrate > 0.0) feedrate = next_feedrate;
    }
    #if EXTRUDERS > 1
      if (tmp_extruder != active_extruder) {
        // Save current position to return to after applying extruder offset
        set_destination_to_current();
        #ifdef DUAL_X_CARRIAGE
          if (dual_x_carriage_mode == DXC_AUTO_PARK_MODE && IsRunning() &&
                (delayed_move_time != 0 || current_position[X_AXIS] != x_home_pos(active_extruder))) {
            // Park old head: 1) raise 2) move to park position 3) lower
            plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS] + TOOLCHANGE_PARK_ZLIFT,
                  current_position[E_AXIS], max_feedrate[Z_AXIS], active_extruder);
            plan_buffer_line(x_home_pos(active_extruder), current_position[Y_AXIS], current_position[Z_AXIS] + TOOLCHANGE_PARK_ZLIFT,
                  current_position[E_AXIS], max_feedrate[X_AXIS], active_extruder);
            plan_buffer_line(x_home_pos(active_extruder), current_position[Y_AXIS], current_position[Z_AXIS],
                  current_position[E_AXIS], max_feedrate[Z_AXIS], active_extruder);
            st_synchronize();
          }

          // apply Y & Z extruder offset (x offset is already used in determining home pos)
          current_position[Y_AXIS] = current_position[Y_AXIS] -
                       extruder_offset[Y_AXIS][active_extruder] +
                       extruder_offset[Y_AXIS][tmp_extruder];
          current_position[Z_AXIS] = current_position[Z_AXIS] -
                       extruder_offset[Z_AXIS][active_extruder] +
                       extruder_offset[Z_AXIS][tmp_extruder];

          active_extruder = tmp_extruder;

          // This function resets the max/min values - the current position may be overwritten below.
          axis_is_at_home(X_AXIS);

          if (dual_x_carriage_mode == DXC_FULL_CONTROL_MODE) {
            current_position[X_AXIS] = inactive_extruder_x_pos;
            inactive_extruder_x_pos = destination[X_AXIS];
          }
          else if (dual_x_carriage_mode == DXC_DUPLICATION_MODE) {
            active_extruder_parked = (active_extruder == 0); // this triggers the second extruder to move into the duplication position
            if (active_extruder == 0 || active_extruder_parked)
              current_position[X_AXIS] = inactive_extruder_x_pos;
            else
              current_position[X_AXIS] = destination[X_AXIS] + duplicate_extruder_x_offset;
            inactive_extruder_x_pos = destination[X_AXIS];
            extruder_duplication_enabled = false;
          }
          else {
            // record raised toolhead position for use by unpark
            memcpy(raised_parked_position, current_position, sizeof(raised_parked_position));
            raised_parked_position[Z_AXIS] += TOOLCHANGE_UNPARK_ZLIFT;
            active_extruder_parked = true;
            delayed_move_time = 0;
          }
        #else // !DUAL_X_CARRIAGE
          // Offset extruder (only by XY)
          for (int i=X_AXIS; i<=Y_AXIS; i++)
            current_position[i] += extruder_offset[i][tmp_extruder] - extruder_offset[i][active_extruder];
          // Set the new active extruder and position
          active_extruder = tmp_extruder;
        #endif // !DUAL_X_CARRIAGE
        #ifdef DELTA
          sync_plan_position_delta();
        #else
          sync_plan_position();
        #endif
        // Move to the old position if 'F' was in the parameters
        if (make_move && IsRunning()) prepare_move();
      }

      #ifdef EXT_SOLENOID
        st_synchronize();
        disable_all_solenoids();
        enable_solenoid_on_active_extruder();
      #endif // EXT_SOLENOID

    #endif // EXTRUDERS > 1
    SERIAL_ECHO_START;
    SERIAL_ECHO(MSG_ACTIVE_EXTRUDER);
    SERIAL_PROTOCOLLN((int)active_extruder);
  }
}

/**
 * Process Commands and dispatch them to handlers
 * This is called from the main loop()
 */
void process_next_command() {

  if ((marlin_debug_flags & DEBUG_ECHO)) {
    SERIAL_ECHO_START;
    SERIAL_ECHOLN(command_queue[cmd_queue_index_r]);
  }

  if (code_seen('G')) {

    int codenum = code_value_short();

    switch (codenum) {

    // G0, G1
    case 0:
    case 1:
      gcode_G0_G1();
      break;

    // G2, G3
    #ifndef SCARA
      case 2: // G2  - CW ARC
      case 3: // G3  - CCW ARC
        gcode_G2_G3(codenum == 2);
        break;
    #endif

    // G4 Dwell
    case 4:
      gcode_G4();
      break;

    #ifdef FWRETRACT

      case 10: // G10: retract
      case 11: // G11: retract_recover
        gcode_G10_G11(codenum == 10);
        break;

    #endif //FWRETRACT

    case 28: // G28: Home all axes, one at a time
      gcode_G28();
      break;

    #if defined(ENABLE_AUTO_BED_LEVELING) || defined(MESH_BED_LEVELING)
      case 29: // G29 Detailed Z-Probe, probes the bed at 3 or more points.
        gcode_G29();
        break;
    #endif

    #ifdef ENABLE_AUTO_BED_LEVELING

      #ifndef Z_PROBE_SLED

        case 30: // G30 Single Z Probe
          gcode_G30();
          break;

      #else // Z_PROBE_SLED

          case 31: // G31: dock the sled
          case 32: // G32: undock the sled
            dock_sled(codenum == 31);
            break;

      #endif // Z_PROBE_SLED

    #endif // ENABLE_AUTO_BED_LEVELING

    case 90: // G90
      relative_mode = false;
      break;
    case 91: // G91
      relative_mode = true;
      break;

    case 92: // G92
      gcode_G92();
      break;
    }
  }

  else if (code_seen('M')) {
    switch(code_value_short()) {
      #ifdef ULTIPANEL
        case 0: // M0 - Unconditional stop - Wait for user button press on LCD
        case 1: // M1 - Conditional stop - Wait for user button press on LCD
          gcode_M0_M1();
          break;
      #endif // ULTIPANEL

      case 17:
        gcode_M17();
        break;

      #ifdef SDSUPPORT

        case 20: // M20 - list SD card
          gcode_M20(); break;
        case 21: // M21 - init SD card
          gcode_M21(); break;
        case 22: //M22 - release SD card
          gcode_M22(); break;
        case 23: //M23 - Select file
          gcode_M23(); break;
        case 24: //M24 - Start SD print
          gcode_M24(); break;
        case 25: //M25 - Pause SD print
          gcode_M25(); break;
        case 26: //M26 - Set SD index
          gcode_M26(); break;
        case 27: //M27 - Get SD status
          gcode_M27(); break;
        case 28: //M28 - Start SD write
          gcode_M28(); break;
        case 29: //M29 - Stop SD write
          gcode_M29(); break;
        case 30: //M30 <filename> Delete File
          gcode_M30(); break;
        case 32: //M32 - Select file and start SD print
          gcode_M32(); break;
        case 928: //M928 - Start SD write
          gcode_M928(); break;

      #endif //SDSUPPORT

      case 31: //M31 take time since the start of the SD print or an M109 command
        gcode_M31();
        break;

      case 42: //M42 -Change pin status via gcode
        gcode_M42();
        break;

      #if defined(ENABLE_AUTO_BED_LEVELING) && defined(Z_PROBE_REPEATABILITY_TEST)
        case 48: // M48 Z-Probe repeatability
          gcode_M48();
          break;
      #endif // ENABLE_AUTO_BED_LEVELING && Z_PROBE_REPEATABILITY_TEST

      case 104: // M104
        gcode_M104();
        break;

      case 111: // M111: Set debug level
        gcode_M111();
        break;

      case 112: // M112: Emergency Stop
        gcode_M112();
        break;

      case 140: // M140: Set bed temp
        gcode_M140();
        break;

      case 105: // M105: Read current temperature
        gcode_M105();
        return;
        break;

      case 109: // M109: Wait for temperature
        gcode_M109();
        break;

      #if HAS_TEMP_BED
        case 190: // M190: Wait for bed heater to reach target
          gcode_M190();
          break;
      #endif // HAS_TEMP_BED

      #if HAS_FAN
        case 106: // M106: Fan On
          gcode_M106();
          break;
        case 107: // M107: Fan Off
          gcode_M107();
          break;
      #endif // HAS_FAN

      #ifdef BARICUDA
        // PWM for HEATER_1_PIN
        #if HAS_HEATER_1
          case 126: // M126: valve open
            gcode_M126();
            break;
          case 127: // M127: valve closed
            gcode_M127();
            break;
        #endif // HAS_HEATER_1

        // PWM for HEATER_2_PIN
        #if HAS_HEATER_2
          case 128: // M128: valve open
            gcode_M128();
            break;
          case 129: // M129: valve closed
            gcode_M129();
            break;
        #endif // HAS_HEATER_2
      #endif // BARICUDA

      #if HAS_POWER_SWITCH

        case 80: // M80: Turn on Power Supply
          gcode_M80();
          break;

      #endif // HAS_POWER_SWITCH

      case 81: // M81: Turn off Power, including Power Supply, if possible
        gcode_M81();
        break;

      case 82:
        gcode_M82();
        break;
      case 83:
        gcode_M83();
        break;
      case 18: // (for compatibility)
      case 84: // M84
        gcode_M18_M84();
        break;
      case 85: // M85
        gcode_M85();
        break;
      case 92: // M92: Set the steps-per-unit for one or more axes
        gcode_M92();
        break;
      case 115: // M115: Report capabilities
        gcode_M115();
        break;

      #ifdef ULTIPANEL
        case 117: // M117: Set LCD message text
          gcode_M117();
          break;
      #endif

      case 114: // M114: Report current position
        gcode_M114();
        break;
      case 120: // M120: Enable endstops
        gcode_M120();
        break;
      case 121: // M121: Disable endstops
        gcode_M121();
        break;
      case 119: // M119: Report endstop states
        gcode_M119();
        break;

      #ifdef ULTIPANEL

        case 145: // M145: Set material heatup parameters
          gcode_M145();
          break;

      #endif

      #ifdef BLINKM

        case 150: // M150
          gcode_M150();
          break;

      #endif //BLINKM

      case 200: // M200 D<millimeters> set filament diameter and set E axis units to cubic millimeters (use S0 to set back to millimeters).
        gcode_M200();
        break;
      case 201: // M201
        gcode_M201();
        break;
      #if 0 // Not used for Sprinter/grbl gen6
      case 202: // M202
        gcode_M202();
        break;
      #endif
      case 203: // M203 max feedrate mm/sec
        gcode_M203();
        break;
      case 204: // M204 acclereration S normal moves T filmanent only moves
        gcode_M204();
        break;
      case 205: //M205 advanced settings:  minimum travel speed S=while printing T=travel only,  B=minimum segment time X= maximum xy jerk, Z=maximum Z jerk
        gcode_M205();
        break;
      case 206: // M206 additional homing offset
        gcode_M206();
        break;

      #ifdef DELTA
        case 665: // M665 set delta configurations L<diagonal_rod> R<delta_radius> S<segments_per_sec>
          gcode_M665();
          break;
      #endif

      #if defined(DELTA) || defined(Z_DUAL_ENDSTOPS)
        case 666: // M666 set delta / dual endstop adjustment
          gcode_M666();
          break;
      #endif

      #ifdef FWRETRACT
        case 207: //M207 - set retract length S[positive mm] F[feedrate mm/min] Z[additional zlift/hop]
          gcode_M207();
          break;
        case 208: // M208 - set retract recover length S[positive mm surplus to the M207 S*] F[feedrate mm/min]
          gcode_M208();
          break;
        case 209: // M209 - S<1=true/0=false> enable automatic retract detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
          gcode_M209();
          break;
      #endif // FWRETRACT

      #if EXTRUDERS > 1
        case 218: // M218 - set hotend offset (in mm), T<extruder_number> X<offset_on_X> Y<offset_on_Y>
          gcode_M218();
          break;
      #endif

      case 220: // M220 S<factor in percent>- set speed factor override percentage
        gcode_M220();
        break;

      case 221: // M221 S<factor in percent>- set extrude factor override percentage
        gcode_M221();
        break;

      case 226: // M226 P<pin number> S<pin state>- Wait until the specified pin reaches the state required
        gcode_M226();
        break;

      #if NUM_SERVOS > 0
        case 280: // M280 - set servo position absolute. P: servo index, S: angle or microseconds
          gcode_M280();
          break;
      #endif // NUM_SERVOS > 0

      #if HAS_LCD_BUZZ
        case 300: // M300 - Play beep tone
          gcode_M300();
          break;
      #endif // HAS_LCD_BUZZ

      #ifdef PIDTEMP
        case 301: // M301
          gcode_M301();
          break;
      #endif // PIDTEMP

      #ifdef PIDTEMPBED
        case 304: // M304
          gcode_M304();
          break;
      #endif // PIDTEMPBED

      #if defined(CHDK) || HAS_PHOTOGRAPH
        case 240: // M240  Triggers a camera by emulating a Canon RC-1 : http://www.doc-diy.net/photo/rc-1_hacked/
          gcode_M240();
          break;
      #endif // CHDK || PHOTOGRAPH_PIN

      #ifdef HAS_LCD_CONTRAST
        case 250: // M250  Set LCD contrast value: C<value> (value 0..63)
          gcode_M250();
          break;
      #endif // HAS_LCD_CONTRAST

      #ifdef PREVENT_DANGEROUS_EXTRUDE
        case 302: // allow cold extrudes, or set the minimum extrude temperature
          gcode_M302();
          break;
      #endif // PREVENT_DANGEROUS_EXTRUDE

      case 303: // M303 PID autotune
        gcode_M303();
        break;

      #ifdef SCARA
        case 360:  // M360 SCARA Theta pos1
          if (gcode_M360()) return;
          break;
        case 361:  // M361 SCARA Theta pos2
          if (gcode_M361()) return;
          break;
        case 362:  // M362 SCARA Psi pos1
          if (gcode_M362()) return;
          break;
        case 363:  // M363 SCARA Psi pos2
          if (gcode_M363()) return;
          break;
        case 364:  // M364 SCARA Psi pos3 (90 deg to Theta)
          if (gcode_M364()) return;
          break;
        case 365: // M365 Set SCARA scaling for X Y Z
          gcode_M365();
          break;
      #endif // SCARA

      case 400: // M400 finish all moves
        gcode_M400();
        break;

      #if defined(ENABLE_AUTO_BED_LEVELING) && (defined(SERVO_ENDSTOPS) || defined(Z_PROBE_ALLEN_KEY)) && !defined(Z_PROBE_SLED)
        case 401:
          gcode_M401();
          break;
        case 402:
          gcode_M402();
          break;
      #endif // ENABLE_AUTO_BED_LEVELING && (SERVO_ENDSTOPS || Z_PROBE_ALLEN_KEY) && !Z_PROBE_SLED

      #ifdef FILAMENT_SENSOR
        case 404:  //M404 Enter the nominal filament width (3mm, 1.75mm ) N<3.0> or display nominal filament width
          gcode_M404();
          break;
        case 405:  //M405 Turn on filament sensor for control
          gcode_M405();
          break;
        case 406:  //M406 Turn off filament sensor for control
          gcode_M406();
          break;
        case 407:   //M407 Display measured filament diameter
          gcode_M407();
          break;
      #endif // FILAMENT_SENSOR

      case 410: // M410 quickstop - Abort all the planned moves.
        gcode_M410();
        break;

      #ifdef MESH_BED_LEVELING
        case 420: // M420 Enable/Disable Mesh Bed Leveling
          gcode_M420();
          break;
        case 421: // M421 Set a Mesh Bed Leveling Z coordinate
          gcode_M421();
          break;
      #endif

      case 428: // M428 Apply current_position to home_offset
        gcode_M428();
        break;

      case 500: // M500 Store settings in EEPROM
        gcode_M500();
        break;
      case 501: // M501 Read settings from EEPROM
        gcode_M501();
        break;
      case 502: // M502 Revert to default settings
        gcode_M502();
        break;
      case 503: // M503 print settings currently in memory
        gcode_M503();
        break;

      #ifdef ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED
        case 540:
          gcode_M540();
          break;
      #endif

      #ifdef CUSTOM_M_CODE_SET_Z_PROBE_OFFSET
        case CUSTOM_M_CODE_SET_Z_PROBE_OFFSET:
          gcode_SET_Z_PROBE_OFFSET();
          break;
      #endif // CUSTOM_M_CODE_SET_Z_PROBE_OFFSET

      #ifdef FILAMENTCHANGEENABLE
        case 600: //Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]
          gcode_M600();
          break;
      #endif // FILAMENTCHANGEENABLE

      #ifdef DUAL_X_CARRIAGE
        case 605:
          gcode_M605();
          break;
      #endif // DUAL_X_CARRIAGE

      case 907: // M907 Set digital trimpot motor current using axis codes.
        gcode_M907();
        break;

      #if HAS_DIGIPOTSS
        case 908: // M908 Control digital trimpot directly.
          gcode_M908();
          break;
      #endif // HAS_DIGIPOTSS

      #if HAS_MICROSTEPS

        case 350: // M350 Set microstepping mode. Warning: Steps per unit remains unchanged. S code sets stepping mode for all drivers.
          gcode_M350();
          break;

        case 351: // M351 Toggle MS1 MS2 pins directly, S# determines MS1 or MS2, X# sets the pin high/low.
          gcode_M351();
          break;

      #endif // HAS_MICROSTEPS

      case 999: // M999: Restart after being Stopped
        gcode_M999();
        break;
    }
  }

  else if (code_seen('T')) {
    gcode_T();
  }

  else {
    SERIAL_ECHO_START;
    SERIAL_ECHOPGM(MSG_UNKNOWN_COMMAND);
    SERIAL_ECHO(command_queue[cmd_queue_index_r]);
    SERIAL_ECHOLNPGM("\"");
  }

  ok_to_send();
}

void FlushSerialRequestResend() {
  //char command_queue[cmd_queue_index_r][100]="Resend:";
  MYSERIAL.flush();
  SERIAL_PROTOCOLPGM(MSG_RESEND);
  SERIAL_PROTOCOLLN(gcode_LastN + 1);
  ok_to_send();
}

void ok_to_send() {
  refresh_cmd_timeout();
  #ifdef SDSUPPORT
    if (fromsd[cmd_queue_index_r]) return;
  #endif
  SERIAL_PROTOCOLPGM(MSG_OK);
  #ifdef ADVANCED_OK
    SERIAL_PROTOCOLPGM(" N"); SERIAL_PROTOCOL(gcode_LastN);
    SERIAL_PROTOCOLPGM(" P"); SERIAL_PROTOCOL(int(BLOCK_BUFFER_SIZE - movesplanned() - 1));
    SERIAL_PROTOCOLPGM(" B"); SERIAL_PROTOCOL(BUFSIZE - commands_in_queue);
  #endif
  SERIAL_EOL;  
}

void clamp_to_software_endstops(float target[3]) {
  if (min_software_endstops) {
    NOLESS(target[X_AXIS], min_pos[X_AXIS]);
    NOLESS(target[Y_AXIS], min_pos[Y_AXIS]);
    
    float negative_z_offset = 0;
    #ifdef ENABLE_AUTO_BED_LEVELING
      if (Z_PROBE_OFFSET_FROM_EXTRUDER < 0) negative_z_offset += Z_PROBE_OFFSET_FROM_EXTRUDER;
      if (home_offset[Z_AXIS] < 0) negative_z_offset += home_offset[Z_AXIS];
    #endif
    NOLESS(target[Z_AXIS], min_pos[Z_AXIS] + negative_z_offset);
  }

  if (max_software_endstops) {
    NOMORE(target[X_AXIS], max_pos[X_AXIS]);
    NOMORE(target[Y_AXIS], max_pos[Y_AXIS]);
    NOMORE(target[Z_AXIS], max_pos[Z_AXIS]);
  }
}

#ifdef DELTA

  void recalc_delta_settings(float radius, float diagonal_rod) {
    delta_tower1_x = -SIN_60 * radius;  // front left tower
    delta_tower1_y = -COS_60 * radius;
    delta_tower2_x =  SIN_60 * radius;  // front right tower
    delta_tower2_y = -COS_60 * radius;
    delta_tower3_x = 0.0;               // back middle tower
    delta_tower3_y = radius;
    delta_diagonal_rod_2 = sq(diagonal_rod);
  }

  void calculate_delta(float cartesian[3]) {
    delta[X_AXIS] = sqrt(delta_diagonal_rod_2
                         - sq(delta_tower1_x-cartesian[X_AXIS])
                         - sq(delta_tower1_y-cartesian[Y_AXIS])
                         ) + cartesian[Z_AXIS];
    delta[Y_AXIS] = sqrt(delta_diagonal_rod_2
                         - sq(delta_tower2_x-cartesian[X_AXIS])
                         - sq(delta_tower2_y-cartesian[Y_AXIS])
                         ) + cartesian[Z_AXIS];
    delta[Z_AXIS] = sqrt(delta_diagonal_rod_2
                         - sq(delta_tower3_x-cartesian[X_AXIS])
                         - sq(delta_tower3_y-cartesian[Y_AXIS])
                         ) + cartesian[Z_AXIS];
    /*
    SERIAL_ECHOPGM("cartesian x="); SERIAL_ECHO(cartesian[X_AXIS]);
    SERIAL_ECHOPGM(" y="); SERIAL_ECHO(cartesian[Y_AXIS]);
    SERIAL_ECHOPGM(" z="); SERIAL_ECHOLN(cartesian[Z_AXIS]);

    SERIAL_ECHOPGM("delta x="); SERIAL_ECHO(delta[X_AXIS]);
    SERIAL_ECHOPGM(" y="); SERIAL_ECHO(delta[Y_AXIS]);
    SERIAL_ECHOPGM(" z="); SERIAL_ECHOLN(delta[Z_AXIS]);
    */
  }

  #ifdef ENABLE_AUTO_BED_LEVELING

    // Adjust print surface height by linear interpolation over the bed_level array.
    void adjust_delta(float cartesian[3]) {
      if (delta_grid_spacing[0] == 0 || delta_grid_spacing[1] == 0) return; // G29 not done!

      int half = (AUTO_BED_LEVELING_GRID_POINTS - 1) / 2;
      float h1 = 0.001 - half, h2 = half - 0.001,
            grid_x = max(h1, min(h2, cartesian[X_AXIS] / delta_grid_spacing[0])),
            grid_y = max(h1, min(h2, cartesian[Y_AXIS] / delta_grid_spacing[1]));
      int floor_x = floor(grid_x), floor_y = floor(grid_y);
      float ratio_x = grid_x - floor_x, ratio_y = grid_y - floor_y,
            z1 = bed_level[floor_x + half][floor_y + half],
            z2 = bed_level[floor_x + half][floor_y + half + 1],
            z3 = bed_level[floor_x + half + 1][floor_y + half],
            z4 = bed_level[floor_x + half + 1][floor_y + half + 1],
            left = (1 - ratio_y) * z1 + ratio_y * z2,
            right = (1 - ratio_y) * z3 + ratio_y * z4,
            offset = (1 - ratio_x) * left + ratio_x * right;

      delta[X_AXIS] += offset;
      delta[Y_AXIS] += offset;
      delta[Z_AXIS] += offset;

      /*
      SERIAL_ECHOPGM("grid_x="); SERIAL_ECHO(grid_x);
      SERIAL_ECHOPGM(" grid_y="); SERIAL_ECHO(grid_y);
      SERIAL_ECHOPGM(" floor_x="); SERIAL_ECHO(floor_x);
      SERIAL_ECHOPGM(" floor_y="); SERIAL_ECHO(floor_y);
      SERIAL_ECHOPGM(" ratio_x="); SERIAL_ECHO(ratio_x);
      SERIAL_ECHOPGM(" ratio_y="); SERIAL_ECHO(ratio_y);
      SERIAL_ECHOPGM(" z1="); SERIAL_ECHO(z1);
      SERIAL_ECHOPGM(" z2="); SERIAL_ECHO(z2);
      SERIAL_ECHOPGM(" z3="); SERIAL_ECHO(z3);
      SERIAL_ECHOPGM(" z4="); SERIAL_ECHO(z4);
      SERIAL_ECHOPGM(" left="); SERIAL_ECHO(left);
      SERIAL_ECHOPGM(" right="); SERIAL_ECHO(right);
      SERIAL_ECHOPGM(" offset="); SERIAL_ECHOLN(offset);
      */
    }
  #endif // ENABLE_AUTO_BED_LEVELING

#endif // DELTA

#ifdef MESH_BED_LEVELING

// This function is used to split lines on mesh borders so each segment is only part of one mesh area
void mesh_plan_buffer_line(float x, float y, float z, const float e, float feed_rate, const uint8_t &extruder, uint8_t x_splits=0xff, uint8_t y_splits=0xff)
{
  if (!mbl.active) {
    plan_buffer_line(x, y, z, e, feed_rate, extruder);
    set_current_to_destination();
    return;
  }
  int pix = mbl.select_x_index(current_position[X_AXIS]);
  int piy = mbl.select_y_index(current_position[Y_AXIS]);
  int ix = mbl.select_x_index(x);
  int iy = mbl.select_y_index(y);
  pix = min(pix, MESH_NUM_X_POINTS - 2);
  piy = min(piy, MESH_NUM_Y_POINTS - 2);
  ix = min(ix, MESH_NUM_X_POINTS - 2);
  iy = min(iy, MESH_NUM_Y_POINTS - 2);
  if (pix == ix && piy == iy) {
    // Start and end on same mesh square
    plan_buffer_line(x, y, z, e, feed_rate, extruder);
    set_current_to_destination();
    return;
  }
  float nx, ny, ne, normalized_dist;
  if (ix > pix && (x_splits) & BIT(ix)) {
    nx = mbl.get_x(ix);
    normalized_dist = (nx - current_position[X_AXIS])/(x - current_position[X_AXIS]);
    ny = current_position[Y_AXIS] + (y - current_position[Y_AXIS]) * normalized_dist;
    ne = current_position[E_AXIS] + (e - current_position[E_AXIS]) * normalized_dist;
    x_splits ^= BIT(ix);
  } else if (ix < pix && (x_splits) & BIT(pix)) {
    nx = mbl.get_x(pix);
    normalized_dist = (nx - current_position[X_AXIS])/(x - current_position[X_AXIS]);
    ny = current_position[Y_AXIS] + (y - current_position[Y_AXIS]) * normalized_dist;
    ne = current_position[E_AXIS] + (e - current_position[E_AXIS]) * normalized_dist;
    x_splits ^= BIT(pix);
  } else if (iy > piy && (y_splits) & BIT(iy)) {
    ny = mbl.get_y(iy);
    normalized_dist = (ny - current_position[Y_AXIS])/(y - current_position[Y_AXIS]);
    nx = current_position[X_AXIS] + (x - current_position[X_AXIS]) * normalized_dist;
    ne = current_position[E_AXIS] + (e - current_position[E_AXIS]) * normalized_dist;
    y_splits ^= BIT(iy);
  } else if (iy < piy && (y_splits) & BIT(piy)) {
    ny = mbl.get_y(piy);
    normalized_dist = (ny - current_position[Y_AXIS])/(y - current_position[Y_AXIS]);
    nx = current_position[X_AXIS] + (x - current_position[X_AXIS]) * normalized_dist;
    ne = current_position[E_AXIS] + (e - current_position[E_AXIS]) * normalized_dist;
    y_splits ^= BIT(piy);
  } else {
    // Already split on a border
    plan_buffer_line(x, y, z, e, feed_rate, extruder);
    set_current_to_destination();
    return;
  }
  // Do the split and look for more borders
  destination[X_AXIS] = nx;
  destination[Y_AXIS] = ny;
  destination[E_AXIS] = ne;
  mesh_plan_buffer_line(nx, ny, z, ne, feed_rate, extruder, x_splits, y_splits);
  destination[X_AXIS] = x;
  destination[Y_AXIS] = y;
  destination[E_AXIS] = e;
  mesh_plan_buffer_line(x, y, z, e, feed_rate, extruder, x_splits, y_splits);
}
#endif  // MESH_BED_LEVELING

#ifdef PREVENT_DANGEROUS_EXTRUDE

  inline void prevent_dangerous_extrude(float &curr_e, float &dest_e) {
    float de = dest_e - curr_e;
    if (de) {
      if (degHotend(active_extruder) < extrude_min_temp) {
        curr_e = dest_e; // Behave as if the move really took place, but ignore E part
        SERIAL_ECHO_START;
        SERIAL_ECHOLNPGM(MSG_ERR_COLD_EXTRUDE_STOP);
      }
      #ifdef PREVENT_LENGTHY_EXTRUDE
        if (labs(de) > EXTRUDE_MAXLENGTH) {
          curr_e = dest_e; // Behave as if the move really took place, but ignore E part
          SERIAL_ECHO_START;
          SERIAL_ECHOLNPGM(MSG_ERR_LONG_EXTRUDE_STOP);
        }
      #endif
    }
  }

#endif // PREVENT_DANGEROUS_EXTRUDE

#if defined(DELTA) || defined(SCARA)

  inline bool prepare_move_delta() {
    float difference[NUM_AXIS];
    for (int8_t i=0; i < NUM_AXIS; i++) difference[i] = destination[i] - current_position[i];

    float cartesian_mm = sqrt(sq(difference[X_AXIS]) + sq(difference[Y_AXIS]) + sq(difference[Z_AXIS]));
    if (cartesian_mm < 0.000001) cartesian_mm = abs(difference[E_AXIS]);
    if (cartesian_mm < 0.000001) return false;
    float seconds = 6000 * cartesian_mm / feedrate / feedrate_multiplier;
    int steps = max(1, int(delta_segments_per_second * seconds));

    // SERIAL_ECHOPGM("mm="); SERIAL_ECHO(cartesian_mm);
    // SERIAL_ECHOPGM(" seconds="); SERIAL_ECHO(seconds);
    // SERIAL_ECHOPGM(" steps="); SERIAL_ECHOLN(steps);

    for (int s = 1; s <= steps; s++) {

      float fraction = float(s) / float(steps);

      for (int8_t i = 0; i < NUM_AXIS; i++)
        destination[i] = current_position[i] + difference[i] * fraction;

      calculate_delta(destination);

      #ifdef ENABLE_AUTO_BED_LEVELING
        adjust_delta(destination);
      #endif

      //SERIAL_ECHOPGM("destination[X_AXIS]="); SERIAL_ECHOLN(destination[X_AXIS]);
      //SERIAL_ECHOPGM("destination[Y_AXIS]="); SERIAL_ECHOLN(destination[Y_AXIS]);
      //SERIAL_ECHOPGM("destination[Z_AXIS]="); SERIAL_ECHOLN(destination[Z_AXIS]);
      //SERIAL_ECHOPGM("delta[X_AXIS]="); SERIAL_ECHOLN(delta[X_AXIS]);
      //SERIAL_ECHOPGM("delta[Y_AXIS]="); SERIAL_ECHOLN(delta[Y_AXIS]);
      //SERIAL_ECHOPGM("delta[Z_AXIS]="); SERIAL_ECHOLN(delta[Z_AXIS]);

      plan_buffer_line(delta[X_AXIS], delta[Y_AXIS], delta[Z_AXIS], destination[E_AXIS], feedrate/60*feedrate_multiplier/100.0, active_extruder);
    }
    return true;
  }

#endif // DELTA || SCARA

#ifdef SCARA
  inline bool prepare_move_scara() { return prepare_move_delta(); }
#endif

#ifdef DUAL_X_CARRIAGE

  inline bool prepare_move_dual_x_carriage() {
    if (active_extruder_parked) {
      if (dual_x_carriage_mode == DXC_DUPLICATION_MODE && active_extruder == 0) {
        // move duplicate extruder into correct duplication position.
        plan_set_position(inactive_extruder_x_pos, current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS]);
        plan_buffer_line(current_position[X_AXIS] + duplicate_extruder_x_offset,
          current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], max_feedrate[X_AXIS], 1);
        sync_plan_position();
        st_synchronize();
        extruder_duplication_enabled = true;
        active_extruder_parked = false;
      }
      else if (dual_x_carriage_mode == DXC_AUTO_PARK_MODE) { // handle unparking of head
        if (current_position[E_AXIS] == destination[E_AXIS]) {
          // This is a travel move (with no extrusion)
          // Skip it, but keep track of the current position
          // (so it can be used as the start of the next non-travel move)
          if (delayed_move_time != 0xFFFFFFFFUL) {
            set_current_to_destination();
            NOLESS(raised_parked_position[Z_AXIS], destination[Z_AXIS]);
            delayed_move_time = millis();
            return false;
          }
        }
        delayed_move_time = 0;
        // unpark extruder: 1) raise, 2) move into starting XY position, 3) lower
        plan_buffer_line(raised_parked_position[X_AXIS], raised_parked_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], max_feedrate[Z_AXIS], active_extruder);
        plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], min(max_feedrate[X_AXIS], max_feedrate[Y_AXIS]), active_extruder);
        plan_buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], max_feedrate[Z_AXIS], active_extruder);
        active_extruder_parked = false;
      }
    }
    return true;
  }

#endif // DUAL_X_CARRIAGE

#if !defined(DELTA) && !defined(SCARA)

  inline bool prepare_move_cartesian() {
    // Do not use feedrate_multiplier for E or Z only moves
    if (current_position[X_AXIS] == destination[X_AXIS] && current_position[Y_AXIS] == destination[Y_AXIS]) {
      line_to_destination();
    }
    else {
      #ifdef MESH_BED_LEVELING
        mesh_plan_buffer_line(destination[X_AXIS], destination[Y_AXIS], destination[Z_AXIS], destination[E_AXIS], (feedrate/60)*(feedrate_multiplier/100.0), active_extruder);
        return false;
      #else
        line_to_destination(feedrate * feedrate_multiplier / 100.0);
      #endif
    }
    return true;
  }

#endif // !DELTA && !SCARA

/**
 * Prepare a single move and get ready for the next one
 */
void prepare_move() {
  clamp_to_software_endstops(destination);
  refresh_cmd_timeout();

  #ifdef PREVENT_DANGEROUS_EXTRUDE
    prevent_dangerous_extrude(current_position[E_AXIS], destination[E_AXIS]);
  #endif

  #ifdef SCARA
    if (!prepare_move_scara()) return;
  #elif defined(DELTA)
    if (!prepare_move_delta()) return;
  #endif

  #ifdef DUAL_X_CARRIAGE
    if (!prepare_move_dual_x_carriage()) return;
  #endif

  #if !defined(DELTA) && !defined(SCARA)
    if (!prepare_move_cartesian()) return;
  #endif

  set_current_to_destination();
}

#if HAS_CONTROLLERFAN

  void controllerFan() {
    static millis_t lastMotor = 0;      // Last time a motor was turned on
    static millis_t lastMotorCheck = 0; // Last time the state was checked
    millis_t ms = millis();
    if (ms >= lastMotorCheck + 2500) { // Not a time critical function, so we only check every 2500ms
      lastMotorCheck = ms;
      if (X_ENABLE_READ == X_ENABLE_ON || Y_ENABLE_READ == Y_ENABLE_ON || Z_ENABLE_READ == Z_ENABLE_ON || soft_pwm_bed > 0
        || E0_ENABLE_READ == E_ENABLE_ON // If any of the drivers are enabled...
        #if EXTRUDERS > 1
          || E1_ENABLE_READ == E_ENABLE_ON
          #if HAS_X2_ENABLE
            || X2_ENABLE_READ == X_ENABLE_ON
          #endif
          #if EXTRUDERS > 2
            || E2_ENABLE_READ == E_ENABLE_ON
            #if EXTRUDERS > 3
              || E3_ENABLE_READ == E_ENABLE_ON
            #endif
          #endif
        #endif
      ) {
        lastMotor = ms; //... set time to NOW so the fan will turn on
      }
      uint8_t speed = (lastMotor == 0 || ms >= lastMotor + (CONTROLLERFAN_SECS * 1000UL)) ? 0 : CONTROLLERFAN_SPEED;
      // allows digital or PWM fan output to be used (see M42 handling)
      digitalWrite(CONTROLLERFAN_PIN, speed);
      analogWrite(CONTROLLERFAN_PIN, speed);
    }
  }

#endif // HAS_CONTROLLERFAN

#ifdef SCARA

  void calculate_SCARA_forward_Transform(float f_scara[3]) {
    // Perform forward kinematics, and place results in delta[3]
    // The maths and first version has been done by QHARLEY . Integrated into masterbranch 06/2014 and slightly restructured by Joachim Cerny in June 2014

    float x_sin, x_cos, y_sin, y_cos;

    //SERIAL_ECHOPGM("f_delta x="); SERIAL_ECHO(f_scara[X_AXIS]);
    //SERIAL_ECHOPGM(" y="); SERIAL_ECHO(f_scara[Y_AXIS]);

    x_sin = sin(f_scara[X_AXIS]/SCARA_RAD2DEG) * Linkage_1;
    x_cos = cos(f_scara[X_AXIS]/SCARA_RAD2DEG) * Linkage_1;
    y_sin = sin(f_scara[Y_AXIS]/SCARA_RAD2DEG) * Linkage_2;
    y_cos = cos(f_scara[Y_AXIS]/SCARA_RAD2DEG) * Linkage_2;

    //SERIAL_ECHOPGM(" x_sin="); SERIAL_ECHO(x_sin);
    //SERIAL_ECHOPGM(" x_cos="); SERIAL_ECHO(x_cos);
    //SERIAL_ECHOPGM(" y_sin="); SERIAL_ECHO(y_sin);
    //SERIAL_ECHOPGM(" y_cos="); SERIAL_ECHOLN(y_cos);

    delta[X_AXIS] = x_cos + y_cos + SCARA_offset_x;  //theta
    delta[Y_AXIS] = x_sin + y_sin + SCARA_offset_y;  //theta+phi

    //SERIAL_ECHOPGM(" delta[X_AXIS]="); SERIAL_ECHO(delta[X_AXIS]);
    //SERIAL_ECHOPGM(" delta[Y_AXIS]="); SERIAL_ECHOLN(delta[Y_AXIS]);
  }  

  void calculate_delta(float cartesian[3]){
    //reverse kinematics.
    // Perform reversed kinematics, and place results in delta[3]
    // The maths and first version has been done by QHARLEY . Integrated into masterbranch 06/2014 and slightly restructured by Joachim Cerny in June 2014
    
    float SCARA_pos[2];
    static float SCARA_C2, SCARA_S2, SCARA_K1, SCARA_K2, SCARA_theta, SCARA_psi; 
    
    SCARA_pos[X_AXIS] = cartesian[X_AXIS] * axis_scaling[X_AXIS] - SCARA_offset_x;  //Translate SCARA to standard X Y
    SCARA_pos[Y_AXIS] = cartesian[Y_AXIS] * axis_scaling[Y_AXIS] - SCARA_offset_y;  // With scaling factor.
    
    #if (Linkage_1 == Linkage_2)
      SCARA_C2 = ( ( sq(SCARA_pos[X_AXIS]) + sq(SCARA_pos[Y_AXIS]) ) / (2 * (float)L1_2) ) - 1;
    #else
      SCARA_C2 =   ( sq(SCARA_pos[X_AXIS]) + sq(SCARA_pos[Y_AXIS]) - (float)L1_2 - (float)L2_2 ) / 45000; 
    #endif
    
    SCARA_S2 = sqrt( 1 - sq(SCARA_C2) );
    
    SCARA_K1 = Linkage_1 + Linkage_2 * SCARA_C2;
    SCARA_K2 = Linkage_2 * SCARA_S2;
    
    SCARA_theta = ( atan2(SCARA_pos[X_AXIS],SCARA_pos[Y_AXIS])-atan2(SCARA_K1, SCARA_K2) ) * -1;
    SCARA_psi   =   atan2(SCARA_S2,SCARA_C2);
    
    delta[X_AXIS] = SCARA_theta * SCARA_RAD2DEG;  // Multiply by 180/Pi  -  theta is support arm angle
    delta[Y_AXIS] = (SCARA_theta + SCARA_psi) * SCARA_RAD2DEG;  //       -  equal to sub arm angle (inverted motor)
    delta[Z_AXIS] = cartesian[Z_AXIS];
    
    /*
    SERIAL_ECHOPGM("cartesian x="); SERIAL_ECHO(cartesian[X_AXIS]);
    SERIAL_ECHOPGM(" y="); SERIAL_ECHO(cartesian[Y_AXIS]);
    SERIAL_ECHOPGM(" z="); SERIAL_ECHOLN(cartesian[Z_AXIS]);
    
    SERIAL_ECHOPGM("scara x="); SERIAL_ECHO(SCARA_pos[X_AXIS]);
    SERIAL_ECHOPGM(" y="); SERIAL_ECHOLN(SCARA_pos[Y_AXIS]);
    
    SERIAL_ECHOPGM("delta x="); SERIAL_ECHO(delta[X_AXIS]);
    SERIAL_ECHOPGM(" y="); SERIAL_ECHO(delta[Y_AXIS]);
    SERIAL_ECHOPGM(" z="); SERIAL_ECHOLN(delta[Z_AXIS]);
    
    SERIAL_ECHOPGM("C2="); SERIAL_ECHO(SCARA_C2);
    SERIAL_ECHOPGM(" S2="); SERIAL_ECHO(SCARA_S2);
    SERIAL_ECHOPGM(" Theta="); SERIAL_ECHO(SCARA_theta);
    SERIAL_ECHOPGM(" Psi="); SERIAL_ECHOLN(SCARA_psi);
    SERIAL_EOL;
    */
  }

#endif // SCARA

#ifdef TEMP_STAT_LEDS

  static bool red_led = false;
  static millis_t next_status_led_update_ms = 0;

  void handle_status_leds(void) {
    float max_temp = 0.0;
    if (millis() > next_status_led_update_ms) {
      next_status_led_update_ms += 500; // Update every 0.5s
      for (int8_t cur_extruder = 0; cur_extruder < EXTRUDERS; ++cur_extruder)
         max_temp = max(max(max_temp, degHotend(cur_extruder)), degTargetHotend(cur_extruder));
      #if HAS_TEMP_BED
        max_temp = max(max(max_temp, degTargetBed()), degBed());
      #endif
      bool new_led = (max_temp > 55.0) ? true : (max_temp < 54.0) ? false : red_led;
      if (new_led != red_led) {
        red_led = new_led;
        digitalWrite(STAT_LED_RED, new_led ? HIGH : LOW);
        digitalWrite(STAT_LED_BLUE, new_led ? LOW : HIGH);
      }
    }
  }

#endif

void enable_all_steppers() {
  enable_x();
  enable_y();
  enable_z();
  enable_e0();
  enable_e1();
  enable_e2();
  enable_e3();
}

void disable_all_steppers() {
  disable_x();
  disable_y();
  disable_z();
  disable_e0();
  disable_e1();
  disable_e2();
  disable_e3();
}

/**
 * Manage several activities:
 *  - Check for Filament Runout
 *  - Keep the command buffer full
 *  - Check for maximum inactive time between commands
 *  - Check for maximum inactive time between stepper commands
 *  - Check if pin CHDK needs to go LOW
 *  - Check for KILL button held down
 *  - Check for HOME button held down
 *  - Check if cooling fan needs to be switched on
 *  - Check if an idle but hot extruder needs filament extruded (EXTRUDER_RUNOUT_PREVENT)
 */
void manage_inactivity(bool ignore_stepper_queue/*=false*/) {
  
  #if HAS_FILRUNOUT
    if (IS_SD_PRINTING && !(READ(FILRUNOUT_PIN) ^ FIL_RUNOUT_INVERTING))
      filrunout();
  #endif

  if (commands_in_queue < BUFSIZE - 1) get_command();

  millis_t ms = millis();

  if (max_inactive_time && ms > previous_cmd_ms + max_inactive_time) kill(PSTR(MSG_KILLED));

  if (stepper_inactive_time && ms > previous_cmd_ms + stepper_inactive_time
      && !ignore_stepper_queue && !blocks_queued())
    disable_all_steppers();

  #ifdef CHDK // Check if pin should be set to LOW after M240 set it to HIGH
    if (chdkActive && ms > chdkHigh + CHDK_DELAY) {
      chdkActive = false;
      WRITE(CHDK, LOW);
    }
  #endif

  #if HAS_KILL
    
    // Check if the kill button was pressed and wait just in case it was an accidental
    // key kill key press
    // -------------------------------------------------------------------------------
    static int killCount = 0;   // make the inactivity button a bit less responsive
    const int KILL_DELAY = 750;
    if (!READ(KILL_PIN))
       killCount++;
    else if (killCount > 0)
       killCount--;

    // Exceeded threshold and we can confirm that it was not accidental
    // KILL the machine
    // ----------------------------------------------------------------
    if (killCount >= KILL_DELAY) kill(PSTR(MSG_KILLED));
  #endif

  #if HAS_HOME
    // Check to see if we have to home, use poor man's debouncer
    // ---------------------------------------------------------
    static int homeDebounceCount = 0;   // poor man's debouncing count
    const int HOME_DEBOUNCE_DELAY = 750;
    if (!READ(HOME_PIN)) {
      if (!homeDebounceCount) {
        enqueuecommands_P(PSTR("G28"));
        LCD_MESSAGEPGM(MSG_AUTO_HOME);
      }
      if (homeDebounceCount < HOME_DEBOUNCE_DELAY)
        homeDebounceCount++;
      else
        homeDebounceCount = 0;
    }
  #endif
    
  #if HAS_CONTROLLERFAN
    controllerFan(); // Check if fan should be turned on to cool stepper drivers down
  #endif

  #ifdef EXTRUDER_RUNOUT_PREVENT
    if (ms > previous_cmd_ms + EXTRUDER_RUNOUT_SECONDS * 1000)
    if (degHotend(active_extruder) > EXTRUDER_RUNOUT_MINTEMP) {
      bool oldstatus;
      switch(active_extruder) {
        case 0:
          oldstatus = E0_ENABLE_READ;
          enable_e0();
          break;
        #if EXTRUDERS > 1
          case 1:
            oldstatus = E1_ENABLE_READ;
            enable_e1();
            break;
          #if EXTRUDERS > 2
            case 2:
              oldstatus = E2_ENABLE_READ;
              enable_e2();
              break;
            #if EXTRUDERS > 3
              case 3:
                oldstatus = E3_ENABLE_READ;
                enable_e3();
                break;
            #endif
          #endif
        #endif
      }
      float oldepos = current_position[E_AXIS], oldedes = destination[E_AXIS];
      plan_buffer_line(destination[X_AXIS], destination[Y_AXIS], destination[Z_AXIS],
                      destination[E_AXIS] + EXTRUDER_RUNOUT_EXTRUDE * EXTRUDER_RUNOUT_ESTEPS / axis_steps_per_unit[E_AXIS],
                      EXTRUDER_RUNOUT_SPEED / 60. * EXTRUDER_RUNOUT_ESTEPS / axis_steps_per_unit[E_AXIS], active_extruder);
      current_position[E_AXIS] = oldepos;
      destination[E_AXIS] = oldedes;
      plan_set_e_position(oldepos);
      previous_cmd_ms = ms; // refresh_cmd_timeout()
      st_synchronize();
      switch(active_extruder) {
        case 0:
          E0_ENABLE_WRITE(oldstatus);
          break;
        #if EXTRUDERS > 1
          case 1:
            E1_ENABLE_WRITE(oldstatus);
            break;
          #if EXTRUDERS > 2
            case 2:
              E2_ENABLE_WRITE(oldstatus);
              break;
            #if EXTRUDERS > 3
              case 3:
                E3_ENABLE_WRITE(oldstatus);
                break;
            #endif
          #endif
        #endif
      }
    }
  #endif

  #ifdef DUAL_X_CARRIAGE
    // handle delayed move timeout
    if (delayed_move_time && ms > delayed_move_time + 1000 && IsRunning()) {
      // travel moves have been received so enact them
      delayed_move_time = 0xFFFFFFFFUL; // force moves to be done
      set_destination_to_current();
      prepare_move();
    }
  #endif

  #ifdef TEMP_STAT_LEDS
    handle_status_leds();
  #endif

  check_axes_activity();
}

void kill(const char *lcd_msg) {
  #ifdef ULTRA_LCD
    lcd_setalertstatuspgm(lcd_msg);
  #endif

  cli(); // Stop interrupts
  disable_all_heaters();
  disable_all_steppers();

  #if HAS_POWER_SWITCH
    pinMode(PS_ON_PIN, INPUT);
  #endif

  SERIAL_ERROR_START;
  SERIAL_ERRORLNPGM(MSG_ERR_KILLED);
  
  // FMC small patch to update the LCD before ending
  sei();   // enable interrupts
  for (int i = 5; i--; lcd_update()) delay(200); // Wait a short time
  cli();   // disable interrupts
  suicide();
  while(1) { /* Intentionally left empty */ } // Wait for reset
}

#ifdef FILAMENT_RUNOUT_SENSOR

  void filrunout() {
    if (!filrunoutEnqueued) {
      filrunoutEnqueued = true;
      enqueuecommands_P(PSTR(FILAMENT_RUNOUT_SCRIPT));
      st_synchronize();
    }
  }

#endif // FILAMENT_RUNOUT_SENSOR

#ifdef FAST_PWM_FAN

  void setPwmFrequency(uint8_t pin, int val) {
    val &= 0x07;
    switch (digitalPinToTimer(pin)) {

      #if defined(TCCR0A)
        case TIMER0A:
        case TIMER0B:
             // TCCR0B &= ~(_BV(CS00) | _BV(CS01) | _BV(CS02));
             // TCCR0B |= val;
             break;
      #endif

      #if defined(TCCR1A)
        case TIMER1A:
        case TIMER1B:
             // TCCR1B &= ~(_BV(CS10) | _BV(CS11) | _BV(CS12));
             // TCCR1B |= val;
             break;
      #endif

      #if defined(TCCR2)
        case TIMER2:
        case TIMER2:
             TCCR2 &= ~(_BV(CS10) | _BV(CS11) | _BV(CS12));
             TCCR2 |= val;
             break;
      #endif

      #if defined(TCCR2A)
        case TIMER2A:
        case TIMER2B:
             TCCR2B &= ~(_BV(CS20) | _BV(CS21) | _BV(CS22));
             TCCR2B |= val;
             break;
      #endif

      #if defined(TCCR3A)
        case TIMER3A:
        case TIMER3B:
        case TIMER3C:
             TCCR3B &= ~(_BV(CS30) | _BV(CS31) | _BV(CS32));
             TCCR3B |= val;
             break;
      #endif

      #if defined(TCCR4A)
        case TIMER4A:
        case TIMER4B:
        case TIMER4C:
             TCCR4B &= ~(_BV(CS40) | _BV(CS41) | _BV(CS42));
             TCCR4B |= val;
             break;
      #endif

      #if defined(TCCR5A)
        case TIMER5A:
        case TIMER5B:
        case TIMER5C:
             TCCR5B &= ~(_BV(CS50) | _BV(CS51) | _BV(CS52));
             TCCR5B |= val;
             break;
      #endif

    }
  }

#endif // FAST_PWM_FAN

void Stop() {
  disable_all_heaters();
  if (IsRunning()) {
    Running = false;
    Stopped_gcode_LastN = gcode_LastN; // Save last g_code for restart
    SERIAL_ERROR_START;
    SERIAL_ERRORLNPGM(MSG_ERR_STOPPED);
    LCD_MESSAGEPGM(MSG_STOPPED);
  }
}

bool setTargetedHotend(int code){
  target_extruder = active_extruder;
  if (code_seen('T')) {
    target_extruder = code_value_short();
    if (target_extruder >= EXTRUDERS) {
      SERIAL_ECHO_START;
      switch(code){
        case 104:
          SERIAL_ECHO(MSG_M104_INVALID_EXTRUDER);
          break;
        case 105:
          SERIAL_ECHO(MSG_M105_INVALID_EXTRUDER);
          break;
        case 109:
          SERIAL_ECHO(MSG_M109_INVALID_EXTRUDER);
          break;
        case 218:
          SERIAL_ECHO(MSG_M218_INVALID_EXTRUDER);
          break;
        case 221:
          SERIAL_ECHO(MSG_M221_INVALID_EXTRUDER);
          break;
      }
      SERIAL_ECHOLN(target_extruder);
      return true;
    }
  }
  return false;
}

float calculate_volumetric_multiplier(float diameter) {
  if (!volumetric_enabled || diameter == 0) return 1.0;
  float d2 = diameter * 0.5;
  return 1.0 / (M_PI * d2 * d2);
}

void calculate_volumetric_multipliers() {
  for (int i=0; i<EXTRUDERS; i++)
    volumetric_multiplier[i] = calculate_volumetric_multiplier(filament_size[i]);
}