Configuring Marlin 1.1

Marlin is a huge C++ program composed of many files, but here we’ll only be talking about the two files that contain all of Marlin’s compile-time configuration options:

• Configuration.h contains the core settings for the hardware, language and controller selection, and settings for the most common features and components.
• Configuration_adv.h serves up more detailed customization options, add-ons, experimental features, and other esoterica.

These two files contain all of Marlin’s build-time configuration options. Simply edit or replace these files before building and uploading Marlin to the board. A variety of pre-built configurations are included in the example_configurations folder to get you started.

To use configurations from an earlier version of Marlin, try dropping them into the newer Marlin and building. As part of the build process, the SanityCheck.h will print helpful error messages explaining what needs to be changed.

Compiler Directives

Marlin is configured using C++ compiler directives. This allows Marlin to leverage the C++ preprocessor and include only the code and data needed for the enabled options. This results in the smallest possible binary. A build of Marlin can range from 50K to over 230K in size.

Settings can be enabled, disabled, and assigned values using C preprocessor syntax like so:

#define THIS_IS_ENABLED    // this switch is enabled
//#define THIS_IS_DISABLED // this switch is disabled
#define OPTION_VALUE 22    // this setting is "22"

Sources of Documentation

The most authoritative source on configuration details will always be the configuration files themselves. They provide good descriptions of each option, and are themselves the source for most of the information presented here.

If you’ve never configured and calibrated a RepRap machine before, here are some good resources:

• Calibration
• Calibrating Steps-per-unit
• Prusa’s calculators
• Triffid Hunter’s Calibration Guide
• The Essential Calibration Set
• Calibration of your RepRap
• XY 20 mm Calibration Box
• G-code reference
• Marlin3DprinterTool

Before You Begin

To get your core Configuration.h settings right you’ll need to know the following things about your printer:

• Printer style, such as Cartesian, Delta, CoreXY, or SCARA
• Driver board, such as RAMPS, RUMBA, Teensy, etc.
• Number of extruders
• Steps-per-mm for XYZ axes and extruders (can be tuned later)
• Endstop positions
• Thermistors and/or thermocouples
• Probes and probing settings
• LCD controller brand and model
• Add-ons and custom components

Configuration.h

The core and default settings of Marlin live in the Configuration.h file. Most of these settings are fixed. Once you compile Marlin, that’s it. To change them you need to re-compile. However, several items in Configuration.h only provide defaults -factory settings- that can be changed via the user interface, stored on EEPROM and reloaded or restored to initial values.

This section follows the order of settings as they appear. The order isn’t always logical, so “Search In Page” may be helpful. We’ve tried to keep descriptions brief and to the point. For more detailed information on various topics, please read the main articles and follow the links provided in the option descriptions.

Configuration versioning

#define CONFIGURATION_H_VERSION 010100

Marlin now checks for a configuration version and won’t compile without this setting. If you want to upgrade from an earlier version of Marlin, add this line to your old configuration file. During compilation, Marlin will throw errors explaining what needs to be changed.

Firmware Info

#define STRING_CONFIG_H_AUTHOR "(none, default config)"
#define SHOW_BOOTSCREEN
#define STRING_SPLASH_LINE1 SHORT_BUILD_VERSION // will be shown during bootup in line 1
#define STRING_SPLASH_LINE2 WEBSITE_URL         // will be shown during bootup in line 2

• STRING_CONFIG_H_AUTHOR is shown in the Marlin startup message, and is meant to identify the author (and optional variant) of the firmware. Use this setting as a way to uniquely identify all your custom configurations. The startup message is printed when connecting to host software, and whenever the board reboots.
• SHOW_BOOTSCREEN enables the boot screen for LCD controllers.
• STRING_SPLASH_LINE1 and STRING_SPLASH_LINE2 are shown on the boot screen.

Hardware Info

Serial Port

#define SERIAL_PORT 0

The index of the on-board serial port that will be used for primary host communication. Change this if, for example, you need to connect a wireless adapter to non-default port pins. Serial port 0 will be used by the Arduino bootloader regardless of this setting.

Baud Rate

#define BAUDRATE 115200

The serial communication speed of the printer should be as fast as it can manage without generating errors. In most cases 115200 gives a good balance between speed and stability. Start with 250000 and only go lower if “line number” and “checksum” errors start to appear. Note that some boards (e.g., a temperamental Sanguinololu clone based on the ATMEGA1284P) may not be able to handle a baudrate over 57600. Allowed values: 2400, 9600, 19200, 38400, 57600, 115200, 250000.

Bluetooth

#define BLUETOOTH

Enable the Bluetooth serial interface. For boards based on the AT90USB.

Motherboard

#define MOTHERBOARD BOARD_RAMPS_14_EFB

The most important setting is Marlin is the motherboard. The firmware needs to know what board it will be running on so it can assign the right functions to all pins and take advantage of the full capabilities of the board. Setting this incorrectly will lead to unpredictable results.

Using boards.h as a reference, replace BOARD_RAMPS_14_EFB with your board’s ID. The boards.h file has the most up-to-date listing of supported boards, so check it first if you don’t see yours listed here.

Custom Machine Name

//#define CUSTOM_MACHINE_NAME "3D Printer"

This is the name of your printer as displayed on the LCD and by M115. For example, if you set this to “My Delta” the LCD will display “My Delta ready” when the printer starts up.

Machine UUID

//#define MACHINE_UUID "00000000-0000-0000-0000-000000000000"

A unique ID for your 3D printer. A suitable unique ID can be generated randomly at uuidgenerator.net. Some host programs and slicers may use this identifier to differentiate between specific machines on your network.

Extruder Info

Extruders

#define EXTRUDERS 1

This value, from 1 to 4, defines how many extruders (or E steppers) the printer has. By default Marlin will assume separate nozzles all moving together on a single carriage. If you have a single nozzle, a switching extruder, a mixing extruder, or dual X carriages, specify that below.

This value should be set to the total number of E stepper motors on the machine, even if there’s only a single nozzle.

Filament Diameter

#define DEFAULT_NOMINAL_FILAMENT_DIA 3.00

This is the “nominal” filament diameter as written on the filament spool (1.75, 2.85, 3.0). If you typically use 1.75mm filament, but physically measure the diameter as 1.70mm, you should still use 1.75 if that’s what you have set in your slicer.

This value is used by Marlin to compensate for Filament Width when printing in volumetric mode (See M200), and by the Unified Bed Leveling command G26 when printing a test grid.

You can override this value with M404 W.

Single Nozzle

#define SINGLENOZZLE

Enable SINGLENOZZLE if you have an E3D Cyclops or any other “multi-extruder” system that shares a single nozzle. In a single-nozzle setup, only one filament drive is engaged at a time, and each needs to retract before the next filament can be loaded and begin purging and extruding.

Switching Extruder

//#define SWITCHING_EXTRUDER
#if ENABLED(SWITCHING_EXTRUDER)
  #define SWITCHING_EXTRUDER_SERVO_NR 0
  #define SWITCHING_EXTRUDER_SERVO_ANGLES { 0, 90 } // Angles for E0, E1
#endif

A Switching Extruder is a dual extruder that uses a single stepper motor to drive two filaments, but only one at a time. The servo is used to switch the side of the extruder that will drive the filament. The E motor also reverses direction for the second filament. Set the servo sub-settings above according to your particular extruder’s setup instructions.

Switching Nozzle

//#define SWITCHING_NOZZLE
#if ENABLED(SWITCHING_NOZZLE)
  #define SWITCHING_NOZZLE_SERVO_NR 0
  #define SWITCHING_NOZZLE_SERVO_ANGLES { 0, 90 } // Angles for E0, E1
  //#define HOTEND_OFFSET_Z {0.0, 0.0}
#endif

A Switching Nozzle is a carriage with 2 nozzles. A servo is used to move one of the nozzles up and down. The servo either lowers the active nozzle or raises the inactive one. Set the servo sub-settings above according to your particular extruder’s setup instructions.

Mixing Extruder

/**
 * "Mixing Extruder"
 *   - Adds a new code, M165, to set the current mix factors.
 *   - Extends the stepping routines to move multiple steppers in proportion to the mix.
 *   - Optional support for Repetier Host M163, M164, and virtual extruder.
 *   - This implementation supports only a single extruder.
 *   - Enable DIRECT_MIXING_IN_G1 for Pia Taubert's reference implementation
 */
//#define MIXING_EXTRUDER
#if ENABLED(MIXING_EXTRUDER)
  #define MIXING_STEPPERS 2        // Number of steppers in your mixing extruder
  #define MIXING_VIRTUAL_TOOLS 16  // Use the Virtual Tool method with M163 and M164
  //#define DIRECT_MIXING_IN_G1    // Allow ABCDHI mix factors in G1 movement commands
#endif

A Mixing Extruder uses two or more stepper motors to drive multiple filaments into a mixing chamber, with the mixed filaments extruded from a single nozzle. This option adds the ability to set a mixture, to save mixtures, and to recall mixtures using the T command. The extruder still uses a single E axis, while the current mixture is used to determine the proportion of each filament to use. An “experimental” G1 direct mixing option is included.

Prusa MMU2 (Marlin 2.0)

/**
 * Prusa Multi-Material Unit v2
 *
 * Requires NOZZLE_PARK_FEATURE to park print head in case MMU unit fails.
 * Requires EXTRUDERS = 5
 *
 * For additional configuration see Configuration_adv.h
 */
#define PRUSA_MMU2

Enable support for the Prusa Multi-material unit 2. This requires a free serial port on your printer board. To use the MMU2 you also have to

• enable NOZZLE_PARK_FEATURE
• set EXTRUDERS = 5

All details are configured in Configuration_adv.h.

Hotend Offsets

//#define HOTEND_OFFSET_X {0.0, 20.00} // (in mm) for each extruder, offset of the hotend on the X axis
//#define HOTEND_OFFSET_Y {0.0, 5.00}  // (in mm) for each extruder, offset of the hotend on the Y axis

Hotend offsets are needed if your extruder has more than one nozzle. These values specify the offset from the first nozzle to each nozzle. So the first element is always set to 0.0. The next element corresponds to the next nozzle, and so on. Add more offsets if you have 3 or more nozzles.

Power Supply

#define POWER_SUPPLY 1

Use this option to specify the type of power supply you’re using. Marlin uses this setting to decide how to switch the power supply on and off. The options are None (0), ATX (1), or X-Box 360 (2). For a non-switchable power supply use 0. A common example of this is the power “brick” (like a big laptop power supply). For a PC power supply (ATX) or LED Constant-Voltage Power Supply select 1. These are the most commonly-used power supplies.

//#define PS_DEFAULT_OFF

Enable this if you don’t want the power supply to switch on when you turn on the printer. This is for printers that have dual power supplies. For instance some setups have a separate power supply for the heaters. In this situation you can save power by leaving the power supply off until needed. If you don’t know what this is leave it.

Thermal Settings

Temperature Sensors

#define TEMP_SENSOR_0 5
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_3 0
#define TEMP_SENSOR_4 0
#define TEMP_SENSOR_BED 3

Temperature sensors are vital components in a 3D printer. Fast and accurate sensors ensure that the temperature will be well controlled, to keep plastic flowing smoothly and to prevent mishaps. Use these settings to specify the hotend and bed temperature sensors. Every 3D printer will have a hotend thermistor, and most will have a bed thermistor.

The listing above these options in Configuration.h contains all the thermistors and thermocouples that Marlin knows and supports. Try to match your brand and model with one of the sensors in the list. If no match is found, use a profile for a similar sensor of the same brand, or try “1” – the generic profile. Each profile is calibrated for a particular temperature sensor so it’s important to be as precise as possible.

// Dummy thermistor constant temperature readings, for use with 998 and 999
#define DUMMY_THERMISTOR_998_VALUE 25
#define DUMMY_THERMISTOR_999_VALUE 100

Marlin provides two dummy sensors for testing purposes. Set their constant temperature readings here.

//#define TEMP_SENSOR_1_AS_REDUNDANT
#define MAX_REDUNDANT_TEMP_SENSOR_DIFF 10

Enable this option to use sensor 1 as a redundant sensor for sensor 0. This is an advanced way to protect against temp sensor failure. If the temperature difference between sensors exceeds MAX_REDUNDANT_TEMP_SENSOR_DIFF Marlin will abort the print and disable the heater.

Temperature Stability

#define TEMP_RESIDENCY_TIME 10  // (seconds)
#define TEMP_HYSTERESIS 3       // (degC) range of +/- temperatures considered "close" to the target one
#define TEMP_WINDOW 1           // (degC) Window around target to start the residency timer x degC early.

Extruders must maintain a stable temperature for TEMP_RESIDENCY_TIME before M109 will return success and start the print. Tune what “stable” means using TEMP_HYSTERESIS and TEMP_WINDOW.

#define TEMP_BED_RESIDENCY_TIME 10  // (seconds)
#define TEMP_BED_HYSTERESIS 3       // (degC) range of +/- temperatures considered "close" to the target one
#define TEMP_BED_WINDOW 1           // (degC) Window around target to start the residency timer x degC early.

The bed must maintain a stable temperature for TEMP_BED_RESIDENCY_TIME before M109 will return success and start the print. Tune what “stable” means using TEMP_BED_HYSTERESIS and TEMP_BED_WINDOW.

Temperature Ranges

#define HEATER_0_MINTEMP 5
#define HEATER_1_MINTEMP 5
#define HEATER_2_MINTEMP 5
#define HEATER_3_MINTEMP 5
#define HEATER_4_MINTEMP 5
#define BED_MINTEMP 5

These parameters help prevent the printer from overheating and catching fire. Temperature sensors report abnormally low values when they fail or become disconnected. Set these to the lowest value (in degrees C) that the machine is likely to experience. Indoor temperatures range from 10C-40C, but a value of 0 might be appropriate for an unheated workshop.

If any sensor goes below the minimum temperature set here, Marlin will shut down the printer with a “MINTEMP” error.

#define HEATER_0_MAXTEMP 285
#define HEATER_1_MAXTEMP 275
#define HEATER_2_MAXTEMP 275
#define HEATER_3_MAXTEMP 275
#define HEATER_4_MAXTEMP 275
#define BED_MAXTEMP 130

Maximum temperature for each temperature sensor. If Marlin reads a temperature above these values, it will immediately shut down for safety reasons. For the E3D V6 hotend, many use 285 as a maximum value.

PID

Marlin uses PID (Proportional, Integral, Derivative) control (Wikipedia) to stabilize the dynamic heating system for the hotends and bed. When PID values are set correctly, heaters reach their target temperatures faster, maintain temperature better, and experience less wear over time.

Most vitally, correct PID settings will prevent excessive overshoot, which is a safety hazard. During PID calibration, use the highest target temperature you intend to use (where overshoots are more critical).

See the PID Tuning topic on the RepRap wiki for detailed instructions on M303 auto-tuning. The PID settings should be tuned whenever changing a hotend, temperature sensor, heating element, board, power supply voltage (12v/24v), or anything else related to the high-voltage circuitry.

Hotend PID Options

#define PIDTEMP
#define BANG_MAX 255     // limits current to nozzle while in bang-bang mode; 255=full current
#define PID_MAX BANG_MAX // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 255=full current

Disable PIDTEMP to run extruders in bang-bang mode. Bang-bang is a pure binary mode - the heater is either fully-on or fully-off for a long period. PID control uses higher frequency PWM and (in most cases) is superior for maintaining a stable temperature.

#if ENABLED(PIDTEMP)
  //#define PID_AUTOTUNE_MENU
  //#define PID_DEBUG
  //#define PID_OPENLOOP 1
  //#define SLOW_PWM_HEATERS
  //#define PID_PARAMS_PER_HOTEND
  #define PID_FUNCTIONAL_RANGE 10
  #define K1 0.95

Enable PID_AUTOTUNE_MENU to add an option on the LCD to run an Autotune cycle and automatically apply the result. Enable PID_PARAMS_PER_HOTEND if you have more than one extruder and they are different models.

PID Values

  // Ultimaker
  #define  DEFAULT_Kp 22.2
  #define  DEFAULT_Ki 1.08
  #define  DEFAULT_Kd 114

  // MakerGear
  //#define  DEFAULT_Kp 7.0
  //#define  DEFAULT_Ki 0.1
  //#define  DEFAULT_Kd 12

  // Mendel Parts V9 on 12V
  //#define  DEFAULT_Kp 63.0
  //#define  DEFAULT_Ki 2.25
  //#define  DEFAULT_Kd 440

Sample PID values are included for reference, but they won’t apply to most setups. The PID values you get from M303 may be very different, but will be better for your specific machine.

Bed PID Options

//#define PIDTEMPBED

Enable PIDTEMPBED to use PID for the bed heater (at the same PWM frequency as the extruders). With the default PID_dT the PWM frequency is 7.689Hz, fine for driving a square wave into a resistive load without significant impact on FET heating. This also works fine on a Fotek SSR-10DA Solid State Relay into a 250W heater. If your configuration is significantly different than this and you don’t understand the issues involved, you probably shouldn’t use bed PID until it’s verified that your hardware works. Use M303 E-1 to tune the bed PID for this option.

#define MAX_BED_POWER 255

The max power delivered to the bed. All forms of bed control obey this (PID, bang-bang, bang-bang with hysteresis). Setting this to anything other than 255 enables a form of PWM. As with PIDTEMPBED, don’t enable this unless your bed hardware is ok with PWM.

Bed PID Values

#if ENABLED(PIDTEMPBED)

  //#define PID_BED_DEBUG // Sends debug data to the serial port.

  //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
  //from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, aggressive factor of .15 (vs .1, 1, 10)
  #define  DEFAULT_bedKp 10.00
  #define  DEFAULT_bedKi .023
  #define  DEFAULT_bedKd 305.4

  //120V 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
  //from pidautotune
  //#define  DEFAULT_bedKp 97.1
  //#define  DEFAULT_bedKi 1.41
  //#define  DEFAULT_bedKd 1675.16

  // FIND YOUR OWN: "M303 E-1 C8 S90" to run autotune on the bed at 90 degreesC for 8 cycles.
#endif // PIDTEMPBED

Sample Bed PID values are included for reference, but use the result from M303 E-1 for your specific machine.

Safety

Prevent Cold Extrusion

#define PREVENT_COLD_EXTRUSION
#define EXTRUDE_MINTEMP 170

So-called “cold extrusion” can damage a machine in several ways, but it usually just results in gouged filament and a jammed extruder. With this option, the extruder motor won’t move if the hotend is below the specified temperature. Override this setting with M302 if needed.

Prevent Lengthy Extrude

#define PREVENT_LENGTHY_EXTRUDE
#define EXTRUDE_MAXLENGTH 200

A lengthy extrusion may not damage your machine, but it can be an awful waste of filament. This feature is meant to prevent a typo or glitch in a G1 command from extruding some enormous amount of filament. For Bowden setups, the max length should be set greater than or equal to the load/eject length.

Thermal Protection

#define THERMAL_PROTECTION_HOTENDS // Enable thermal protection for all extruders
#define THERMAL_PROTECTION_BED     // Enable thermal protection for the heated bed

Thermal protection is one of the most vital safety features in Marlin, allowing the firmware to catch a bad situation and shut down heaters before it goes too far. Consider what happens when a thermistor comes loose during printing. The firmware sees a low temperature reading so it keeps the heat on. As long as the temperature reading is low, the hotend will continue to heat up indefinitely, leading to smoke, oozing, a ruined print, and possibly even fire.

Marlin offers two levels of thermal protection:

1. Check that the temperature is actually increasing when a heater is on. If the temperature fails to rise enough within a certain time period (by default, 2 degrees in 20 seconds), the machine will shut down with a “Heating failed” error. This will detect a disconnected, loose, or misconfigured thermistor, or a disconnected heater.
2. Monitor thermal stability. If the measured temperature drifts too far from the target temperature for too long, the machine will shut down with a “Thermal runaway” error. This error may indicate poor contact between thermistor and hot end, poor PID tuning, or a cold environment.

More thermal protection options are located in Configuration_adv.h. In most setups these can be left unchanged, but should be tuned as needed to prevent false positives.

Kinematics

Marlin supports four kinematic motion systems: Cartesian, Core (H-Bot), Delta, and SCARA. Cartesian is the simplest, applying each stepper directly to an axis. CoreXY uses a special belt arrangement to do XY motion, requiring a little extra maths. Delta robots convert the motion of three vertical carriages into XYZ motion in an “effector” attached to the carriages by six arms. SCARA robots move an arm in the XY plane using two angular joints.

CoreXY

//#define COREXY
//#define COREXZ
//#define COREYZ
//#define COREYX
//#define COREZX
//#define COREZY

Enable the option that applies to the specific Core setup. Both normal and reversed options are included for completeness.

Delta

//#define DELTA

For Delta use one of the sample configurations in the example_configurations/delta folder as a starting point.

SCARA

//#define SCARA

For SCARA use the sample configuration in the example_configurations/SCARA folder as a starting point.

Endstops

In open loop systems, endstops are an inexpensive way to establish the actual position of the carriage on all axes. In the procedure known as “homing,” each axis is moved towards one end until the endstop switch is triggered, at which point the machine knows that the axis is at the endstop (home) position. From this point on, the machine “knows” its position by keeping track of how far the steppers have been moved. If the machine gets out of step for any reason, re-homing may be required.

Endstop Plugs

#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

Specify all the endstop connectors that are connected to any endstop or probe. Most printers will use all three min plugs. On delta machines, all the max plugs should be used. Probes can share the Z min plug, or can use one or more of the extra connectors. Don’t enable plugs used for non-endstop and non-probe purposes here.

Endstop Pullups

#define ENDSTOPPULLUPS

#if DISABLED(ENDSTOPPULLUPS)
  // fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined
  //#define ENDSTOPPULLUP_XMAX
  //#define ENDSTOPPULLUP_YMAX
  //#define ENDSTOPPULLUP_ZMAX
  //#define ENDSTOPPULLUP_XMIN
  //#define ENDSTOPPULLUP_YMIN
  //#define ENDSTOPPULLUP_ZMIN
  //#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

By default all endstops have pullup resistors enabled. This is best for NC switches, preventing the values from “floating.” If only some endstops should have pullup resistors, you can disable ENDSTOPPULLUPS and enable pullups individually.

Endstop Inverting

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
#define X_MIN_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.

Use M119 to test if these are set correctly. If an endstop shows up as “TRIGGERED” when not pressed, and “open” when pressed, then it should be inverted here.

Endstop Interrupts

//#define ENDSTOP_INTERRUPTS_FEATURE

Enable this feature if all enabled endstop pins are interrupt-capable. This will remove the need to poll the interrupt pins, saving many CPU cycles.

Movement

Distinct E Factors

//#define DISTINCT_E_FACTORS

Enable DISTINCT_E_FACTORS if your extruders are not all mechanically identical. With this setting you can optionally specify different steps-per-mm, max feedrate, and max acceleration for each extruder.

Default Steps per mm

/**
 * Default Axis Steps Per Unit (steps/mm)
 * Override with M92
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 4000, 500 }

These are the most crucial settings for your printer, as they determine how accurately the steppers will position the axes. Here we’re telling the firmware how many individual steps produce a single millimeter (or degree on SCARA) of movement. These depend on various factors, including belt pitch, number of teeth on the pulley, thread pitch on leadscrews, micro-stepping settings, and extruder style.

A useful trick is to let the compiler do the calculations for you and just supply the raw values. For example:

#define NEMA17_FULL_STEPS 200.0
#define NEMA17_MICROSTEPS 16.0
#define NEMA17_MOTOR_STEPS (NEMA17_FULL_STEPS * NEMA17_MICROSTEPS)
#define PULLEY_PITCH 2.0
#define PULLEY_TEETH 20.0
#define Z_ROD_PITCH 0.8

#define WADE_PULLEY_TEETH 11.0
#define WADE_GEAR_TEETH 45.0
#define HOBBED_BOLT_DIAM 6.0

#define XY_STEPS (NEMA17_MOTOR_STEPS / (PULLEY_PITCH * PULLEY_TEETH))
#define Z_STEPS (NEMA17_MOTOR_STEPS / Z_ROD_PITCH)
#define WADE_GEAR_RATIO (WADE_GEAR_TEETH / WADE_PULLEY_TEETH)
#define HOBBED_BOLD_CIRC (M_PI * HOBBED_BOLT_DIAM)
#define WADE_E_STEPS (NEMA17_MOTOR_STEPS * WADE_GEAR_RATIO / HOBBED_BOLD_CIRC)

#define DEFAULT_AXIS_STEPS_PER_UNIT   { XY_STEPS, XY_STEPS, Z_STEPS, ENG2_E_STEPS }

Default Max Feed Rate

/**
 * Default Max Feed Rate (mm/s)
 * Override with M203
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_FEEDRATE { 500, 500, 2.25, 45 }

In any move, the velocities (in mm/sec) in the X, Y, Z, and E directions will be limited to the corresponding DEFAULT_MAX_FEEDRATE.

Acceleration

Default Max Acceleration

/**
 * Default Max Acceleration (change/s) change = mm/s
 * (Maximum start speed for accelerated moves)
 * Override with M201
 *                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
 */
#define DEFAULT_MAX_ACCELERATION      { 3000, 3000, 100, 10000 }

When the velocity of any axis changes, its acceleration (or deceleration) in mm/s/s is limited by the current max acceleration setting. Also see the jerk settings below, which specify the largest instant speed change that can occur between segments.

A value of 3000 means that an axis may accelerate from 0 to 3000mm/m (50mm/s) within a one second movement.

Jerk sets the floor for accelerated moves. If the change in top speed for a given axis between segments is less than the jerk value for the axis, an instantaneous change in speed may be allowed. Limits placed on other axes also apply. Basically, lower jerk values result in more accelerated moves, which may be near-instantaneous in some cases, depending on the final acceleration determined by the planner.

Default Acceleration

/**
 * Default Acceleration (change/s) change = mm/s
 * Override with M204
 *
 *   M204 P    Acceleration
 *   M204 R    Retract Acceleration
 *   M204 T    Travel Acceleration
 */
#define DEFAULT_ACCELERATION          3000    // X, Y, Z and E acceleration for printing moves
#define DEFAULT_RETRACT_ACCELERATION  3000    // E acceleration for retracts
#define DEFAULT_TRAVEL_ACCELERATION   3000    // X, Y, Z acceleration for travel (non printing) moves

The planner uses the default accelerations set here (or by M204) as the starting values for movement acceleration, and then constrains them further, if needed. There are separate default acceleration values for printing moves, retraction moves, and travel moves.

• Printing moves include E plus at least one of the XYZ axes.
• Retraction moves include only the E axis.
• Travel moves include only the XYZ axes.

In print/travel moves, DEFAULT_ACCELERATION and DEFAULT_TRAVEL_ACCELERATION apply to the XYZ axes. In retraction moves, DEFAULT_RETRACT_ACCELERATION applies only to the E-axis. During movement planning, Marlin constrains the default accelerations to the maximum acceleration of all axes involved in the move.

Jerk

/**
 * Default Jerk (mm/s)
 * Override with M205 X Y Z E
 *
 * "Jerk" specifies the minimum speed change that requires acceleration.
 * When changing speed and direction, if the difference is less than the
 * value set here, it may happen instantaneously.
 */
#define DEFAULT_XJERK                 20.0
#define DEFAULT_YJERK                 20.0
#define DEFAULT_ZJERK                  0.4
#define DEFAULT_EJERK                  5.0

Jerk works in conjunction with acceleration (see above). Jerk is the maximum change in velocity (in mm/sec) that can occur instantaneously. It can also be thought of as the minimum change in velocity that will be done as an accelerated (not instantaneous) move.

Both acceleration and jerk affect your print quality. If jerk is too low, the extruder will linger too long on small segments and corners, possibly leaving blobs. If the jerk is set too high, direction changes will apply too much torque and you may see “ringing” artifacts or dropped steps.

Z Probe Options

Probe Pins

//#define Z_MIN_PROBE_ENDSTOP

Use this option if you’ve connected the probe to a pin other than the Z MIN endstop pin. With this option enabled, by default Marlin will use the Z_MIN_PROBE_PIN specified in your board’s pins file (usually the X or Z MAX endstop pin since these are the most likely to be unused). If you need to use a different pin, define your custom pin number for Z_MIN_PROBE_PIN in Configuration.h.

#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN

Use this option in all cases when the probe is connected to the Z MIN endstop plug. This option is used for DELTA robots, which always home to MAX, and may be used in other setups.

You can use this option to configure a machine with no Z endstops. In that case the probe will be used to home Z and you will need to enable Z_SAFE_HOMING to ensure that the probe is positioned over the bed when homing the Z axis - done after X and Y.

Probe Type

Marlin supports any kind of probe that can be made to work like a switch. Specific types of probes have different needs.

Manual Probe (no probe)

//#define PROBE_MANUALLY

Even if you have no bed probe you can still use any of the core AUTO_BED_LEVELING_* options below by selecting this option. With PROBE_MANUALLY the G29 command only moves the nozzle to the next probe point where it pauses. You adjust the Z height with a piece of paper or feeler gauge, then send G29 again to continue to the next point. You can also enable LCD_BED_LEVELING to add a “Level Bed” Menu item to the LCD for a fully interactive leveling process.

Fix Mounted Probe

//#define FIX_MOUNTED_PROBE

This option is for any probe that’s fixed in place, with no need to be deployed or stowed. Specify this type for an inductive probe or when using the nozzle itself as the probe.

BLTouch

//#define BLTOUCH

The ANTCLABS BLTouch probe uses custom circuitry and a magnet to raise and lower a metal pin which acts as a touch probe. The BLTouch uses the servo connector and is controlled using specific servo angles. With this option enabled the other required settings are automatically configured (so there’s no need to enter servo angles, for example).

Servo Z Probe

//#define Z_ENDSTOP_SERVO_NR 0
//#define Z_SERVO_ANGLES {70,0} // Z Servo Deploy and Stow angles

To indicate a Servo Z Probe (e.g., an endstop switch mounted on a rotating arm) just specify the servo index. Use the M280 command to find the best Z_SERVO_ANGLES values.

Solenoid Probe

//#define SOLENOID_PROBE

A probe that is deployed and stowed with a solenoid pin (Defined as SOL1_PIN.)

Z Probe Sled

//#define Z_PROBE_SLED
//#define SLED_DOCKING_OFFSET 5

This type of probe is mounted on a detachable “sled” that sits at the far end of the X axis. Before probing, the X carriage moves to the far end and picks up the sled. When probing is completed, it drops the sled off. The SLED_DOCKING_OFFSET specifies the extra distance the X axis must travel to pickup the sled. 0 should be fine but it may be pushed further if needed.

See the Prusa i3 Z-probe Sled Mount for an example of this kind of probe.

Allen Key

//#define Z_PROBE_ALLEN_KEY

A retractable z-probe for deltas that uses an Allen key as the probe. See “Kossel automatic bed leveling probe” at the RepRap wiki. It deploys by leveraging against the z-axis belt, and retracts by pushing the probe down.

More information will be included in an upcoming Delta configuration page.

Probe Offsets

#define X_PROBE_OFFSET_FROM_EXTRUDER -44  // X offset: -left  [of the nozzle] +right
#define Y_PROBE_OFFSET_FROM_EXTRUDER -8  // Y offset: -front [of the nozzle] +behind
#define Z_PROBE_OFFSET_FROM_EXTRUDER -2.50   // Z offset: -below [the nozzle](for most negative! positive when using tilt probes or the nozzle based probes)

These offsets specify the distance from the tip of the nozzle to the probe — or more precisely, to the point at which the probe triggers. The X and Y offsets are specified as integers. The Z offset should be specified as exactly as possible using a decimal value. The Z offset can be overridden with M851 Z or the LCD controller. The M851 offset is saved to EEPROM with M500.

Probing Speed

// X and Y axis travel speed (mm/m) between probes
#define XY_PROBE_SPEED 4000
// Speed for the first approach when double-probing (with PROBE_DOUBLE_TOUCH)
#define Z_PROBE_SPEED_FAST HOMING_FEEDRATE_Z
// Speed for the "accurate" probe of each point
#define Z_PROBE_SPEED_SLOW (Z_PROBE_SPEED_FAST / 2)

Probing should be done quickly, but the Z speed should be tuned for best repeatability. Depending on the probe, a slower Z probing speed may be needed for repeatable results.

Probe Double Touch

// Use double touch for probing
//#define PROBE_DOUBLE_TOUCH

Some probes may be more accurate with this option, which causes all probes to be done twice — first fast, then slow. The second result is used as the measured Z position.

Probe Clearance

#define Z_CLEARANCE_DEPLOY_PROBE   10 // Z Clearance for Deploy/Stow
#define Z_CLEARANCE_BETWEEN_PROBES  5 // Z Clearance between probe points

Z probes require clearance when deploying, stowing, and moving between probe points to avoid hitting the bed and other hardware. Servo-mounted probes require extra space for the arm to rotate. Inductive probes need space to keep from triggering early.

Use these settings to specify the distance (mm) to raise the probe (or lower the bed). The values set here apply over and above any (negative) probe Z Offset set with Z_PROBE_OFFSET_FROM_EXTRUDER, M851, or the LCD. Only integer values >= 1 are valid for these settings.

• Example: M851 Z-5 with a CLEARANCE of 4 => 9mm from bed to nozzle.
• But: M851 Z+1 with a CLEARANCE of 2 => 2mm from bed to nozzle.

#define Z_PROBE_OFFSET_RANGE_MIN -20
#define Z_PROBE_OFFSET_RANGE_MAX 20

For M851 and LCD menus give a range for adjusting the Z probe offset.

Probe Testing

#define Z_MIN_PROBE_REPEATABILITY_TEST

This enables you to test the reliability of your probe. Issue a M48 command to start testing. It will give you a standard deviation for the probe. Tip: 0.02 mm is normally acceptable for bed leveling to work.

Stepper Drivers

Motor Enable

#define X_ENABLE_ON 0
#define Y_ENABLE_ON 0
#define Z_ENABLE_ON 0
#define E_ENABLE_ON 0 // For all extruders

These options set the pin states used for stepper enable. The most common setting is 0 (LOW) for Active Low. For Active High use 1 or HIGH.

Motor Disable

#define DISABLE_X false
#define DISABLE_Y false
#define DISABLE_Z false

Use these options to disable steppers when not being issued a movement. This was implemented as a hack to run steppers at higher-than-normal current in an effort to produce more torque at the cost of increased heat for drivers and steppers.

Disabling the steppers between moves gives the motors and drivers a chance to cool off. It sounds good in theory, but in practice it has drawbacks. Disabled steppers can’t hold the carriage stable. This results in poor accuracy and carries a strong probability of axial drift (i.e., lost steps).

Most 3D printers use an “open loop” control system, meaning the software can’t ascertain the actual carriage position at a given time. It simply sends commands and assumes they have been obeyed. In practice with a well-calibrated machine this is not an issue and using open loop is a major cost saving with excellent quality.

We don’t recommend this hack. There are much better ways to address the problem of stepper/driver overheating. Some examples: stepper/driver heatsink, active cooling, dual motors on the axis, reduce microstepping, check belt for over tension, check components for smooth motion, etc.

//#define DISABLE_REDUCED_ACCURACY_WARNING

Enable this option to suppress the warning given in cases when reduced accuracy is likely to occur.

#define DISABLE_E false // For all extruders
#define DISABLE_INACTIVE_EXTRUDER true //disable only inactive extruders and keep active extruder enabled

The E disable option works like DISABLE_[XYZ] but pertains to one or more extruders. The default setting keeps the active extruder enabled, disabling all inactive extruders. This is reasonable for situations where a “wipe tower” or other means is used to ensure that the nozzle is primed and not oozing between uses.

Motor Direction

#define INVERT_X_DIR true
#define INVERT_Y_DIR false
#define INVERT_Z_DIR true

#define INVERT_E0_DIR false
#define INVERT_E1_DIR false
#define INVERT_E2_DIR false
#define INVERT_E3_DIR false
#define INVERT_E4_DIR false

These settings reverse the motor direction for each axis. Be careful when first setting these. Axes moving the wrong direction can cause damage. Get these right without belts attached first, if possible. Before testing, move the carriage and bed to the middle. Test each axis for proper movemnt using the host or LCD “Move Axis” menu. If an axis is inverted, either flip the plug around or change its invert setting.

Toshiba Drivers

// Enable this option for Toshiba stepper drivers
//#define CONFIG_STEPPERS_TOSHIBA

Leave this option disabled for typical stepper drivers such as A4988 or DVR8825.

Homing and Bounds

Z Homing Height

//#define Z_HOMING_HEIGHT 4

This value raises Z to the specified height above the bed before homing X or Y. This is useful to prevent the head crashing into bed mountings such as screws, bulldog clips, etc. This also works with auto bed leveling enabled and will be triggered only when the Z axis height is less than the defined value, otherwise the Z axis will not move.

Homing Direction

#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

Homing direction for each axis: -1 = min, 1 = max. Most cartesian and core machines have three min endstops. Deltas have three max endstops. For other configurations set these values appropriately.

Software Endstops

#define MIN_SOFTWARE_ENDSTOPS
#define MAX_SOFTWARE_ENDSTOPS

Set to true to enable the option to constrain movement to the physical boundaries of the machine (as set by [XYZ]_(MIN|MAX)_POS). For example, G1 Z-100 can be min constrained to G1 Z0. It is recommended to enable these options as a safety feature. If software endstops need to be disabled, use M211 S0.

Movement Bounds

#define X_BED_SIZE 200
#define Y_BED_SIZE 200

With Marlin 1.1.5 and up you can directly specify the bed size. This allows Marlin to do extra logic related to the bed size when it differs from the movement limits below. If the XY carriage is able to move outside of the bed, you can specify a wider range below.

#define X_MIN_POS 0
#define Y_MIN_POS 0
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 170

These values specify the physical limits of the machine. Usually the [XYZ]_MIN_POS values are set to 0, because endstops are positioned at the bed limits. [XYZ]_MAX_POS should be set to the farthest reachable point. By default, these are used as your homing positions as well. However, the MANUAL_[XYZ]_HOME_POS options can be used to override these, if needed.

Filament Runout Sensor

//#define FILAMENT_RUNOUT_SENSOR
#if ENABLED(FILAMENT_RUNOUT_SENSOR)
  #define FIL_RUNOUT_INVERTING false // set to true to invert the logic of the sensor.
  #define ENDSTOPPULLUP_FIL_RUNOUT // Uncomment to use internal pullup for filament runout pins if the sensor is defined.
  #define FILAMENT_RUNOUT_SCRIPT "M600"
#endif

With this feature, a mechanical or opto endstop switch is used to check for the presence of filament in the feeder (usually the switch is closed when filament is present). If the filament runs out, Marlin will run the specified GCode script (by default “M600”). RAMPS-based boards use SERVO3_PIN. For other boards you may need to define FIL_RUNOUT_PIN.

Bed Leveling

There are many cases where it’s useful to measure variances in bed height. Even if the bed on a 3D printer is perfectly flat and level, there may still be imperfections in the mechanics. For example, a machine may have a very flat bed, but a corner of the XY gantry is a half-mm high. The ends of the Z axis may not be perfectly level. The bed may move slightly in the Z plane as it moves in the X and/or Y plane. On a Delta there may be a lingering bowl-shape to its XY trajectory.

Bed Compensation or “— Bed Leveling” allows the machine —with a bed probe or user assistance— to take accurate measurements of the “bed height” at various points in the XY plane. With this data the machine can then adjust movement to align better to the tilt or “height” variances in the bed. (I’m scare-quoting “height” here because variances may come from other than the bed.)

For more details on these features, see G29 for MBL and G29 for ABL.

Debug Leveling

//#define DEBUG_LEVELING_FEATURE

Use this option to enable extra debugging of homing and leveling. You can then use M111 S32 before issuing G28 and G29 V4 to get a detailed log of the process for diagnosis. This option is useful to figure out the cause of unexpected behaviors, or when reporting issues to the project.

G26 Mesh Validation Pattern

/**
 * Enable the G26 Mesh Validation Pattern tool.
 */
#define G26_MESH_VALIDATION   // Enable G26 mesh validation
#if ENABLED(G26_MESH_VALIDATION)
  #define MESH_TEST_NOZZLE_SIZE     0.4   // (mm) Diameter of primary nozzle.
  #define MESH_TEST_LAYER_HEIGHT    0.2   // (mm) Default layer height for the G26 Mesh Validation Tool.
  #define MESH_TEST_HOTEND_TEMP   205.0   // (°C) Default nozzle temperature for the G26 Mesh Validation Tool.
  #define MESH_TEST_BED_TEMP       60.0   // (°C) Default bed temperature for the G26 Mesh Validation Tool.
#endif

When using any of the mesh-based leveling systems (1.1.7) you can activate G26_MESH_VALIDATION to print test patterns and fine-tune the mesh. See G26 Mesh Validation for full details. The G26 command accepts parameters for nozzle size, layer height, etc. The sub-options above specify the default values that will be applied for omitted parameters.

Leveling Fade Height

#define ENABLE_LEVELING_FADE_HEIGHT

Available with MESH_BED_LEVELING, AUTO_BED_LEVELING_BILINEAR, and AUTO_BED_LEVELING_UBL.

This option adds the Z parameter to M420 which sets a fade distance over which leveling will be gradually reduced. Above the given Z height, leveling compensation will no longer be applied.

This feature exists to prevent irregularities in the bed from propagating through the model’s entire height. Fading out leveling also reduces computational requirements and resonance from the Z axis above the fade height. For a well-aligned machine, this feature can improve print results.

Example: To have leveling fade out over the first 10mm of layer printing use M420 Z10. If each layer is 0.2mm high, leveling compensation will be reduced by 1/50th (2%) after each layer. Above 10mm the machine will move without compensation.

Bed Leveling Style

Bed Leveling is a standard feature on many 3D printers. It takes the guess-work out of getting a good first layer and good bed adhesion. All forms of bed leveling add G29 Bed Probing, M420 enable/disable, and can save their results to EEPROM with M500. Bravo!

With Bed Leveling enabled:

• G28 disables bed leveling, but leaves previous leveling data intact.
• G29 automatically or manually probes the bed at various points, measures the bed height, calculates a correction grid or matrix, and turns on leveling compensation. Specific behavior depends on configuration and type of bed leveling.
• M500 saves the bed leveling data to EEPROM. Use M501 to load it, M502 to clear it, and M503 to report it.
• M420 S<bool> can be used to enable/disable bed leveling. For example, M420 S1 must be used after M501 to enable the loaded mesh or matrix, and to re-enable leveling after G28, which disables leveling compensation.
• A “Level Bed” menu item can be added to the LCD with the LCD_BED_LEVELING option.

//#define AUTO_BED_LEVELING_3POINT
//#define AUTO_BED_LEVELING_LINEAR
//#define AUTO_BED_LEVELING_BILINEAR
//#define AUTO_BED_LEVELING_UBL
//#define MESH_BED_LEVELING

Enable just one type of Bed Leveling.

• AUTO_BED_LEVELING_3POINT probes three points in a triangle. The flat plane gives a transform matrix suitable to compensate for a flat but tilted bed.
• AUTO_BED_LEVELING_LINEAR probes the bed in a grid. A transform matrix is produced by least-squares method to compensate for a flat but tilted bed.
• AUTO_BED_LEVELING_BILINEAR probes the bed in a grid, with optional Catmull-Rom subdivision. The mesh data is used to adjust Z height across the bed using bilinear interpolation. Good for delta, large, or uneven beds.
• AUTO_BED_LEVELING_UBL (recommended) combines the features of 3-point, linear, bilinear, and mesh leveling. As with bilinear leveling, the mesh data generated by UBL is used to adjust Z height across the bed using bilinear interpolation. An LCD controller is currently required.
• MESH_BED_LEVELING provides a custom G29 command to measure the bed height at several grid points using a piece of paper or feeler gauge. See G29 for MBL for the full procedure. This type of leveling is only compatible with PROBE_MANUALLY.

Linear / Bilinear Options

#define LEFT_PROBE_BED_POSITION 15
#define RIGHT_PROBE_BED_POSITION 145
#define FRONT_PROBE_BED_POSITION 20
#define BACK_PROBE_BED_POSITION 150

These settings specify the boundaries for probing with G29. This will most likely be a sub-section of the bed because probes are not usually able to reach every point that the nozzle can. Take account of the probe’s XY offsets when setting these boundaries.

#define GRID_MAX_POINTS_X 3
#define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

These options specify the default number of points to probe in each dimension during G29.

//#define PROBE_Y_FIRST

Enable this option if probing should proceed in the Y dimension first instead of X first.

Bilinear Options

//#define EXTRAPOLATE_BEYOND_GRID

Usually the probed grid doesn’t extend all the way to the edges of the bed. So, outside the bounds of the probed grid, Z adjustment can take one of two approaches. Either the Z height can continue to raise/lower by the established tilt of the nearest grid box (best when most of the bed was probed), or it can follow the contour of the nearest edge (the default). Enable this option for extrapolation.

//#define ABL_BILINEAR_SUBDIVISION
#if ENABLED(ABL_BILINEAR_SUBDIVISION)
  // Number of subdivisions between probe points
  #define BILINEAR_SUBDIVISIONS 3
#endif

If you have SRAM to spare, this option will multiply the resolution of the bilinear grid using the Catmull-Rom subdivision method. This option only applies to bilinear leveling. If the default value of 3 is too expensive, try 2 or 1. (In Marlin 1.1.1, the default grid will be stored in PROGMEM, as UBL now does.)

3-Point Options

#define ABL_PROBE_PT_1_X 15
#define ABL_PROBE_PT_1_Y 180
#define ABL_PROBE_PT_2_X 15
#define ABL_PROBE_PT_2_Y 20
#define ABL_PROBE_PT_3_X 170
#define ABL_PROBE_PT_3_Y 20

These options specify the three points that will be probed during G29.

Unified Bed Leveling Options

Probe Points

#define UBL_MESH_INSET 1          // Mesh inset margin on print area
#define GRID_MAX_POINTS_X 10      // Don't use more than 15 points per axis, implementation limited.
#define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X
#define UBL_PROBE_PT_1_X 39       // These set the probe locations for when UBL does a 3-Point leveling
#define UBL_PROBE_PT_1_Y 180      // of the mesh.
#define UBL_PROBE_PT_2_X 39
#define UBL_PROBE_PT_2_Y 20
#define UBL_PROBE_PT_3_X 180
#define UBL_PROBE_PT_3_Y 20

These options specify the inset, grid, and 3-point triangle to use for UBL. Note that probe XY offsets and movement limits may constrain the probeable area of the bed.

Mesh Bed Leveling Options

#define MESH_INSET 10          // Mesh inset margin on print area
#define GRID_MAX_POINTS_X 3    // Don't use more than 7 points per axis, implementation limited.
#define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

//#define MESH_G28_REST_ORIGIN // After homing all axes ('G28' or 'G28 XYZ') rest Z at Z_MIN_POS

These options specify the number of points that will always be probed in each dimension during G29. The mesh inset is used to automatically calculate the probe boundaries. These can be set explicitly in Configuration_adv.h. MESH_G28_REST_ORIGIN moves the nozzle to rest at Z_MIN_POS when mesh probing is done. If Z is offset (e.g., due to home_offset or some other cause) this is intended to move Z to a good starting point, usually Z=0.

LCD Bed Leveling

#define LCD_BED_LEVELING

LCD_BED_LEVELING adds a “Level Bed” menu to the LCD that starts a step-by-step guided leveling procedure that requires no probe. For Mesh Bed Leveling see G29 for MBL, and for PROBE_MANUALLY see G29 for ABL.

Available with MESH_BED_LEVELING and PROBE_MANUALLY (all forms of Auto Bed Leveling). See the Configuration.h file for sub-options.

Z Probe End Script

//#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10"

A custom script to do at the very end of G29. If multiple commands are needed, divide them with \n (the newline character).

Homing Options

Bed Center at 0,0

//#define BED_CENTER_AT_0_0

Enable this option if the bed center is at X0 Y0. This setting affects the way automatic home positions (those not set with MANUAL_[XYZ]_POS) are calculated. This should always be enabled with DELTA.

Manual Home Position

//#define MANUAL_X_HOME_POS 0
//#define MANUAL_Y_HOME_POS 0
//#define MANUAL_Z_HOME_POS 0 // Distance from nozzle to printbed after homing

These settings are used to override the home position. Leave them undefined for automatic settings. For DELTA Z home must be set to the top-most position.

Z Safe Homing

#define Z_SAFE_HOMING

#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
#endif

Z Safe Homing prevents Z from homing when the probe (or nozzle) is outside bed area by moving to a defined XY point (by default, the middle of the bed) before Z Homing when homing all axes with G28. As a side-effect, X and Y homing are required before Z homing. If stepper drivers time out, X and Y homing will be required again.

Enable this option if a probe (not an endstop) is being used for Z homing. Z Safe Homing isn’t needed if a Z endstop is used for homing, but it may also be enabled just to have XY always move to some custom position after homing.

Homing Speed

// Homing speeds (mm/m)
#define HOMING_FEEDRATE_XY (50*60)
#define HOMING_FEEDRATE_Z  (4*60)

Homing speed for use in auto home and auto bed leveling. These values may be set to the fastest speeds your machine can achieve. Homing and probing speeds are constrained by the current max feedrate and max acceleration settings.

Extras 1

EEPROM

//#define EEPROM_SETTINGS

Commands like M92 only change the settings in volatile memory, and these settings are lost when the machine is powered off. With this option enabled, Marlin uses the built-in EEPROM to preserve settings across reboots. Settings saved to EEPROM (with M500) are loaded automatically whenever the machine restarts (and in most setups, when connecting to a host), overriding the defaults set in the configuration files. This option is highly recommended, as it makes configurations easier to manage.

The EEPROM-related commands are:

• M500: Save all current settings to EEPROM.
• M501: Load all settings last saved to EEPROM.
• M502: Reset all settings to their default values (as set by Configuration.h)
• M503: Print the current settings (in RAM, not EEPROM)

EEPROM Options

//#define DISABLE_M503    // Saves ~2700 bytes of PROGMEM. Disable for release!
#define EEPROM_CHITCHAT   // Give feedback on EEPROM commands. Disable to save PROGMEM.

These EEPROM options should be left as they are, but for 128K and smaller boards they may be used to recover some program memory. Vendors are strongly discouraged from using DISABLE_M503.

Host Keepalive

#define HOST_KEEPALIVE_FEATURE        // Disable this if your host doesn't like keepalive messages
#define DEFAULT_KEEPALIVE_INTERVAL 2  // Number of seconds between "busy" messages. Set with M113.
#define BUSY_WHILE_HEATING            // Some hosts require "busy" messages even during heating

When Host Keepalive is enabled Marlin will send a busy status message to the host every couple of seconds when it can’t accept commands. Disable if your host doesn’t like keepalive messages. Use DEFAULT_KEEPALIVE_INTERVAL for the default number of seconds between “busy” messages. Override with M113. Marlin 1.1.5 and up include the BUSY_WHILE_HEATING option for hosts that treat host keepalive as a strict busy protocol.

Free Memory Watcher

//#define M100_FREE_MEMORY_WATCHER

Uncomment to add the M100 Free Memory Watcher for debugging purposes.

Inch Units

//#define INCH_MODE_SUPPORT

This option adds support for the G20 and G21 commands, allowing G-code to specify units in inches.

Temperature Units

//#define TEMPERATURE_UNITS_SUPPORT

This option adds support for M149 C, M149 K, and M149 F to set temperature units to Celsius, Kelvin, or Fahrenheit. Without this option all temperatures must be specified in Celsius units.

LCD Material Presets

#define PREHEAT_1_TEMP_HOTEND 180
#define PREHEAT_1_TEMP_BED     70
#define PREHEAT_1_FAN_SPEED     0 // Value from 0 to 255

#define PREHEAT_2_TEMP_HOTEND 240
#define PREHEAT_2_TEMP_BED    110
#define PREHEAT_2_FAN_SPEED     0 // Value from 0 to 255

These are the default values for the Prepare > Preheat LCD menu options. These values can be overridden using the M145 command or the Control > Temperature > Preheat Material X conf submenus.

Nozzle Park

//#define NOZZLE_PARK_FEATURE
#if ENABLED(NOZZLE_PARK_FEATURE)
  // Specify a park position as { X, Y, Z }
  #define NOZZLE_PARK_POINT { (X_MIN_POS + 10), (Y_MAX_POS - 10), 20 }
#endif

Park the nozzle at the given XYZ position on idle or G27.

The “P” parameter controls the action applied to the Z axis:

• P0 - (Default) If Z is below park Z raise the nozzle.
• P1 - Raise the nozzle always to Z-park height.
• P2 - Raise the nozzle by Z-park amount, limited to Z_MAX_POS.

Nozzle Clean

//#define NOZZLE_CLEAN_FEATURE

Adds the G12 command to perform a nozzle cleaning process. See Configuration.h for additional configuration options.

Print Job Timer

#define PRINTJOB_TIMER_AUTOSTART

Automatically start and stop the print job timer when M104/M109/M190 commands are received. Also adds the following commands to control the timer:

• M75 - Start the print job timer.
• M76 - Pause the print job timer.
• M77 - Stop the print job timer.

Print Counter

//#define PRINTCOUNTER

When enabled Marlin will keep track of some print statistics such as:

• Total print jobs
• Total successful print jobs
• Total failed print jobs
• Total time printing

This information can be viewed by the M78 command.

LCD Language

User Interface Language

#define LCD_LANGUAGE en

Choose your preferred language for the LCD controller here. Supported languages include:

See language.h for the latest list of supported languages and their international language codes.

HD44780 Character Set

#define DISPLAY_CHARSET_HD44780 JAPANESE

This option applies only to character-based displays. Character-based displays (based on the Hitachi HD44780) provide an ASCII character set plus one of the following language extensions:

• JAPANESE … the most common
• WESTERN …. with more accented characters
• CYRILLIC … for the Russian language

To determine the language extension installed on your controller:

• Compile and upload with LCD_LANGUAGE set to ‘test’
• Click the controller to view the LCD menu
• The LCD will display Japanese, Western, or Cyrillic text

See LCD Language System for in-depth info on how the Marlin display system currently works.

LCD Type

//#define ULTRA_LCD // Character based
//#define DOGLCD    // Full graphics display

The base LCD Type is either character-based or graphical. Marlin will automatically set the correct one for your specific display, specified below. Unless your display is unsupported by Marlin, you can leave these options disabled.

SD Card

//#define SDSUPPORT // Enable SD Card Support in Hardware Console

Enable to use SD printing, whether as part of an LCD controller or as a standalone SDCard slot.

SPI Speed

//#define SPI_SPEED SPI_HALF_SPEED
//#define SPI_SPEED SPI_QUARTER_SPEED
//#define SPI_SPEED SPI_EIGHTH_SPEED

Uncomment ONE of these options to use a slower SPI transfer speed. This is usually required if you’re getting volume init errors.

Enable CRC

//#define SD_CHECK_AND_RETRY

Use CRC checks and retries on the SD communication.

Encoder

Encoder Resolution

//#define ENCODER_PULSES_PER_STEP 1

This option overrides the default number of encoder pulses needed to produce one step. Should be increased for high-resolution encoders.

//#define ENCODER_STEPS_PER_MENU_ITEM 5

Use this option to override the number of step signals required to move between next/prev menu items.

Encoder Direction

Test your encoder’s behavior first with both of the following options disabled.

• Reversed Value Edit and Menu Nav? Enable REVERSE_ENCODER_DIRECTION.
• Reversed Menu Navigation only? Enable REVERSE_MENU_DIRECTION.
• Reversed Value Editing only? Enable BOTH options.

//#define REVERSE_ENCODER_DIRECTION

This option reverses the encoder direction everywhere. Set if CLOCKWISE causes values to DECREASE.

//#define REVERSE_MENU_DIRECTION

This option reverses the encoder direction for navigating LCD menus. If CLOCKWISE normally moves DOWN this makes it go UP. If CLOCKWISE normally moves UP this makes it go DOWN.

//#define INDIVIDUAL_AXIS_HOMING_MENU

Add individual axis homing items (Home X, Home Y, and Home Z) to the LCD menu.

Speaker

//#define SPEAKER

By default Marlin assumes you have a buzzer with a fixed frequency. If you have a speaker that can produce tones, enable it here.

//#define LCD_FEEDBACK_FREQUENCY_DURATION_MS 100
//#define LCD_FEEDBACK_FREQUENCY_HZ 1000

The duration and frequency for the UI feedback sound. Set these to 0 to disable audio feedback in the LCD menus. Test audio output with the G-code M300 S<frequency Hz> P<duration ms>

LCD Controller

Marlin includes support for several controllers. The two most popular controllers supported by Marlin are:

• REPRAP_DISCOUNT_SMART_CONTROLLER A 20 x 4 character-based LCD controller with click-wheel.
• REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER A monochrome 128 x 64 pixel-based LCD controller with click-wheel. Able to display simple bitmap graphics and up to 5 lines of text.

Most other LCD controllers are variants of these. Enable just one of the following options for your specific controller:

Character LCDs

Graphical LCDs

Keypads

I2C Character LCDs

These controllers all require the LiquidCrystal_I2C library.

I2C Graphical LCDs

These controllers all require the LiquidCrystal_I2C library.

Extras 2

Fan PWM

//#define FAST_PWM_FAN

Increase the FAN PWM frequency. Removes the PWM noise but increases heating in the FET/Arduino.

//#define FAN_SOFT_PWM

Use software PWM to drive the fan, as with the heaters. This uses a very low frequency which is not as annoying as with the hardware PWM. On the other hand, if this frequency is too low, you should also increment SOFT_PWM_SCALE.

#define SOFT_PWM_SCALE 0

Incrementing this by 1 will double the software PWM frequency, affecting heaters (and the fan if FAN_SOFT_PWM is enabled). However, control resolution will be halved for each increment; at zero value, there are 128 effective control positions.

//#define SOFT_PWM_DITHER

If SOFT_PWM_SCALE is set to a value higher than 0, dithering can be used to mitigate the associated resolution loss. If enabled, some of the PWM cycles are stretched so on average the desired duty cycle is attained.

Temperature Status LEDs

//#define TEMP_STAT_LEDS

Temperature status LEDs that display the hotend and bed temperature. If all hotend and bed temperature setpoint are < 54C then the BLUE led is on. Otherwise the RED led is on. There is 1C hysteresis.

Photo Pin

//#define PHOTOGRAPH_PIN     23

M240 triggers a camera by emulating a Canon RC-1 Remote Data as described on this site.

SkeinForge Arc Fix

//#define SF_ARC_FIX

Files sliced with SkeinForge contain the wrong arc GCodes when using “Arc Point” as fillet procedure. This option works around that bug, but otherwise should be left off.

Extras 3

Paste Extruder

// Support for the BariCUDA Paste Extruder.
//#define BARICUDA

Marlin includes support for the Baricuda Extruder for 3D Printing Sugar and Chocolate also hosted on GitHub. The feature adds the codes M126, M127, M128, and M129 for controlling the pump and valve of the Baricuda.

RGB Color LEDs

Marlin currently supplies two options for RGB-addressable color indicators. In both cases the color is set using M150 Rr Ug Bb to specify RGB components from 0 to 255.

//define BlinkM/CyzRgb Support
//#define BLINKM

The BLINKM board supplies the backlighting for some LCD controllers. Its color is set using I2C messages.

//define PCA9632 PWM LED driver Support
//#define PCA9632

The Philips PCA9632 is a common PWM LED driver, controlled (like BlinkM) using I2C.

//#define RGB_LED
//#define RGBW_LED
#if ENABLED(RGB_LED) || ENABLED(RGBW_LED)
  #define RGB_LED_R_PIN 34
  #define RGB_LED_G_PIN 43
  #define RGB_LED_B_PIN 35
  #define RGB_LED_W_PIN -1
#endif

Enable support for an RGB(W) LED connected to 5V digital pins, or an RGB(W) Strip connected to MOSFETs controlled by digital pins. An inexpensive RGB LED can be used simply by assigning digital pins for each component. If the pins are able to do hardware PWM then a wide range of colors will be available. With simple digital pins only 7 colors are possible.

Adds the M150 command to set the LED (or LED strip) color. If pins are PWM capable (e.g., 4, 5, 6, 11) then a range of luminance values can be set from 0 to 255.

Printer Event LEDs

#if ENABLED(BLINKM) || ENABLED(RGB_LED) || ENABLED(RGBW_LED) || ENABLED(PCA9632)
  #define PRINTER_EVENT_LEDS
#endif

This option causes the printer to give status feedback on the installed color LED, BLINKM, or PCA9632:

• Gradually change from blue to violet as the heated bed gets to target temp.
• Gradually change from violet to red as the hotend gets to temperature.
• Change to white to illuminate work surface.
• Change to green once print has finished.
• Turn off after the print has finished and the user has pushed a button.

Servos

Number of Servos

#define NUM_SERVOS 1 // Servo index starts with 0 for M280 command

The total number of servos to enable for use. One common application for a servo is a Z bed probe consisting of an endstop switch mounted on a rotating arm. To use one of the servo connectors for this type of probe, set Z_ENDSTOP_SERVO_NR in the probe options above.

Servo Deactivation

#define SERVO_DELAY 300

Delay (in microseconds) before the next move will start, to give the servo time to reach its target angle. 300ms is a good value but you can try less delay. Specify a large enough delay so the servo has enough time to complete a full motion before deactivation.

//#define DEACTIVATE_SERVOS_AFTER_MOVE

With this option servos are powered only during movement, then turned off to prevent jitter. We recommend enabling this option to keep electrical noise from active servos from interfering with other components. The high amperage generated by extruder motor wiring during movement can also induce movement in active servos. Leave this option enabled to avoid all such servo-related troubles.

Configuration_adv.h

Temperature Options

Bang-Bang Bed Heating

#if DISABLED(PIDTEMPBED)
  #define BED_CHECK_INTERVAL 5000 // ms between checks in bang-bang control
  #if ENABLED(BED_LIMIT_SWITCHING)
    #define BED_HYSTERESIS 2 // Only disable heating if T>target+BED_HYSTERESIS and enable heating if T>target-BED_HYSTERESIS
  #endif
#endif

These sub-options can be used when the bed isn’t using PID heating. A “bang-bang” heating method will be used instead, simply checking against current temperature at regular intervals.

Thermal Protection Settings

Hotend Thermal Protection

#if ENABLED(THERMAL_PROTECTION_HOTENDS)
  #define THERMAL_PROTECTION_PERIOD 40        // Seconds
  #define THERMAL_PROTECTION_HYSTERESIS 4     // Degrees Celsius
  #define WATCH_TEMP_PERIOD 20                // Seconds
  #define WATCH_TEMP_INCREASE 2               // Degrees Celsius
#endif

Hot end thermal protection can be tuned with these sub-options.

The first two options deal with continuous thermal protection during an entire print job.

The second set of options applies to changes in target temperature. Whenever an M104 or M109 increases the target temperature the firmware will wait for the WATCH_TEMP_PERIOD to expire, and if the temperature hasn’t increased by WATCH_TEMP_INCREASE degrees, the machine is halted, requiring a hard reset. This test restarts with any M104/M109, but only if the current temperature is far enough below the target for a reliable test.

If you get false positives for “Heating failed” increase WATCH_TEMP_PERIOD and/or decrease WATCH_TEMP_INCREASE. (WATCH_TEMP_INCREASE should not be set below 2.)

Bed Thermal Protection

#if ENABLED(THERMAL_PROTECTION_BED)
  #define THERMAL_PROTECTION_BED_PERIOD 20    // Seconds
  #define THERMAL_PROTECTION_BED_HYSTERESIS 2 // Degrees Celsius
  #define WATCH_BED_TEMP_PERIOD 60            // Seconds
  #define WATCH_BED_TEMP_INCREASE 2           // Degrees Celsius
#endif

Heated bed thermal protection can be tuned with these sub-options.

The first two options deal with continuous thermal protection during an entire print job.

The second set of options applies to changes in target temperature. Whenever an M140 or M190 increases the target temperature the firmware will wait for the WATCH_BED_TEMP_PERIOD to expire, and if the temperature hasn’t increased by WATCH_BED_TEMP_INCREASE degrees, the machine is halted, requiring a hard reset. This test restarts with any M140/M190, but only if the current temperature is far enough below the target for a reliable test.

If you get too many “Heating failed” errors, increase WATCH_BED_TEMP_PERIOD and/or decrease WATCH_BED_TEMP_INCREASE. (WATCH_BED_TEMP_INCREASE should not be set below 2.)

PID Extrusion Scaling

#if ENABLED(PIDTEMP)
  // this adds an experimental additional term to the heating power, proportional to the extrusion speed.
  // if Kc is chosen well, the additional required power due to increased melting should be compensated.
  //#define PID_EXTRUSION_SCALING
  #if ENABLED(PID_EXTRUSION_SCALING)
    #define DEFAULT_Kc (100) //heating power=Kc*(e_speed)
    #define LPQ_MAX_LEN 50
  #endif
#endif

This option further improves hotend temperature control by accounting for the extra heat energy consumed by cold filament entering the hotend melt chamber. If material enters the hotend more quickly, then more heat will need to be added to maintain energy balance. This option adds a scaling factor that must be tuned for your setup and material.

Extrusion scaling keeps a circular buffer of forward E movements done at each temperature measurement which acts to delay the applied factor and allow for heat dissipation. The size of this queue during printing is set by M301 L, limited by LPQ_MAX_LEN.

Automatic Temperature

#define AUTOTEMP
#if ENABLED(AUTOTEMP)
  #define AUTOTEMP_OLDWEIGHT 0.98
#endif

With Automatic Temperature the hotend target temperature is calculated by all the buffered lines of gcode. The maximum buffered steps/sec of the extruder motor is called “se”. Start autotemp mode with M109 F<factor> S<mintemp> B<maxtemp>, giving a range of temperatures. The target temperature is set to mintemp + factor * se[steps/sec] and is limited by mintemp and maxtemp. Turn this off by executing M109 without F. If the temperature is set to a value below mintemp (e.g., by M104) autotemp will not be applied.

Example: Try M109 S215 B260 F1 in your start.gcode to set a minimum temperature of 215 when idle, which will boost up to 260 as extrusion increases in speed.

Temperature Report ADC

//#define SHOW_TEMP_ADC_VALUES

Enable this option to have M105 and automatic temperature reports include raw ADC values from the temperature sensors.

High Temperature Thermistors

//#define MAX_CONSECUTIVE_LOW_TEMPERATURE_ERROR_ALLOWED 0

High temperature thermistors may give aberrant readings. If this is an issue, use this option to set the maximum number of consecutive low temperature errors that can occur before Min Temp Error is triggered. If you require a value over 10, this could indicate a problem.

//#define MILLISECONDS_PREHEAT_TIME 0

High Temperature Thermistors tend to give poor readings at ambient and lower temperatures. Until they reach a sufficient temperature, these sensors usually return the lowest raw value, and this will cause a Min Temp Error.

To solve this issue, this option sets the number of milliseconds a hotend will preheat before Marlin starts to check the temperature. Set a delay sufficient to reach a temperature your sensor can reliably read. Lower values are better and safer. If you require a value over 30000, this could indicate a problem.

AD595

#define TEMP_SENSOR_AD595_OFFSET 0.0
#define TEMP_SENSOR_AD595_GAIN   1.0

These defines help to calibrate the AD595 sensor in case you get wrong temperature measurements. The final reading is derived from measuredTemp * TEMP_SENSOR_AD595_GAIN + TEMP_SENSOR_AD595_OFFSET.

Extruder Runout Prevention

//#define EXTRUDER_RUNOUT_PREVENT
#if ENABLED(EXTRUDER_RUNOUT_PREVENT)
  #define EXTRUDER_RUNOUT_MINTEMP 190
  #define EXTRUDER_RUNOUT_SECONDS 30
  #define EXTRUDER_RUNOUT_SPEED 1500  // mm/m
  #define EXTRUDER_RUNOUT_EXTRUDE 5   // mm
#endif

When the machine is idle and the temperature over a given value, Marlin can extrude a short length of filament every couple of seconds.

Cooling Fans

Cooling fans are needed on 3D printers to keep components cool and prevent failure.

Controller Fan

//#define USE_CONTROLLER_FAN
#if ENABLED(USE_CONTROLLER_FAN)
  //#define CONTROLLER_FAN_PIN FAN1_PIN  // Set a custom pin for the controller fan
  #define CONTROLLERFAN_SECS 60          // Duration in seconds for the fan to run after all motors are disabled
  #define CONTROLLERFAN_SPEED 255        // 255 == full speed
#endif

A controller fan is useful to cool down the stepper drivers and MOSFETs. When stepper drivers reach a certain temperature they’ll turn off, either stuttering or stopping. With this option enabled the fan will turn on automatically whenever any steppers are enabled and turn off after a set period when all steppers are turned off.

PWM Fans Kickstart

//#define FAN_KICKSTART_TIME 100

When PWM fans are set to low speed, they may need a higher-energy kickstart first to get moving. Once up to speed the fan can drop back to the set speed. This option specifies the kickstart duration in milliseconds. This option doesn’t work with the software PWM fan on Sanguinololu.

PWM Fans Minimum Speed

//#define FAN_MIN_PWM 50

This option can be defined to set the minimum PWM speed (1-255) required to keep the PWM fans moving. Fan speeds set by M106 will be scaled to the reduced range above this minimum.

Extruder Auto-Cooling Fans

#define E0_AUTO_FAN_PIN -1
#define E1_AUTO_FAN_PIN -1
#define E2_AUTO_FAN_PIN -1
#define E3_AUTO_FAN_PIN -1
#define E4_AUTO_FAN_PIN -1
#define EXTRUDER_AUTO_FAN_TEMPERATURE 50
#define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed

Extruder auto fans turn on whenever their extruder temperatures go above EXTRUDER_AUTO_FAN_TEMPERATURE. Your board’s pins file already specifies the recommended pins. Override those here or set to -1 to disable the fans completely.

Multiple extruders can be assigned to the same pin in which case the fan will turn on when any selected extruder is above the threshold.

Part-Cooling Fan Multiplexer

#define FANMUX0_PIN -1
#define FANMUX1_PIN -1
#define FANMUX2_PIN -1

This feature allows you to digitally multiplex the fan output. The multiplexer is automatically switched at tool-change. To enable, just assign one or more FANMUX[012]_PIN values for up to 2, 4, or 8 multiplexed fans.

Case Light

//#define CASE_LIGHT_ENABLE
#if ENABLED(CASE_LIGHT_ENABLE)
  //#define CASE_LIGHT_PIN 4                  // Override the default pin if needed
  #define INVERT_CASE_LIGHT false             // Set true if Case Light is ON when pin is LOW
  #define CASE_LIGHT_DEFAULT_ON true          // Set default power-up state on
  #define CASE_LIGHT_DEFAULT_BRIGHTNESS 105   // Set default power-up brightness (0-255, requires PWM pin)
  //#define MENU_ITEM_CASE_LIGHT              // Add a Case Light option to the LCD main menu
#endif

Enable this option for a firmware-controlled digital or PWM case light.

Endstops Always On

//#define ENDSTOPS_ALWAYS_ON_DEFAULT

Enable this option to keep the endstops on (by default) even when not homing. Override at any time with M120, M121.

Z Late Enable

//#define Z_LATE_ENABLE

With this option is active, the Z steppers will only turn on at the last moment before they move. This option may be needed if your Z driver tends to overheat. Not compatible with Core kinematics.

Dual Steppers / Dual Endstops

//#define X_DUAL_STEPPER_DRIVERS
#if ENABLED(X_DUAL_STEPPER_DRIVERS)
  #define INVERT_X2_VS_X_DIR true   // Set 'true' if X motors should rotate in opposite directions
  //#define X_DUAL_ENDSTOPS
  #if ENABLED(X_DUAL_ENDSTOPS)
    #define X2_USE_ENDSTOP _XMAX_
    #define X_DUAL_ENDSTOPS_ADJUSTMENT  0
  #endif
#endif

//#define Y_DUAL_STEPPER_DRIVERS
#if ENABLED(Y_DUAL_STEPPER_DRIVERS)
  #define INVERT_Y2_VS_Y_DIR true   // Set 'true' if Y motors should rotate in opposite directions
  //#define Y_DUAL_ENDSTOPS
  #if ENABLED(Y_DUAL_ENDSTOPS)
    #define Y2_USE_ENDSTOP _YMAX_
    #define Y_DUAL_ENDSTOPS_ADJUSTMENT  0
  #endif
#endif

//#define Z_DUAL_STEPPER_DRIVERS
#if ENABLED(Z_DUAL_STEPPER_DRIVERS)
  //#define Z_DUAL_ENDSTOPS
  #if ENABLED(Z_DUAL_ENDSTOPS)
    #define Z2_USE_ENDSTOP _XMAX_
    #define Z_DUAL_ENDSTOPS_ADJUSTMENT  0
  #endif
#endif

These options allow you to use extra E drivers to drive a second motor for X, Y, and/or Z axes.

Set X_DUAL_STEPPER_DRIVERS to use a second X motor. If the X motors need to spin in opposite directions set INVERT_X2_VS_X_DIR to true. If the second motor has its own endstop set X_DUAL_ENDSTOPS. (This can adjust for “racking.”) Use X2_USE_ENDSTOP to set the endstop plug that should be used for the second endstop. Extra endstops will appear in the output of ‘M119’.

If the two X axes aren’t perfectly aligned, use X_DUAL_ENDSTOP_ADJUSTMENT to adjust for the difference. This offset is applied to the X2 motor after homing with G28. The dual endstop offsets can be set at runtime with M666 X[offset] Y[offset] Z[offset].

Dual X Carriage

//#define DUAL_X_CARRIAGE
#if ENABLED(DUAL_X_CARRIAGE)
  #define X2_MIN_POS  80          // Minimum X to ensure that X-carriage T1 doesn't hit parked X-carriage T0
  #define X2_MAX_POS 353          // Maximum to the distance between toolheads when both heads are homed
  #define X2_HOME_DIR  1          // The second X-carriage always homes to the max endstop position
  #define X2_HOME_POS X2_MAX_POS  // Default home position is the maximum carriage position

  // Default power-up mode. Set at runtime with `M605 S[mode]`.
  #define DEFAULT_DUAL_X_CARRIAGE_MODE DXC_FULL_CONTROL_MODE

  // Default settings in Auto-park Mode
  #define TOOLCHANGE_PARK_ZLIFT   0.2      // (mm) Amount to raise Z axis when parking
  #define TOOLCHANGE_UNPARK_ZLIFT 1        // (mm) Amount to raise Z axis when unparking

  // Default X offset in Duplication Mode (typically set to half print bed width)
  #define DEFAULT_DUPLICATION_X_OFFSET 100
#endif

Enable this option if you have Dual X-Carriages that move independently. The Dual X-Carriage design allows the inactive extruder to be parked, which keeps ooze from contaminating the print, reduces the weight of each carriage, and enables faster printing speeds. With this option simply connect the X2 stepper to the first unused E plug.

In a Dual X-Carriage setup the first x-carriage (T0) homes to the minimum endstop, while the second x-carriage (T1) homes to the maximum endstop.

With Dual X-Carriage the HOTEND_OFFSET_X setting for T1 overrides X2_HOME_POS. Use M218 T1 X[homepos] to set a custom X2 home position, and M218 T1 X0 to use X2_HOME_POS. This offset can be saved to EEPROM with M500.

In your slicer, be sure to set the second extruder X-offset to 0.

Dual X-Carriage has three different movement modes, set with M605 S[mode]:

• Mode 0: Full Control Mode. (M605 S1) Slicers that fully support dual x-carriages can use this mode for optimal travel results.
• Mode 1: Auto-park Mode. (M605 S1) The firmware automatically parks/unparks the carriages on tool-change. No slicer support is required. (M605 S1)
• Mode 2: Duplication Mode. (M605 S2 X[offs] R[temp]) The firmware will transparently make the second x-carriage and extruder copy all actions of the first x-carriage. This allows the printer to print 2 arbitrary items at once. (The 2nd extruder’s X and temp offsets are set using: M605 S2 X[offs] R[offs].)

TODO Options…

// Activate a solenoid on the active extruder with M380. Disable all with M381.
// Define SOL0_PIN, SOL1_PIN, etc., for each extruder that has a solenoid.
//#define EXT_SOLENOID

// Homing hits each endstop, retracts by these distances, then does a slower bump.
#define X_HOME_BUMP_MM 5
#define Y_HOME_BUMP_MM 5
#define Z_HOME_BUMP_MM 2
#define HOMING_BUMP_DIVISOR { 2, 2, 4 }  // Re-Bump Speed Divisor (Divides the Homing Feedrate)
//#define QUICK_HOME                     // If homing includes X and Y, do a diagonal move initially

// When G28 is called, this option will make Y home before X
//#define HOME_Y_BEFORE_X

#define AXIS_RELATIVE_MODES {false, false, false, false}

// Allow duplication mode with a basic dual-nozzle extruder
//#define DUAL_NOZZLE_DUPLICATION_MODE

// By default pololu step drivers require an active high signal. However, some high power drivers require an active low signal as step.
#define INVERT_X_STEP_PIN false
#define INVERT_Y_STEP_PIN false
#define INVERT_Z_STEP_PIN false
#define INVERT_E_STEP_PIN false

// Default stepper release if idle. Set to 0 to deactivate.
// Steppers will shut down DEFAULT_STEPPER_DEACTIVE_TIME seconds after the last move when DISABLE_INACTIVE_? is true.
// Time can be set by M18 and M84.
#define DEFAULT_STEPPER_DEACTIVE_TIME 120
#define DISABLE_INACTIVE_X true
#define DISABLE_INACTIVE_Y true
#define DISABLE_INACTIVE_Z true  // set to false if the nozzle will fall down on your printed part when print has finished.
#define DISABLE_INACTIVE_E true

#define DEFAULT_MINIMUMFEEDRATE       0.0     // minimum feedrate
#define DEFAULT_MINTRAVELFEEDRATE     0.0

//#define HOME_AFTER_DEACTIVATE  // Require rehoming after steppers are deactivated

#if ENABLED(ULTIPANEL)
  #define MANUAL_FEEDRATE {50*60, 50*60, 4*60, 60} // Feedrates for manual moves along X, Y, Z, E from panel
  #define ULTIPANEL_FEEDMULTIPLY  // Comment to disable setting feedrate multiplier via encoder
#endif

// minimum time in microseconds that a movement needs to take if the buffer is emptied.
#define DEFAULT_MINSEGMENTTIME        20000

// If defined the movements slow down when the look ahead buffer is only half full
#define SLOWDOWN

// Frequency limit
// See nophead's blog for more info
// Not working O
//#define XY_FREQUENCY_LIMIT  15

// Minimum planner junction speed. Sets the default minimum speed the planner plans for at the end
// of the buffer and all stops. This should not be much greater than zero and should only be changed
// if unwanted behavior is observed on a user's machine when running at very slow speeds.
#define MINIMUM_PLANNER_SPEED 0.05 // (mm/sec)

// Microstep setting (Only functional when stepper driver microstep pins are connected to MCU.
#define MICROSTEP_MODES {16,16,16,16,16} // [1,2,4,8,16]

/**
 *  Some boards have a means of setting the stepper motor current via firmware.
 *
 *  The power on motor currents are set by:
 *    PWM_MOTOR_CURRENT - used by MINIRAMBO & ULTIMAIN_2
 *                         known compatible chips: A4982
 *    DIGIPOT_MOTOR_CURRENT - used by BQ_ZUM_MEGA_3D, RAMBO & SCOOVO_X9H
 *                         known compatible chips: AD5206
 *    DAC_MOTOR_CURRENT_DEFAULT - used by PRINTRBOARD_REVF & RIGIDBOARD_V2
 *                         known compatible chips: MCP4728
 *    DIGIPOT_I2C_MOTOR_CURRENTS - used by 5DPRINT, AZTEEG_X3_PRO, MIGHTYBOARD_REVE
 *                         known compatible chips: MCP4451, MCP4018
 *
 *  Motor currents can also be set by M907 - M910 and by the LCD.
 *    M907 - applies to all.
 *    M908 - BQ_ZUM_MEGA_3D, RAMBO, PRINTRBOARD_REVF, RIGIDBOARD_V2 & SCOOVO_X9H
 *    M909, M910 & LCD - only PRINTRBOARD_REVF & RIGIDBOARD_V2
 */
//#define PWM_MOTOR_CURRENT { 1300, 1300, 1250 }          // Values in milliamps
//#define DIGIPOT_MOTOR_CURRENT { 135,135,135,135,135 }   // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)
//#define DAC_MOTOR_CURRENT_DEFAULT { 70, 80, 90, 80 }    // Default drive percent - X, Y, Z, E axis

// Use an I2C based DIGIPOT (e.g., Azteeg X3 Pro)
//#define DIGIPOT_I2C
#if ENABLED(DIGIPOT_I2C) && !defined(DIGIPOT_I2C_ADDRESS_A)
  /**
   * Common slave addresses:
   *
   *                    A   (A shifted)   B   (B shifted)  IC
   * Smoothie          0x2C (0x58)       0x2D (0x5A)       MCP4451
   * AZTEEG_X3_PRO     0x2C (0x58)       0x2E (0x5C)       MCP4451
   * MIGHTYBOARD_REVE  0x2F (0x5E)                         MCP4018
   */
  #define DIGIPOT_I2C_ADDRESS_A 0x2C  // unshifted slave address for first DIGIPOT
  #define DIGIPOT_I2C_ADDRESS_B 0x2D  // unshifted slave address for second DIGIPOT
#endif

//#define DIGIPOT_MCP4018          // Requires library from https://github.com/stawel/SlowSoftI2CMaster
#define DIGIPOT_I2C_NUM_CHANNELS 8 // 5DPRINT: 4     AZTEEG_X3_PRO: 8
// Actual motor currents in Amps, need as many here as DIGIPOT_I2C_NUM_CHANNELS
#define DIGIPOT_I2C_MOTOR_CURRENTS { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 }  //  AZTEEG_X3_PRO

//===========================================================================
//=============================Additional Features===========================
//===========================================================================

#define ENCODER_RATE_MULTIPLIER         // If defined, certain menu edit operations automatically multiply the steps when the encoder is moved quickly
#define ENCODER_10X_STEPS_PER_SEC 75    // If the encoder steps per sec exceeds this value, multiply steps moved x10 to quickly advance the value
#define ENCODER_100X_STEPS_PER_SEC 160  // If the encoder steps per sec exceeds this value, multiply steps moved x100 to really quickly advance the value

//#define CHDK 4        //Pin for triggering CHDK to take a picture see how to use it here http://captain-slow.dk/2014/03/09/3d-printing-timelapses/
#define CHDK_DELAY 50 //How long in ms the pin should stay HIGH before going LOW again

// Include a page of printer information in the LCD Main Menu
//#define LCD_INFO_MENU

// Scroll a longer status message into view
//#define STATUS_MESSAGE_SCROLLING

// On the Info Screen, display XY with one decimal place when possible
//#define LCD_DECIMAL_SMALL_XY

// The timeout (in ms) to return to the status screen from sub-menus
//#define LCD_TIMEOUT_TO_STATUS 15000

SD Card Extras

The options listed below help to fix, improve, and optimize SD Card performance.

SD Detect Inverted

  #define SD_DETECT_INVERTED

Some RAMPS and other boards don’t detect when an SD card is inserted. You can work around this by connecting a push button or single throw switch to the pin defined as SD_DETECT_PIN in your board’s pins definitions. This setting should be disabled unless you are using a push button, pulling the pin to ground. Note: This option is forced off for most LCD controllers (all ULTIPANEL except ELB_FULL_GRAPHIC_CONTROLLER).

SD Finished Stepper Release

#define SD_FINISHED_STEPPERRELEASE true          // Disable steppers when SD Print is finished
#define SD_FINISHED_RELEASECOMMAND "M84 X Y Z E" // You might want to keep the z enabled so your bed stays in place.

SD Menu Autostart

//#define MENU_ADDAUTOSTART  // Add an option in the menu to run all auto#.g files

SD Card Sorting

Recent First

#define SDCARD_RATHERRECENTFIRST

Reverse SD sort to show “more recent” files first, according to the card’s FAT. Since the FAT gets out of order with usage, SDCARD_SORT_ALPHA is recommended.

Alpha Sort

//#define SDCARD_SORT_ALPHA

// SD Card Sorting options
#if ENABLED(SDCARD_SORT_ALPHA)
  #define SDSORT_LIMIT       40     // Maximum number of sorted items (10-256). Costs 27 bytes each.
  #define FOLDER_SORTING     -1     // -1=above  0=none  1=below
  #define SDSORT_GCODE       false  // Allow turning sorting on/off with LCD and M34 g-code.
  #define SDSORT_USES_RAM    false  // Pre-allocate a static array for faster pre-sorting.
  #define SDSORT_USES_STACK  false  // Prefer the stack for pre-sorting to give back some SRAM. (Negated by next 2 options.)
  #define SDSORT_CACHE_NAMES false  // Keep sorted items in RAM longer for speedy performance. Most expensive option.
  #define SDSORT_DYNAMIC_RAM false  // Use dynamic allocation (within SD menus). Least expensive option. Set SDSORT_LIMIT before use!
  #define SDSORT_CACHE_VFATS 2      // Maximum number of 13-byte VFAT entries to use for sorting.
                                    // Note: Only affects SCROLL_LONG_FILENAMES with SDSORT_CACHE_NAMES but not SDSORT_DYNAMIC_RAM.
#endif

With this option enabled, items on SD cards will be sorted by name for easier navigation.

By default…

• Use the slowest -but safest- method for sorting.
• Folders are sorted to the top.
• The sort key is statically allocated.
• No added G-code (M34) support.
• 40 item sorting limit. (Items after the first 40 are unsorted.)

SD sorting uses static allocation (as set by SDSORT_LIMIT), allowing the compiler to calculate the worst-case usage and throw an error if the SRAM limit is exceeded.

• SDSORT_USES_RAM provides faster sorting via a static directory buffer.
• SDSORT_USES_STACK does the same, but uses a local stack-based buffer.
• SDSORT_CACHE_NAMES will retain the sorted file listing in RAM. (Expensive!)
• SDSORT_DYNAMIC_RAM only uses RAM when the SD menu is visible. (Use with caution!)

Progress Bar (character LCD)

//#define LCD_PROGRESS_BAR
#if ENABLED(LCD_PROGRESS_BAR)
  #define PROGRESS_BAR_BAR_TIME 2000  // Amount of time (ms) to show the progress bar
  #define PROGRESS_BAR_MSG_TIME 3000  // Amount of time (ms) to show the status message
  #define PROGRESS_MSG_EXPIRE      0  // Amount of time (ms) to retain the status message (0=forever)
  //#define PROGRESS_MSG_ONCE         // Show messages for MSG_TIME then hide them
  //#define LCD_PROGRESS_BAR_TEST     // Add a menu item to test the progress bar.
#endif

Show a progress bar on HD44780 LCDs for SD printing. Sub-options determine how long to show the progress bar and status message, how long to retain the status message, and whether to include a progress bar test in the Debug menu.

Set Print Progress

//#define LCD_SET_PROGRESS_MANUALLY

Add an M73 G-code to set the current percentage.

Long Filename Host Support

//#define LONG_FILENAME_HOST_SUPPORT

Allow hosts to request long names for files and folders with M33 [path].

Scroll Long Filenames

//#define SCROLL_LONG_FILENAMES

Enable this option to scroll long filenames in the SD card menu.

Abort on Endstop Hit

//#define ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED

Add an option for the firmware to abort SD printing if any endstop is triggered. Turn on with M540 S1 (or from the LCD menu) and make sure endstops are enabled (M120) during SD printing.

Reprint Last File

//#define SD_REPRINT_LAST_SELECTED_FILE

This option makes it easier to print the same SD Card file again. Whenever an SD print completes the LCD Menu will open with the same file selected. From there you can click to start a new print, or you can navigate elsewhere.

Graphical Display Extras

#if ENABLED(DOGLCD)
  #define XYZ_HOLLOW_FRAME      // Enable to save many cycles by drawing a hollow frame on the Info Screen
  #define MENU_HOLLOW_FRAME     // Enable to save many cycles by drawing a hollow frame on Menu Screens
  //#define USE_BIG_EDIT_FONT   // A bigger font is available for edit items. Costs 3120 bytes of PROGMEM.
                                // Western only. Not available for Cyrillic, Kana, Turkish, Greek, or Chinese.
  //#define USE_SMALL_INFOFONT  // A smaller font may be used on the Info Screen. Costs 2300 bytes of PROGMEM.
                                // Western only. Not available for Cyrillic, Kana, Turkish, Greek, or Chinese.
  //#define DOGM_SPI_DELAY_US 5 // Enable this option and reduce the value to optimize screen updates.
                                // The normal delay is 10µs. Use the lowest value that still gives a reliable display.
#endif

Use the optimizations here to improve printing performance, which can be adversely affected by graphical display drawing, especially when doing several short moves, and when printing on DELTA and SCARA machines.

Some of these options may result in the display lagging behind controller events, as there is a trade-off between reliable printing performance versus fast display updates.

Watchdog

#define USE_WATCHDOG

The hardware watchdog should reset the microcontroller, disabling all outputs, in case the firmware gets stuck and doesn’t do temperature regulation.

Watchdog Manual Reset

#if ENABLED(USE_WATCHDOG)
  //#define WATCHDOG_RESET_MANUAL
#endif

If you have a watchdog reboot in an ATmega2560 the device can hang forever, as a watchdog reset will leave the watchdog on. The WATCHDOG_RESET_MANUAL option works around this by eschewing the hardware reset. However, this feature is unsafe because it only works if interrupts are disabled, and the code could hang in an interrupt routine with interrupts disabled.

Babystepping

//#define BABYSTEPPING
#if ENABLED(BABYSTEPPING)
  //#define BABYSTEP_XY              // Also enable X/Y Babystepping. Not supported on DELTA!
  #define BABYSTEP_INVERT_Z false    // Change if Z babysteps should go the other way
  #define BABYSTEP_MULTIPLICATOR 1   // Babysteps are very small. Increase for faster motion.
  //#define BABYSTEP_ZPROBE_OFFSET   // Enable to combine M851 and Babystepping
  //#define DOUBLECLICK_FOR_Z_BABYSTEPPING // Double-click on the Status Screen for Z Babystepping.
  #define DOUBLECLICK_MAX_INTERVAL 1250 // Maximum interval between clicks, in milliseconds.
                                        // Note: Extra time may be added to mitigate controller latency.
  //#define BABYSTEP_ZPROBE_GFX_OVERLAY // Enable graphical overlay on Z-offset editor
  //#define BABYSTEP_ZPROBE_GFX_REVERSE // Reverses the direction of the CW/CCW indicators
#endif

Babystepping enables M290 and LCD menu items to move the axes by tiny increments without changing the current position values. This feature is used primarily to adjust the Z axis in the first layer of a print in real-time. Warning: Does not respect endstops!

Linear Advance

//#define LIN_ADVANCE

#if ENABLED(LIN_ADVANCE)
  #define LIN_ADVANCE_K 75
  #define LIN_ADVANCE_E_D_RATIO 0 // The calculated ratio (or 0) according to the formula W * H / ((D / 2) ^ 2 * PI)
                                  // Example: 0.4 * 0.2 / ((1.75 / 2) ^ 2 * PI) = 0.033260135
#endif

This feature allows Marlin to use linear pressure control for print extrusion, to eliminate ooze, improve corners, etc. See Configuration_adv.h and the Linear Advance page for more complete documentation.

Delta / Scara Limits

#if ENABLED(DELTA) && !defined(DELTA_PROBEABLE_RADIUS)
  #define DELTA_PROBEABLE_RADIUS DELTA_PRINTABLE_RADIUS
#elif IS_SCARA && !defined(SCARA_PRINTABLE_RADIUS)
  #define SCARA_PRINTABLE_RADIUS (SCARA_LINKAGE_1 + SCARA_LINKAGE_2)
#endif

Custom Mesh Bounds

#if ENABLED(MESH_BED_LEVELING) || ENABLED(AUTO_BED_LEVELING_UBL)
  // Override the mesh area if the automatic (max) area is too large
  //#define MESH_MIN_X MESH_INSET
  //#define MESH_MIN_Y MESH_INSET
  //#define MESH_MAX_X X_BED_SIZE - (MESH_INSET)
  //#define MESH_MAX_Y Y_BED_SIZE - (MESH_INSET)
#endif

Enhanced G-code

G2/G3 Arc

//
// G2/G3 Arc Support
//
#define ARC_SUPPORT               // Disable this feature to save ~3226 bytes
#if ENABLED(ARC_SUPPORT)
  #define MM_PER_ARC_SEGMENT  1   // Length of each arc segment
  #define N_ARC_CORRECTION   25   // Number of intertpolated segments between corrections
  //#define ARC_P_CIRCLES         // Enable the 'P' parameter to specify complete circles
  //#define CNC_WORKSPACE_PLANES  // Allow G2/G3 to operate in XY, ZX, or YZ planes
#endif

G5 Bezier Curve

//#define BEZIER_CURVE_SUPPORT

Support for G5 with XYZE destination and IJPQ offsets. Requires ~2666 bytes.

G38.2/G38.3 Probe Target

//#define G38_PROBE_TARGET
#if ENABLED(G38_PROBE_TARGET)
  #define G38_MINIMUM_MOVE 0.0275 // (mm) Minimum distance that will produce a move
#endif

Add commands G38.2 and G38.3 to probe towards target. Enable PROBE_DOUBLE_TOUCH if you want G38 to double touch.

Minimum Steps Per Segment

#define MIN_STEPS_PER_SEGMENT 6

Moves (or segments) with fewer steps than this will be joined with the next move.

Minimum Stepper Pulse

#define MINIMUM_STEPPER_PULSE 0 // (µs) The smallest stepper pulse allowed

The minimum pulse width (in µs) for stepping a stepper. Set this if you find stepping unreliable, or if using a very fast CPU.

Parallel Heaters

//#define HEATERS_PARALLEL

Control heater 0 and heater 1 in parallel.

Buffer / Hosts

Block Buffer

#if ENABLED(SDSUPPORT)
  #define BLOCK_BUFFER_SIZE 16 // SD,LCD,Buttons take more memory, block buffer needs to be smaller
#else
  #define BLOCK_BUFFER_SIZE 16 // maximize block buffer
#endif

The number of linear motions that can be in the plan at any give time. The BLOCK_BUFFER_SIZE must be a power of 2, (8, 16, 32, etc.) because shifts and ors are used to do the ring-buffering.

Serial Command Buffer

#define MAX_CMD_SIZE 96
#define BUFSIZE 4

The ASCII buffer for serial input. Individual command line length is set by MAX_CMD_SIZE, and should be long enough to hold a complete G-code line. Set the number of lines with BUFSIZE.

Transmit to Host Buffer

#define TX_BUFFER_SIZE 0

Transmission to Host buffer size. To save 386 bytes of PROGMEM (and TX_BUFFER_SIZE+3 bytes of SRAM) set to 0. To buffer a simple “ok” you need 4 bytes. An ADVANCED_OK (M105) needs 32 bytes. For debug-echo: 128 bytes for the optimal speed. Other output doesn’t need to be that speedy.

Host Receive Buffer

//#define RX_BUFFER_SIZE 1024
#if RX_BUFFER_SIZE >= 1024
  // Enable to have the controller send XON/XOFF control characters to
  // the host to signal the RX buffer is becoming full.
  //#define SERIAL_XON_XOFF
#endif

Host Receive buffer size. Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough. To use flow control, set this buffer size to at least 1024 bytes.

SD Transfer Stats

#if ENABLED(SDSUPPORT)
  // Collect and display the maximum RX queue usage after an SD file transfer.
  //#define SERIAL_STATS_MAX_RX_QUEUED

  // Collect and display the number of dropped bytes after an SD file transfer.
  //#define SERIAL_STATS_DROPPED_RX
#endif

Emergency Parser

//#define EMERGENCY_PARSER

Enable an emergency-command parser to intercept certain commands as they enter the serial receive buffer, so they cannot be blocked. Currently handles M108, M112, and M410. Does not work on boards using AT90USB (USBCON) processors!

No Timeouts

//#define NO_TIMEOUTS 1000 // (ms)

Bad serial connections can miss a received command by sending an “ok”, and some hosts will abort after 30 seconds. Some hosts start sending commands while receiving a ‘wait’. This “wait” is only sent when the buffer is empty. 1 second is a good value here. The HOST_KEEPALIVE feature provides another way to keep the host alive.

Advanced OK

//#define ADVANCED_OK

Include extra information about the buffer in “ok” messages. Some hosts will have this feature soon. This could make the NO_TIMEOUTS unnecessary.

Firmware Retraction

//#define FWRETRACT  // ONLY PARTIALLY TESTED
#if ENABLED(FWRETRACT)
  #define MIN_AUTORETRACT 0.1             // When auto-retract is on, convert E moves of this length and over
  #define MAX_AUTORETRACT 10.0            // Upper limit for auto-retract conversion
  #define RETRACT_LENGTH 3                // Default retract length (positive mm)
  #define RETRACT_LENGTH_SWAP 13          // Default swap retract length (positive mm), for extruder change
  #define RETRACT_FEEDRATE 45             // Default feedrate for retracting (mm/s)
  #define RETRACT_ZLIFT 0                 // Default retract Z-lift
  #define RETRACT_RECOVER_LENGTH 0        // Default additional recover length (mm, added to retract length when recovering)
  #define RETRACT_RECOVER_LENGTH_SWAP 0   // Default additional swap recover length (mm, added to retract length when recovering from extruder change)
  #define RETRACT_RECOVER_FEEDRATE 8      // Default feedrate for recovering from retraction (mm/s)
  #define RETRACT_RECOVER_FEEDRATE_SWAP 8 // Default feedrate for recovering from swap retraction (mm/s)
#endif

This option adds G10/G11 commands for automatic firmware-based retract/recover. Use M207 and M208 to set the parameters, and M209 to enable/disable. With auto-retract enabled, all G1 E moves within the set range will be converted to firmware-based retract/recover moves.

Be sure to turn off auto-retract during filament change! All M207/M208/M209 settings are saved to EEPROM.

Extra Fan Speed

//#define EXTRA_FAN_SPEED

Add a secondary fan speed for each print-cooling fan.

• M106 P[fan] T3-255 sets a secondary speed for [fan].
• M106 P[fan] T2 uses the set secondary speed.
• M106 P[fan] T1 restores the previous fan speed

Advanced Pause

//#define ADVANCED_PAUSE_FEATURE
#if ENABLED(ADVANCED_PAUSE_FEATURE)
  #define PAUSE_PARK_X_POS 3                  // X position of hotend
  #define PAUSE_PARK_Y_POS 3                  // Y position of hotend
  #define PAUSE_PARK_Z_ADD 10                 // Z addition of hotend (lift)
  #define PAUSE_PARK_XY_FEEDRATE 100          // X and Y axes feedrate in mm/s (also used for delta printers Z axis)
  #define PAUSE_PARK_Z_FEEDRATE 5             // Z axis feedrate in mm/s (not used for delta printers)
  #define PAUSE_PARK_RETRACT_FEEDRATE 60      // Initial retract feedrate in mm/s
  #define PAUSE_PARK_RETRACT_LENGTH 2         // Initial retract in mm
                                              // It is a short retract used immediately after print interrupt before move to filament exchange position
  #define FILAMENT_CHANGE_UNLOAD_FEEDRATE 10  // Unload filament feedrate in mm/s - filament unloading can be fast
  #define FILAMENT_CHANGE_UNLOAD_LENGTH 100   // Unload filament length from hotend in mm
                                              // Longer length for bowden printers to unload filament from whole bowden tube,
                                              // shorter length for printers without bowden to unload filament from extruder only,
                                              // 0 to disable unloading for manual unloading
  #define FILAMENT_CHANGE_LOAD_FEEDRATE 6     // Load filament feedrate in mm/s - filament loading into the bowden tube can be fast
  #define FILAMENT_CHANGE_LOAD_LENGTH 0       // Load filament length over hotend in mm
                                              // Longer length for bowden printers to fast load filament into whole bowden tube over the hotend,
                                              // Short or zero length for printers without bowden where loading is not used
  #define ADVANCED_PAUSE_EXTRUDE_FEEDRATE 3   // Extrude filament feedrate in mm/s - must be slower than load feedrate
  #define ADVANCED_PAUSE_EXTRUDE_LENGTH 50    // Extrude filament length in mm after filament is loaded over the hotend,
                                              // 0 to disable for manual extrusion
                                              // Filament can be extruded repeatedly from the filament exchange menu to fill the hotend,
                                              // or until outcoming filament color is not clear for filament color change
  #define PAUSE_PARK_NOZZLE_TIMEOUT 45        // Turn off nozzle if user doesn't change filament within this time limit in seconds
  #define FILAMENT_CHANGE_NUMBER_OF_ALERT_BEEPS 5 // Number of alert beeps before printer goes quiet
  #define PAUSE_PARK_NO_STEPPER_TIMEOUT       // Enable to have stepper motors hold position during filament change
                                              // even if it takes longer than DEFAULT_STEPPER_DEACTIVE_TIME.
  //#define PARK_HEAD_ON_PAUSE                // Go to filament change position on pause, return to print position on resume
  //#define HOME_BEFORE_FILAMENT_CHANGE       // Ensure homing has been completed prior to parking for filament change
#endif

Experimental feature for filament change support and parking the nozzle when paused. Adds the M600 command to perform a filament change. With PARK_HEAD_ON_PAUSE enabled also adds the M125 command to pause printing and park the nozzle. Requires an LCD display. Note that M600 is required for the default FILAMENT_RUNOUT_SCRIPT.

Stepper Drivers

Trinamic TMC26X

//#define HAVE_TMCDRIVER

Enable this section if you have TMC26X motor drivers. You’ll need to import the TMC26XStepper library into the Arduino IDE. See the Configuration_adv.h file for the full set of sub-options.

Trinamic TMC2130

//#define HAVE_TMC2130

Enable this option for SilentStepStick Trinamic TMC2130 SPI-configurable stepper drivers. You’ll also need the TMC2130Stepper Arduino library. See the Configuration_adv.h file for the full set of sub-options.

To use TMC2130 stepper drivers in SPI mode connect your SPI2130 pins to the hardware SPI interface on your board and define the required CS pins in your pins_MYBOARD.h file. (e.g., RAMPS 1.4 uses AUX3 pins X_CS_PIN 53, Y_CS_PIN 49, etc.).

L6470 Drivers

//#define HAVE_L6470DRIVER

Enable this section if you have L6470 motor drivers. You need to import the L6470 library into the Arduino IDE for this. See the Configuration_adv.h file for the full set of sub-options.

Experimental i2c Bus

//#define EXPERIMENTAL_I2CBUS
#define I2C_SLAVE_ADDRESS  0 // Set a value from 8 to 127 to act as a slave

This feature can be used to talk to slave devices on the i2c bus, passing data back to the host. With additional work the TWIBus class can be used to build a full protocol and add remote control features to Marlin, distributing load over two or more boards.

; Example #1
; This macro send the string "Marlin" to the slave device with address 0x63 (99)
; It uses multiple M260 commands with one B[base 10] arg
M260 A99  ; Target slave address
M260 B77  ; M
M260 B97  ; a
M260 B114 ; r
M260 B108 ; l
M260 B105 ; i
M260 B110 ; n
M260 S1   ; Send the current buffer

; Example #2
; Request 6 bytes from slave device with address 0x63 (99)
M261 A99 B5

; Example #3
; Example serial output of a M261 request
echo:i2c-reply: from:99 bytes:5 data:hello

Spindle / Laser

//#define SPINDLE_LASER_ENABLE
#if ENABLED(SPINDLE_LASER_ENABLE)

  #define SPINDLE_LASER_ENABLE_INVERT   false  // set to "true" if the on/off function is reversed
  #define SPINDLE_LASER_PWM             true   // set to true if your controller supports setting the speed/power
  #define SPINDLE_LASER_PWM_INVERT      true   // set to "true" if the speed/power goes up when you want it to go slower
  #define SPINDLE_LASER_POWERUP_DELAY   5000   // delay in milliseconds to allow the spindle/laser to come up to speed/power
  #define SPINDLE_LASER_POWERDOWN_DELAY 5000   // delay in milliseconds to allow the spindle to stop
  #define SPINDLE_DIR_CHANGE            true   // set to true if your spindle controller supports changing spindle direction
  #define SPINDLE_INVERT_DIR            false
  #define SPINDLE_STOP_ON_DIR_CHANGE    true   // set to true if Marlin should stop the spindle before changing rotation direction

  /**
   *  The M3 & M4 commands use the following equation to convert PWM duty cycle to speed/power
   *
   *  SPEED/POWER = PWM duty cycle * SPEED_POWER_SLOPE + SPEED_POWER_INTERCEPT
   *    where PWM duty cycle varies from 0 to 255
   *
   *  Set the following for your controller (ALL MUST BE SET)
   */

  #define SPEED_POWER_SLOPE    118.4
  #define SPEED_POWER_INTERCEPT  0
  #define SPEED_POWER_MIN     5000
  #define SPEED_POWER_MAX    30000    // SuperPID router controller 0 - 30,000 RPM

  //#define SPEED_POWER_SLOPE      0.3922
  //#define SPEED_POWER_INTERCEPT  0
  //#define SPEED_POWER_MIN       10
  //#define SPEED_POWER_MAX      100      // 0-100%
#endif

Enable for Spindle and Laser control. Adds the M3, M4, and M5 commands to turn the spindle/laser on and off, and to set spindle speed, spindle direction, and laser power.

SuperPid is a router/spindle speed controller used in the CNC milling community. Marlin can be used to turn the spindle on and off. It can also be used to set the spindle speed from 5,000 to 30,000 RPM.

You’ll need to select a pin for the ON/OFF function and optionally choose a 0-5V hardware PWM pin for the speed control and a pin for the rotation direction.

See the Laser and Spindle page for more details.

Filament Width Sensor

//#define FILAMENT_WIDTH_SENSOR

Enable to add support for a filament width sensor such as Filament Width Sensor Prototype Version 3. With a filament sensor installed, Marlin can adjust the flow rate according to the measured filament width. Adjust the sub-options below according to your setup.

Only a single extruder is supported at this time.

#define FILAMENT_SENSOR_EXTRUDER_NUM 0

Only one extruder can have a filament sensor. Specify here which extruder has it.

#define MEASUREMENT_DELAY_CM        14

Distance from the filament width sensor to the melt chamber.

#define MEASURED_UPPER_LIMIT         3.30 // (mm) Upper limit used to validate sensor reading
#define MEASURED_LOWER_LIMIT         1.90 // (mm) Lower limit used to validate sensor reading

The range of your filament width. Set these according to your filament preferences. The sample values here apply to 3mm. For 1.75mm you’ll use a range more like 1.60 to 1.90.

#define MAX_MEASUREMENT_DELAY       20

This defines the size of the buffer to allocate for use with MEASUREMENT_DELAY_CM. The value must be greater than or equal to MEASUREMENT_DELAY_CM. Keep this setting low to reduce RAM usage.

#define FILAMENT_LCD_DISPLAY

Periodically display a message on the LCD showing the measured filament diameter.

CNC Coordinate Systems

//#define CNC_COORDINATE_SYSTEMS

Enables G53 and G54-G59.3 commands to select coordinate systems, plus G92.1 to reset the current workspace to native machine space. Workspaces set with this feature are also saved to EEPROM.

Pins Debugging

//#define PINS_DEBUGGING

Enable this option to add the M43 Debug Pins G-code. This command can be used to list pins, display their status, to watch pins for changes, observe endstops, toggle LEDs, test Z servo probe, toggle pins, etc.

Temperature Auto-Report

#define AUTO_REPORT_TEMPERATURES

It is recommended to enable this feature (along with EXTENDED_CAPABILITIES_REPORT) to install the M155 Auto-Report Temperature command. M115 tells Marlin to send the current temperature to the host at regular intervals, instead of requiring the host software to send M105 repeatedly. This saves a space in the command buffer and reduces overhead.

Extended Capabilities Report

#define EXTENDED_CAPABILITIES_REPORT

This option adds a list of capabilities to the output of M115, allowing savvy host software to take advantage of add-ons like AUTO_REPORT_TEMPERATURES.

Volumetric Mode Default

//#define VOLUMETRIC_DEFAULT_ON

Activate this option to make volumetric extrusion the default method The last values loaded or set by M404 W and M200 D will be used as the Nominal and Actual filament diameters. With this option, M200 D0 must be used to disable volumetric mode when running length-based G-code.

No Workspace Offsets

//#define NO_WORKSPACE_OFFSETS

Enable this option for a leaner build of Marlin that removes all workspace offsets. This simplifies all coordinate transformations, leveling, etc., and may allow for slightly faster printing. With this option, M206 and M428 are disabled, and G92 reverts to its old behavior, as it is in Marlin 1.0.

Proportional Font Ratio

#define PROPORTIONAL_FONT_RATIO 1.0

Some hosts use a proportional font in their output console. This makes it hard to read output from Marlin that relies on fixed-width for alignment. This option tells Marlin how many spaces are required to fill up a typical character space in the host font. For clients that use a fixed-width font (like OctoPrint), leave this set to 1.0. Otherwise, adjust according to your host.

Faster G-code Parser

#define FASTER_GCODE_PARSER

This option uses a 28 byte SRAM buffer and an alternative method to get parameter values so the G-code parser can run a little faster. If possible, always leave this option enabled.

Even More Options…

/**
 * User-defined menu items that execute custom GCode
 */
//#define CUSTOM_USER_MENUS
#if ENABLED(CUSTOM_USER_MENUS)
  #define USER_SCRIPT_DONE "M117 User Script Done"
  #define USER_SCRIPT_AUDIBLE_FEEDBACK
  //#define USER_SCRIPT_RETURN  // Return to status screen after a script

  #define USER_DESC_1 "Home & UBL Info"
  #define USER_GCODE_1 "G28\nG29 W"

  #define USER_DESC_2 "Preheat for PLA"
  #define USER_GCODE_2 "M140 S" STRINGIFY(PREHEAT_1_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_1_TEMP_HOTEND)

  #define USER_DESC_3 "Preheat for ABS"
  #define USER_GCODE_3 "M140 S" STRINGIFY(PREHEAT_2_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_2_TEMP_HOTEND)

  #define USER_DESC_4 "Heat Bed/Home/Level"
  #define USER_GCODE_4 "M140 S" STRINGIFY(PREHEAT_2_TEMP_BED) "\nG28\nG29"

  #define USER_DESC_5 "Home & Info"
  #define USER_GCODE_5 "G28\nM503"
#endif

/**
 * Specify an action command to send to the host when the printer is killed.
 * Will be sent in the form '//action:ACTION_ON_KILL', e.g. '//action:poweroff'.
 * The host must be configured to handle the action command.
 */
//#define ACTION_ON_KILL "poweroff"

/**
 *  I2C position encoders for closed loop control.
 *  Developed by Chris Barr at Aus3D.
 *
 *  Wiki: http://wiki.aus3d.com.au/Magnetic_Encoder
 *  Github: https://github.com/Aus3D/MagneticEncoder
 *
 *  Supplier: http://aus3d.com.au/magnetic-encoder-module
 *  Alternative Supplier: http://reliabuild3d.com/
 *
 *  Reilabuild encoders have been modified to improve reliability.
 */

//#define I2C_POSITION_ENCODERS
#if ENABLED(I2C_POSITION_ENCODERS)

  #define I2CPE_ENCODER_CNT         1                       // The number of encoders installed; max of 5
                                                            // encoders supported currently.

  #define I2CPE_ENC_1_ADDR          I2CPE_PRESET_ADDR_X     // I2C address of the encoder. 30-200.
  #define I2CPE_ENC_1_AXIS          X_AXIS                  // Axis the encoder module is installed on.  <X|Y|Z|E>_AXIS.
  #define I2CPE_ENC_1_TYPE          I2CPE_ENC_TYPE_LINEAR   // Type of encoder:  I2CPE_ENC_TYPE_LINEAR -or-
                                                            // I2CPE_ENC_TYPE_ROTARY.
  #define I2CPE_ENC_1_TICKS_UNIT    2048                    // 1024 for magnetic strips with 2mm poles; 2048 for
                                                            // 1mm poles. For linear encoders this is ticks / mm,
                                                            // for rotary encoders this is ticks / revolution.
  //#define I2CPE_ENC_1_TICKS_REV     (16 * 200)            // Only needed for rotary encoders; number of stepper
                                                            // steps per full revolution (motor steps/rev * microstepping)
  //#define I2CPE_ENC_1_INVERT                              // Invert the direction of axis travel.
  #define I2CPE_ENC_1_EC_METHOD     I2CPE_ECM_NONE          // Type of error error correction.
  #define I2CPE_ENC_1_EC_THRESH     0.10                    // Threshold size for error (in mm) above which the
                                                            // printer will attempt to correct the error; errors
                                                            // smaller than this are ignored to minimize effects of
                                                            // measurement noise / latency (filter).

  #define I2CPE_ENC_2_ADDR          I2CPE_PRESET_ADDR_Y     // Same as above, but for encoder 2.
  #define I2CPE_ENC_2_AXIS          Y_AXIS
  #define I2CPE_ENC_2_TYPE          I2CPE_ENC_TYPE_LINEAR
  #define I2CPE_ENC_2_TICKS_UNIT    2048
  //#define I2CPE_ENC_2_TICKS_REV   (16 * 200)
  //#define I2CPE_ENC_2_INVERT
  #define I2CPE_ENC_2_EC_METHOD     I2CPE_ECM_NONE
  #define I2CPE_ENC_2_EC_THRESH     0.10

  #define I2CPE_ENC_3_ADDR          I2CPE_PRESET_ADDR_Z     // Encoder 3.  Add additional configuration options
  #define I2CPE_ENC_3_AXIS          Z_AXIS                  // as above, or use defaults below.

  #define I2CPE_ENC_4_ADDR          I2CPE_PRESET_ADDR_E     // Encoder 4.
  #define I2CPE_ENC_4_AXIS          E_AXIS

  #define I2CPE_ENC_5_ADDR          34                      // Encoder 5.
  #define I2CPE_ENC_5_AXIS          E_AXIS

  // Default settings for encoders which are enabled, but without settings configured above.
  #define I2CPE_DEF_TYPE            I2CPE_ENC_TYPE_LINEAR
  #define I2CPE_DEF_ENC_TICKS_UNIT  2048
  #define I2CPE_DEF_TICKS_REV       (16 * 200)
  #define I2CPE_DEF_EC_METHOD       I2CPE_ECM_NONE
  #define I2CPE_DEF_EC_THRESH       0.1

  //#define I2CPE_ERR_THRESH_ABORT  100.0                   // Threshold size for error (in mm) error on any given
                                                            // axis after which the printer will abort. Comment out to
                                                            // disable abort behaviour.

  #define I2CPE_TIME_TRUSTED        10000                   // After an encoder fault, there must be no further fault
                                                            // for this amount of time (in ms) before the encoder
                                                            // is trusted again.

  /**
   * Position is checked every time a new command is executed from the buffer but during long moves,
   * this setting determines the minimum update time between checks. A value of 100 works well with
   * error rolling average when attempting to correct only for skips and not for vibration.
   */
  #define I2CPE_MIN_UPD_TIME_MS     100                     // Minimum time in miliseconds between encoder checks.

  // Use a rolling average to identify persistant errors that indicate skips, as opposed to vibration and noise.
  #define I2CPE_ERR_ROLLING_AVERAGE

#endif // I2C_POSITION_ENCODERS

/**
 * MAX7219 Debug Matrix
 *
 * Add support for a low-cost 8x8 LED Matrix based on the Max7219 chip, which can be used as a status
 * display. Requires 3 signal wires. Some useful debug options are included to demonstrate its usage.
 *
 * Fully assembled MAX7219 boards can be found on the internet for under $2(US).
 * For example, see https://www.ebay.com/sch/i.html?_nkw=332349290049
 */
//#define MAX7219_DEBUG
#if ENABLED(MAX7219_DEBUG)
  #define MAX7219_CLK_PIN   64  // 77 on Re-ARM       // Configuration of the 3 pins to control the display
  #define MAX7219_DIN_PIN   57  // 78 on Re-ARM
  #define MAX7219_LOAD_PIN  44  // 79 on Re-ARM

  /**
   * Sample debug features
   * If you add more debug displays, be careful to avoid conflicts!
   */
  #define MAX7219_DEBUG_PRINTER_ALIVE    // Blink corner LED of 8x8 matrix to show that the firmware is functioning
  #define MAX7219_DEBUG_STEPPER_HEAD  3  // Show the stepper queue head position on this and the next LED matrix row
  #define MAX7219_DEBUG_STEPPER_TAIL  5  // Show the stepper queue tail position on this and the next LED matrix row

  #define MAX7219_DEBUG_STEPPER_QUEUE 0  // Show the current stepper queue depth on this and the next LED matrix row
                                         // If you experience stuttering, reboots, etc. this option can reveal how
                                         // tweaks made to the configuration are affecting the printer in real-time.
#endif

Prusa MMU2 advanced settings (since Marlin 2.0)

Serial connection

A serial connection is required for communication between the printer board and the MMU2. The configuration differs between 8- and 32-bit boards.

8-bit AVR boards

On a board with a ATmega2560/1280 microcontroller you have three potential serial ports to use for the MMU2: serial 1 (pins 18/19), serial 2 (pins 16/17), serial 3 (pins 14/15). Define the port your MMU2 is connected to

  #define INTERNAL_SERIAL_PORT 2

This activates an additional serial connection in Marlin named internalSerial. So the second define in the example configuration can just remain as it is.

  #define MMU2_SERIAL internalSerial

32-bit boards

When using a 32-bit board you just have to define the name of the serial port which will be used for communication with the MMU2.

  #define MMU2_SERIAL Serial1

MMU2 Reset

The MMU2 provides two options how the printer board can trigger a reset: software and hardware reset. By default software reset is enabled. Hardware reset requires a digital output pin wired to the reset pin on the MMU2. To activate hardware reset you define the pin to use on the printer board

  #define MMU2_RST_PIN 23

12V mode

If your MMU2 is powered from 12 V you can activate a special mode on the MMU2.

  // Enable if the MMU2 has 12V stepper motors (MMU2 Firmware 1.0.2 and up)
  #define MMU2_MODE_12V

This should reduce the noise of the MMU2 but has no effect on the general operation.

Filament runout handling

Her you define the gcode script which will be executed when the so-called FINDA sensor on the MMU2 detects a filament runout.

  // G-code to execute when MMU2 F.I.N.D.A. probe detects filament runout
  #define MMU2_FILAMENT_RUNOUT_SCRIPT "M600"

The default is M600 which requires ADVANCED_PAUSE_FEATURE.

LCD Menu

  // G-code to execute when MMU2 F.I.N.D.A. probe detects filament runout
  #define MMU2_MENUS

Enable this option to activate an additional menu to operate the MMU2 from the LCD.

Filament load/unload settings

Load to nozzle

The MMU2 LCD menu allows you to load filament to the nozzle. The MMU2 will transport the filament all the way to the extruder gears. The required extruder steps to load it into the hotend have to be defined in Marlin.

    // This is for Prusa MK3-style extruders. Customize for your hardware.
    #define MMU2_LOAD_TO_NOZZLE_SEQUENCE \
      {  7.2,  562 }, \
      { 14.4,  871 }, \
      { 36.0, 1393 }, \
      { 14.4,  871 }, \
      { 50.0,  198 }

The values are relative E distances and feed rates in mm/m. The defaults are based on the nozzle to extruder gear distance of a Prusa MK3 extruder, so if required you have to modifiy those to your extruder/hotend setup accordingly.

Unload filament

To unload filament using the LCD menu a generic ramming sequence will be exectued before the MMU2 will retract the filament. The steps to do so are defined using

    #define MMU2_RAMMING_SEQUENCE \
      {   1.0, 1000 }, \
      {   1.0, 1500 }, \
      {   2.0, 2000 }, \
      {   1.5, 3000 }, \
      {   2.5, 4000 }, \
      { -15.0, 5000 }, \
      { -14.0, 1200 }, \
      {  -6.0,  600 }, \
      {  10.0,  700 }, \
      { -10.0,  400 }, \
      { -50.0, 2000 }

The values are relative E distances and feed rates in mm/m. The default values are based on a E3D V6 hotend and the nozzle to extruder gear distance of a Prusa MK3 extruder, so if required you have to modifiy those to your extruder/hotend setup accordingly.

Eject filament

Eject filament will do a simple retraction of the filament out of the hotend without ramming. The feedrate to do so is defined using

    #define MMU2_FILAMENTCHANGE_EJECT_FEED 80.0

Debug

  #define MMU2_DEBUG  // Write debug info to serial output

Enable this option to get debug output related to the printer to MMU2 communication. This will consume some PROGMEM.