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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:

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


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.

Settings that can be changed and saved to EEPROM are marked with . Options marked with can be changed from the LCD controller.

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


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 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.



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




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.

The Sanguino board requires adding “Sanguino” support to Arduino IDE. Open Preferences and locate the Additional Boards Manager URLs field. Copy and paste this source URL. Then use Tools > Boards > Boards Manager to install “Sanguino” from the list. An internet connection is required. (Thanks to Dust’s RepRap Blog for the tip.)

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 Some host programs and slicers may use this identifier to differentiate between specific machines on your network.

Extruder Info



#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.

Single Nozzle


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_SERVO_ANGLES { 0, 90 } // Angles for E0, E1

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_SERVO_ANGLES { 0, 90 } // Angles for E0, E1
  //#define HOTEND_OFFSET_Z {0.0, 0.0}

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_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

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.

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

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.

It is crucial to obtain accurate temperature measurements. As a last resort, use 100k thermistor for TEMP_SENSOR and TEMP_SENSOR_BED but be highly skeptical of the temperature accuracy.

// Dummy thermistor constant temperature readings, for use with 998 and 999

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


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.

Err: MINTEMP: This error means your thermistor has disconnected or become an open circuit. (Or the machine is just very cold.)

#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.

Err: MAXTEMP: This error usually means that the temperature sensor wires are shorted together. It may also indicate an issue with the heater MOSFET or relay that is causing it to stay on.


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.

  //#define PID_DEBUG
  //#define PID_OPENLOOP 1
  //#define SLOW_PWM_HEATERS
  #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.

M301 can be used to set Hotend PID and is also accessible through the LCD. M304 can be used to set bed PID. M303 should be used to tune PID values before using any new hotend components.

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


  //#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.



Prevent Cold Extrusion


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


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.


For false thermal runaways not caused by a loose temperature sensor, try increasing WATCH_TEMP_PERIOD or decreasing WATCH_TEMP_INCREASE. Heating may be slowed in a cold environment, if a fan is blowing on the thermistor, or if the heater has high resistance.



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.


//#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.


//#define DELTA

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


//#define SCARA

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

Endstop switch


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_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


  // fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined

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


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.



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 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



Step Calculator

The Prusa Calculator is a great tool to help find the right values for your specific printer configuration.

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.

Setting these too high will cause the corresponding stepper motor to lose steps, especially on high speed movements.


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.

Don’t set these too high. Larger acceleration values can lead to excessive vibration, noisy steppers, or even skipped steps. Lower acceleration produces smoother motion, eliminates vibration, and helps reduce wear on mechanical parts.


 * 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


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 assume the probe is connected to the Z MAX endstop pin (since this is the most likely to be unused). If you need to use a different pin, you can set a custom pin number for Z_MIN_PROBE_PIN in Configuration.h.


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)


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


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.


//#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


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

Z Probe Sled

//#define Z_PROBE_SLED

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


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)
// Speed for the "accurate" probe of each point

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

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.

G29 Movement

Make sure you have enough clearance for the probe to move between points!


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

Probe Testing


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 Spin

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.


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

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

Homing and Bounds

Z Homing Height

Home Icon

//#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


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 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.

Home Offset

Although home positions are fixed, M206 can be used to apply offsets to the home position if needed.

Filament Runout Sensor

Filament 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.

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

Bed Level

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


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.

Leveling Fade Height



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.

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.

MESH_BED_LEVELING is incompatible with Delta and SCARA.

Linear / Bilinear Options


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.


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


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.

  // Number of subdivisions between probe points

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 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.

G26 Mesh Editing & Debugging

//#define UBL_G26_MESH_EDITING

Enable this option for G26 Mesh Editing. (Documentation coming soon!)

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 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


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_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).

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.

Setting these values too high may result in reduced accuracy and/or skipped steps. Reducing acceleration may help to achieve higher top speeds.

Extras 1



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.

Settings that can be changed and saved to EEPROM are marked with . Options marked with can be changed from the LCD controller.

When you change saveable settings in the configuration files and re-flash, the new values don’t take effect right away. They are still overridden by the saved values in EEPROM. To get your new default settings into the EEPROM, use M502 followed by M500.

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


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

Inch Units


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

Temperature Units


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_BED     70
#define PREHEAT_1_FAN_SPEED     0 // Value from 0 to 255

#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

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

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


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


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.

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:

Code Language   Code Language   Code Language
en English (Default)   an Aragonese   bg Bulgarian
ca Catalan   cn Chinese   cz Czech
de German   el Greek   el-gr Greek (Greece)
es Spanish   eu Basque-Euskera   fi Finnish
fr French   gl Galician   hr Croatian
it Italian   kana Japanese   kana_utf8 Japanese (UTF8)
nl Dutch   pl Polish   pt Portuguese
pt-br Portuguese (Brazilian)   pt- Portuguese (Brazilian UTF8)   pt_utf8 Portuguese (UTF8)
ru Russian   sk_utf8 Slovak (UTF8)   tr Turkish
uk Ukrainian            

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

HD44780 Character Set

LCD Charset


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.

SD Card

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.

The SDSUPPORT option must be enabled or SD printing will not be supported. It is no longer enabled automatically for LCD controllers with built-in SDCard slot.

SPI 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


Use CRC checks and retries on the SD communication.

Encoder Knob


Encoder Resolution


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


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.

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


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.


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



//#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.


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

LCD Controllers

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

Option Description
ULTIMAKERCONTROLLER The original Ultimaker Controller.
ULTIPANEL ULTIPANEL as seen on Thingiverse.
PANEL_ONE PanelOne from T3P3 (via RAMPS 1.4 AUX2/AUX3). A variant of ULTIMAKERCONTROLLER.
REPRAP_DISCOUNT_SMART_CONTROLLER RepRapDiscount Smart Controller. Usually sold with a white PCB.
G3D_PANEL Gadgets3D G3D LCD/SD Controller. Usually sold with a blue PCB.
RIGIDBOT_PANEL RigidBot Panel V1.0.
ANET_KEYPAD_LCD Anet Keypad LCD for the Anet A3

Graphical LCDs

Option Description
MAKRPANEL MaKr3d Makr-Panel with graphic controller and SD support.
VIKI2 Panucatt Devices Viki 2.0.
miniVIKI mini Viki with Graphic LCD.
ELB_FULL_GRAPHIC_CONTROLLER Adafruit ST7565 Full Graphic Controller.
MINIPANEL MakerLab Mini Panel with graphic controller and SD support.
BQ_LCD_SMART_CONTROLLER BQ LCD Smart Controller shipped with the BQ Hephestos 2 and Witbox 2.
ANET_FULL_GRAPHICS_LCD Anet Full Graphics LCD for the Anet A3


Option Description
REPRAPWORLD_KEYPAD RepRapWorld Keypad v1.1 Use REPRAPWORLD_KEYPAD_MOVE_STEP to set how much the robot should move on each keypress (e.g., 10mm per click).

I2C Character LCDs

These controllers all require the LiquidCrystal_I2C library.

Option Description
RA_CONTROL_PANEL Elefu RA Board Control Panel
LCD_I2C_SAINSMART_YWROBOT Sainsmart YWRobot LCM1602 LCD Display.
LCM1602 Generic LCM1602 LCD adapter
LCD_I2C_PANELOLU2 PANELOLU2 LCD with status LEDs, separate encoder and click inputs. The click input can either be directly connected to a pin (if BTN_ENC is defined) or read through I2C (with BTN_ENC undefined). Requires LiquidTWI2 library v1.2.3 or later.
LCD_I2C_VIKI Panucatt VIKI LCD with status LEDs, integrated click & L/R/U/D buttons, separate encoder inputs.
SAV_3DLCD Shift register panels. 2 wire Non-latching LCD SR. See LCD configuration.

I2C Graphical LCDs

These controllers all require the LiquidCrystal_I2C library.

Option Description
U8GLIB_SSD1306 SSD1306 OLED full graphics generic display.
SAV_3DGLCD SAV OLED LCD module support using either SSD1306 or SH1106 based LCD modules.
OLED_PANEL_TINYBOY2 TinyBoy2 128x64 OLED / Encoder Panel

Extras 2


//#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.


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.

LED Lights

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
  #define RGB_LED_R_PIN 34
  #define RGB_LED_G_PIN 43
  #define RGB_LED_B_PIN 35
  #define RGB_LED_W_PIN -1

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.

LED Strips require a MOFSET Chip between PWM lines and LEDs, as the Arduino cannot handle the current the LEDs will require. Failure to follow this precaution can destroy your Arduino!

Printer Event LEDs


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.



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.


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.

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.


The “nominal” filament diameter as written on the filament spool. If you typically use 1.75mm filament, but physically measure the diameter as 1.70mm, you should still use 1.75. Marlin will compensate automatically. The same goes for 3.00mm filament that measures closer to 2.85mm.


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 middle of the filament path (i.e., the nozzle opening).

#define MEASURED_UPPER_LIMIT         3.30  //upper limit factor used for sensor reading validation in mm
#define MEASURED_LOWER_LIMIT         1.90  //lower limit factor for sensor reading validation in mm

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.


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


Temperature Options

Bang-Bang Bed Heating

  #define BED_CHECK_INTERVAL 5000 // ms between checks in bang-bang control
    #define BED_HYSTERESIS 2 // Only disable heating if T>target+BED_HYSTERESIS and enable heating if T>target-BED_HYSTERESIS

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

  #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

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

  #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

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

  // 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 DEFAULT_Kc (100) //heating power=Kc*(e_speed)
    #define LPQ_MAX_LEN 50

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.

Your M301 C M301 L values are saved to EEPROM when EEPROM_SETTINGS is enabled.

Automatic Temperature

#define AUTOTEMP

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


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

High Temperature Thermistors


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.


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.

To Be Continued…